1
|
Yamamoto R, Tanaka Y, Orii S, Shiba K, Inaba K, Kon T. Chlamydomonas IC97, an intermediate chain of the flagellar dynein f/I1, is required for normal flagellar and cellular motility. mSphere 2024; 9:e0055824. [PMID: 39601552 DOI: 10.1128/msphere.00558-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Accepted: 10/22/2024] [Indexed: 11/29/2024] Open
Abstract
Motile flagella (also called "motile cilia") play a variety of important roles in lower and higher eukaryotes, including cellular motility and fertility. Flagellar motility is driven by several species of the gigantic motor-protein complexes, flagellar dyneins, that reside within these organelles. Among the flagellar-dynein species, a hetero-dimeric dynein called "IDA f/I1" has been shown to be particularly important in controlling the flagellar waveform, and defects in this dynein species in humans cause ciliopathies such as multiple morphological abnormalities of the flagella and asthenoteratozoospermia. IDA f/I1 is composed of many subunits, including two HCs (HCα and HCβ) and three ICs (IC140, IC138, and IC97), and among the three ICs of IDA f/I1, the exact molecular function(s) of IC97 in flagellar motility is not well understood. In this study, we isolated a Chlamydomonas mutant lacking IC97 and analyzed the phenotypes. The ic97 mutant phenocopied several aspects of the previously isolated IDA-f/I1-related mutants in Chlamydomonas and showed slow swimming compared to the wild type but retained the ability to phototaxis. Further analysis revealed that the mutant had low flagellar beat frequency and miscoordination between the two (cis- and trans-) flagella. In addition, the mutant cells swam in a comparatively straight path compared to the wild-type cells. Taken together, our results highlight the importance of proper assembly of IC97 in the IDA-f/I1 complex for the regulation of flagellar and cellular motility in Chlamydomonas and provide valuable insights into both the molecular functions of IC97 orthologs in higher eukaryotes and the pathogenetic mechanisms of human ciliopathies caused by IDA-f/I1 defects. IMPORTANCE IDA f/I1 is a hetero-dimeric flagellar dynein that is particularly important for the regulation of flagellar waveform and whose defects are associated with human ciliopathies. IC97 is an evolutionarily conserved intermediate chain of IDA f/I1, but the detailed molecular functions of IC97 in flagellar motility have not been elucidated. In this study, mutational and biochemical analyses of the previously uncharacterized Chlamydomonas ic97 mutant revealed that IC97 is required for both the normal flagellar and cellular motility. In particular, IC97 appears to play an important role in both the control of flagellar beat frequency and the coordination between the two (cis- and trans-) flagella in Chlamydomonas. Our results provide important insights into the regulation of IDA-f/I1 activity by IC97 and the pathogenetic mechanisms of human ciliopathies caused by IDA-f/I1 defects.
Collapse
Affiliation(s)
- Ryosuke Yamamoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Yui Tanaka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Shunsuke Orii
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Kogiku Shiba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Takahide Kon
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| |
Collapse
|
2
|
Strain A, Kratzberg N, Vu D, Miller E, Wakabayashi KI, Melvin A, Kato N. COP5/HKR1 changes ciliary beat pattern and biases cell steering during chemotaxis in Chlamydomonas reinhardtii. Sci Rep 2024; 14:30354. [PMID: 39639079 PMCID: PMC11621555 DOI: 10.1038/s41598-024-81455-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2024] [Accepted: 11/26/2024] [Indexed: 12/07/2024] Open
Abstract
This study investigates the control of ciliary beat patterns during ammonium chemotaxis in the model ciliate microalga Chlamydomonas reinhardtii. Screening the chemotaxis response of mutant strains with ciliary defects revealed that a strain lacking CAV2, the alpha subunit of the voltage-gated calcium channel, is deficient in ammonium chemotaxis. CAV2 regulates the switching of the ciliary beat pattern from the asymmetric to the symmetric waveform. Strains lacking COP5/HKR1 (chlamyopsin 5/histidine kinase rhodopsin 1) are also deficient in ammonium chemotaxis. Conversely, strains defective in phototaxis perform ammonium chemotaxis normally. Cell motility analysis revealed wild-type cells reduce the incidences of switching the ciliary beat pattern from the asymmetric to symmetric waveform when swimming up the ammonium gradient. In contrast, the COP5/HKR1 disrupted strain does not bias ciliary beat pattern switching in the gradient. This finding reveals that COP5/HKR1 plays a critical role in Chlamydomonas chemotaxis signaling transduction, similarly to animal chemotaxis. On the other hand, ciliary beat pattern switching induces randomized directional changes, analogous to run-and-tumble chemotaxis of bacteria and archaea. This study reveals that Chlamydomonas signaling transduction is similar to the eukaryotic mechanism, yet the cellular locomotion follows the bacteria and archaea mechanism.
Collapse
Affiliation(s)
- Alexis Strain
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Nathan Kratzberg
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Dan Vu
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Emmaline Miller
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Ken-Ichi Wakabayashi
- Department of Industrial Life Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Adam Melvin
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, 29634, USA
| | - Naohiro Kato
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
| |
Collapse
|
3
|
Marshall WF. Chlamydomonas as a model system to study cilia and flagella using genetics, biochemistry, and microscopy. Front Cell Dev Biol 2024; 12:1412641. [PMID: 38872931 PMCID: PMC11169674 DOI: 10.3389/fcell.2024.1412641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/13/2024] [Indexed: 06/15/2024] Open
Abstract
The unicellular green alga, Chlamydomonas reinhardtii, has played a central role in discovering much of what is currently known about the composition, assembly, and function of cilia and flagella. Chlamydomonas combines excellent genetics, such as the ability to grow cells as haploids or diploids and to perform tetrad analysis, with an unparalleled ability to detach and isolate flagella in a single step without cell lysis. The combination of genetics and biochemistry that is possible in Chlamydomonas has allowed many of the key components of the cilium to be identified by looking for proteins that are missing in a defined mutant. Few if any other model organisms allow such a seamless combination of genetic and biochemical approaches. Other major advantages of Chlamydomonas compared to other systems include the ability to induce flagella to regenerate in a highly synchronous manner, allowing the kinetics of flagellar growth to be measured, and the ability of Chlamydomonas flagella to adhere to glass coverslips allowing Intraflagellar Transport to be easily imaged inside the flagella of living cells, with quantitative precision and single-molecule resolution. These advantages continue to work in favor of Chlamydomonas as a model system going forward, and are now augmented by extensive genomic resources, a knockout strain collection, and efficient CRISPR gene editing. While Chlamydomonas has obvious limitations for studying ciliary functions related to animal development or organ physiology, when it comes to studying the fundamental biology of cilia and flagella, Chlamydomonas is simply unmatched in terms of speed, efficiency, cost, and the variety of approaches that can be brought to bear on a question.
Collapse
Affiliation(s)
- Wallace F. Marshall
- Department Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, United States
| |
Collapse
|
4
|
Wei D, Quaranta G, Aubin-Tam ME, Tam DSW. The younger flagellum sets the beat for Chlamydomonas reinhardtii. eLife 2024; 13:e86102. [PMID: 38752724 PMCID: PMC11098555 DOI: 10.7554/elife.86102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/03/2024] [Indexed: 05/18/2024] Open
Abstract
Eukaryotes swim with coordinated flagellar (ciliary) beating and steer by fine-tuning the coordination. The model organism for studying flagellate motility, Chlamydomonas reinhardtii, employs synchronous, breaststroke-like flagellar beating to swim, and it modulates the beating amplitudes differentially to steer. This strategy hinges on both inherent flagellar asymmetries (e.g. different response to chemical messengers) and such asymmetries being effectively coordinated in the synchronous beating. In C. reinhardtii, the synchrony of beating is known to be supported by a mechanical connection between flagella; however, how flagellar asymmetries persist in the synchrony remains elusive. For example, it has been speculated for decades that one flagellum leads the beating, as its dynamic properties (i.e. frequency, waveform, etc.) appear to be copied by the other one. In this study, we combine experiments, computations, and modeling efforts to elucidate the roles played by each flagellum in synchronous beating. With a non-invasive technique to selectively load each flagellum, we show that the coordinated beating essentially only responds to load exerted on the cis flagellum; and that such asymmetry in response derives from a unilateral coupling between the two flagella. Our results highlight a distinct role for each flagellum in coordination and have implication for biflagellates' tactic behaviors.
Collapse
Affiliation(s)
- Da Wei
- Department of Bionanoscience, Delft University of TechnologyDelftNetherlands
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of SciencesBeijingChina
| | - Greta Quaranta
- Laboratory for Aero and Hydrodynamics, Delft University of TechnologyDelftNetherlands
| | - Marie-Eve Aubin-Tam
- Department of Bionanoscience, Delft University of TechnologyDelftNetherlands
| | - Daniel SW Tam
- Laboratory for Aero and Hydrodynamics, Delft University of TechnologyDelftNetherlands
| |
Collapse
|
5
|
Poirier M, Osmers P, Wilkins K, Morgan-Kiss RM, Cvetkovska M. Aberrant light sensing and motility in the green alga Chlamydomonas priscuii from the ice-covered Antarctic Lake Bonney. PLANT SIGNALING & BEHAVIOR 2023; 18:2184588. [PMID: 38126947 PMCID: PMC10012900 DOI: 10.1080/15592324.2023.2184588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 02/20/2023] [Indexed: 12/23/2023]
Abstract
The Antarctic green alga Chlamydomonas priscuii is an obligate psychrophile and an emerging model for photosynthetic adaptation to extreme conditions. Endemic to the ice-covered Lake Bonney, this alga thrives at highly unusual light conditions characterized by very low light irradiance (<15 μmol m-2 s-1), a narrow wavelength spectrum enriched in blue light, and an extreme photoperiod. Genome sequencing of C. priscuii exposed an unusually large genome, with hundreds of highly similar gene duplicates and expanded gene families, some of which could be aiding its survival in extreme conditions. In contrast to the described expansion in the genetic repertoire in C. priscuii, here we suggest that the gene family encoding for photoreceptors is reduced when compared to related green algae. This alga also possesses a very small eyespot and exhibits an aberrant phototactic response, compared to the model Chlamydomonas reinhardtii. We also investigated the genome and behavior of the closely related psychrophilic alga Chlamydomonas sp. ICE-MDV, that is found throughout the photic zone of Lake Bonney and is naturally exposed to higher light levels. Our analyses revealed a photoreceptor gene family and a robust phototactic response similar to those in the model Chlamydomonas reinhardtii. These results suggest that the aberrant phototactic response in C. priscuii is a result of life under extreme shading rather than a common feature of all psychrophilic algae. We discuss the implications of these results on the evolution and survival of shade adapted polar algae.
Collapse
Affiliation(s)
| | - Pomona Osmers
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
| | - Kieran Wilkins
- Department of Biology, University of Ottawa, Ottawa, OH, Canada
| | | | | |
Collapse
|
6
|
Leptos KC, Chioccioli M, Furlan S, Pesci AI, Goldstein RE. Phototaxis of Chlamydomonas arises from a tuned adaptive photoresponse shared with multicellular Volvocine green algae. Phys Rev E 2023; 107:014404. [PMID: 36797913 PMCID: PMC7616094 DOI: 10.1103/physreve.107.014404] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 12/16/2022] [Indexed: 06/18/2023]
Abstract
A fundamental issue in biology is the nature of evolutionary transitions from unicellular to multicellular organisms. Volvocine algae are models for this transition, as they span from the unicellular biflagellate Chlamydomonas to multicellular species of Volvox with up to 50,000 Chlamydomonas-like cells on the surface of a spherical extracellular matrix. The mechanism of phototaxis in these species is of particular interest since they lack a nervous system and intercellular connections; steering is a consequence of the response of individual cells to light. Studies of Volvox and Gonium, a 16-cell organism with a plate-like structure, have shown that the flagellar response to changing illumination of the cellular photosensor is adaptive, with a recovery time tuned to the rotation period of the colony around its primary axis. Here, combining high-resolution studies of the flagellar photoresponse of micropipette-held Chlamydomonas with 3D tracking of freely swimming cells, we show that such tuning also underlies its phototaxis. A mathematical model is developed based on the rotations around an axis perpendicular to the flagellar beat plane that occur through the adaptive response to oscillating light levels as the organism spins. Exploiting a separation of timescales between the flagellar photoresponse and phototurning, we develop an equation of motion that accurately describes the observed photoalignment. In showing that the adaptive timescales in Volvocine algae are tuned to the organisms' rotational periods across three orders of magnitude in cell number, our results suggest a unified picture of phototaxis in green algae in which the asymmetry in torques that produce phototurns arise from the individual flagella of Chlamydomonas, the flagellated edges of Gonium, and the flagellated hemispheres of Volvox.
Collapse
Affiliation(s)
- Kyriacos C. Leptos
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | | | | | | | | |
Collapse
|
7
|
Yamamoto R, Hwang J, Ishikawa T, Kon T, Sale WS. Composition and function of ciliary inner-dynein-arm subunits studied in Chlamydomonas reinhardtii. Cytoskeleton (Hoboken) 2021; 78:77-96. [PMID: 33876572 DOI: 10.1002/cm.21662] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/30/2021] [Accepted: 04/15/2021] [Indexed: 11/09/2022]
Abstract
Motile cilia (also interchangeably called "flagella") are conserved organelles extending from the surface of many animal cells and play essential functions in eukaryotes, including cell motility and environmental sensing. Large motor complexes, the ciliary dyneins, are present on ciliary outer-doublet microtubules and drive movement of cilia. Ciliary dyneins are classified into two general types: the outer dynein arms (ODAs) and the inner dynein arms (IDAs). While ODAs are important for generation of force and regulation of ciliary beat frequency, IDAs are essential for control of the size and shape of the bend, features collectively referred to as waveform. Also, recent studies have revealed unexpected links between IDA components and human diseases. In spite of their importance, studies on IDAs have been difficult since they are very complex and composed for several types of IDA motors, each unique in composition and location in the axoneme. Thanks in part to genetic, biochemical, and structural analysis of Chlamydomonas reinhardtii, we are beginning to understand the organization and function of the ciliary IDAs. In this review, we summarize the composition of Chlamydomonas IDAs particularly focusing on each subunit, and discuss the assembly, conservation, and functional role(s) of these IDA subunits. Furthermore, we raise several additional questions/challenges regarding IDAs, and discuss future perspectives of IDA studies.
Collapse
Affiliation(s)
- Ryosuke Yamamoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Juyeon Hwang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Takashi Ishikawa
- Department of Biology and Chemistry, Paul Scherrer Institute, Villigen PSI, Switzerland.,Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Takahide Kon
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
| | - Winfield S Sale
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| |
Collapse
|
8
|
Heme-binding protein CYB5D1 is a radial spoke component required for coordinated ciliary beating. Proc Natl Acad Sci U S A 2021; 118:2015689118. [PMID: 33875586 DOI: 10.1073/pnas.2015689118] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coordinated beating is crucial for the function of multiple cilia. However, the molecular mechanism is poorly understood. Here, we characterize a conserved ciliary protein CYB5D1 with a heme-binding domain and a cordon-bleu ubiquitin-like domain. Mutation or knockdown of Cyb5d1 in zebrafish impaired coordinated ciliary beating in the otic vesicle and olfactory epithelium. Similarly, the two flagella of an insertional mutant of the CYB5D1 ortholog in Chlamydomonas (Crcyb5d1) showed an uncoordinated pattern due to a defect in the cis-flagellum. Biochemical analyses revealed that CrCYB5D1 is a radial spoke stalk protein that binds heme only under oxidizing conditions. Lack of CrCYB5D1 resulted in a reductive shift in flagellar redox state and slowing down of the phototactic response. Treatment of Crcyb5d1 with oxidants restored coordinated flagellar beating. Taken together, these data suggest that CrCYB5D1 may integrate environmental and intraciliary signals and regulate the redox state of cilia, which is crucial for the coordinated beating of multiple cilia.
Collapse
|
9
|
Cortese D, Wan KY. Control of Helical Navigation by Three-Dimensional Flagellar Beating. PHYSICAL REVIEW LETTERS 2021; 126:088003. [PMID: 33709750 DOI: 10.1103/physrevlett.126.088003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 12/10/2020] [Accepted: 01/13/2021] [Indexed: 06/12/2023]
Abstract
Helical swimming is a ubiquitous strategy for motile cells to generate self-gradients for environmental sensing. The model biflagellate Chlamydomonas reinhardtii rotates at a constant 1-2 Hz as it swims, but the mechanism is unclear. Here, we show unequivocally that the rolling motion derives from a persistent, nonplanar flagellar beat pattern. This is revealed by high-speed imaging and micromanipulation of live cells. We construct a fully 3D model to relate flagellar beating directly to the free-swimming trajectories. For realistic geometries, the model reproduces both the sense and magnitude of the axial rotation of live cells. We show that helical swimming requires further symmetry breaking between the two flagella. These functional differences underlie all tactic responses, particularly phototaxis. We propose a control strategy by which cells steer toward or away from light by modulating the sign of biflagellar dominance.
Collapse
Affiliation(s)
- Dario Cortese
- Living Systems Institute and College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Kirsty Y Wan
- Living Systems Institute and College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| |
Collapse
|
10
|
Channelrhodopsin-Dependent Photo-Behavioral Responses in the Unicellular Green Alga Chlamydomonas reinhardtii. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:21-33. [PMID: 33398805 DOI: 10.1007/978-981-15-8763-4_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Channelrhodopsins (ChRs) are the light-gated ion channels that have opened the research field of optogenetics. They were originally identified in the green alga Chlamydomonas reinhardtii, a biciliated unicellular alga that inhabits in freshwater, swims with the cilia, and undergoes photosynthesis. It has various advantages as an experimental organism and is used in a wide range of research fields including photosynthesis, cilia, and sexual reproduction. ChRs function as the primary photoreceptor for the cell's photo-behavioral responses, seen as changes in the manner of swimming after photoreception. In this chapter, we will introduce C. reinhardtii as an experimental organism and explain our current understanding of how the cell senses light and shows photo-behavioral responses.
Collapse
|
11
|
Muramatsu S, Atsuji K, Yamada K, Ozasa K, Suzuki H, Takeuchi T, Hashimoto-Marukawa Y, Kazama Y, Abe T, Suzuki K, Iwata O. Isolation and characterization of a motility-defective mutant of Euglena gracilis. PeerJ 2020; 8:e10002. [PMID: 33062431 PMCID: PMC7528813 DOI: 10.7717/peerj.10002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/30/2020] [Indexed: 12/15/2022] Open
Abstract
Euglena gracilis is a green photosynthetic microalga that swims using its flagellum. This species has been used as a model organism for over half a century to study its metabolism and the mechanisms of its behavior. The development of mass-cultivation technology has led to E. gracilis application as a feedstock in various products such as foods. Therefore, breeding of E. gracilis has been attempted to improve the productivity of this feedstock for potential industrial applications. For this purpose, a characteristic that preserves the microalgal energy e.g., reduces motility, should be added to the cultivars. The objective of this study was to verify our hypothesis that E. gracilis locomotion-defective mutants are suitable for industrial applications because they save the energy required for locomotion. To test this hypothesis, we screened for E. gracilis mutants from Fe-ion-irradiated cell suspensions and established a mutant strain,M 3 - ZFeL, which shows defects in flagellum formation and locomotion. The mutant strain exhibits a growth rate comparable to that of the wild type when cultured under autotrophic conditions, but had a slightly slower growth under heterotrophic conditions. It also stores 1.6 times the amount of paramylon, a crystal of β-1,3-glucan, under autotrophic culture conditions, and shows a faster sedimentation compared with that of the wild type, because of the deficiency in mobility and probably the high amount of paramylon accumulation. Such characteristics make E. gracilis mutant cells suitable for cost-effective mass cultivation and harvesting.
Collapse
Affiliation(s)
- Shuki Muramatsu
- Department of Health Science, Showa Women's University, Tokyo, Japan
- euglena Co., Ltd., Tokyo, Japan
| | - Kohei Atsuji
- euglena Co., Ltd., Tokyo, Japan
- Baton Zone Program, RIKEN, Saitama, Japan
| | - Koji Yamada
- euglena Co., Ltd., Tokyo, Japan
- Baton Zone Program, RIKEN, Saitama, Japan
| | - Kazunari Ozasa
- Bioengineering Laboratory, Cluster for Pioneering Research, RIKEN, Saitama, Japan
| | | | | | | | - Yusuke Kazama
- RIKEN Nishina Center, Saitama, Japan
- Faculty of Bioscience and Biotechnology, Fukui Prefectural University, Fukui, Japan
| | | | - Kengo Suzuki
- euglena Co., Ltd., Tokyo, Japan
- Baton Zone Program, RIKEN, Saitama, Japan
| | | |
Collapse
|
12
|
Genome-wide identification and biochemical characterization of calcineurin B-like calcium sensor proteins in Chlamydomonas reinhardtii. Biochem J 2020; 477:1879-1892. [DOI: 10.1042/bcj20190960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/17/2020] [Accepted: 04/09/2020] [Indexed: 12/18/2022]
Abstract
Calcium (Ca2+) signaling is involved in the regulation of diverse biological functions through association with several proteins that enable them to respond to abiotic and biotic stresses. Though Ca2+-dependent signaling has been implicated in the regulation of several physiological processes in Chlamydomonas reinhardtii, Ca2+ sensor proteins are not characterized completely. C. reinhardtii has diverged from land plants lineage, but shares many common genes with animals, particularly those encoding proteins of the eukaryotic flagellum (or cilium) along with the basal body. Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, is an important effector of Ca2+ signaling in animals, while calcineurin B-like proteins (CBLs) play an important role in Ca2+ sensing and signaling in plants. The present study led to the identification of 13 novel CBL-like Ca2+ sensors in C. reinhardtii genome. One of the archetypical genes of the newly identified candidate, CrCBL-like1 was characterized. The ability of CrCBL-like1 protein to sense as well as bind Ca2+ were validated using two-step Ca2+-binding kinetics. The CrCBL-like1 protein localized around the plasma membrane, basal bodies and in flagella, and interacted with voltage-gated Ca2+ channel protein present abundantly in the flagella, indicating its involvement in the regulation of the Ca2+ concentration for flagellar movement. The CrCBL-like1 transcript and protein expression were also found to respond to abiotic stresses, suggesting its involvement in diverse physiological processes. Thus, the present study identifies novel Ca2+ sensors and sheds light on key players involved in Ca2+signaling in C. reinhardtii, which could further be extrapolated to understand the evolution of Ca2+ mediated signaling in other eukaryotes.
Collapse
|
13
|
Amador GJ, Wei D, Tam D, Aubin-Tam ME. Fibrous Flagellar Hairs of Chlamydomonas reinhardtii Do Not Enhance Swimming. Biophys J 2020; 118:2914-2925. [PMID: 32502384 PMCID: PMC7300311 DOI: 10.1016/j.bpj.2020.05.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/06/2020] [Accepted: 04/27/2020] [Indexed: 01/18/2023] Open
Abstract
The flagella of Chlamydomonas reinhardtii possess fibrous ultrastructures of a nanometer-scale thickness known as mastigonemes. These structures have been widely hypothesized to enhance flagellar thrust; however, detailed hydrodynamic analysis supporting this claim is lacking. In this study, we present a comprehensive investigation into the hydrodynamic effects of mastigonemes using a genetically modified mutant lacking the fibrous structures. Through high-speed observations of freely swimming cells, we found the average and maximum swimming speeds to be unaffected by the presence of mastigonemes. In addition to swimming speeds, no significant difference was found for flagellar gait kinematics. After our observations of swimming kinematics, we present direct measurements of the hydrodynamic forces generated by flagella with and without mastigonemes. These measurements were conducted using optical tweezers, which enabled high temporal and spatial resolution of hydrodynamic forces. Through our measurements, we found no significant difference in propulsive flows due to the presence of mastigonemes. Direct comparison between measurements and fluid mechanical modeling revealed that swimming hydrodynamics were accurately captured without including mastigonemes on the modeled swimmer's flagella. Therefore, mastigonemes do not appear to increase the flagella's effective area while swimming, as previously thought. Our results refute the longstanding claim that mastigonemes enhance flagellar thrust in C. reinhardtii, and so, their function still remains enigmatic.
Collapse
Affiliation(s)
- Guillermo J Amador
- Laboratory for Aero and Hydrodynamics, Delft University of Technology, Delft, the Netherlands; Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Da Wei
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Daniel Tam
- Laboratory for Aero and Hydrodynamics, Delft University of Technology, Delft, the Netherlands.
| | - Marie-Eve Aubin-Tam
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
| |
Collapse
|
14
|
Dutcher SK. Asymmetries in the cilia of Chlamydomonas. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190153. [PMID: 31884924 PMCID: PMC7017335 DOI: 10.1098/rstb.2019.0153] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2019] [Indexed: 01/10/2023] Open
Abstract
The generation of ciliary waveforms requires the spatial and temporal regulation of dyneins. This review catalogues many of the asymmetric structures and proteins in the cilia of Chlamydomonas, a unicellular alga with two cilia that are used for motility in liquid medium. These asymmetries, which have been identified through mutant analysis, cryo-EM tomography and proteomics, provide a wealth of information to use for modelling how waveforms are generated and propagated. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
Collapse
Affiliation(s)
- Susan K. Dutcher
- Department of Genetics, Washington University in St Louis, Saint Louis, MO, USA
| |
Collapse
|
15
|
Abstract
Female anglerfishes have a lantern-shape luminous organ sprouting from the middle of their heads to lure their prey in the dark deep sea. Inspired by the anglerfish, we designed an electromagnetic anglerfish-shaped millirobot that can receive energy and transform it into light to attract algae cells to specific locations. The small wireless powered robot can receive about 658 mW of power from external energy supply coils, and light LEDs (light-emitting diodes). The wireless power generation and moving control of the robot are analyzed systematically. Transmitting electric energy to smaller scale receivers to endow milli or micro robots with wireless power function is an interesting and promising research direction. With this function, the wireless powered robot is expected to be extensively used at the small scale in the near future, such as to provide electricity to drive microdevices (microgrippers, microsensors, etc.), provide light or heat in small-scale space, stimulate/kill pathological cells in minimally invasive treatment and so on.
Collapse
|
16
|
Sekiguchi M, Kameda S, Kurosawa S, Yoshida M, Yoshimura K. Thermotaxis in Chlamydomonas is brought about by membrane excitation and controlled by redox conditions. Sci Rep 2018; 8:16114. [PMID: 30382191 PMCID: PMC6208428 DOI: 10.1038/s41598-018-34487-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 10/18/2018] [Indexed: 11/09/2022] Open
Abstract
Temperature is physiologically critical for all living organisms, which cope with temperature stress using metabolic and behavioral responses. In unicellular and some multicellular organisms, thermotaxis is a behavioral response to avoid stressful thermal environments and promote accumulation in an optimal thermal environment. In this study, we examined whether Chlamydomonas reinhardtii, a unicellular green alga, demonstrated thermotaxis. We found that between 10 °C and 30 °C, Chlamydomonas cells migrated toward lower temperatures independent of cultivation temperature. Interestingly, when we applied reagents to change intracellular reduction-oxidation (redox) conditions, we saw that thermotaxis was enhanced, suppressed, or reversed, depending on the redox conditions and cultivation temperature. Thermotaxis was almost absent in ppr2 and ppr3 mutants, which cannot swim backward because of a defect in generating calcium current in flagella. The frequency of spontaneous backward swimming was lower at more favorable temperature, suggesting a pivotal role of spontaneous backward swimming generated by flagellar membrane excitation.
Collapse
Affiliation(s)
- Masaya Sekiguchi
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan
| | - Shigetoshi Kameda
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan
| | - Satoshi Kurosawa
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan
| | - Megumi Yoshida
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan
| | - Kenjiro Yoshimura
- Department of Machinery and Control Systems, College of Systems Engineering and Science, Shibaura Institute of Technology, Saitama, 337-8570, Japan.
| |
Collapse
|
17
|
Kubo T, Hou Y, Cochran DA, Witman GB, Oda T. A microtubule-dynein tethering complex regulates the axonemal inner dynein f (I1). Mol Biol Cell 2018. [PMID: 29540525 PMCID: PMC5921573 DOI: 10.1091/mbc.e17-11-0689] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
FAP44 and FAP43/FAP244 form a complex that tethers the Inner dynein subspecies f to the microtubule in Chlamydomonas flagella. The tether complex regulates flagellar motility by restraining conformational change in the dynein motor. Motility of cilia/flagella is generated by a coordinated activity of thousands of dyneins. Inner dynein arms (IDAs) are particularly important for the formation of ciliary/flagellar waveforms, but the molecular mechanism of IDA regulation is poorly understood. Here we show using cryoelectron tomography and biochemical analyses of Chlamydomonas flagella that a conserved protein FAP44 forms a complex that tethers IDA f (I1 dynein) head domains to the A-tubule of the axonemal outer doublet microtubule. In wild-type flagella, IDA f showed little nucleotide-dependent movement except for a tilt in the f β head perpendicular to the microtubule-sliding direction. In the absence of the tether complex, however, addition of ATP and vanadate caused a large conformational change in the IDA f head domains, suggesting that the movement of IDA f is mechanically restricted by the tether complex. Motility defects in flagella missing the tether demonstrates the importance of the IDA f-tether interaction in the regulation of ciliary/flagellar beating.
Collapse
Affiliation(s)
- Tomohiro Kubo
- Department of Anatomy and Structural Biology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Yuqing Hou
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Deborah A Cochran
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655
| | - George B Witman
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Toshiyuki Oda
- Department of Anatomy and Structural Biology, Graduate School of Medical Science, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| |
Collapse
|
18
|
Ueki N, Wakabayashi KI. Phototaxis Assay for Chlamydomonas reinhardtii. Bio Protoc 2017; 7:e2356. [PMID: 34541103 DOI: 10.21769/bioprotoc.2356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 05/12/2017] [Accepted: 05/23/2017] [Indexed: 11/02/2022] Open
Abstract
Phototaxis is a behavior in which organisms move toward or away from the light source (positive or negative phototaxis, respectively). It is crucial for phototrophic microorganisms to inhabit under proper light conditions for phototaxis. The unicellular green alga Chlamydomonas reinhardtii rapidly changes its swimming direction upon light illumination, and thus is a nice model organism for phototaxis research. Here we show two methods to assay Chlamydomonas phototaxis; one is a quick, easy and qualitative analysis, so-called the dish assay; and the other is a quantitative single-cell analysis.
Collapse
Affiliation(s)
- Noriko Ueki
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Ken-Ichi Wakabayashi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| |
Collapse
|
19
|
Zhu X, Liu Y, Yang P. Radial Spokes-A Snapshot of the Motility Regulation, Assembly, and Evolution of Cilia and Flagella. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028126. [PMID: 27940518 DOI: 10.1101/cshperspect.a028126] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Propulsive forces generated by cilia and flagella are used in events that are critical for the thriving of diverse eukaryotic organisms in their environments. Despite distinctive strokes and regulations, the majority of them adopt the 9+2 axoneme that is believed to exist in the last eukaryotic common ancestor. Only a few outliers have opted for a simpler format that forsakes the signature radial spokes and the central pair apparatus, although both are unnecessary for force generation or rhythmicity. Extensive evidence has shown that they operate as an integral system for motility control. Recent studies have made remarkable progress on the radial spoke. This review will trace how the new structural, compositional, and evolutional insights pose significant implications on flagella biology and, conversely, ciliopathy.
Collapse
Affiliation(s)
- Xiaoyan Zhu
- The Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - Yi Liu
- The Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201
| | - Pinfen Yang
- The Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin 53201
| |
Collapse
|
20
|
Calcium-Dependent Signalling Processes in Chlamydomonas. CHLAMYDOMONAS: MOLECULAR GENETICS AND PHYSIOLOGY 2017. [DOI: 10.1007/978-3-319-66365-4_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
21
|
Wan KY, Goldstein RE. Coordinated beating of algal flagella is mediated by basal coupling. Proc Natl Acad Sci U S A 2016; 113:E2784-93. [PMID: 27140605 PMCID: PMC4878519 DOI: 10.1073/pnas.1518527113] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cilia and flagella often exhibit synchronized behavior; this includes phase locking, as seen in Chlamydomonas, and metachronal wave formation in the respiratory cilia of higher organisms. Since the observations by Gray and Rothschild of phase synchrony of nearby swimming spermatozoa, it has been a working hypothesis that synchrony arises from hydrodynamic interactions between beating filaments. Recent work on the dynamics of physically separated pairs of flagella isolated from the multicellular alga Volvox has shown that hydrodynamic coupling alone is sufficient to produce synchrony. However, the situation is more complex in unicellular organisms bearing few flagella. We show that flagella of Chlamydomonas mutants deficient in filamentary connections between basal bodies display markedly different synchronization from the wild type. We perform micromanipulation on configurations of flagella and conclude that a mechanism, internal to the cell, must provide an additional flagellar coupling. In naturally occurring species with 4, 8, or even 16 flagella, we find diverse symmetries of basal body positioning and of the flagellar apparatus that are coincident with specific gaits of flagellar actuation, suggesting that it is a competition between intracellular coupling and hydrodynamic interactions that ultimately determines the precise form of flagellar coordination in unicellular algae.
Collapse
Affiliation(s)
- Kirsty Y Wan
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom
| | - Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom
| |
Collapse
|
22
|
Steude A, Jahnel M, Thomschke M, Schober M, Gather MC. Controlling the Behavior of Single Live Cells with High Density Arrays of Microscopic OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:7657-7661. [PMID: 26476816 DOI: 10.1002/adma.201503253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 07/31/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Anja Steude
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS, UK
| | - Matthias Jahnel
- Fraunhofer Institut für Elektronenstrahl und Plasmatechnik und COMEDD (FEP), Maria-Reiche-Str. 2, 01109, Dresden, Germany
| | - Michael Thomschke
- Fraunhofer Institut für Elektronenstrahl und Plasmatechnik und COMEDD (FEP), Maria-Reiche-Str. 2, 01109, Dresden, Germany
| | - Matthias Schober
- Fraunhofer Institut für Elektronenstrahl und Plasmatechnik und COMEDD (FEP), Maria-Reiche-Str. 2, 01109, Dresden, Germany
| | - Malte C Gather
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS, UK
| |
Collapse
|
23
|
Wilson KS, Gonzalez O, Dutcher SK, Bayly PV. Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes. Cytoskeleton (Hoboken) 2015; 72:477-90. [PMID: 26314933 DOI: 10.1002/cm.21252] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/22/2015] [Accepted: 08/25/2015] [Indexed: 12/24/2022]
Abstract
Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation.
Collapse
Affiliation(s)
- Kate S Wilson
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
| | - Olivia Gonzalez
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
| | - Susan K Dutcher
- Department of Genetics, Washington University, St. Louis, Missouri
| | - Philip V Bayly
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
| |
Collapse
|
24
|
Saegusa Y, Yoshimura K. cAMP controls the balance of the propulsive forces generated by the two flagella of Chlamydomonas. Cytoskeleton (Hoboken) 2015; 72:412-21. [PMID: 26257199 DOI: 10.1002/cm.21235] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 08/03/2015] [Accepted: 08/04/2015] [Indexed: 02/03/2023]
Abstract
The motility of cilia and flagella of eukaryotic cells is controlled by second messengers such as Ca(2+), cAMP, and cGMP. In this study, the cAMP-dependent control of flagellar bending of Chlamydomonas is investigated by applying cAMP through photolysis of 4,5-dimethoxy-2-nitrobenzyl adenosine 3',5'-cyclicmonophosphate (caged cAMP). When cAMP is applied to demembranated and reactivated cells, cells begin to swim with a larger helical path. This change is due to a larger turn about the axis normal to the anterior-posterior axis, indicating an increased imbalance in the propulsive forces generated by the cis-flagellum (flagellum nearer to the eyespot) and trans-flagellum (flagellum farther from the eyespot). Consistently, when cAMP is applied to isolated axonemes, some axonemes show attenuated motility whereas others do not. Axonemes from uni1 mutants, which have only trans-flagella, do not respond to cAMP. These observations indicate that cAMP controls the balance of the forces generated by cis- and trans-flagella in Chlamydomonas.
Collapse
Affiliation(s)
- Yu Saegusa
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan.,Kichijo Girls' School, Musashino, 180-0002, Japan
| | - Kenjiro Yoshimura
- Department of Machinery and Control Systems, Shibaura Institute of Technology, Saitama, 337-8570, Japan
| |
Collapse
|
25
|
Kage A, Mogami Y. Individual Flagellar Waveform Affects Collective Behavior of Chlamydomonas reinhardtii. Zoolog Sci 2015; 32:396-404. [PMID: 26245228 DOI: 10.2108/zs150015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bioconvection is a form of collective motion that occurs spontaneously in the suspension of swimming microorganisms. In a previous study, we quantitatively described the "pattern transition," a phase transition phenomenon that so far has exclusively been observed in bioconvection of the unicellular green alga Chlamydomonas. We suggested that the transition could be induced by changes in the balance between the gravitational and shear-induced torques, both of which act to determine the orientation of the organism in the shear flow. As both of the torques should be affected by the geometry of the Chlamydomonas cell, alteration in the flagellar waveform might change the extent of torque generation by altering overall geometry of the cell. Based on this working hypothesis, we examined bioconvection behavior of two flagellar mutants of Chlamydomonas reinhardtii, ida1 and oda2, making reference to the wild type. Flagella of ida1 beat with an abnormal waveform, while flagella of oda2 show a normal waveform but lower beat frequency. As a result, both mutants had swimming speed of less than 50% of the wild type. ida1 formed bioconvection patterns with smaller spacing than those of wild type and oda2. Two-axis view revealed the periodic movement of the settling blobs of ida1, while oda2 showed qualitatively similar behavior to that of wild type. Unexpectedly, ida1 showed stronger negative gravitaxis than did wild type, while oda2 showed relatively weak gravitaxis. These findings suggest that flagellar waveform, not swimming speed or beat frequency, strongly affect bioconvection behavior in C. reinhardtii.
Collapse
Affiliation(s)
- Azusa Kage
- 1 Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka 2-1-1, Bunkyo-ku, Tokyo 112-8610, Japan.,2 Present address: Department of Bioengineering and Robotics, Tohoku University, Aramaki Aza Aoba 6-6-01, Aoba-ku, Sendai 980-8579, Japan
| | - Yoshihiro Mogami
- 1 Graduate School of Humanities and Sciences, Ochanomizu University, Otsuka 2-1-1, Bunkyo-ku, Tokyo 112-8610, Japan
| |
Collapse
|
26
|
Abstract
Motile cilia and flagella rapidly propagate bending waves and produce water flow over the cell surface. Their function is important for the physiology and development of various organisms including humans. The movement is based on the sliding between outer doublet microtubules driven by axonemal dyneins, and is regulated by various axonemal components and environmental factors. For studies aiming to elucidate the mechanism of cilia/flagella movement and regulation, Chlamydomonas is an invaluable model organism that offers a variety of mutants. This chapter introduces standard methods for studying Chlamydomonas flagellar motility including analysis of swimming paths, measurements of swimming speed and beat frequency, motility reactivation in demembranated cells (cell models), and observation of microtubule sliding in disintegrating axonemes. Most methods may be easily applied to other organisms with slight modifications of the medium conditions.
Collapse
Affiliation(s)
| | - Ritsu Kamiya
- Department of Life Science, Faculty of Science, Gakushuin University, Tokyo, Japan
| |
Collapse
|
27
|
Fu G, Nagasato C, Oka S, Cock JM, Motomura T. Proteomics analysis of heterogeneous flagella in brown algae (stramenopiles). Protist 2014; 165:662-75. [PMID: 25150613 DOI: 10.1016/j.protis.2014.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/22/2014] [Accepted: 07/22/2014] [Indexed: 10/25/2022]
Abstract
Flagella are conserved organelles among eukaryotes and they are composed of many proteins, which are necessary for flagellar assembly, maintenance and function. Stramenopiles, which include brown algae, diatoms and oomycetes, possess two laterally inserted flagella. The anterior flagellum (AF) extends forward and bears tripartite mastigonemes, whilst the smooth posterior flagellum (PF) often has a paraflagellar body structure. These heterogeneous flagella have served as crucial structures in algal studies especially from a viewpoint of phylogeny. However, the protein compositions of the flagella are still largely unknown. Here we report a LC-MS/MS based proteomics analysis of brown algal flagella. In total, 495 flagellar proteins were identified. Functional annotation of the proteome data revealed that brown algal flagellar proteins were associated with cell motility, signal transduction and various metabolic activities. We separately isolated AF and PF and analyzed their protein compositions. This analysis led to the identification of several AF- and PF-specific proteins. Among the PF-specific proteins, we found a candidate novel blue light receptor protein involved in phototaxis, and named it HELMCHROME because of the steering function of PF. Immunological analysis revealed that this protein was localized along the whole length of the PF and concentrated in the paraflagellar body.
Collapse
Affiliation(s)
- Gang Fu
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan
| | - Chikako Nagasato
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan
| | - Seiko Oka
- Instrumental Analysis Division, Equipment Management Center, Creative Research Institution, Hokkaido University, Sapporo 001-0021, Hokkaido, Japan
| | - J Mark Cock
- University Pierre et Marie Curie and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, 29682 Roscoff Cedex, France
| | - Taizo Motomura
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran 051-0013, Hokkaido, Japan.
| |
Collapse
|
28
|
Wan KY, Leptos KC, Goldstein RE. Lag, lock, sync, slip: the many 'phases' of coupled flagella. J R Soc Interface 2014; 11:20131160. [PMID: 24573332 PMCID: PMC3973360 DOI: 10.1098/rsif.2013.1160] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In a multitude of life's processes, cilia and flagella are found indispensable. Recently, the biflagellated chlorophyte alga Chlamydomonas has become a model organism for the study of ciliary motility and synchronization. Here, we use high-speed, high-resolution imaging of single pipette-held cells to quantify the rich dynamics exhibited by their flagella. Underlying this variability in behaviour are biological dissimilarities between the two flagella-termed cis and trans, with respect to a unique eyespot. With emphasis on the wild-type, we derive limit cycles and phase parametrizations for self-sustained flagellar oscillations from digitally tracked flagellar waveforms. Characterizing interflagellar phase synchrony via a simple model of coupled oscillators with noise, we find that during the canonical swimming breaststroke the cis flagellum is consistently phase-lagged relative to, while remaining robustly phase-locked with, the trans flagellum. Transient loss of synchrony, or phase slippage, may be triggered stochastically, in which the trans flagellum transitions to a second mode of beating with attenuated beat envelope and increased frequency. Further, exploiting this alga's ability for flagellar regeneration, we mechanically induced removal of one or the other flagellum of the same cell to reveal a striking disparity between the beatings of the cis and trans flagella, in isolation. These results are evaluated in the context of the dynamic coordination of Chlamydomonas flagella.
Collapse
Affiliation(s)
- Kirsty Y Wan
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, , Wilberforce Road, Cambridge CB3 0WA, UK
| | | | | |
Collapse
|
29
|
Leptos KC, Wan KY, Polin M, Tuval I, Pesci AI, Goldstein RE. Antiphase synchronization in a flagellar-dominance mutant of Chlamydomonas. PHYSICAL REVIEW LETTERS 2013; 111:158101. [PMID: 24160630 PMCID: PMC7616080 DOI: 10.1103/physrevlett.111.158101] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Indexed: 06/02/2023]
Abstract
Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report the discovery that ptx1, a flagellar-dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. High-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wild-type. Possible mechanisms underlying these observations are discussed.
Collapse
Affiliation(s)
- Kyriacos C Leptos
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | | | | | | | | | | |
Collapse
|
30
|
Yamamoto R, Song K, Yanagisawa HA, Fox L, Yagi T, Wirschell M, Hirono M, Kamiya R, Nicastro D, Sale WS. The MIA complex is a conserved and novel dynein regulator essential for normal ciliary motility. ACTA ACUST UNITED AC 2013; 201:263-78. [PMID: 23569216 PMCID: PMC3628515 DOI: 10.1083/jcb.201211048] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The MIA complex, composed of FAP100 and FAP73, interacts with I1 dynein components and is required for normal ciliary beat frequency. Axonemal dyneins must be precisely regulated and coordinated to produce ordered ciliary/flagellar motility, but how this is achieved is not understood. We analyzed two Chlamydomonas reinhardtii mutants, mia1 and mia2, which display slow swimming and low flagellar beat frequency. We found that the MIA1 and MIA2 genes encode conserved coiled-coil proteins, FAP100 and FAP73, respectively, which form the modifier of inner arms (MIA) complex in flagella. Cryo–electron tomography of mia mutant axonemes revealed that the MIA complex was located immediately distal to the intermediate/light chain complex of I1 dynein and structurally appeared to connect with the nexin–dynein regulatory complex. In axonemes from mutants that lack both the outer dynein arms and the MIA complex, I1 dynein failed to assemble, suggesting physical interactions between these three axonemal complexes and a role for the MIA complex in the stable assembly of I1 dynein. The MIA complex appears to regulate I1 dynein and possibly outer arm dyneins, which are both essential for normal motility.
Collapse
Affiliation(s)
- Ryosuke Yamamoto
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
DiPetrillo CG, Smith EF. Methods for analysis of calcium/calmodulin signaling in cilia and flagella. Methods Enzymol 2013; 524:37-57. [PMID: 23498733 DOI: 10.1016/b978-0-12-397945-2.00003-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The axonemal microtubules of cilia/flagella act as a scaffold for assembly of the protein complexes that ultimately regulate dynein activity to control the size and shape of ciliary bends. Despite our general understanding of the contribution of microtubule sliding to ciliary and flagellar motility, many questions regarding the regulation of dynein remain unanswered. For example, we know that the second messenger calcium plays an important role in modulating dynein activity in response to extracellular cues, but it remains unclear how calcium-binding proteins anchored to the axoneme contribute to this regulation. Recent work has focused on determining the identity and specific functions of these axonemal calcium-binding proteins. Here, we review our current knowledge of calcium-mediated motility and highlight key experiments that have substantially aided our understanding of calcium signaling within the axoneme.
Collapse
Affiliation(s)
- Christen G DiPetrillo
- Division of Infectious Diseases, Boston Children's Hospital, Boston, Massachusetts, USA
| | | |
Collapse
|
32
|
The DPY-30 domain and its flanking sequence mediate the assembly and modulation of flagellar radial spoke complexes. Mol Cell Biol 2012; 32:4012-24. [PMID: 22851692 DOI: 10.1128/mcb.06602-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RIIa is known as the dimerization and docking (D/D) domain of the cyclic AMP (cAMP)-dependent protein kinase. However, numerous molecules, including radial spoke protein 2 (RSP2) in Chlamydomonas flagella, also contain an RIIa or a similar DPY-30 domain. To elucidate new roles of D/D domain-containing proteins, we investigated a panel of RSP2 mutants. An RSP2 mutant had paralyzed flagella defective in RSP2 and multiple subunits near the spokehead. New transgenic strains lacking only the DPY-30 domain in RSP2 were also paralyzed. In contrast, motility was restored in strains that lacked only RSP2's calmodulin-binding C-terminal region. These cells swam normally in dim light but could not maintain typical swimming trajectories under bright illumination. In both deletion transgenic strains, the subunits near the spokehead were restored, but their firm attachment to the spokestalk required the DPY-30 domain. We postulate that the DPY-30-helix dimer is a conserved two-prong linker, required for normal motility, organizing duplicated subunits in the radial spoke stalk and formation of a symmetrical spokehead. Further, the dispensable calmodulin-binding region appears to fine-tune the spokehead for regulation of "steering" motility in the green algae. Thus, in general, D/D domains may function to localize molecular modules for both the assembly and modulation of macromolecular complexes.
Collapse
|
33
|
DiPetrillo CG, Smith EF. The Pcdp1 complex coordinates the activity of dynein isoforms to produce wild-type ciliary motility. Mol Biol Cell 2011; 22:4527-38. [PMID: 21998195 PMCID: PMC3226472 DOI: 10.1091/mbc.e11-08-0739] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Generating the complex waveforms characteristic of beating cilia requires the coordinated activity of multiple dynein isoforms anchored to the axoneme. We previously identified a complex associated with the C1d projection of the central apparatus that includes primary ciliary dyskinesia protein 1 (Pcdp1). Reduced expression of complex members results in severe motility defects, indicating that C1d is essential for wild-type ciliary beating. To define a mechanism for Pcdp1/C1d regulation of motility, we took a functional and structural approach combined with mutants lacking C1d and distinct subsets of dynein arms. Unlike mutants completely lacking the central apparatus, dynein-driven microtubule sliding velocities are wild type in C1d- defective mutants. However, coordination of dynein activity among microtubule doublets is severely disrupted. Remarkably, mutations in either outer or inner dynein arm restore motility to mutants lacking C1d, although waveforms and beat frequency differ depending on which isoform is mutated. These results define a unique role for C1d in coordinating the activity of specific dynein isoforms to control ciliary motility.
Collapse
|
34
|
Elam CA, Wirschell M, Yamamoto R, Fox LA, York K, Kamiya R, Dutcher SK, Sale WS. An axonemal PP2A B-subunit is required for PP2A localization and flagellar motility. Cytoskeleton (Hoboken) 2011; 68:363-72. [PMID: 21692192 PMCID: PMC3152255 DOI: 10.1002/cm.20519] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/26/2011] [Accepted: 06/03/2011] [Indexed: 11/10/2022]
Abstract
Analysis of Chlamydomonas axonemes revealed that the protein phosphatase, PP2A, is localized to the outer doublet microtubules and is implicated in regulation of dynein-driven motility. We tested the hypothesis that PP2A is localized to the axoneme by a specialized, highly conserved 55-kDa B-type subunit identified in the Chlamydomonas flagellar proteome. The B-subunit gene is defective in the motility mutant pf4. Consistent with our hypothesis, both the B- and C- subunits of PP2A fail to assemble in pf4 axonemes, while the dyneins and other axonemal structures are fully assembled in pf4 axonemes. Two pf4 intragenic revertants were recovered that restore PP2A to the axonemes and re-establish nearly wild-type motility. The revertants confirmed that the slow-swimming Pf4 phenotype is a result of the defective PP2A B-subunit. These results demonstrate that the axonemal B-subunit is, in part, an anchor protein required for PP2A localization and that PP2A is required for normal ciliary motility.
Collapse
Affiliation(s)
- Candice A. Elam
- Department of Cell Biology, Emory University School of Medicine, 465 Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, Georgia 30322, (404)-727-6265 Phone, (404)-727-6256 Fax,
| | - Maureen Wirschell
- Department of Cell Biology, Emory University School of Medicine, 465 Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, Georgia 30322, (404)-727-6265 Phone, (404)-727-6256 Fax,
| | - Ryosuke Yamamoto
- Department of Cell Biology, Emory University School of Medicine, 465 Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, Georgia 30322, (404)-727-6265 Phone, (404)-727-6256 Fax,
| | - Laura. A. Fox
- Department of Cell Biology, Emory University School of Medicine, 465 Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, Georgia 30322, (404)-727-6265 Phone, (404)-727-6256 Fax,
| | - Kerry York
- Department of Genetics, Department of Cell Biology and Physiology, Washington University School of Medicine, Box 8232, 660 S. Euclid Avenue, St. Louis, MO 63110,
| | - Ritsu Kamiya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Room 141, Science Building 2, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan
| | - Susan K. Dutcher
- Department of Genetics, Department of Cell Biology and Physiology, Washington University School of Medicine, Box 8232, 660 S. Euclid Avenue, St. Louis, MO 63110,
| | - Winfield S. Sale
- Department of Cell Biology, Emory University School of Medicine, 465 Whitehead Biomedical Research Building, 615 Michael Street, Atlanta, Georgia 30322, (404)-727-6265 Phone, (404)-727-6256 Fax,
| |
Collapse
|
35
|
VanderWaal KE, Yamamoto R, Wakabayashi KI, Fox L, Kamiya R, Dutcher SK, Bayly PV, Sale WS, Porter ME. bop5 Mutations reveal new roles for the IC138 phosphoprotein in the regulation of flagellar motility and asymmetric waveforms. Mol Biol Cell 2011; 22:2862-74. [PMID: 21697502 PMCID: PMC3154882 DOI: 10.1091/mbc.e11-03-0270] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mutations in the IC138 regulatory subunit of I1 dynein alter dynein motor activity and the flagellar waveform but do not affect phototaxis. I1 dynein, or dynein f, is a highly conserved inner arm isoform that plays a key role in the regulation of flagellar motility. To understand how the IC138 IC/LC subcomplex modulates I1 activity, we characterized the molecular lesions and motility phenotypes of several bop5 alleles. bop5-3, bop5-4, and bop5-5 are null alleles, whereas bop5-6 is an intron mutation that reduces IC138 expression. I1 dynein assembles into the axoneme, but the IC138 IC/LC subcomplex is missing. bop5 strains, like other I1 mutants, swim forward with reduced swimming velocities and display an impaired reversal response during photoshock. Unlike mutants lacking the entire I1 dynein, however, bop5 strains exhibit normal phototaxis. bop5 defects are rescued by transformation with the wild-type IC138 gene. Analysis of flagellar waveforms reveals that loss of the IC138 subcomplex reduces shear amplitude, sliding velocities, and the speed of bend propagation in vivo, consistent with the reduction in microtubule sliding velocities observed in vitro. The results indicate that the IC138 IC/LC subcomplex is necessary to generate an efficient waveform for optimal motility, but it is not essential for phototaxis. These findings have significant implications for the mechanisms by which IC/LC complexes regulate dynein motor activity independent of effects on cargo binding or complex stability.
Collapse
Affiliation(s)
- Kristyn E VanderWaal
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Reduction-oxidation poise regulates the sign of phototaxis in Chlamydomonas reinhardtii. Proc Natl Acad Sci U S A 2011; 108:11280-4. [PMID: 21690384 DOI: 10.1073/pnas.1100592108] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many phototrophic microorganisms and plants, chloroplasts change their positions relative to the incident light to achieve optimal photosynthesis. In the case of motile green algae, cells change their swimming direction by switching between positive and negative phototaxis, i.e., swimming toward or away from the light source, depending on environmental and internal conditions. However, little is known about the molecular signals that determine the phototactic direction. Using the green alga Chlamydomonas reinhardtii, we found that cellular reduction-oxidation (redox) poise plays a key role: Cells always exhibited positive phototaxis after treatment with reactive oxygen species (ROS) and always displayed negative phototaxis after treatment with ROS quenchers. The redox-dependent switching of the sign of phototaxis may contribute in turn to the maintenance of cellular redox homeostasis.
Collapse
|
37
|
Wirschell M, Yamamoto R, Alford L, Gokhale A, Gaillard A, Sale WS. Regulation of ciliary motility: conserved protein kinases and phosphatases are targeted and anchored in the ciliary axoneme. Arch Biochem Biophys 2011; 510:93-100. [PMID: 21513695 PMCID: PMC3114296 DOI: 10.1016/j.abb.2011.04.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/05/2011] [Accepted: 04/06/2011] [Indexed: 12/31/2022]
Abstract
Recent evidence has revealed that the dynein motors and highly conserved signaling proteins are localized within the ciliary 9+2 axoneme. One key mechanism for regulation of motility is phosphorylation. Here, we review diverse evidence, from multiple experimental organisms, that ciliary motility is regulated by phosphorylation/dephosphorylation of the dynein arms through kinases and phosphatases that are anchored immediately adjacent to their axonemal substrates.
Collapse
Affiliation(s)
- Maureen Wirschell
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA USA 30322
| | - Ryosuke Yamamoto
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA USA 30322
| | - Lea Alford
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA USA 30322
| | - Avanti Gokhale
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA USA 30322
| | - Anne Gaillard
- Sam Houston State University, Department of Biological Sciences, 1900 Ave. I, P.O Box 2116, Huntsville, TX USA 77341
| | - Winfield S. Sale
- Emory University School of Medicine, Department of Cell Biology, 615 Michael St. Atlanta, GA USA 30322
| |
Collapse
|
38
|
Toba S, Fox LA, Sakakibara H, Porter ME, Oiwa K, Sale WS. Distinct roles of 1alpha and 1beta heavy chains of the inner arm dynein I1 of Chlamydomonas flagella. Mol Biol Cell 2010; 22:342-53. [PMID: 21148301 PMCID: PMC3031465 DOI: 10.1091/mbc.e10-10-0806] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We took advantage of Chlmaydomonas flagellar mutant strains lacking either the 1α or 1β motor domain in I1 dynein to distinguish the functional role of each. The 1β motor domain is an effective motor required for control of microtubule sliding, whereas the 1α motor domain may restrain microtubule sliding driven by other dyneins. The Chlamydomonas I1 dynein is a two-headed inner dynein arm important for the regulation of flagellar bending. Here we took advantage of mutant strains lacking either the 1α or 1β motor domain to distinguish the functional role of each motor domain. Single- particle electronic microscopic analysis confirmed that both the I1α and I1β complexes are single headed with similar ringlike, motor domain structures. Despite similarity in structure, however, the I1β complex has severalfold higher ATPase activity and microtubule gliding motility compared to the I1α complex. Moreover, in vivo measurement of microtubule sliding in axonemes revealed that the loss of the 1β motor results in a more severe impairment in motility and failure in regulation of microtubule sliding by the I1 dynein phosphoregulatory mechanism. The data indicate that each I1 motor domain is distinct in function: The I1β motor domain is an effective motor required for wild-type microtubule sliding, whereas the I1α motor domain may be responsible for local restraint of microtubule sliding.
Collapse
Affiliation(s)
- Shiori Toba
- Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, Kobe, Japan
| | | | | | | | | | | |
Collapse
|
39
|
Ueki N, Matsunaga S, Inouye I, Hallmann A. How 5000 independent rowers coordinate their strokes in order to row into the sunlight: phototaxis in the multicellular green alga Volvox. BMC Biol 2010; 8:103. [PMID: 20663212 PMCID: PMC2920248 DOI: 10.1186/1741-7007-8-103] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 07/27/2010] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The evolution of multicellular motile organisms from unicellular ancestors required the utilization of previously evolved tactic behavior in a multicellular context. Volvocine green algae are uniquely suited for studying tactic responses during the transition to multicellularity because they range in complexity from unicellular to multicellular genera. Phototactic responses are essential for these flagellates because they need to orientate themselves to receive sufficient light for photosynthesis, but how does a multicellular organism accomplish phototaxis without any known direct communication among cells? Several aspects of the photoresponse have previously been analyzed in volvocine algae, particularly in the unicellular alga Chlamydomonas. RESULTS In this study, the phototactic behavior in the spheroidal, multicellular volvocine green alga Volvox rousseletii (Volvocales, Chlorophyta) was analyzed. In response to light stimuli, not only did the flagella waveform and beat frequency change, but the effective stroke was reversed. Moreover, there was a photoresponse gradient from the anterior to the posterior pole of the spheroid, and only cells of the anterior hemisphere showed an effective response. The latter caused a reverse of the fluid flow that was confined to the anterior hemisphere. The responsiveness to light is consistent with an anterior-to-posterior size gradient of eyespots. At the posterior pole, the eyespots are tiny or absent, making the corresponding cells appear to be blind. Pulsed light stimulation of an immobilized spheroid was used to simulate the light fluctuation experienced by a rotating spheroid during phototaxis. The results demonstrated that in free-swimming spheroids, only those cells of the anterior hemisphere that face toward the light source reverse the beating direction in the presence of illumination; this behavior results in phototactic turning. Moreover, positive phototaxis is facilitated by gravitational forces. Under our conditions, V. rousseletii spheroids showed no negative phototaxis. CONCLUSIONS On the basis of our results, we developed a mechanistic model that predicts the phototactic behavior in V. rousseletii. The model involves photoresponses, periodically changing light conditions, morphological polarity, rotation of the spheroid, two modes of flagellar beating, and the impact of gravity. Our results also indicate how recently evolved multicellular organisms adapted the phototactic capabilities of their unicellular ancestors to multicellular life.
Collapse
Affiliation(s)
- Noriko Ueki
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
- Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
| | - Shigeru Matsunaga
- Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
- The Promotion Center for Research and Education, Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa, 240-0193 Japan
| | - Isao Inouye
- Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577 Japan
| | - Armin Hallmann
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany
| |
Collapse
|
40
|
Bayly PV, Lewis BL, Kemp PS, Pless RB, Dutcher SK. Efficient spatiotemporal analysis of the flagellar waveform of Chlamydomonas reinhardtii. Cytoskeleton (Hoboken) 2010; 67:56-69. [PMID: 20169530 PMCID: PMC4109274 DOI: 10.1002/cm.20424] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2009] [Accepted: 10/23/2009] [Indexed: 01/04/2023]
Abstract
The 9 + 2 axoneme is a microtubule-based machine that powers the oscillatory beating of cilia and flagella. Its highly regulated movement is essential for the normal function of many organs; ciliopathies cause congenital defects, chronic respiratory tract infections and infertility. We present an efficient method to obtain a quantitative description of flagellar motion, with high spatial and temporal resolution, from high speed video recording of bright field images. This highly automated technique provides the shape, shear angle, curvature, and bend propagation speeds along the length of the flagellum, with approximately 200 temporal samples per beat. We compared the waveforms of uniflagellated wild-type and ida3 mutant cells, which lack the I1 inner dynein complex. Video images were captured at 350 fps. Rigid-body motion was eliminated by fast Fourier transform (FFT)-based registration, and the Cartesian (x-y) coordinates of points on the flagellum were identified. These x-y "point clouds" were embedded in two data dimensions using Isomap, a nonlinear dimension reduction method, and sorted by phase in the flagellar cycle. A smooth surface was fitted to the sorted point clouds, which provides high-resolution estimates of shear angle and curvature. Wild-type and ida3 cells exhibit large differences in shear amplitude, but similar maximum and minimum curvature values. In ida3 cells, the reverse bend begins earlier and travels more slowly relative to the principal bend, than in wild-type cells. The regulation of flagellar movement must involve I1 dynein in a manner consistent with these results.
Collapse
Affiliation(s)
- P V Bayly
- Department of Mechanical, Aerospace, and Structural Engineering, Washington University, St. Louis, Missouri 63130, USA.
| | | | | | | | | |
Collapse
|
41
|
Abstract
Eukaryotic flagella and cilia are alternative names, for the slender cylindrical protrusions of a cell (240nm diameter, approximately 12,800nm-long in Chlamydomonas reinhardtii) that propel a cell or move fluid. Cilia are extraordinarily successful complex organelles abundantly found in animals performing many tasks. They play a direct or developmental role in the sensors of fluid flow, light, sound, gravity, smells, touch, temperature, and taste in mammals. The failure of cilia can lead to hydrocephalus, infertility, and blindness. However, in spite of their large role in human function and pathology, there is as yet no consensus on how cilia beat and perform their many functions, such as moving fluids in brain ventricles and lungs and propelling and steering sperm, larvae, and many microorganisms. One needs to understand and analyze ciliary beating and its hydrodynamic interactions. This chapter provides a guide for measuring, analyzing, and interpreting ciliary behavior in various contexts studied in the model system of Chlamydomonas. It describes: (1) how cilia work as self-organized beating structures (SOBSs), (2) the overlaid control in the cilia that optimizes the SOBS to achieve cell dispersal, phototaxis steering, and avoidance of obstacles, (3) the assay of a model intracellular signal processing system that responds to multiple external and internal inputs, choosing mode of behavior and then controlling the cilia, (4) how cilia sense their environment, and (5) potentially an assay of ciliary performance for toxicology or medical assessment.
Collapse
Affiliation(s)
- Kenneth W Foster
- Department of Physics, Syracuse University, Syracuse, New York 13244-1130, USA
| |
Collapse
|
42
|
DiPetrillo C, Smith E. Calcium regulation of ciliary motility analysis of axonemal calcium-binding proteins. Methods Cell Biol 2009; 92:163-80. [PMID: 20409805 DOI: 10.1016/s0091-679x(08)92011-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Substantial data have contributed to a model in which the axonemal microtubules act as a scaffold for the assembly of molecules that form a signal transduction pathway that ultimately regulates dynein. We have also known for some time that for virtually all motile cilia and flagella, the second messenger, calcium, impacts upon these signaling pathways to modulate beating in response to extracellular cues. Yet we are only beginning to identify the axonemal proteins that bind this second messenger and determine their role in regulating dynein-driven microtubule sliding to alter the size and shape of ciliary bends. Here, we review our current understanding of calcium regulation of motility, emphasizing recent advances in the detection and characterization of calcium-binding proteins anchored to the axoneme.
Collapse
Affiliation(s)
- Christen DiPetrillo
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | | |
Collapse
|
43
|
Wakabayashi KI, Ide T, Kamiya R. Calcium-dependent flagellar motility activation in Chlamydomonas reinhardtii in response to mechanical agitation. ACTA ACUST UNITED AC 2009; 66:736-42. [PMID: 19544401 DOI: 10.1002/cm.20402] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Flagellar beating in Chlamydomonas was found to be activated by mechanical stimulation. Immediately after a wild-type cell suspension was vortexed, the average swimming velocity of cells increased from 130 mum/second to 150 mum/second, due to an elevation of flagellar beat frequency from approximately 60 Hz to approximately 70 Hz without detectable change in the flagellar waveforms. This response required outer arm dynein. Treatment with EGTA, Ca(2+)-channel blockers, or mechanosensitive-channel blockers inhibited it. In demembranated and reactivated cell models, a modest increase in Ca(2+) concentration elevated the axonemal beat frequency. These data indicate that the mechanical agitation increases beat frequency because it causes Ca(2+) influx into flagella, which then activates outer arm dynein.
Collapse
Affiliation(s)
- Ken-Ichi Wakabayashi
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
| | | | | |
Collapse
|
44
|
Goldstein RE, Polin M, Tuval I. Noise and synchronization in pairs of beating eukaryotic flagella. PHYSICAL REVIEW LETTERS 2009; 103:168103. [PMID: 19905728 DOI: 10.1103/physrevlett.103.168103] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Indexed: 05/28/2023]
Abstract
It has long been conjectured that hydrodynamic interactions between beating eukaryotic flagella underlie their ubiquitous forms of synchronization; yet there has been no experimental test of this connection. The biflagellate alga Chlamydomonas is a simple model for such studies, as its two flagella are representative of those most commonly found in eukaryotes. Using micromanipulation and high-speed imaging, we show that the flagella of a C. reinhardtii cell present periods of synchronization interrupted by phase slips. The dynamics of slips and the statistics of phase-locked intervals are consistent with a low-dimensional stochastic model of hydrodynamically coupled oscillators, with a noise amplitude set by the intrinsic fluctuations of single flagellar beats.
Collapse
Affiliation(s)
- Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | | | | |
Collapse
|
45
|
Gokhale A, Wirschell M, Sale WS. Regulation of dynein-driven microtubule sliding by the axonemal protein kinase CK1 in Chlamydomonas flagella. ACTA ACUST UNITED AC 2009; 186:817-24. [PMID: 19752022 PMCID: PMC2753152 DOI: 10.1083/jcb.200906168] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CK1 puts the brakes on dynein activity when added to purified axonemes in vitro, presumably to regulate how flagella bend. Experimental analysis of isolated ciliary/flagellar axonemes has implicated the protein kinase casein kinase I (CK1) in regulation of dynein. To test this hypothesis, we developed a novel in vitro reconstitution approach using purified recombinant Chlamydomonas reinhardtii CK1, together with CK1-depleted axonemes from the paralyzed flagellar mutant pf17, which is defective in radial spokes and impaired in dynein-driven microtubule sliding. The CK1 inhibitors (DRB and CK1-7) and solubilization of CK1 restored microtubule sliding in pf17 axonemes, which is consistent with an inhibitory role for CK1. The phosphatase inhibitor microcystin-LR blocked rescue of microtubule sliding, indicating that the axonemal phosphatases, required for rescue, were retained in the CK1-depleted axonemes. Reconstitution of depleted axonemes with purified, recombinant CK1 restored inhibition of microtubule sliding in a DRB– and CK1-7–sensitive manner. In contrast, a purified “kinase-dead” CK1 failed to restore inhibition. These results firmly establish that an axonemal CK1 regulates dynein activity and flagellar motility.
Collapse
Affiliation(s)
- Avanti Gokhale
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | |
Collapse
|
46
|
Ikeda K, Yamamoto R, Wirschell M, Yagi T, Bower R, Porter ME, Sale WS, Kamiya R. A novel ankyrin-repeat protein interacts with the regulatory proteins of inner arm dynein f (I1) of Chlamydomonas reinhardtii. CELL MOTILITY AND THE CYTOSKELETON 2009; 66:448-56. [PMID: 19021242 PMCID: PMC3102495 DOI: 10.1002/cm.20324] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
How ciliary and flagellar motility is regulated is a challenging problem. The flagellar movement in Chlamydomonas reinhardtii is in part regulated by phosphorylation of a 138 kD intermediate chain (IC138) of inner arm dynein f (also called I1). In the present study, we found that the axoneme of mutants lacking dynein f lacks a novel protein having ankyrin repeat motifs, registered as FAP120 in the flagellar proteome database. FAP120 is also missing or decreased in the axonemes of bop5, a mutant that has a mutation in the structural gene of IC138 but assembles the dynein f complex. Intriguingly, the amounts of FAP120 in the axonemes of different alleles of bop5 and several dynein f-lacking mutants roughly parallel their contents of IC138. These results suggest a weak but stoichiometric interaction between FAP120 and IC138. We propose that FAP120 functions in the regulatoryprocess as part of a protein complex involving IC138. Cell Motil. Cytoskeleton 2008. (c) 2008 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Kazuho Ikeda
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Polin M, Tuval I, Drescher K, Gollub JP, Goldstein RE. Chlamydomonas swims with two "gears" in a eukaryotic version of run-and-tumble locomotion. Science 2009; 325:487-90. [PMID: 19628868 DOI: 10.1126/science.1172667] [Citation(s) in RCA: 244] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The coordination of eukaryotic flagella is essential for many of the most basic processes of life (motility, sensing, and development), yet its emergence and regulation and its connection to locomotion are poorly understood. Previous studies show that the unicellular alga Chlamydomonas, widely regarded as an ideal system in which to study flagellar biology, swims forward by the synchronous action of its two flagella. Using high-speed imaging over long intervals, we found a richer behavior: A cell swimming in the dark stochastically switches between synchronous and asynchronous flagellar beating. Three-dimensional tracking shows that these regimes lead, respectively, to nearly straight swimming and to abrupt large reorientations, which yield a eukaryotic version of the "run-and-tumble" motion of peritrichously flagellated bacteria.
Collapse
Affiliation(s)
- Marco Polin
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
| | | | | | | | | |
Collapse
|
48
|
Wirschell M, Yang C, Yang P, Fox L, Yanagisawa HA, Kamiya R, Witman GB, Porter ME, Sale WS. IC97 is a novel intermediate chain of I1 dynein that interacts with tubulin and regulates interdoublet sliding. Mol Biol Cell 2009; 20:3044-54. [PMID: 19420136 PMCID: PMC2704156 DOI: 10.1091/mbc.e09-04-0276] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 04/23/2009] [Accepted: 04/29/2009] [Indexed: 11/11/2022] Open
Abstract
Our goal is to understand the assembly and regulation of flagellar dyneins, particularly the Chlamydomonas inner arm dynein called I1 dynein. Here, we focus on the uncharacterized I1-dynein IC IC97. The IC97 gene encodes a novel IC without notable structural domains. IC97 shares homology with the murine lung adenoma susceptibility 1 (Las1) protein--a candidate tumor suppressor gene implicated in lung tumorigenesis. Multiple, independent biochemical assays determined that IC97 interacts with both alpha- and beta-tubulin subunits within the axoneme. I1-dynein assembly mutants suggest that IC97 interacts with both the IC138 and IC140 subunits within the I1-dynein motor complex and that IC97 is part of a regulatory complex that contains IC138. Microtubule sliding assays, using axonemes containing I1 dynein but devoid of IC97, show reduced microtubule sliding velocities that are not rescued by kinase inhibitors, revealing a critical role for IC97 in I1-dynein function and control of dynein-driven motility.
Collapse
Affiliation(s)
- Maureen Wirschell
- *Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Chun Yang
- Department of Biology, Marquette University, Milwaukee, WI 53201
| | - Pinfen Yang
- Department of Biology, Marquette University, Milwaukee, WI 53201
| | - Laura Fox
- *Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Haru-aki Yanagisawa
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Ritsu Kamiya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - George B. Witman
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655; and
| | - Mary E. Porter
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455
| | - Winfield S. Sale
- *Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| |
Collapse
|
49
|
Bower R, VanderWaal K, O'Toole E, Fox L, Perrone C, Mueller J, Wirschell M, Kamiya R, Sale WS, Porter ME. IC138 defines a subdomain at the base of the I1 dynein that regulates microtubule sliding and flagellar motility. Mol Biol Cell 2009; 20:3055-63. [PMID: 19420135 DOI: 10.1091/mbc.e09-04-0277] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
To understand the mechanisms that regulate the assembly and activity of flagellar dyneins, we focused on the I1 inner arm dynein (dynein f) and a null allele, bop5-2, defective in the gene encoding the IC138 phosphoprotein subunit. I1 dynein assembles in bop5-2 axonemes but lacks at least four subunits: IC138, IC97, LC7b, and flagellar-associated protein (FAP) 120--defining a new I1 subcomplex. Electron microscopy and image averaging revealed a defect at the base of the I1 dynein, in between radial spoke 1 and the outer dynein arms. Microtubule sliding velocities also are reduced. Transformation with wild-type IC138 restores assembly of the IC138 subcomplex and rescues microtubule sliding. These observations suggest that the IC138 subcomplex is required to coordinate I1 motor activity. To further test this hypothesis, we analyzed microtubule sliding in radial spoke and double mutant strains. The results reveal an essential role for the IC138 subcomplex in the regulation of I1 activity by the radial spoke/phosphorylation pathway.
Collapse
Affiliation(s)
- Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Kreimer G. The green algal eyespot apparatus: a primordial visual system and more? Curr Genet 2008; 55:19-43. [PMID: 19107486 DOI: 10.1007/s00294-008-0224-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Revised: 11/28/2008] [Accepted: 12/02/2008] [Indexed: 10/21/2022]
Abstract
Most flagellate green algae exhibiting phototaxis posses a singular specialized light sensitive organelle, the eyespot apparatus (EA). Its design principles are similar in all green algae and produce, in conjunction with the movement pattern of the cell, a highly directional optical device. It enables an oriented movement response with respect to the direction and intensity of light. The functional EA involves local specializations of different compartments (plasma membrane, cytosol, and chloroplast) and utilizes specialized microbial-type rhodopsins, which act as directly light-gated ion channels. Due to their elaborate structures and the presence of retinal-based photoreceptors in some lineages, algal EAs are thought to play an important role in the evolution of photoreception and are thus not only of interest to plant biologists. In green algae considerable progress in the molecular dissection of components of this primordial visual system has been made by genetic and proteomic approaches in recent years. This review summarizes general aspects of the green algal EA as well as recent progress in the identification of proteins related to it. Further, novel data supporting a link between eyespot globules and plastoglobules will be presented and potential additional roles of the EA besides those in photoreception will be discussed.
Collapse
Affiliation(s)
- Georg Kreimer
- Department Biologie, Friedrich-Alexander Universität Erlangen, 91058, Erlangen, Germany.
| |
Collapse
|