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Ali MF, Shin JM, Fatema U, Kurihara D, Berger F, Yuan L, Kawashima T. Cellular dynamics of coenocytic endosperm development in Arabidopsis thaliana. NATURE PLANTS 2023; 9:330-342. [PMID: 36646830 DOI: 10.1038/s41477-022-01331-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
After double fertilization, the endosperm in the seeds of many flowering plants undergoes repeated mitotic nuclear divisions without cytokinesis, resulting in a large coenocytic endosperm that then cellularizes. Growth during the coenocytic phase is strongly associated with the final seed size; however, a detailed description of the cellular dynamics controlling the unique coenocytic development in flowering plants has remained elusive. By integrating confocal microscopy live-cell imaging and genetics, we have characterized the entire development of the coenocytic endosperm of Arabidopsis thaliana including nuclear divisions, their timing intervals, nuclear movement and cytoskeleton dynamics. Around each nucleus, microtubules organize into aster-shaped structures that drive actin filament (F-actin) organization. Microtubules promote nuclear movement after division, while F-actin restricts it. F-actin is also involved in controlling the size of both the coenocytic endosperm and the mature seed. The characterization of cytoskeleton dynamics in real time throughout the entire coenocyte endosperm period provides foundational knowledge of plant coenocytic development, insights into the coordination of F-actin and microtubules in nuclear dynamics, and new opportunities to increase seed size and our food security.
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Affiliation(s)
- Mohammad Foteh Ali
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Ji Min Shin
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
- Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY, USA
| | - Umma Fatema
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Daisuke Kurihara
- Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Nagoya, Japan
- Institute for Advanced Research (IAR), Nagoya University, Nagoya, Japan
| | - Frédéric Berger
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Ling Yuan
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
- Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY, USA
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Tomokazu Kawashima
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA.
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Maeda K, Sasabe M, Hanamata S, Machida Y, Hasezawa S, Higaki T. Actin Filament Disruption Alters Phragmoplast Microtubule Dynamics during the Initial Phase of Plant Cytokinesis. PLANT & CELL PHYSIOLOGY 2020; 61:445-456. [PMID: 32030404 DOI: 10.1093/pcp/pcaa003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/07/2020] [Indexed: 06/10/2023]
Abstract
Plant growth and development relies on the accurate positioning of the cell plate between dividing cells during cytokinesis. The cell plate is synthetized by a specialized structure called the phragmoplast, which contains bipolar microtubules that polymerize to form a framework with the plus ends at or near the division site. This allows the transport of Golgi-derived vesicles toward the plus ends to form and expand the cell plate. Actin filaments play important roles in cell plate expansion and guidance in plant cytokinesis at the late phase, but whether they are involved at the early phase is unknown. To investigate this further, we disrupted the actin filaments in cell cycle-synchronized tobacco BY-2 cells with latrunculin B (LatB), an actin polymerization inhibitor. We observed the cells under a transmission electron microscope or a spinning-disk confocal laser scanning microscope. We found that disruption of actin filaments by LatB caused the membrane vesicles at the equatorial plane of the cell plate to be dispersed rather than form clusters as they did in the untreated cells. The midzone constriction of phragmoplast microtubules also was perturbed in LatB-treated cells. The live cell imaging and kymograph analysis showed that disruption of actin filaments also changed the accumulation timing of NACK1 kinesin, which plays a crucial role in cell plate expansion. This suggests that there are two functionally different types of microtubules in the phragmoplast. Together, our results show that actin filaments regulate phragmoplast microtubules at the initial phase of plant cytokinesis.
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Affiliation(s)
- Keisho Maeda
- Faculty of Advanced Science and Technology, Kumamoto University, Chuo-ku, Kumamoto, 860-8555 Japan
| | - Michiko Sasabe
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, 036-8561 Japan
| | - Shigeru Hanamata
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba, 277-8562 Japan
| | - Yasunori Machida
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602 Japan
| | - Seiichiro Hasezawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba, 277-8562 Japan
| | - Takumi Higaki
- International Research Organization for Advanced Science and Technology, Kumamoto University, Chuo-ku, Kumamoto, 860-8555 Japan
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Bednara J, Willemse MTM, Van Lammeren AAM. Organization of the actin cytoskeleton during megasporogenesis inGasteria verrucosavisualized with fluorescent-labelled phalloidin. ACTA ACUST UNITED AC 2015. [DOI: 10.1111/j.1438-8677.1990.tb01444.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Bednara
- Plant Anatomy and Cytology Department; Maria Curie Slodowska University Lublin; Poland
| | - M. T. M. Willemse
- Plant Anatomy and Cytology Department; Maria Curie Slodowska University Lublin; Poland
- Department of Plant Cytology and Morphology; Wageningen Agricultural University; Wageningen The Netherlands
| | - A. A. M. Van Lammeren
- Plant Anatomy and Cytology Department; Maria Curie Slodowska University Lublin; Poland
- Department of Plant Cytology and Morphology; Wageningen Agricultural University; Wageningen The Netherlands
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Xu C, Liu Z, Zhang L, Zhao C, Yuan S, Zhang F. Organization of actin cytoskeleton during meiosis I in a wheat thermo-sensitive genic male sterile line. PROTOPLASMA 2013; 250:415-422. [PMID: 22350736 DOI: 10.1007/s00709-012-0386-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/30/2012] [Indexed: 05/31/2023]
Abstract
BS366 is a thermo-sensitive male sterile line of wheat (Triticum aestivum L.) for two-line hybrid breeding, which exhibits aberrant meiotic cytokinesis under low temperature. Through transcriptome analysis, a possible regulatory role for plant actin cytoskeleton was suggested. However, the organization of actin cytoskeleton in meiosis has been poorly understood so far. Here, fixed microsporocytes during meiosis were labeled with tetramethylrhodamine isothiocyanate-phalloidin and 4',6-diamidino-2-phenylindole. Quantities of fluorescent micrographs were captured using a confocal microscope, including the transient state from metaphase to telophase. We observed that actin filaments were abundant in typical kariokinetic spindle, central spindle (parallel microtubules or actin fibers between two separated chromosomes in anaphase), and phragmoplast. Interestingly, we identified the Chinese lantern-shaped actin phragmoplast in wheat meiosis for the first time. Under low temperature, phragmoplast actin filaments were chaotic and normal cell plate failed to form. These data provide new insights into the organization of actin filaments during male meiosis of plant and support a role of actin cytoskeleton in bringing about thermo-sensitive male sterility in wheat.
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Affiliation(s)
- Chenguang Xu
- Beijing Engineering and Technique Research Center for Hybrid Wheat, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
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Sandquist JC, Kita AM, Bement WM. And the dead shall rise: actin and myosin return to the spindle. Dev Cell 2011; 21:410-9. [PMID: 21920311 DOI: 10.1016/j.devcel.2011.07.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
The spindle directs chromosome partitioning in eukaryotes and, for the last three decades, has been considered primarily a structure based on microtubules, microtubule motors, and other microtubule binding proteins. However, a surprisingly large body of both old and new studies suggests roles for actin filaments (F-actin) and myosins (F-actin-based motor proteins) in spindle assembly and function. Here we review these data and conclude that in several cases the evidence for the participation of F-actin and myosins in spindle function is very strong, and in the situations where it is less strong, there is nevertheless enough evidence to warrant further investigation.
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Affiliation(s)
- Joshua C Sandquist
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Yamagishi T, Kawai H. Cytoskeleton organization during the cell cycle in two stramenopile microalgae, Ochromonas danica (Chrysophyceae) and Heterosigma akashiwo (Raphidophyceae), with special reference to F-actin organization and its role in cytokinesis. Protist 2011; 163:686-700. [PMID: 22104586 DOI: 10.1016/j.protis.2011.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/11/2011] [Accepted: 09/20/2011] [Indexed: 11/25/2022]
Abstract
F-actin organization during the cell cycle was investigated in two stramenopile microalgae, Ochromonas danica (Chrysophyceae; UTEX LB1298) and Heterosigma akashiwo (Raphidophyceae; NIES-6) using FITC-phalloidin. In the interphase cell of O. danica, F-actin bundles were localized forming a network structure in the cortical region, which converged from the anterior region to the posterior, whereas in the interphase cell of H. akashiwo, F-actin bundles were observed forming a network structure in the cortical region without any polarity. In both O. danica and H. akashiwo, at the initial stage of mitosis the cortical F-actin disappeared, and then during cytokinesis assembly of an actin-based ring-like structure occurred in the cell cortex in the plane of cytokinesis. The ring-like structure initiated from aster-like structures was composed of F-actin in both O. danica and H. akashiwo. Different from animal cells, later stages of cytokinesis of O. danica seemed to be promoted by microtubules, although the early stages of cytokinesis progressed with a constriction of the ring-like structure, whereas cytokinesis of H. akashiwo was apparently completed by constriction of the cell mediated by the F-actin ring, as in animal cells.
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Smertenko AP, Deeks MJ, Hussey PJ. Strategies of actin reorganisation in plant cells. J Cell Sci 2010; 123:3019-28. [DOI: 10.1242/jcs.071126] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Spatial-temporal flexibility of the actin filament network (F-actin) is essential for all basic cellular functions and is governed by a stochastic dynamic model. In this model, actin filaments that randomly polymerise from a pool of free actin are bundled with other filaments and severed by ADF/cofilin. The fate of the severed fragments is not known. It has been proposed that the fragments are disassembled and the monomeric actin recycled for the polymerisation of new filaments. Here, we have generated tobacco cell lines and Arabidopsis plants expressing the actin marker Lifeact to address the mechanisms of F-actin reorganisation in vivo. We found that F-actin is more dynamic in isotropically expanding cells and that the density of the network changes with a periodicity of 70 seconds. The depolymerisation rate, but not the polymerisation rate, of F-actin increases when microtubules are destabilised. New filaments can be assembled from shorter free cytoplasmic fragments, from the products of F-actin severing and by polymerisation from the ends of extant filaments. Thus, remodelling of F-actin might not require bulk depolymerisation of the entire network, but could occur via severing and end-joining of existing polymers.
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Affiliation(s)
- Andrei P. Smertenko
- School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK
| | - Michael J. Deeks
- School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK
| | - Patrick J. Hussey
- School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK
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Li Y, Shen Y, Cai C, Zhong C, Zhu L, Yuan M, Ren H. The type II Arabidopsis formin14 interacts with microtubules and microfilaments to regulate cell division. THE PLANT CELL 2010; 22:2710-26. [PMID: 20709814 PMCID: PMC2947165 DOI: 10.1105/tpc.110.075507] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 07/17/2010] [Accepted: 07/28/2010] [Indexed: 05/18/2023]
Abstract
Formins have long been known to regulate microfilaments but have also recently been shown to associate with microtubules. In this study, Arabidopsis thaliana FORMIN14 (AFH14), a type II formin, was found to regulate both microtubule and microfilament arrays. AFH14 expressed in BY-2 cells was shown to decorate preprophase bands, spindles, and phragmoplasts and to induce coalignment of microtubules with microfilaments. These effects perturbed the process of cell division. Localization of AFH14 to microtubule-based structures was confirmed in Arabidopsis suspension cells. Knockdown of AFH14 in mitotic cells altered interactions between microtubules and microfilaments, resulting in the formation of an abnormal mitotic apparatus. In Arabidopsis afh14 T-DNA insertion mutants, microtubule arrays displayed abnormalities during the meiosis-associated process of microspore formation, which corresponded to altered phenotypes during tetrad formation. In vitro biochemical experiments showed that AFH14 bound directly to either microtubules or microfilaments and that the FH2 domain was essential for cytoskeleton binding and bundling. However, in the presence of both microtubules and microfilaments, AFH14 promoted interactions between microtubules and microfilaments. These results demonstrate that AFH14 is a unique plant formin that functions as a linking protein between microtubules and microfilaments and thus plays important roles in the process of plant cell division.
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Affiliation(s)
- Yanhua Li
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Yuan Shen
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Chao Cai
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Chenchun Zhong
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Lei Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China
| | - Ming Yuan
- State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100094, People's Republic of China
| | - Haiyun Ren
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, People's Republic of China
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9
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Engler JDA, Rodiuc N, Smertenko A, Abad P. Plant actin cytoskeleton re-modeling by plant parasitic nematodes. PLANT SIGNALING & BEHAVIOR 2010; 5:213-7. [PMID: 20038822 PMCID: PMC2881263 DOI: 10.4161/psb.5.3.10741] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The cytoskeleton is an important component of the plant's defense mechanism against the attack of pathogenic organisms. Plants however, are defenseless against parasitic root-knot and cyst nematodes and respond to the invasion by the development of a special feeding site that supplies the parasite with nutrients required for the completion of its life cycle. Recent studies of nematode invasion under treatment with cytoskeletal drugs and in mutant plants where normal functions of the cytoskeleton have been affected, demonstrate the importance of the cytoskeleton in the establishment of a feeding site and successful nematode reproduction. It appears that in the case of microfilaments, nematodes hijack the intracellular machinery that regulates actin dynamics and modulate the organization and properties of the actin filament network. Intervening with this process reduces the nematode infection efficiency and inhibits its life cycle. This discovery uncovers a new pathway that can be exploited for the protection of plants against nematodes.
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Higaki T, Kutsuna N, Sano T, Hasezawa S. Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis. BMC PLANT BIOLOGY 2008; 8:80. [PMID: 18637163 PMCID: PMC2490694 DOI: 10.1186/1471-2229-8-80] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2008] [Accepted: 07/17/2008] [Indexed: 05/19/2023]
Abstract
BACKGROUND Plant cells divide by the formation of new cross walls, known as cell plates, from the center to periphery of each dividing cell. Formation of the cell plate occurs in the phragmoplast, a complex structure composed of membranes, microtubules (MTs) and actin microfilaments (MFs). Disruption of phragmoplast MTs was previously found to completely inhibit cell plate formation and expansion, indicative of their crucial role in the transport of cell plate membranes and materials. In contrast, disruption of MFs only delays cell plate expansion but does not completely inhibit cell plate formation. Despite such findings, the significance and molecular mechanisms of MTs and MFs remain largely unknown. RESULTS Time-sequential changes in MF-distribution were monitored by live imaging of tobacco BY-2 cells stably expressing the GFP-actin binding domain 2 (GFP-ABD2) fusion protein, which vitally co-stained with the endocytic tracer, FM4-64, that labels the cell plate. During cytokinesis, MFs accumulated near the newly-separated daughter nuclei towards the emerging cell plate, and subsequently approached the expanding cell plate edges. Treatment with an actin polymerization inhibitor caused a decrease in the cell plate expansion rate, which was quantified using time-lapse imaging and regression analysis. Our results demonstrated time-sequential changes in the contribution of MFs to cell plate expansion; MF-disruption caused about a 10% decrease in the cell plate expansion rate at the early phase of cytokinesis, but about 25% at the late phase. MF-disruption also caused malformation of the emerging cell plate at the early phase, indicative of MF involvement in early cell plate formation and expansion. The dynamic movement of endosomes around the cell plate was also inhibited by treatment with an actin polymerization inhibitor and a myosin ATPase inhibitor, respectively. Furthermore, time-lapse imaging of the endoplasmic reticulum (ER) revealed that MFs were involved in ER accumulation in the phragmoplast at the late phase. CONCLUSION By expression of GFP-ABD2 and vital staining with FM4-64, the dynamics of MFs and the cell plate could be followed throughout plant cytokinesis in living cells. Pharmacological treatment and live imaging analysis also allowed us to quantify MF contribution to cell plate expansion during cytokinesis. Our results suggest that MFs play significant roles in cell plate formation and expansion via regulation of endomembrane dynamics.
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Affiliation(s)
- Takumi Higaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
| | - Natsumaro Kutsuna
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
| | - Toshio Sano
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
| | - Seiichiro Hasezawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
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Panteris E. Cortical actin filaments at the division site of mitotic plant cells: a reconsideration of the 'actin-depleted zone'. THE NEW PHYTOLOGIST 2008; 179:334-341. [PMID: 19086286 DOI: 10.1111/j.1469-8137.2008.02474.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The preprophase bands of microtubules and F-actin are primary markers of the division site for most plant cells. After preprophase band breakdown, the division site has been considered to be 'negatively' memorized by the local absence of cortical actin filaments. However, there have been reports of cortical F-actin at the division site of mitotic plant cells, calling into question its distribution and possible role there. In this article, previous and recent data on this issue are reviewed. It is proposed that the division site of mitotic plant cells is not devoid of F-actin but is traversed by scarce cortical actin filaments. The description of the division site as an 'actin exclusion zone' might therefore be attributed to a failure to preserve and/or image the notoriously sensitive actin filaments. Accordingly, the 'actin-depleted zone' should be considered as a site with fewer actin filaments than the rest of the cortical cytoplasm. Taking into account recent molecular data on division site components, a possible role for the scarcity of cortical actin filaments in establishing a zone of minimum mobility is also proposed.
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Affiliation(s)
- Emmanuel Panteris
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, Thessaloniki GR-541 24, Macedonia, Greece
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Aoyama N, Oka A, Kitayama K, Kurumizaka H, Harata M. The actin-related protein hArp8 accumulates on the mitotic chromosomes and functions in chromosome alignment. Exp Cell Res 2007; 314:859-68. [PMID: 18163988 DOI: 10.1016/j.yexcr.2007.11.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 10/30/2007] [Accepted: 11/21/2007] [Indexed: 11/19/2022]
Abstract
The actin family consists of conventional actin and various actin-related proteins (Arps). Some of these Arps are localized in the nucleus, and a fraction of each of these nuclear Arps is functionally involved in chromatin remodeling and histone acetyltransferase complexes. On the other hand, in mitotic cells, the localization and function of the nuclear Arps are largely unknown. Human Arp8 (hArp8), an ortholog of yeast nuclear Arp8, was recently found to be associated with the hINO80-chromatin remodeling complex along with hArp5. Here we report that hArp8, but not hArp5, accumulates on mitotic chromosomes. This is the first example where a member of the actin family is found to be associated with mitotic chromosomes. Expression of truncated hArp8 proteins and depletion of endogenous hArp8 by RNA interference caused misalignment of mitotic chromosomes, suggesting that chromosome-associated hArp8 has a role in chromosome behavior. In contrast, depletion of hIno80 and hArp5 did not cause misalignment of chromosomes, suggesting that the role of hArp8 at mitotic chromosomes is independent of the activity of hINO80 complexes. These findings provide the first insight into a novel function of actin family members in mitosis.
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Affiliation(s)
- Naoki Aoyama
- Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
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Johansen KM, Johansen J. Cell and Molecular Biology of the Spindle Matrix. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 263:155-206. [PMID: 17725967 DOI: 10.1016/s0074-7696(07)63004-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The concept of a spindle matrix has long been proposed to account for incompletely understood features of microtubule spindle dynamics and force production during mitosis. In its simplest formulation, the spindle matrix is hypothesized to provide a stationary or elastic molecular matrix that can provide a substrate for motor molecules to interact with during microtubule sliding and which can stabilize the spindle during force production. Although this is an attractive concept with the potential to greatly simplify current models of microtubule spindle behavior, definitive evidence for the molecular nature of a spindle matrix or for its direct role in microtubule spindle function has been lagging. However, as reviewed here multiple studies spanning the evolutionary spectrum from lower eukaryotes to vertebrates have provided new and intriguing evidence that a spindle matrix may be a general feature of mitosis.
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Affiliation(s)
- Kristen M Johansen
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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Yasuda H, Kanda K, Koiwa H, Suenaga K, Kidou SI, Ejiri SI. Localization of actin filaments on mitotic apparatus in tobacco BY-2 cells. PLANTA 2005; 222:118-29. [PMID: 15856282 DOI: 10.1007/s00425-005-1522-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 02/18/2005] [Indexed: 05/24/2023]
Abstract
Actin filaments are among the major components of the cytoskeleton, and participate in various cellular dynamic processes. However, conflicting results had been obtained on the localization of actin filaments on the mitotic apparatus and their participation in the process of chromosome segregation. We demonstrated by using rhodamine-phalloidin staining, the localization of actin filaments on the mitotic spindles of tobacco BY-2 cells when the cells were treated with cytochalasin D. At prophase, several clear spots were observed at or near the kinetochores of the chromosomes. At anaphase, the actin filaments that appeared to be pulling chromosomes toward the division poles were demonstrated. However, as there was a slight possibility that these results might have been the artifacts of cytochalasin D treatment or the phalloidin staining, we analyzed the localization of actin filaments at the mitotic apparatus immunologically. We cloned a novel BY-2 alpha-type actin cDNA and prepared a BY-2 actin antibody. The fluorescence of the anti-BY-2 actin antibody was clearly observed at the mitotic apparatus in both non-treated and cytochalasin D-treated BY-2 cells during mitosis. The facts that similar results were obtained in both actin staining with rhodamine-phalloidin and immunostaining with actin antibody strongly indicate the participation of actin in the organization of the spindle body or in the process of chromosome segregation. Furthermore, both filamentous actin and spindle bodies disappeared in the cells treated with propyzamide, which depolymerizes microtubules, supporting the notion that actin filaments are associated with microtubules organizing the spindle body.
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Affiliation(s)
- Hiroshi Yasuda
- Cryobiosystem Research Center, Iwate University, Morioka, Iwate 020-8550, Japan
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15
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Dhonukshe P, Mathur J, Hülskamp M, Gadella TWJ. Microtubule plus-ends reveal essential links between intracellular polarization and localized modulation of endocytosis during division-plane establishment in plant cells. BMC Biol 2005; 3:11. [PMID: 15831100 PMCID: PMC1087477 DOI: 10.1186/1741-7007-3-11] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Accepted: 04/14/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A key event in plant morphogenesis is the establishment of a division plane. A plant-specific microtubular preprophase band (PPB) accurately predicts the line of cell division, whereas the phragmoplast, another plant-specific array, executes cell division by maintaining this predicted line. Although establishment of these specific arrays apparently involves intracellular repolarization events that focus cellular resources to a division site, it still remains unclear how microtubules position the cell division planes. Here we study GFP-AtEB1 decorated microtubule plus-ends to dissect events at the division plane. RESULTS Early mitotic events included guided growth of endoplasmic microtubules (EMTs) towards the PPB site and their coincident localization with endocytic vesicles. Consequently, an endosomal belt lay in close proximity to the microtubular PPB at its maturation and was maintained during spindle formation. During cytokinesis, EMTs radiated from the former spindle poles in a geometrical conformation correlating with cell-plate navigation and tilt-correction. Naphthylphtalamic acid (NPA), an inhibitor of polar auxin efflux, caused abnormal PPBs and shifted division planes. CONCLUSION Our observations reveal a spatio-temporal link between microtubules and intracellular polarization essential for localized endocytosis and precise establishment of the division plane in plants. Additionally, they implicate the growth regulator, auxin, in this important cellular event.
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Affiliation(s)
- Pankaj Dhonukshe
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands
- Centre for Molecular Biology of Plants, University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany
| | - Jaideep Mathur
- Department of Plant Agriculture, Molecular Cell Biology Laboratory, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Martin Hülskamp
- Botanical Institute III, University of Köln, Gyrhofstrasse 15, Köln, 50931, Germany
| | - Theodorus WJ Gadella
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 316, 1098 SM Amsterdam, The Netherlands
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Ingouff M, Fitz Gerald JN, Guérin C, Robert H, Sørensen MB, Van Damme D, Geelen D, Blanchoin L, Berger F. Plant formin AtFH5 is an evolutionarily conserved actin nucleator involved in cytokinesis. Nat Cell Biol 2005; 7:374-80. [PMID: 15765105 DOI: 10.1038/ncb1238] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Accepted: 01/15/2005] [Indexed: 11/08/2022]
Abstract
Formins are actin-organizing proteins that are involved in cytokinesis and cell polarity. In the plant Arabidopsis thaliana, there are more than 20 formin homologues, all of which have unknown roles. In this study, we characterize specific cellular and molecular functions of the Arabidopsis formin AtFH5. Despite the low identity of AtFH5 to yeast and mammalian formins, the AtFH5 protein interacts with the barbed end of actin filaments and nucleates actin-filament polymerization in vitro, as is the case in yeast and mammals. In vivo, the AtFH5-GFP fusion protein localizes to the cell plate, a plant-specific membranous component that is assembled at the plane of cell division. Consistent with these data, loss of function of atfh5 compromises cytokinesis in the seed endosperm. Furthermore, endogenous AtFH5 transcripts accumulate in the posterior pole of the endosperm and loss of function of atfh5 perturbs proper morphogenesis of the endosperm posterior pole. Although cytokinesis in animals, yeast and plants occurs through morphologically distinct mechanisms, our study finds that formin recruitment to sites of actin assembly is a common feature of cell division among eukaryotes.
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Affiliation(s)
- Mathieu Ingouff
- EMBO YIP team, Unité Mixte de Recherche 5667, Institut Fédératif de Recherche 128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon, 46 allée d'Italie, F-69364 Lyon cedex 07, France
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Vitha S, Baluska F, Braun M, Samaj J, Volkmann D, Barlow PW. Comparison of cryofixation and aldehyde fixation for plant actin immunocytochemistry: aldehydes do not destroy F-actin. THE HISTOCHEMICAL JOURNAL 2000; 32:457-66. [PMID: 11095070 DOI: 10.1023/a:1004171431449] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
For walled plant cells, the immunolocalization of actin microfilaments, also known as F-actin, has proved to be much trickier than that of microtubules. These difficulties are commonly attributed to the high sensitivity of F-actin to aldehyde fixatives. Therefore, most plant studies have been accomplished using fluorescent phallotoxins in fresh tissues. Nevertheless, concerns regarding the questionable ability of phallotoxins to bind the whole complement of F-actin necessitate further optimization of actin immunofluorescence methods. We have compared two procedures: (1) formaldehyde fixation and (2) rapid freezing and freeze substitution (cryofixation), both followed by embedding in low-melting polyester wax. Actin immunofluorescence in sections of garden cress (Lepidium sativum L.) root gave similar results with both methods. The compatibility of aldehydes with actin immunodetection was further confirmed by the freeze-shattering technique that does not require embedding after aldehyde fixation. It appears that rather than aldehyde fixation, some further steps in the procedures used for actin visualization are critical for preserving F-actin. Wax embedding, combined with formaldehyde fixation, has proved to be also suitable for the detection of a wide range of other antigens.
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Affiliation(s)
- S Vitha
- Institute of Plant Molecular Biology, Academy of Sciences of Czech Republic, Ceské Budejovice
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18
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Abstract
The plant actin cytoskeleton is characterized by a high diversity in regard to gene families, isoforms, and degree of polymerization. In addition to the most abundant F-actin assemblies like filaments and their bundles, G-actin obviously assembles in the form of actin oligomers composed of a few actin molecules which can be extensively cross-linked into complex dynamic meshworks. The role of the actomyosin complex as a force generating system - based on principles operating as in muscle cells - is clearly established for long-range mass transport in large algal cells and specialized cell types of higher plants. Extended F-actin networks, mainly composed of F-actin bundles, are the structural basis for this cytoplasmic streaming of high velocities On the other hand, evidence is accumulating that delicate meshworks built of short F-actin oligomers are critical for events occurring at the plasma membrane, e.g., actin interventions into activities of ion channels and hormone carriers, signaling pathways based on phospholipids, and exo- and endocytotic processes. These unique F-actin arrays, constructed by polymerization-depolymerization processes propelled via synergistic actions of actin-binding proteins such as profilin and actin depolymerizing factor (ADF)/cofilin are supposed to be engaged in diverse aspects of plant morphogenesis. Finally, rapid rearrangements of F-actin meshworks interconnecting endocellular membranes turn out to be especially important for perception-signaling purposes of plant cells, e.g., in association with guard cell movements, mechano- and gravity-sensing, plant host-pathogen interactions, and wound-healing.
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Affiliation(s)
- D Volkmann
- Botany Institute, University of Bonn, Germany.
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19
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Fukui Y, Kitanishi-Yumura T, Yumura S. Myosin II-independent F-actin flow contributes to cell locomotion in dictyostelium. J Cell Sci 1999; 112 ( Pt 6):877-86. [PMID: 10036237 DOI: 10.1242/jcs.112.6.877] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
While the treadmilling and retrograde flow of F-actin are believed to be responsible for the protrusion of leading edges, little is known about the mechanism that brings the posterior cell body forward. To elucidate the mechanism for global cell locomotion, we examined the organizational changes of filamentous (F-) actin in live Dictyostelium discoideum. We labeled F-actin with a trace amount of fluorescent phalloidin and analyzed its dynamics in nearly two-dimensional cells by using a sensitive, high-resolution charge-coupled device. We optically resolved a cyclic mode of tightening and loosening of fibrous cortical F-actin and quantitated its flow by measuring temporal and spatial intensity changes. The rate of F-actin flow was evaluated with respect to migration velocity and morphometric changes. In migrating monopodial cells, the cortical F-actin encircling the posterior cell body gradually accumulated into the tail end at a speed of 0.35 microm/minute. We show qualitatively and quantitatively that the F-actin flow is closely associated with cell migration. Similarly, in dividing cells, the cortical F-actin accumulated into the cleavage furrow. Although five times slower than the wild type, the F-actin also flows rearward in migrating mhcA- cells demonstrating that myosin II (‘conventional’ myosin) is not absolutely required for the observed dynamics of F-actin. Yet consistent with the reported transportation of ConA-beads, the direction of observed F-actin flow in Dictyostelium is conceptually opposite from a barbed-end binding to the plasma membrane. This study suggests that the posterior end of the cell has a unique motif that tugs the cortical actin layer rearward by means of a mechanism independent from myosin II; this mechanism may be also involved in cleavage furrow formation.
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Affiliation(s)
- Y Fukui
- Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois, USA.
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20
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Forer A, Pickett-Heaps JD. Cytochalasin D and latrunculin affect chromosome behaviour during meiosis in crane-fly spermatocytes. Chromosome Res 1998; 6:533-49. [PMID: 9886773 DOI: 10.1023/a:1009224322399] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Living crane-fly spermatocytes were treated with 10-20 microg/ml cytochalasin D (CD) or 0.3 microg/ml latrunculin (LAT) at various stages of meiosis I. The drugs had the same effects on chromosome behaviour, but CD effects were reversible and LAT effects generally were not. When applied in mid-prometaphase to metaphase, both drugs altered subsequent anaphase poleward movements: half-bivalents either moved more slowly than normal, or moved more slowly after a brief period of movement at normal rate or stalled for 10 min or more immediately after disjunction. CD effects were reversible: within 1 min after washing out the CD, stopped chromosomes started moving and slowed chromosomes sped up. When applied in anaphase, both drugs stopped or slowed poleward chromosome movements, usually reversibly. When applied near the end of prophase, both drugs often prevented one or more bivalents in the cell from attaching to the spindle. Attached bivalents behaved as in cells treated with drugs at later stages, as described above. Unattached bivalents in the same cells moved to poles or cytoplasm in early prometaphase, where they remained motionless; at anaphase they sometimes did not disjoin, but when they did disjoin the half-bivalents did not move, either in the continued presence of the drug or when CD was washed out, confirming that they were not atttached. When CD or LAT prevented all bivalents in the cell from attaching, spindles kept in the drug were invaded by granules at about the time of normal anaphase. Conversely, when CD was washed out during late prometaphase, chromosomes often attached to spindle fibres and later entered anaphase. As CD and LAT are different antiactin drugs, but have the same effect on chromosome behaviour, the results implicate actin in early interactions of chromosomes with spindle fibres and in anaphase chromosome movements.
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Affiliation(s)
- A Forer
- Biology Department, York University, Downsview, Ontario, Canada.
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21
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Endlé MC, Stoppin V, Lambert AM, Schmit AC. The growing cell plate of higher plants is a site of both actin assembly and vinculin-like antigen recruitment. Eur J Cell Biol 1998; 77:10-8. [PMID: 9808284 DOI: 10.1016/s0171-9335(98)80097-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Compelling evidence supports the idea that actin filaments play an active role in the cytokinetic process of higher plant cells. However, the mechanisms that control the growth of the cell plate and its stabilization remain so far unknown. We show that a novel population of short actin filaments continuously assembles in the phragmoplast at the growing cell plate. Microinjection of rhodamine-phalloidin during these final stages of telophase revealed the dynamic assembly and organization of these actin filaments during vesicle fusion. Comparable data were obtained in endosperm syncytia during the development of the cell plate between non sister nuclei, i.e. independently of the formation of the mitotic phragmoplast. Concomitantly, plant polypeptides sharing epitopes with human vinculin are revealed within the forming cell plate, suggesting their recruitment during cytokinesis-associated actin assembly. These vinculin-like antigens may participate in membrane/F-actin anchorage protein complexes. Our data, in addition to the identification of plant integrin homologues reported by several authors, suggest the existence of a cell wall/extracellular matrix/plasma membrane/actin cytoskeleton continuum. Such an architecture may control cell-cell interactions during cell plate formation and may contribute to the establishment of polarity in higher plants.
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Affiliation(s)
- M C Endlé
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique UPR 406, Université Louis Pasteur, Strasbourg, France
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22
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Maniotis AJ, Bojanowski K, Ingber DE. Mechanical continuity and reversible chromosome disassembly within intact genomes removed from living cells. J Cell Biochem 1997. [DOI: 10.1002/(sici)1097-4644(199704)65:1<114::aid-jcb12>3.0.co;2-k] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Vitha S, Baluska F, Mews M, Volkmann D. Immunofluorescence detection of F-actin on low melting point wax sections from plant tissues. J Histochem Cytochem 1997; 45:89-95. [PMID: 9010473 DOI: 10.1177/002215549704500112] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We developed a simple and reliable technique for immunofluorescence detection of F-actin on microtome sections of plant tissues. For the first time, large numbers of plant cells from various tissues that pass through their developmental stages could be consistently visualized on one section from plant organs. n-Maleimidobenzoic acid N-hydroxysuccinimide ester-pretreated and formalin-fixed segments of plant roots and shoots were embedded in low melting point ester wax at 37C and sectioned on a microtome. After dewaxing and rehydration, microfilaments were visualized by indirect immunofluorescence technique with a monoclonal anti-actin antibody. The technique has been successfully used for visualization of tissue- and development-specific F-actin arrays in cells of Zea mays and Lepidium sativum root tips and of maize stem nodes.
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Affiliation(s)
- S Vitha
- Institute of Plant Molecular Biology, Academy of Sciences of Czech Republic, Ceské Budĕjovice, Czech Republic
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24
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The plant cytoskeleton. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1874-6020(96)80016-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
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25
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Hess MW, Mittermann I, Luschnig C, Valenta R. Immunocytochemical localisation of actin and profilin in the generative cell of angiosperm pollen: TEM studies on high-pressure frozen and freeze-substituted Ledebouria socialis Roth (Hyacinthaceae). Histochem Cell Biol 1995; 104:443-51. [PMID: 8777730 DOI: 10.1007/bf01464334] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Actin was demonstrated for the first time at the EM level in the generative cell of mature angiosperm pollen by using immuno-gold labelling of high-pressure frozen and freeze-substituted Ledebouria socialis Roth anthers. In addition, profilin, an actin-monomer binding protein, is shown to coexist in the generative cell. We attribute the detection of actin and profilin to the applied cryomethods which yield a much better preservation of ultrastructure and antigenicity of delicate cytoskeletal constituents than conventional fixation techniques. Actin labelling was observed within the cytoplasm of the generative cell and became especially clear in close vicinity to microtubular bundles. Filamentous structures congruent with the actin labelling patterns do occur, but are not a frequent feature. Profilin was localised throughout the cytoplasm.
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Affiliation(s)
- M W Hess
- Institut für Botanik, Universität Wien, Vienna, Austria
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26
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Pozueta-Romero J, Klein M, Houlné G, Schantz ML, Meyer B, Schantz R. Characterization of a family of genes encoding a fruit-specific wound-stimulated protein of bell pepper (Capsicum annuum): identification of a new family of transposable elements. PLANT MOLECULAR BIOLOGY 1995; 28:1011-25. [PMID: 7548820 DOI: 10.1007/bf00032663] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Using a fruit-specific cDNA as a probe we isolated and sequenced the two corresponding homologous genes (Sn-1 and Sn-2) of the bell pepper (Capsicum annuum) genome. Both genes have a single intron and numerous unusual long inverted repeat sequences. The introns share 87% homology and Sn-2 contains one 450 bp additional sequence with structural features of a transposable element, which is highly repetitive in the bell pepper genome. Surprisingly, analysis in data banks showed that genes encoding the potato starch phosphorylase (EC 2.4.1.1) and patatin contain a similar element, named Alien, in their 5'-upstream region. Alien elements are characterized by a conserved 28 bp terminal inverted repeat (TIR), small size, high AT content, potential to form stable DNA secondary structures and they have probably been inserted in TA target sites. Interestingly, the TIR of the Alien elements shares high homology with sequences existing in the TIR of extrachromosomal linear pSKL DNA plasmid of Saccharomyces kluyveri. Northern blot analyses detected Sn-1 transcripts principally in the red fruit whereas no Sn-2 transcripts were detected in neither of the samples monitored. Western blot analyses detected a 16.8 kDa Sn protein principally in the ripe red fruit and wounded areas of green unripe fruit. A comparison of the deduced amino acid sequence of Sn-1 with protein sequences in data banks revealed a significant homology with proteins likely involved in the plant's disease resistance response. Analyses at the subcellular level showed that Sn-1 is localized in the membrane of vacuoles.
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Affiliation(s)
- J Pozueta-Romero
- Institut de Biologie Moléculaire des Plantes, Université Louis Pasteur, Strasbourg, France
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27
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Zhang D, Wadsworth P, Hepler PK. Dynamics of microfilaments are similar, but distinct from microtubules during cytokinesis in living, dividing plant cells. ACTA ACUST UNITED AC 1993. [DOI: 10.1002/cm.970240302] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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28
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Cleary A, Gunning B, Wasteneys G, Hepler P. Microtubule and F-actin dynamics at the division site in living Tradescantia stamen hair cells. J Cell Sci 1992. [DOI: 10.1242/jcs.103.4.977] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have visualised F-actin and microtubules in living Tradescantia virginiana stamen hair cells by confocal laser scanning microscopy after microinjecting rhodamine-phalloidin or carboxyfluorescein-labelled brain tubulin. We monitored these components of the cytoskeleton as the cells prepared for division at preprophase and progressed through mitosis to cytokinesis. Reorganisation of the interphase cortical cytoskeleton results in preprophase bands of both F-actin and microtubules that coexist in the cell cortex, centred on the site at which the future cell plate will fuse with the parent cell wall. The preprophase band of microtubules is formed from microtubules that polymerise and incorporate tubulin during prophase. The preprophase band of actin may form either by reorganisation of pre-existing filaments or by de novo polymerisation. Both cytoskeletal components disappear from the future division site approximately five minutes prior to the breakdown of the nuclear envelope. Cortical microtubules are undetectable throughout mitosis and cytokinesis, whereas cortical F-actin remains abundant, although it is notably excluded from the division site. The phragmoplast, containing both F-actin and microtubules, expands towards the cortical actin exclusion-zone through a region that has no detectable microtubules or F-actin. The phragmoplast comes to rest in the predefined region of the cortex that is devoid of F-actin. It is proposed that cortical F-actin may act as a “negative” template which could position the phragmoplast and cell plate correctly. This is the first in vivo documentation of F- actin dynamics at the division site in living plant cells.
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29
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30
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Liu B, Palevitz BA. Organization of cortical microfilaments in dividing root cells. ACTA ACUST UNITED AC 1992. [DOI: 10.1002/cm.970230405] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Harper JD, McCurdy DW, Sanders MA, Salisbury JL, John PC. Actin dynamics during the cell cycle in Chlamydomonas reinhardtii. CELL MOTILITY AND THE CYTOSKELETON 1992; 22:117-26. [PMID: 1378775 DOI: 10.1002/cm.970220205] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have used two monoclonal antibodies to demonstrate the presence and localization of actin in interphase and mitotic vegetative cells of the green alga Chlamydomonas reinhardtii. Commercially available monoclonal antibodies raised against smooth muscle actin (Lessard: Cell Motil. Cytoskeleton 10:349-362, 1988; Lin: Proc. Natl. Acad. Sci. USA 78:2335-2339, 1981) identify Chlamydomonas actin as a approximately 43,000-M(r) protein by Western immunoblot procedures. In an earlier study, Detmers and coworkers (Cell Motil. 5:415-430, 1985) first identified Chlamydomonas actin using NBD-phallacidin and an antibody raised against Dictyostelium actin; they demonstrated that F-actin is localized in the fertilization tubule of mating gametes. Here, we show by immunofluorescence that vegetative Chlamydomonas cells have an array of actin that surrounds the nucleus in interphase cells and undergoes dramatic reorganization during mitosis and cytokinesis. This includes the following: reorganization of actin to the anterior of the cell during preprophase; the formation of a cruciate actin band in prophase; reorganization to a single anterior actin band in metaphase; rearrangement forming a focus of actin anterior to the metaphase plate; reextension of the actin band in anaphase; presence of actin in the forming cleavage furrow during telophase and cytokinesis; and finally reestablishment of the interphase actin array. The studies presented here do not allow us to discriminate between G and F-actin. None the less, our observations, demonstrating dynamic reorganization of actin during the cell cycle, suggest a role for actin that may include the movement of basal bodies toward the spindle poles in mitosis and the formation of the cleavage furrow during cytokinesis.
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Affiliation(s)
- J D Harper
- Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra
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32
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Andersland JM, Parthasarathy MV. Phalloidin binds and stabilizes pea root actin. ACTA ACUST UNITED AC 1992. [DOI: 10.1002/cm.970220404] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Tourte M, Besse C, Mounolou JC. Cytochemical evidence of an organized microtubular cytoskeleton in Xenopus laevis oocytes: involvement in the segregation of mitochondrial populations. Mol Reprod Dev 1991; 30:353-9. [PMID: 1751040 DOI: 10.1002/mrd.1080300410] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An organized microtubular cytoskeleton was discovered in the cytoplasm of Xenopus laevis oocytes. The microtubules were observed in 10- to 30-micron cryostat sections by indirect immunoperoxidase labeling using an antibody to tubulin. A gradual extraction of cells with a nonionic detergent was essential for good penetration of the antibody into the cells. In the cytoplasm of all previtellogenic oocytes, a dense network of criss-crossed long microtubules was associated in a basket-like structure surrounding the mitochondrial mass. At the beginning of vitellogenesis, the network meshes enlarged, while clusters of mitochondria migrated, in close association with microtubule bundles. At the beginning of vitellogenesis, the reorganization of the microtubular network, mostly in the vegetal hemisphere, occurred during the segregation of the mitochondrial populations. Reorganization is characterized by (1) a temporary enlargement of the network and close association of mitochondrial clusters with microtubular bundles, and (2) a progressive organization of a ring-shaped microtubular structure in the crown elaboration area. It is hypothesized that these modifications of the microtubular cytoskeleton contribute to the maintenance of cell shape and the polarized organization of the cell.
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Affiliation(s)
- M Tourte
- Laboratoire de Biologie Végétale et Cellulaire, Bâtiment de Botanique, Université de Poitiers, France
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Cho SO, Wick SM. Actin in the developing stomatal complex of winter rye: A comparison of actin antibodies and Rh-phalloidin labeling of control and CB-treated tissues. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/cm.970190105] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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McCurdy DW, Palevitz BA, Gunning BES. Effect of cytochalasins on actin in dividing root tip cells ofAllium andTriticum: A comparative immunocytochemical study. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/cm.970180205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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McCurdy DW, Gunning BES. Reorganization of cortical actin microfilaments and microtubules at preprophase and mitosis in wheat root-tip cells: A double label immunofluorescence study. ACTA ACUST UNITED AC 1990. [DOI: 10.1002/cm.970150204] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Van Lammeren AA, Bednara J, Willemse MT. Organization of the actin cytoskeleton during pollen development inGasteria verrucosa (Mill.) H. Duval visualized with rhodamine-phalloidin. PLANTA 1989; 178:531-9. [PMID: 24213050 DOI: 10.1007/bf00963823] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/1988] [Accepted: 01/13/1989] [Indexed: 05/25/2023]
Abstract
The three-dimensional organization of the microfilamental cytoskeleton of developingGasteria pollen was investigated by light microscopy using whole cells and fluorescently labelled phalloidin. Cells were not fixed chemically but their walls were permeabilized with dimethylsulphoxide and Nonidet P-40 at premicrospore stages or with dimethylsulphoxide, Nonidet P-40 and 4-methylmorpholinoxide-monohydrate at free-microspore and pollen stages to dissolve the intine.Four strikingly different microfilamentous configurations were distinguished. (i) Actin filaments were observed in the central cytoplasm throughout the successive stages of pollen development. The network was commonly composed of thin bundles ramifying throughout the cytoplasm at interphase stages but as thick bundles encaging the nucleus prior to the first and second meiotic division. (ii) In released microspores and pollen, F-actin filaments formed remarkably parallel arrays in the peripheral cytoplasm. (iii) In the first and second meiotic spindles there was an apparent localization of massive arrays of phalloidin-reactive material. Fluorescently labelled F-actin was present in kinetochore fibers and pole-to-pole fibers during metaphase and anaphase. (iv) At telophase, microfilaments radiated from the nuclear envelopes and after karyokinesis in the second meiotic division, F-actin was observed in phragmoplasts.We did not observe rhodamine-phalloidin-labelled filaments in the cytoplasm after cytochalasin-B treatment whereas F-actin persisted in the spindle. Incubation at 4° C did not influence the existence of cytoplasmic microfilaments whereas spindle filaments disappeared. This points to a close interdependence of spindle microfilaments and spindle tubules.Based on present data and earlier observations on the configuration of microtubules during pollen development in the same species (Van Lammeren et al., 1985, Planta165, 1-11) there appear to be apparent codistributions of F-actin and microtubules during various stages of male meiosis inGasteria verrucosa.
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Affiliation(s)
- A A Van Lammeren
- Department of Plant Cytology and Morphology, Agricultural University Wageningen, Arboretumlaan 4, NL-6703 BD, Wageningen, The Netherlands
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Cyr RJ, Palevitz BA. Microtubule-binding proteins from carrot : I. Initial characterization and microtubule bundling. PLANTA 1989; 177:245-260. [PMID: 24212347 DOI: 10.1007/bf00392813] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/1988] [Accepted: 09/23/1988] [Indexed: 06/02/2023]
Abstract
Microtubules (MTs) participate in several processes of fundamental importance to growth and development in higher plants, yet little is known about the proteins with which they associate. Information about these molecules is important because they probably play a role in mediating functional and structural differences between various MT arrays. As a first step in gaining insight into this problem, we have isolated, from suspension-cultured cells of carrot (Daucus carota L.), non-tubulin proteins which bind to and affect microtubules (MTs) in vitro. These proteins were isolated using taxol-stabilized neuronal MTs as an affinity substrate. They cause MT bundling at substoichiometric concentrations, support the assembly of tubulin in vitro, and at low concentrations, decorate single MTs in a periodic fashion. The bundled MTs formed in vitro share similarities with those seen in situ in a variety of plant cells, including a center-center spacing of 34 nm, cold stability, resistance to anti-microtubule drugs, and sensitivity to calcium. The bundling activity is specific; other cationic proteins, as well as poly-L-lysine, do not behave in a similar manner. The bundling activity is insensitive to ATP. By assaying bundling activity with dark-field microscopy and employing standard biochemical procedures, a small number of polypeptides involved in the bundling process were identified. Affinity-isolated antibodies to one of these polypeptides (Mr=76000) were found to co-localize with MTs in the cortical array of protoplasts. Our findings are discussed with reference to the importance of these proteins in the cell and to their relationship to microtubule-associated proteins in other eukaryotes.
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Affiliation(s)
- R J Cyr
- Department of Botany, University of Georgia, 30602, Athens, GA, USA
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Affiliation(s)
- C W Lloyd
- Department of Cell Biology, John Innes Institute, Norwich, UK
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40
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Kropf DL, Berge SK, Quatrano RS. Actin Localization during Fucus Embryogenesis. THE PLANT CELL 1989; 1:191-200. [PMID: 12359891 PMCID: PMC159751 DOI: 10.1105/tpc.1.2.191] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Embryogenesis in the Fucales serves as a model system for studying the acquisition of cellular and developmental polarity. Fertilized eggs bear no asymmetry, yet within 16 hours, a developmental axis is formed and the unicellular zygote germinates in accordance with this axis. Microfilaments (actin) play a crucial role in establishing the axis as evidenced by the inhibitory effects of cytochalasins on axis fixation. The cellular content of actin was determined by immunoblot, whereas the localization of F-actin was investigated using the fluorescent probe rhodamine phalloidin. Three isoforms of actin were detected in constant amounts at all developmental stages. Actin networks were found to be distributed uniformly in eggs and zygotes through the period of early zygote development when the polar axis was formed. However, as the polar axis became irreversibly fixed in space, actin was localized at the presumptive germination site by a cytochalasin-sensitive process. This correlation supports the proposal that actin networks play a critical role in axis fixation, and is consistent with our hypothesis that this process involves stabilization of membrane components by transmembrane bridges from the cell wall to the microfilament cytoskeleton.
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Affiliation(s)
- D. L. Kropf
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
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41
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La Claire JW. Actin cytoskeleton in intact and wounded coenocytic green algae. PLANTA 1989; 177:47-57. [PMID: 24212271 DOI: 10.1007/bf00392153] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/1988] [Accepted: 08/26/1988] [Indexed: 06/02/2023]
Abstract
The subcellular distribution of actin was investigated in two related species of coenocytic green algae, with immunofluorescence microscopy. Either no, or fine punctate fluorescence was detected in intact cells of Ernodesmis verticillata (Kützing) Børgesen and Boergesenia forbesii (Harvey) Feldmann. A reticulate pattern of fluorescence appears throughout the cortical cytoplasm of Ernodesmis cells shortly after wounding; this silhouettes chloroplasts and small vacuoles. Slender, longitudinal bundles of actin become evident in contracting regions of the cell, superimposed over the reticulum. Thicker portions of the bundles were observed in well-contracted regions, and the highly-convoluted appearance of nearby cortical microtubules indicates contraction of the bundles in these thicker areas. Bundles are no longer evident after healing; only the reticulum remains. In Boergesenia, a wider-mesh reticulum of actin develops in the cortex of wounded cells, which widens further as contractions continue. Cells wounded in Ca(2+)-free medium do not contract, and although the actin reticulum is apparent, no actin bundles were ever observed in these cells. Exogenously applied cytochalasins have no effect on contractions of cut cells or extruded cytoplasm, and normal actin-bundle formation occurs in treated cells. In contrast, erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA) completely inhibits longitudinal contractions in wounded cells, and few uniformly slender actin bundles develop in inhibited cells. These results indicate that wounding stimulates a Ca(2+)-dependent, hierarchical assembly of actin into bundles, whose assembly and functioning are inhibited by EHNA. Contraction of the bundles and concomitant wound healing are followed by cessation of motility and disassembly of the bundles. The spatial and temporal association of the bundles with regions of cytoplasmic contraction, indicates that the actin bundles are directly involved in wound-induced cytoplasmic motility in these algae.
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Affiliation(s)
- J W La Claire
- Department of Botany, University of Texas, 78713, Austin, TX, USA
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Carlier MF. Role of nucleotide hydrolysis in the dynamics of actin filaments and microtubules. INTERNATIONAL REVIEW OF CYTOLOGY 1989; 115:139-70. [PMID: 2663760 DOI: 10.1016/s0074-7696(08)60629-4] [Citation(s) in RCA: 123] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- M F Carlier
- Laboratoire d'Enzymologie, C.N.R.S., Gif-sur-Yvette, France
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