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Meister L, Escriva H, Bertrand S. Functions of the FGF signalling pathway in cephalochordates provide insight into the evolution of the prechordal plate. Development 2022; 149:275365. [PMID: 35575387 PMCID: PMC9188755 DOI: 10.1242/dev.200252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 04/05/2022] [Indexed: 12/22/2022]
Abstract
The fibroblast growth factor (FGF) signalling pathway plays various roles during vertebrate embryogenesis, from mesoderm formation to brain patterning. This diversity of functions relies on the fact that vertebrates possess the largest FGF gene complement among metazoans. In the cephalochordate amphioxus, which belongs to the chordate clade together with vertebrates and tunicates, we have previously shown that the main role of FGF during early development is the control of rostral somite formation. Inhibition of this signalling pathway induces the loss of these structures, resulting in an embryo without anterior segmented mesoderm, as in the vertebrate head. Here, by combining several approaches, we show that the anterior presumptive paraxial mesoderm cells acquire an anterior axial fate when FGF signal is inhibited and that they are later incorporated in the anterior notochord. Our analysis of notochord formation in wild type and in embryos in which FGF signalling is inhibited also reveals that amphioxus anterior notochord presents transient prechordal plate features. Altogether, our results give insight into how changes in FGF functions during chordate evolution might have participated to the emergence of the complex vertebrate head. Summary: FGF signalling inhibition in cephalochordates induces a loss of anteriormost somites. After FGFR inhibition, the presomitic anterior region cells are incorporated in the anterior notochord which transiently present prechordal plate features.
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Affiliation(s)
- Lydvina Meister
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650 Banyuls-sur-Mer, France
| | - Hector Escriva
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650 Banyuls-sur-Mer, France
| | - Stéphanie Bertrand
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650 Banyuls-sur-Mer, France
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Leon A, Subirana L, Magre K, Cases I, Tena JJ, Irimia M, Gomez-Skarmeta JL, Escriva H, Bertrand S. Gene regulatory networks of epidermal and neural fate choice in a chordate. Mol Biol Evol 2022; 39:6547258. [PMID: 35276009 PMCID: PMC9004418 DOI: 10.1093/molbev/msac055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Neurons are a highly specialized cell type only found in metazoans. They can be scattered throughout the body or grouped together, forming ganglia or nerve cords. During embryogenesis, centralized nervous systems develop from the ectoderm, which also forms the epidermis. How pluripotent ectodermal cells are directed toward neural or epidermal fates, and to which extent this process is shared among different animal lineages, are still open questions. Here, by using micromere explants, we were able to define in silico the putative gene regulatory networks (GRNs) underlying the first steps of the epidermis and the central nervous system formation in the cephalochordate amphioxus. We propose that although the signal triggering neural induction in amphioxus (i.e., Nodal) is different from vertebrates, the main transcription factors implicated in this process are conserved. Moreover, our data reveal that transcription factors of the neural program seem to not only activate neural genes but also to potentially have direct inputs into the epidermal GRN, suggesting that the Nodal signal might also contribute to neural fate commitment by repressing the epidermal program. Our functional data on whole embryos support this result and highlight the complex interactions among the transcription factors activated by the signaling pathways that drive ectodermal cell fate choice in chordates.
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Affiliation(s)
- Anthony Leon
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650, Banyuls-sur-Mer, France
| | - Lucie Subirana
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650, Banyuls-sur-Mer, France
| | - Kevin Magre
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650, Banyuls-sur-Mer, France
| | - Ildefonso Cases
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Sevilla, Spain
| | - Juan J Tena
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Sevilla, Spain
| | - Manuel Irimia
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Jose Luis Gomez-Skarmeta
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Sevilla, Spain
| | - Hector Escriva
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650, Banyuls-sur-Mer, France
| | - Stéphanie Bertrand
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins, BIOM, F-66650, Banyuls-sur-Mer, France
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Kumar V, Park S, Lee U, Kim J. The Organizer and Its Signaling in Embryonic Development. J Dev Biol 2021; 9:jdb9040047. [PMID: 34842722 PMCID: PMC8628936 DOI: 10.3390/jdb9040047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 12/25/2022] Open
Abstract
Germ layer specification and axis formation are crucial events in embryonic development. The Spemann organizer regulates the early developmental processes by multiple regulatory mechanisms. This review focuses on the responsive signaling in organizer formation and how the organizer orchestrates the germ layer specification in vertebrates. Accumulated evidence indicates that the organizer influences embryonic development by dual signaling. Two parallel processes, the migration of the organizer’s cells, followed by the transcriptional activation/deactivation of target genes, and the diffusion of secreting molecules, collectively direct the early development. Finally, we take an in-depth look at active signaling that originates from the organizer and involves germ layer specification and patterning.
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Affiliation(s)
- Vijay Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea;
| | - Soochul Park
- Department of Biological Sciences, Sookmyung Women’s University, Seoul 04310, Korea;
| | - Unjoo Lee
- Department of Electrical Engineering, Hallym University, Chuncheon 24252, Korea
- Correspondence: (U.L.); (J.K.); Tel.: +82-33-248-2544 (J.K.); Fax: +82-33-244-8425 (J.K.)
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea;
- Correspondence: (U.L.); (J.K.); Tel.: +82-33-248-2544 (J.K.); Fax: +82-33-244-8425 (J.K.)
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Yasuoka Y, Tando Y, Kubokawa K, Taira M. Evolution of cis-regulatory modules for the head organizer gene goosecoid in chordates: comparisons between Branchiostoma and Xenopus. ZOOLOGICAL LETTERS 2019; 5:27. [PMID: 31388442 PMCID: PMC6679436 DOI: 10.1186/s40851-019-0143-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 07/12/2019] [Indexed: 05/03/2023]
Abstract
BACKGROUND In cephalochordates (amphioxus), the notochord runs along the dorsal to the anterior tip of the body. In contrast, the vertebrate head is formed anterior to the notochord, as a result of head organizer formation in anterior mesoderm during early development. A key gene for the vertebrate head organizer, goosecoid (gsc), is broadly expressed in the dorsal mesoderm of amphioxus gastrula. Amphioxus gsc expression subsequently becomes restricted to the posterior notochord from the early neurula. This has prompted the hypothesis that a change in expression patterns of gsc led to development of the vertebrate head during chordate evolution. However, molecular mechanisms of head organizer evolution involving gsc have never been elucidated. RESULTS To address this question, we compared cis-regulatory modules of vertebrate organizer genes between amphioxus, Branchiostoma japonicum, and frogs, Xenopus laevis and Xenopus tropicalis. Here we show conservation and diversification of gene regulatory mechanisms through cis-regulatory modules for gsc, lim1/lhx1, and chordin in Branchiostoma and Xenopus. Reporter analysis using Xenopus embryos demonstrates that activation of gsc by Nodal/FoxH1 signal through the 5' upstream region, that of lim1 by Nodal/FoxH1 signal through the first intron, and that of chordin by Lim1 through the second intron, are conserved between amphioxus and Xenopus. However, activation of gsc by Lim1 and Otx through the 5' upstream region in Xenopus are not conserved in amphioxus. Furthermore, the 5' region of amphioxus gsc recapitulated the amphioxus-like posterior mesoderm expression of the reporter gene in transgenic Xenopus embryos. CONCLUSIONS On the basis of this study, we propose a model, in which the gsc gene acquired the cis-regulatory module bound with Lim1 and Otx at its 5' upstream region to be activated persistently in anterior mesoderm, in the vertebrate lineage. Because Gsc globally represses trunk (notochord) genes in the vertebrate head organizer, this cooption of gsc in vertebrates appears to have resulted in inhibition of trunk genes and acquisition of the head organizer and its derivative prechordal plate.
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Affiliation(s)
- Yuuri Yasuoka
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, 904-0495 Japan
- Laboratory for Comprehensive Genomic Analysis, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045 Japan
| | - Yukiko Tando
- Center for Advance Marine Research, Ocean Research Institute, The University of Tokyo, 1-15-1, Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
- Present address: Cell Resource Center for Biomedical Research, Institute of Development, Aging and Cancer (IDAC), Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575 Japan
| | - Kaoru Kubokawa
- Center for Advance Marine Research, Ocean Research Institute, The University of Tokyo, 1-15-1, Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
- Present address: SIRC, Teikyo University, 2-11-1, Itabashi-ku, Tokyo, 173-8605 Japan
| | - Masanori Taira
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
- Present address: Department of Biological Sciences, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo, 112-8551 Japan
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Segade F, Cota C, Famiglietti A, Cha A, Davidson B. Fibronectin contributes to notochord intercalation in the invertebrate chordate, Ciona intestinalis. EvoDevo 2016; 7:21. [PMID: 27583126 PMCID: PMC5006582 DOI: 10.1186/s13227-016-0056-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 08/13/2016] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/vertebrate ancestor. RESULTS Characterization of developmental genes uniquely shared by tunicates and vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a vertebrate-specific gene, playing a major instructive role in vertebrate embryonic development. However, the recent computational prediction of an orthologous "vertebrate-like" Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn may have arisen in the shared tunicate/vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension. CONCLUSIONS These findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the vertebrate/tunicate ancestor.
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Affiliation(s)
- Fernando Segade
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA 19104 USA
| | - Christina Cota
- Department of Biology, Swarthmore College, 500 College Ave., Swarthmore, PA 19081 USA
| | - Amber Famiglietti
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892 USA
| | - Anna Cha
- Department of Systems Biology, Harvard Medical School, Boston, MA USA
| | - Brad Davidson
- Department of Biology, Swarthmore College, 500 College Ave., Swarthmore, PA 19081 USA
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Di Maio A, Setar L, Tiozzo S, De Tomaso AW. Wnt affects symmetry and morphogenesis during post-embryonic development in colonial chordates. EvoDevo 2015; 6:17. [PMID: 26171140 PMCID: PMC4499891 DOI: 10.1186/s13227-015-0009-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/09/2015] [Indexed: 12/26/2022] Open
Abstract
Background Wnt signaling is one of the earliest and most highly conserved regulatory pathways for the establishment of the body axes during regeneration and early development. In regeneration, body axes determination occurs independently of tissue rearrangement and early developmental cues. Modulation of the Wnt signaling in either process has shown to result in unusual body axis phenotypes. Botryllus schlosseri is a colonial ascidian that can regenerate its entire body through asexual budding. This processes leads to an adult body via a stereotypical developmental pathway (called blastogenesis), without proceeding through any embryonic developmental stages. Results In this study, we describe the role of the canonical Wnt pathway during the early stages of asexual development. We characterized expression of three Wnt ligands (Wnt2B, Wnt5A, and Wnt9A) by in situ hybridization and qRT-PCR. Chemical manipulation of the pathway resulted in atypical budding due to the duplication of the A/P axes, supernumerary budding, and loss of the overall cell apical-basal polarity. Conclusions Our results suggest that Wnt signaling is used for equivalent developmental processes both during embryogenesis and asexual development in an adult organism, suggesting that patterning mechanisms driving morphogenesis are conserved, independent of embryonic, or regenerative development. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0009-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alessandro Di Maio
- School of Bioscience, University of Birmingham, Edgbaston, Birmingham, B19 2TT UK.,Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106 USA
| | - Leah Setar
- Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106 USA
| | - Stefano Tiozzo
- CNRS, Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanographique, 06230 Villefranche-sur-mer, France
| | - Anthony W De Tomaso
- Molecular Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106 USA
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7
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Organizer regions in marine colonial hydrozoans. ZOOLOGY 2015; 118:89-101. [DOI: 10.1016/j.zool.2014.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/20/2014] [Accepted: 12/21/2014] [Indexed: 01/08/2023]
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Liu X, Sun Y, Zhang J, Li G, Wang Y. Identification of up-regulated genes in amphioxus neurula and the expression of AmphiFABP. Genes Genet Syst 2011; 86:37-46. [PMID: 21498921 DOI: 10.1266/ggs.86.37] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Amphioxus is a good model organism for understanding the origin and developmental mechanism of vertebrates owing to its important evolutionary position. During the developmental process of amphioxus embryo, the neurula is a crucial stage because of neural tube and notochord formation as well as somite emergence at this stage. In order to isolate genes up-regulated at the neurula stage, we constructed an 11-hour neurula subtracted cDNA library of amphioxus Branchiostoma belcheri and sequenced 204 ESTs representing 82 contigs. Comparative analysis revealed that 55% of those contigs were homologous to various known genes while 45% of them had no significant similarity to any known genes. Those observations imply that the un-identified ESTs might contain some new genes which are involved in the development of amphioxus neurula. Real-time quantitative PCR (RTqPCR) indicated that the expression levels of 14 genes are up-regulated after gastrulation among 20 assayed genes. Of those up-regulated genes, we further cloned and sequenced the full-length of fatty acid binding protein gene (AmphiFABP). The deduced protein sequence was similar to that of vertebrate brain FABP and heart FABP, and in situ hybridization displayed that AmphiFABP, similar to their vertebrate cognates, was expressed not only in nervous system but also in embryonic somite and gut, hinting a multifunctional property of AmphiFABP in amphioxus.
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Affiliation(s)
- Xiaohui Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Japan
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Kraus YA. Inductive activity of the posterior tip of planula in the marine hydroid Dynamena pumila. Russ J Dev Biol 2011. [DOI: 10.1134/s106236041102010x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Garcia-Fernàndez J, Benito-Gutiérrez E. It's a long way from amphioxus: descendants of the earliest chordate. Bioessays 2009; 31:665-75. [PMID: 19408244 DOI: 10.1002/bies.200800110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The origin of chordates and the consequent genesis of vertebrates were major events in natural history. The amphioxus (lancelet) is now recognised as the closest extant relative to the stem chordate and is the only living invertebrate that retains a vertebrate-like development and body plan through its lifespan, despite more than 500 million years of independent evolution from the stem vertebrate. The inspiring data coming from its recently sequenced genome confirms that amphioxus has a prototypical chordate genome with respect to gene content and structure, and even chromosomal organisation. Pushed by joint efforts of amphioxus researchers, amphioxus is now entering a new era, namely its maturation as a laboratory model, through the availability of a large amount of molecular data and the advent of experimental manipulation of the embryo. These two facts may well serve to illuminate the hidden secrets of the genetic changes that generated, among other vertebrates, ourselves.
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Affiliation(s)
- Jordi Garcia-Fernàndez
- Departament de Genètica and Institut de Biomedicina (IBUB), Universitat de Barcelona, Spain.
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Huminiecki L, Goldovsky L, Freilich S, Moustakas A, Ouzounis C, Heldin CH. Emergence, development and diversification of the TGF-beta signalling pathway within the animal kingdom. BMC Evol Biol 2009; 9:28. [PMID: 19192293 PMCID: PMC2657120 DOI: 10.1186/1471-2148-9-28] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 02/03/2009] [Indexed: 11/20/2022] Open
Abstract
Background The question of how genomic processes, such as gene duplication, give rise to co-ordinated organismal properties, such as emergence of new body plans, organs and lifestyles, is of importance in developmental and evolutionary biology. Herein, we focus on the diversification of the transforming growth factor-β (TGF-β) pathway – one of the fundamental and versatile metazoan signal transduction engines. Results After an investigation of 33 genomes, we show that the emergence of the TGF-β pathway coincided with appearance of the first known animal species. The primordial pathway repertoire consisted of four Smads and four receptors, similar to those observed in the extant genome of the early diverging tablet animal (Trichoplax adhaerens). We subsequently retrace duplications in ancestral genomes on the lineage leading to humans, as well as lineage-specific duplications, such as those which gave rise to novel Smads and receptors in teleost fishes. We conclude that the diversification of the TGF-β pathway can be parsimoniously explained according to the 2R model, with additional rounds of duplications in teleost fishes. Finally, we investigate duplications followed by accelerated evolution which gave rise to an atypical TGF-β pathway in free-living bacterial feeding nematodes of the genus Rhabditis. Conclusion Our results challenge the view of well-conserved developmental pathways. The TGF-β signal transduction engine has expanded through gene duplication, continually adopting new functions, as animals grew in anatomical complexity, colonized new environments, and developed an active immune system.
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Affiliation(s)
- Lukasz Huminiecki
- Ludwig Institute for Cancer Research, Uppsala University, Uppsala, Sweden.
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12
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Nuclear hormone receptor signaling in amphioxus. Dev Genes Evol 2008; 218:651-65. [DOI: 10.1007/s00427-008-0251-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
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Shook DR, Keller R. Morphogenic machines evolve more rapidly than the signals that pattern them: lessons from amphibians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2008; 310:111-35. [PMID: 18041048 DOI: 10.1002/jez.b.21204] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The induction of mesoderm and the patterning of its dorsal-ventral and anterior-posterior axes seems to be relatively conserved throughout the chordates, as do the morphogenic movements that produce a phylotypic stage embryo. What is not conserved is the initial embryonic architecture of the fertilized egg, and the specific cell behaviors used to drive mesoderm morphogenesis. How then do conserved patterning pathways adapt to diverse architectures and where do they diverge to direct the different cell behaviors used to shape the phylotypic body plan? Amphibians in particular, probably because of their broad range of reproductive strategies, show diverse embryonic architectures across their class and use diverse cell behaviors during their early morphogenesis, making them an interesting comparative group. We examine three examples from our work on amphibians that show variations in the use of cell behaviors to drive the morphogenesis of the same tissues. We also consider possible points where the conserved patterning pathways might diverge to produce different cell behaviors.
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Affiliation(s)
- David R Shook
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904-4328, USA.
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