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Lynagh T, Mikhaleva Y, Colding JM, Glover JC, Pless SA. Acid-sensing ion channels emerged over 600 Mya and are conserved throughout the deuterostomes. Proc Natl Acad Sci U S A 2018; 115:8430-8435. [PMID: 30061402 PMCID: PMC6099870 DOI: 10.1073/pnas.1806614115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated ion channels broadly expressed in the vertebrate nervous system, converting decreased extracellular pH into excitatory sodium current. ASICs were previously thought to be a vertebrate-specific branch of the DEG/ENaC family, a broadly conserved but functionally diverse family of channels. Here, we provide phylogenetic and experimental evidence that ASICs are conserved throughout deuterostome animals, showing that ASICs evolved over 600 million years ago. We also provide evidence of ASIC expression in the central nervous system of the tunicate, Oikopleura dioica Furthermore, by comparing broadly related ASICs, we identify key molecular determinants of proton sensitivity and establish that proton sensitivity of the ASIC4 isoform was lost in the mammalian lineage. Taken together, these results suggest that contributions of ASICs to neuronal function may also be conserved broadly in numerous animal phyla.
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Affiliation(s)
- Timothy Lynagh
- Department of Drug Design and Pharmacology, Center for Biopharmaceuticals, University of Copenhagen, 2100 Copenhagen, Denmark;
| | - Yana Mikhaleva
- Sars International Centre for Marine Molecular Biology, University of Bergen, 5006 Bergen, Norway
| | - Janne M Colding
- Department of Drug Design and Pharmacology, Center for Biopharmaceuticals, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Joel C Glover
- Sars International Centre for Marine Molecular Biology, University of Bergen, 5006 Bergen, Norway
- Department of Molecular Medicine, University of Oslo, 0372 Oslo, Norway
| | - Stephan A Pless
- Department of Drug Design and Pharmacology, Center for Biopharmaceuticals, University of Copenhagen, 2100 Copenhagen, Denmark
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2
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Abstract
Severe injury to the central nervous system of chordates often results in permanent and irreversible mental and physical challenges. While some chordates are able to repair and/or regenerate portions of their nervous system, no chordate has been shown to be able to regenerate all regions of its central nervous system after catastrophic injury or amputation. Some hemichordates, on the other hand, are able to efficiently regenerate all neural structures, including their dorsal, hollow neural tube after complete ablation. Solitary hemichordates are marine acorn worms and a sister group to the echinoderms. The hemichordate Ptychodera flava progresses from a pelagic, feeding tornaria larva to a tripartite benthic worm with an anterior proboscis, a middle collar region, and a long posterior trunk. The adult worm regenerates all body parts when bisected in the trunk, but it was unknown whether the regeneration process was present in tornaria larvae. Now, we show that P. flava larvae are capable of robust regeneration after bisection through the sagittal, coronal, and axial planes. We also use antibody staining to show that the apical sensory organ regenerates a rich, serotonin-positive complex of cells within two weeks after amputation. Cells labeled with 5-ethynyl-2'-deoxyuridine confirm that regeneration is occurring through epimorphic processes as new cells are added at the cut site and throughout the regenerating tissue. This study verifies that P. flava larvae can be used for future functional studies aimed at identifying the genetic and morphological mechanisms controlling central nervous system regeneration in a stem deuterostome.
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Del Moral-Flores LF, Morrone JJ, Alcocer J, Pérez-Ponce de León G. [Diversity and biogeographic affinities of sharks, rays and chimaeras (Chondrichthyes: Elasmobranchii, Holocephali) of Mexico]. REV BIOL TROP 2016; 64:1469-1486. [PMID: 29465910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Abstract
The diversity of chondrychthyans in Mexico is described. The fauna is composed by 214 species (111 sharks, 95 rays and 8 chimaeras) and represents 17.3 % of the total number of species recorded worldwide. The families with the highest diversity comprise: Rajidae (14.5 %), Carcharhinidae (12.1 %), Pentanchidae, Triakidae, and Urotrygonidae (5.1 %). In terms of geographical distribution, the diversity on the Mexican Pacific slope reaches up to 56.1 % of those species inhabiting Mexican marine and brackish waters (120 species, 62 genera, 37 families and 14 orders); the diversity in the Atlantic slope resulted similar to that on the Mexican Pacific with 55.1 % of the species (118 species, 59 genera, 35 families and 13 orders). The biogeographical affinities of the Mexican chondrychthyan fauna are complex with 19.7 % of the species being circumglobal, 9.9 % transatlantic, 1.9 % transpacific, and 9.4 % endemic to the exclusive economic zone. Additionally, 36.6 % of the species recorded so far are endemic to the Eastern Pacific coast where the species are similar to those found in the Cortez biogeographic province (27.7 %), followed by the Californian (20.7 %), Panamanian (19.3 %), Galapagos (5.6 %) and Peruvian-Chilean (8.9 %). Likewise, 33.3 % are endemic of the Atlantic coast, where species are similar to those found in the Caribbean province (31.9 %), followed by the Carolinean (24.4 %) and the Brazilian (6.6 %).
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Luttrell SM, Gotting K, Ross E, Alvarado AS, Swalla BJ. Head regeneration in hemichordates is not a strict recapitulation of development. Dev Dyn 2016; 245:1159-1175. [PMID: 27649280 PMCID: PMC5129524 DOI: 10.1002/dvdy.24457] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 09/04/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Head or anterior body part regeneration is commonly associated with protostome, but not deuterostome invertebrates. However, it has been shown that the solitary hemichordate Ptychodera flava possesses the remarkable capacity to regenerate their entire nervous system, including their dorsal neural tube and their anterior head-like structure, or proboscis. Hemichordates, also known as acorn worms, are marine invertebrate deuterostomes that have retained chordate traits that were likely present in the deuterostome ancestor, placing these animals in a vital position to study regeneration and chordate evolution. All acorn worms have a tripartite body plan, with an anterior proboscis, middle collar region, and a posterior trunk. The collar houses a hollow, dorsal neural tube in ptychoderid hemichordates and numerous chordate genes involved in brain and spinal cord development are expressed in a similar anterior-posterior spatial arrangement along the body axis. RESULTS We have examined anterior regeneration in the hemichordate Ptychodera flava and report the spatial and temporal morphological changes that occur. Additionally, we have sequenced, assembled, and analyzed the transcriptome for eight stages of regenerating P. flava, revealing significant differential gene expression between regenerating and control animals. CONCLUSIONS Importantly, we have uncovered developmental steps that are regeneration-specific and do not strictly follow the embryonic program. Developmental Dynamics 245:1159-1175, 2016. © 2016 The Authors. Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Shawn M. Luttrell
- Biology DepartmentUniversity of WashingtonSeattleWashington
- Friday Harbor LaboratoriesUniversity of WashingtonFriday HarborWashington
| | | | - Eric Ross
- Stowers Institute for Medical ResearchKansas CityMissouri
- Howard Hughes Medical InstituteStowers Institute for Medical ResearchKansas CityMissouri
| | - Alejandro Sánchez Alvarado
- Stowers Institute for Medical ResearchKansas CityMissouri
- Howard Hughes Medical InstituteStowers Institute for Medical ResearchKansas CityMissouri
| | - Billie J. Swalla
- Biology DepartmentUniversity of WashingtonSeattleWashington
- Friday Harbor LaboratoriesUniversity of WashingtonFriday HarborWashington
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Kümmell SB, Frey E. Range of movement in ray I of manus and pes and the prehensility of the autopodia in the Early Permian to Late Cretaceous non-anomodont Synapsida. PLoS One 2014; 9:e113911. [PMID: 25517726 PMCID: PMC4269487 DOI: 10.1371/journal.pone.0113911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 10/30/2014] [Indexed: 11/18/2022] Open
Abstract
The mobility of ray I was analysed in seventy-eight Early Permian to Late Cretaceous specimens of non-mammalian Synapsida and one extant mammal. In all non-mammaliamorph Synapsida investigated, ray I formed a digital arcade. The first phalanx was maximally extendable to the zero position in the metapodiophalangeal joint I. Metapodiale I was the functional equivalent to a basal phalanx of digits II–V. In contrast, there was no digital arcade in ray I in Mesozoic Mammaliamorpha. Phalanx 1 I was dorsally extendable and metapodiale I was functionally part of the metapodium. During the propulsion phase, autopodial rotation occurred in the majority of Synapsida with abducted limb posture. Regarding ray I, the reduction of autopodial rotation can be estimated, e.g., from the decrease of lateral rotation and medial abduction of the first phalanx in the metapodiophalangeal joint I. Autopodial rotation was high in Titanophoneus and reduced in derived Cynodontia. In Mammaliamorpha the mobility of the first ray suggests autopodial rolling in an approximately anterior direction. Most non-mammaliamorph Therapsida and probably some Mesozoic Mammaliamorpha had prehensile autopodia with an opposable ray I. In forms with a pronounced relief of the respective joints, ray I could be opposed to 90° against ray III. A strong transverse arch in the row of distalia supported the opposition movement of ray I and resulted in a convergence of the claws of digits II–V just by flexing those digits. A tight articular coherence in the digital joints of digits II–V during strong flexion supported a firm grip capacity. Usually the grip capacity was more pronounced in the manus than in the pes. Prehensile autopodia of carnivorous Therapsida may have been utilized to hold prey while biting, thus helping to avoid fractures of the laterally compressed fangs.
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Affiliation(s)
- Susanna B. Kümmell
- Institute of Evolutionary Biology and Morphology, Center for Biomedical Education and Research, Faculty of Health, School of Medicine, University Witten/Herdecke, Witten, Germany
- * E-mail:
| | - Eberhard Frey
- Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, Germany
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He C, Fitzpatrick DA, O'Halloran DM. A comparative study of the molecular evolution of signalling pathway members across olfactory, gustatory and photosensory modalities. J Genet 2014; 92:327-34. [PMID: 23970093 DOI: 10.1007/s12041-013-0264-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chao He
- Department of Biological Sciences, George Washington University, 333 Lisner Hall, 2023 G St. NW, Washington, DC 20052, USA
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7
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Behie SW, Bidochka MJ. Ubiquity of insect-derived nitrogen transfer to plants by endophytic insect-pathogenic fungi: an additional branch of the soil nitrogen cycle. Appl Environ Microbiol 2014; 80:1553-60. [PMID: 24334669 PMCID: PMC3957595 DOI: 10.1128/aem.03338-13] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/07/2013] [Indexed: 11/20/2022] Open
Abstract
The study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungus Metarhizium robertsii. That is, the endophytic capability and insect pathogenicity of M. robertsii are coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in five Metarhizium species representing those with broad (M. robertsii, M. brunneum, and M. guizhouense) and narrower insect host ranges (M. acridum and M. flavoviride), as well as the insect-pathogenic fungi Beauveria bassiana and Lecanicillium lecanii. Insects were injected with (15)N-labeled nitrogen, and we tracked the incorporation of (15)N into two dicots, haricot bean (Phaseolus vulgaris) and soybean (Glycine max), and two monocots, switchgrass (Panicum virgatum) and wheat (Triticum aestivum), in the presence of these fungi in soil microcosms. All Metarhizium species and B. bassiana but not L. lecanii showed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high, M. robertsii was able to transfer insect-derived nitrogen to plants. Metarhizium spp. and B. bassiana have a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities.
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Affiliation(s)
- Scott W Behie
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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Rinkevich Y, Rinkevich B, Reshef R. Cell signaling and transcription factor genes expressed during whole body regeneration in a colonial chordate. BMC Dev Biol 2008; 8:100. [PMID: 18847507 PMCID: PMC2576188 DOI: 10.1186/1471-213x-8-100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Accepted: 10/12/2008] [Indexed: 11/28/2022]
Abstract
BACKGROUND The restoration of adults from fragments of blood vessels in botryllid ascidians (termed whole body regeneration [WBR]) represents an inimitable event in the chordates, which is poorly understood on the mechanistic level. RESULTS To elucidate mechanisms underlying this phenomenon, a subtracted EST library for early WBR stages was previously assembled, revealing 76 putative genes belonging to major signaling pathways, including Notch/Delta, JAK/STAT, protein kinases, nuclear receptors, Ras oncogene family members, G-Protein coupled receptor (GPCR) and transforming growth factor beta (TGF-beta) signaling. RT-PCR on selected transcripts documented specific up-regulation in only regenerating fragments, pointing to a broad activation of these signaling pathways at onset of WBR. The followed-up expression pattern of seven representative transcripts from JAK/STAT signaling (Bl-STAT), the Ras oncogene family (Bl-Rap1A, Bl-Rab-33), the protein kinase family (Bl-Mnk), Bl-Cnot, Bl-Slit and Bl-Bax inhibitor, revealed systemic and site specific activations during WBR in a sub-population of circulatory cells. CONCLUSION WBR in the non-vertebrate chordate Botrylloides leachi is a multifaceted phenomenon, presided by a complex array of cell signaling and transcription factors. Above results, provide a first insight into the whole genome molecular machinery of this unique regeneration process, and reveal the broad participation of cell signaling and transcription factors in the process. While regeneration involves the participation of specific cell populations, WBR signals are systemically expressed at the organism level.
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Affiliation(s)
- Yuval Rinkevich
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa, Israel
| | - Baruch Rinkevich
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Tel Shikmona, Haifa 31080, Israel
| | - Ram Reshef
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa, Israel
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Burighel P, Caicci F, Zaniolo G, Gasparini F, Degasperi V, Manni L. Does hair cell differentiation predate the vertebrate appearance? Brain Res Bull 2007; 75:331-4. [PMID: 18331894 DOI: 10.1016/j.brainresbull.2007.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Accepted: 10/17/2007] [Indexed: 11/19/2022]
Abstract
It is generally accepted that the three main chordate groups (tunicates, cephalochordates and vertebrates) originated from a common ancestor having the basic features of the chordate body plan, i.e. a neural tube and a notochord flanked by striated musculature. There is now increasing evidence that tunicates, rather than cephalochordates, are the vertebrate sister-group. Correlated with this, tunicates have sensory structures similar to those derived from placodes or neural crest in vertebrates. In this context, we discuss here whether the precursors of vertebrate hair cells, which are placodal in origin, were present in ancestral chordates. The ascidian tunicates possess a coronal organ, consisting of a row of mechanosensory cells that runs around the base of the oral siphon. Its function is to monitor the incoming water flow. The cells are secondary sensory cells, i.e. they lack axons and synapse with neurons whose somata lie in the cerebral ganglion. They are accompanied by supporting cells and, as in vertebrates, have varying morphologies in the species so far examined: in one order (Enterogona), they are multiciliate; in the other (Pleurogona), they may possess an apical apparatus, consisting of one or two cilia accompanied by stereovilli, that are graded in length. Coronal cells thus resemble vertebrate hair cells closely in their morphology, embryonic origin and arrangement, which suggests they originated early in ancestral chordates. We are continuing our study of the coronal organ in other ascidian species, and report new data here on Botrylloides leachi, which conforms with the pattern of Pleurogona and, in particular, with previously published results on other botryllid ascidians.
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Affiliation(s)
- Paolo Burighel
- Department of Biology, University of Padova, Via U. Bassi 58/B 35131, Italy.
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10
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Elphick MR. BfCBR: a cannabinoid receptor ortholog in the cephalochordate Branchiostoma floridae (Amphioxus). Gene 2007; 399:65-71. [PMID: 17553639 DOI: 10.1016/j.gene.2007.04.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 04/17/2007] [Accepted: 04/26/2007] [Indexed: 02/06/2023]
Abstract
A gene encoding an ortholog of vertebrate CB(1)/CB(2) cannabinoid receptors was recently identified in the urochordate Ciona intestinalis (CiCBR; [Elphick, M.R., Satou, Y., Satoh, N., 2003. The invertebrate ancestry of endocannabinoid signalling: an orthologue of vertebrate cannabinoid receptors in the urochordate Ciona intestinalis. Gene 302, 95-101.]). Here a cannabinoid receptor ortholog (BfCBR) has been identified in the cephalochordate Branchiostoma floridae. BfCBR is encoded by a single exon and is 410 amino acid residue protein that shares 28% sequence identity with CiCBR and 23% sequence identity with human CB(1) and human CB(2). The discovery of BfCBR and CiCBR and the absence of cannabinoid receptor orthologs in non-chordate invertebrates indicate that CB(1)/CB(2)-like cannabinoid receptors originated in an invertebrate chordate ancestor of urochordates, cephalochordates and vertebrates. Furthermore, analysis of the relationship of BfCBR and CiCBR with vertebrate CB(1) and CB(2) receptors indicates that the gene/genome duplication that gave rise to CB(1) and CB(2) receptors occurred in the vertebrate lineage. Identification of BfCBR, in addition to CiCBR, paves the way for comparative analysis of the expression and functions of these proteins in Branchiostoma and Ciona, respectively, providing an insight into the ancestral functions of cannabinoid receptors in invertebrate chordates prior to the emergence of CB(1) and CB(2) receptors in vertebrates.
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Affiliation(s)
- Maurice R Elphick
- School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, UK.
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Voskoboynik A, Simon-Blecher N, Soen Y, Rinkevich B, De Tomaso AW, Ishizuka KJ, Weissman IL. Striving for normality: whole body regeneration through a series of abnormal generations. FASEB J 2007; 21:1335-44. [PMID: 17289924 DOI: 10.1096/fj.06-7337com] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Embryogenesis and asexual reproduction are commonly considered to be coordinated developmental processes, which depend on accurate progression through a defined sequence of developmental stages. Here we report a peculiar developmental scenario in a simple chordate, Botryllus schlosseri, wherein a normal colony of individuals (zooids and buds) is regenerated from the vasculature (vascular budding) through a sequence of morphologically abnormal developmental stages. Vascular budding was induced by surgically removing buds and zooids from B. schlosseri colonies, leaving only the vasculature and the tunic that connects them. In vivo imaging and histological sections showed that the timing and morphology of developing structures during vascular budding deviated significantly from other asexual reproduction modes (the regular asexual reproduction mode in this organism and vascular budding in other botryllid species). Subsequent asexual reproduction cycles exhibited gradual regaining of normal developmental patterns, eventually leading to regeneration of a normal colony. The conversion into a normal body form suggests the activation of an alternative pathway of asexual reproduction, which involves gradual regaining of normal positional information. It presents a powerful model for studying the specification of the same body plan by different developmental programs.
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Affiliation(s)
- Ayelet Voskoboynik
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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12
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Provorov NA, Dolgikh EA. [Metabolic integration of organisms within symbiotic systems]. Zh Obshch Biol 2006; 67:403-22. [PMID: 17205789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Adaptation of organisms to coexisence in symbiotic systems is usually related to significant metabolic changes resulting in the integration of the biochemical pathways of the partners. In the symbioses between plants and nitrogen-fixing organisms, between heterotrophic and autotrophic organisms, as well as between animals and microorganisms providing the consumption of plant biomass, the systems of C- and N-metabolism, controlling the utilization of various sources of nitrogen (N2, organic and inorganic compounds, metabolic waste of the host) and carbon (CO2, plant polymers), of the partners are tightly integrated. Bilateral biochemical links between partners are typical to mutualistic symbioses (wherein biotrophic nutrition predominates, in some cases including necrotrophy of secondary origin). In antagonistic symbioses, unilateral links predominate, though active assimilation of the pathogen's secondary metabolites by the host is also possible. In most mutualistic symbioses, integrated metabolic ties have derived from trophic chains in biocenoses (syntrophic consortia, "predator-prey" systems), but not from the systems where the pathogens consume host metabolites. At the same time, molecular analysis of symbiotic interactions has shown that symbioses considerably differ from biocenoses, where the cycling of nutrients and energy implies no functional integration of the partner's genes.
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Candiani S, Oliveri D, Parodi M, Pestarino M. Expression of AmphiNaC, a new member of the amiloride-sensitive sodium channel related to degenerins and epithelial sodium channels in amphioxus. Int J Biol Sci 2006; 2:79-86. [PMID: 16733538 PMCID: PMC1458428 DOI: 10.7150/ijbs.2.79] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Accepted: 03/22/2006] [Indexed: 11/05/2022] Open
Abstract
Degenerins and amiloride-sensitive Na+ channels form a new family of cationic ion channels (DEG/NaC). DEG/NaC family emerged as common denominator within a metazoan mechanosensory apparatus. In this study, we characterized a new member of such family in amphioxus, Branchiostoma floridae. The AmphiNaC cDNA sequence encodes a protein showing amino acid residues characteristic of DEG/NaC family, such as two hydrophobic domains surrounding a large extracellular loop that includes cystein-rich domains; nevertheless its predicted sequence is quite divergent from other family members. AmphiNaC is expressed at early larval stage in some putative sensory epidermal cells in the middle of the body and in neurons of the posterior cerebral vesicle, as well as in some ventrolateral and mediolateral neurons of the neural tube. In late larvae, AmphiNaC expression is maintained in some neurons of the neural tube, and it is expressed in putative sensory epidermal cells of rostrum and mouth. The analysis of AmphiNaC gene expression pattern suggests that it might be involved in neurotransmission and sensory modulation.
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Marlétaz F, Holland LZ, Laudet V, Schubert M. Retinoic acid signaling and the evolution of chordates. Int J Biol Sci 2006; 2:38-47. [PMID: 16733532 PMCID: PMC1458431 DOI: 10.7150/ijbs.2.38] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Accepted: 03/15/2006] [Indexed: 11/05/2022] Open
Abstract
In chordates, which comprise urochordates, cephalochordates and vertebrates, the vitamin A-derived morphogen retinoic acid (RA) has a pivotal role during development. Altering levels of endogenous RA signaling during early embryology leads to severe malformations, mainly due to incorrect positional codes specifying the embryonic anteroposterior body axis. In this review, we present our current understanding of the RA signaling pathway and its roles during chordate development. In particular, we focus on the conserved roles of RA and its downstream mediators, the Hox genes, in conveying positional patterning information to different embryonic tissues, such as the endoderm and the central nervous system. We find that some of the control mechanisms governing RA-mediated patterning are well conserved between vertebrates and invertebrate chordates, such as the cephalochordate amphioxus. In contrast, outside the chordates, evidence for roles of RA signaling is scarce and the evolutionary origin of the RA pathway itself thus remains elusive. In sum, to fully understand the evolutionary history of the RA pathway, future research should focus on identification and study of components of the RA signaling cascade in non-chordate deuterostomes (such as hemichordates and echinoderms) and other invertebrates, such as insects, mollusks and cnidarians.
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Affiliation(s)
- Ferdinand Marlétaz
- Laboratoire de Biologie Moléculaire de la Cellule, CNRS UMR5161/INRA 1237/ENS Lyon, IFR128 BioSciences/Lyon-Gerland, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
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15
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Abstract
Hemichordates, the phylum of bilateral animals closest to chordates, can illuminate the evolutionary origins of various chordate traits to determine whether these were already present in a shared ancestor (the deuterostome ancestor) or were evolved within the chordate line. We find that an anteroposterior map of gene expression domains, representing 42 genes of neural patterning, is closely similar in hemichordates and chordates, though it is restricted to the neural ectoderm in chordates whereas in hemichordates, which have a diffuse nervous system, it encircles the whole body. This map allows an accurate alignment of the anterioposterior axes of members of the two groups. We propose that this map dates back at least to the deuterostome ancestor. The map of dorsoventral expression domains, organized along a Bmp-Chordin developmental axis, is also similar in the two groups in terms of many gene expression domains and for the placement of the gill slits, heart, and post-anal tail. The two groups, however, differ in two major respects along this axis. The nervous system and epidermis are not segregated into distinct territories in hemichordates, as they are in chordates, and furthermore, the mouth is on the Chordin side in hemichordates but the Bmp side in chordates. The dorsoventral dimension has undergone extensive modification in the chordate line, including centralization of the nervous system, segregation of epidermis, derivation of the notochord, perhaps from the gut midline, and relocation of the mouth. Based on the shared domain maps, speculations can be made for the remodeling of the body axis in the chordate line.
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Affiliation(s)
- John Gerhart
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3200, USA.
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Abstract
The genetically and experimentally accessible organs of Drosophila, such as the heart or blood-forming tissues, have become a fertile ground for systematic projects of gene discovery and for functional studies of gene networks and signaling pathways. One argument justifying this approach is the often-tacit assumption that clear-cut homologies can be established between the Drosophila organs and their vertebrate counterparts. Here we investigate this assumption by surveying pertinent aspects of vascular structure and development in different invertebrate phyla, in the hope that this information will help to reveal the ancestral condition of the vascular system. Evolutionary scenarios that derive the structure of the cardiovascular system of extant animal taxa from the ancestral condition will be used to qualify hypotheses regarding homologies that are based on molecular similarities.
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Affiliation(s)
- Volker Hartenstein
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, CA 90095, USA.
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