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Leclercq J, Torres-Paz J, Policarpo M, Agnès F, Rétaux S. Evolution of the regulation of developmental gene expression in blind Mexican cavefish. Development 2024; 151:dev202610. [PMID: 39007346 DOI: 10.1242/dev.202610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 07/08/2024] [Indexed: 07/16/2024]
Abstract
Developmental evolution and diversification of morphology can arise through changes in the regulation of gene expression or protein-coding sequence. To unravel mechanisms underlying early developmental evolution in cavefish of the species Astyanax mexicanus, we compared transcriptomes of surface-dwelling and blind cave-adapted morphs at the end of gastrulation. Twenty percent of the transcriptome was differentially expressed. Allelic expression ratios in cave X surface hybrids showed that cis-regulatory changes are the quasi-exclusive contributors to inter-morph variations in gene expression. Among a list of 108 genes with change at the cis-regulatory level, we explored the control of expression of rx3, which is a master eye gene. We discovered that cellular rx3 levels are cis-regulated in a cell-autonomous manner, whereas rx3 domain size depends on non-autonomous Wnt and Bmp signalling. These results highlight how uncoupled mechanisms and regulatory modules control developmental gene expression and shape morphological changes. Finally, a transcriptome-wide search for fixed coding mutations and differential exon use suggested that variations in coding sequence have a minor contribution. Thus, during early embryogenesis, changes in gene expression regulation are the main drivers of cavefish developmental evolution.
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Affiliation(s)
- Julien Leclercq
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-Saclay, 91400 Saclay, France
| | - Jorge Torres-Paz
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-Saclay, 91400 Saclay, France
| | - Maxime Policarpo
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-Saclay, 91400 Saclay, France
| | - François Agnès
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-Saclay, 91400 Saclay, France
| | - Sylvie Rétaux
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-Saclay, 91400 Saclay, France
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2
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van der Weele CM, Hospes KC, Rowe KE, Jeffery WR. Hypoxia-Sonic Hedgehog Axis as a Driver of Primitive Hematopoiesis Development and Evolution in Cavefish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.09.598120. [PMID: 38895301 PMCID: PMC11185782 DOI: 10.1101/2024.06.09.598120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
The teleost Astyanax mexicanus consists of surface dwelling (surface fish) and cave dwelling (cavefish) forms. Cavefish have evolved in subterranean habitats characterized by reduced oxygen levels (hypoxia) and show constructive and regressive phenotypic traits controlled by increased Sonic hedgehog (Shh) signaling along the embryonic midline. The enhancement of primitive hematopoietic domains, which are formed bilaterally in the anterior and posterior lateral plate mesoderm, are responsible for the development of more larval erythrocytes in cavefish relative to surface fish. In this study, we determine the role of hypoxia and Shh signaling in the development and evolution of primitive hematopoiesis in cavefish. We show that hypoxia treatment during embryogenesis increases primitive hematopoiesis and erythrocyte development in surface fish. We also demonstrate that upregulation of Shh midline signaling by treatment with the Smoothened agonist SAG increases primitive hematopoiesis and erythrocyte development in surface fish, whereas Shh downregulation via treatment with the Smoothened inhibitor cyclopamine decreases these traits in cavefish. Together these results suggest that hematopoietic enhancement is regulated by hypoxia and the Shh signaling system. Lastly, we demonstrate that hypoxia treatment enhances expression of Shh signaling along the midline of surface fish embryos. Thus, we conclude that a hypoxia-Shh axis may drive the adaptive evolution of primitive hematopoiesis and erythrocyte development in cavefish. Highlights Hypoxia increases hematopoiesis and erythrocytes in surface fishShh upregulation increases hematopoiesis and erythrocytes in surface fishShh inhibition decreases hematopoiesis and erythrocytes in cavefishHypoxia upregulates Shh along the embryonic midline in surface fish.
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3
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Blin M, Valay L, Kuratko M, Pavie M, Rétaux S. The evolution of olfactory sensitivity, preferences, and behavioral responses in Mexican cavefish is influenced by fish personality. eLife 2024; 12:RP92861. [PMID: 38832493 PMCID: PMC11149931 DOI: 10.7554/elife.92861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024] Open
Abstract
Animals are adapted to their natural habitats and lifestyles. Their brains perceive the external world via their sensory systems, compute information together with that of internal states and autonomous activity, and generate appropriate behavioral outputs. However, how do these processes evolve across evolution? Here, focusing on the sense of olfaction, we have studied the evolution in olfactory sensitivity, preferences, and behavioral responses to six different food-related amino acid odors in the two eco-morphs of the fish Astyanax mexicanus. To this end, we have developed a high-throughput behavioral setup and pipeline of quantitative and qualitative behavior analysis, and we have tested 489 six-week-old Astyanax larvae. The blind, dark-adapted morphs of the species showed markedly distinct basal swimming patterns and behavioral responses to odors, higher olfactory sensitivity, and a strong preference for alanine, as compared to their river-dwelling eyed conspecifics. In addition, we discovered that fish have an individual 'swimming personality', and that this personality influences their capability to respond efficiently to odors and find the source. Importantly, the personality traits that favored significant responses to odors were different in surface fish and cavefish. Moreover, the responses displayed by second-generation cave × surface F2 hybrids suggested that olfactory-driven behavior and olfactory sensitivity is a quantitative genetic trait. Our findings show that olfactory processing has rapidly evolved in cavefish at several levels: detection threshold, odor preference, and foraging behavior strategy. Cavefish is therefore an outstanding model to understand the genetic, molecular, and neurophysiological basis of sensory specialization in response to environmental change.
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Affiliation(s)
- Maryline Blin
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-SaclaySaclayFrance
| | - Louis Valay
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-SaclaySaclayFrance
| | - Manon Kuratko
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-SaclaySaclayFrance
| | - Marie Pavie
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-SaclaySaclayFrance
| | - Sylvie Rétaux
- Paris-Saclay Institute of Neuroscience, CNRS and University Paris-SaclaySaclayFrance
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4
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Sifuentes-Romero I, Aviles AM, Carter JL, Chan-Pong A, Clarke A, Crotty P, Engstrom D, Meka P, Perez A, Perez R, Phelan C, Sharrard T, Smirnova MI, Wade AJ, Kowalko JE. Trait Loss in Evolution: What Cavefish Have Taught Us about Mechanisms Underlying Eye Regression. Integr Comp Biol 2023; 63:393-406. [PMID: 37218721 PMCID: PMC10445413 DOI: 10.1093/icb/icad032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/18/2023] [Accepted: 04/24/2023] [Indexed: 05/24/2023] Open
Abstract
Reduction or complete loss of traits is a common occurrence throughout evolutionary history. In spite of this, numerous questions remain about why and how trait loss has occurred. Cave animals are an excellent system in which these questions can be answered, as multiple traits, including eyes and pigmentation, have been repeatedly reduced or lost across populations of cave species. This review focuses on how the blind Mexican cavefish, Astyanax mexicanus, has been used as a model system for examining the developmental, genetic, and evolutionary mechanisms that underlie eye regression in cave animals. We focus on multiple aspects of how eye regression evolved in A. mexicanus, including the developmental and genetic pathways that contribute to eye regression, the effects of the evolution of eye regression on other traits that have also evolved in A. mexicanus, and the evolutionary forces contributing to eye regression. We also discuss what is known about the repeated evolution of eye regression, both across populations of A. mexicanus cavefish and across cave animals more generally. Finally, we offer perspectives on how cavefish can be used in the future to further elucidate mechanisms underlying trait loss using tools and resources that have recently become available.
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Affiliation(s)
- Itzel Sifuentes-Romero
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
| | - Ari M Aviles
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
- Department of Cell Biology and Genetics, Texas A&M University, College Station, TX 77843, USA
| | - Joseph L Carter
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Allen Chan-Pong
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Anik Clarke
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Patrick Crotty
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - David Engstrom
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Pranav Meka
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Alexandra Perez
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Riley Perez
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Christine Phelan
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Taylor Sharrard
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Maria I Smirnova
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, USA
- Stiles–Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL 33458, USA
- Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, FL 33431, USA
| | - Amanda J Wade
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
| | - Johanna E Kowalko
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter FL 33458, USA
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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5
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Marconi A, Yang CZ, McKay S, Santos ME. Morphological and temporal variation in early embryogenesis contributes to species divergence in Malawi cichlid fishes. Evol Dev 2023; 25:170-193. [PMID: 36748313 PMCID: PMC10909517 DOI: 10.1111/ede.12429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 12/18/2022] [Accepted: 01/20/2023] [Indexed: 02/08/2023]
Abstract
The cichlid fishes comprise the largest extant vertebrate family and are the quintessential example of rapid "explosive" adaptive radiations and phenotypic diversification. Despite low genetic divergence, East African cichlids harbor a spectacular intra- and interspecific morphological diversity, including the hyper-variable, neural crest (NC)-derived traits such as coloration and craniofacial skeleton. Although the genetic and developmental basis of these phenotypes has been investigated, understanding of when, and specifically how early, in ontogeny species-specific differences emerge, remains limited. Since adult traits often originate during embryonic development, the processes of embryogenesis could serve as a potential source of species-specific variation. Consequently, we designed a staging system by which we compare the features of embryogenesis between three Malawi cichlid species-Astatotilapia calliptera, Tropheops sp. 'mauve' and Rhamphochromis sp. "chilingali"-representing a wide spectrum of variation in pigmentation and craniofacial morphologies. Our results showed fundamental differences in multiple aspects of embryogenesis that could underlie interspecific divergence in adult adaptive traits. First, we identified variation in the somite number and signatures of temporal variation, or heterochrony, in the rates of somite formation. The heterochrony was also evident within and between species throughout ontogeny, up to the juvenile stages. Finally, the identified interspecific differences in the development of pigmentation and craniofacial cartilages, present at the earliest stages of their overt formation, provide compelling evidence that the species-specific trajectories begin divergence during early embryogenesis, potentially during somitogenesis and NC development. Altogether, our results expand our understanding of fundamental cichlid biology and provide new insights into the developmental origins of vertebrate morphological diversity.
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Affiliation(s)
| | | | - Samuel McKay
- Department of ZoologyUniversity of CambridgeCambridgeUK
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6
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Hagadorn MA, Hunter FK, DeLory T, Johnson MM, Pitts-Singer TL, Kapheim KM. Maternal body condition and season influence RNA deposition in the oocytes of alfalfa leafcutting bees ( Megachile rotundata). Front Genet 2023; 13:1064332. [PMID: 36685934 PMCID: PMC9845908 DOI: 10.3389/fgene.2022.1064332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 11/28/2022] [Indexed: 01/06/2023] Open
Abstract
Maternal effects are an important source of phenotypic variance, whereby females influence offspring developmental trajectory beyond direct genetic contributions, often in response to changing environmental conditions. However, relatively little is known about the mechanisms by which maternal experience is translated into molecular signals that shape offspring development. One such signal may be maternal RNA transcripts (mRNAs and miRNAs) deposited into maturing oocytes. These regulate the earliest stages of development of all animals, but are understudied in most insects. Here we investigated the effects of female internal (body condition) and external (time of season) environmental conditions on maternal RNA in the maturing oocytes and 24-h-old eggs (24-h eggs) of alfalfa leafcutting bees. Using gene expression and WGCNA analysis, we found that females adjust the quantity of mRNAs related to protein phosphorylation, transcriptional regulation, and nuclease activity deposited into maturing oocytes in response to both poor body condition and shorter day lengths that accompany the late season. However, the magnitude of these changes was higher for time of season. Females also adjusted miRNA deposition in response to seasonal changes, but not body condition. We did not observe significant changes in maternal RNAs in response to either body condition or time of season in 24-h eggs, which were past the maternal-to-zygotic transition. Our results suggest that females adjust the RNA transcripts they provide for offspring to regulate development in response to both internal and external environmental cues. Variation in maternal RNAs may, therefore, be important for regulating offspring phenotype in response to environmental change.
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Affiliation(s)
- Mallory A. Hagadorn
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Frances K. Hunter
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Tim DeLory
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States
| | - Makenna M. Johnson
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States,United States Department of Agriculture, Agricultural Research Service, Pollinating Insects Research Unit, Logan, UT, United States
| | - Theresa L. Pitts-Singer
- United States Department of Agriculture, Agricultural Research Service, Pollinating Insects Research Unit, Logan, UT, United States
| | - Karen M. Kapheim
- Department of Biology, Department of Biology, Utah State University, Logan, UT, United States,*Correspondence: Karen M. Kapheim ,
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7
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Concha ML, Reig G. Origin, form and function of extraembryonic structures in teleost fishes. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210264. [PMID: 36252221 PMCID: PMC9574637 DOI: 10.1098/rstb.2021.0264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/12/2022] [Indexed: 12/18/2022] Open
Abstract
Teleost eggs have evolved a highly derived early developmental pattern within vertebrates as a result of the meroblastic cleavage pattern, giving rise to a polar stratified architecture containing a large acellular yolk and a small cellular blastoderm on top. Besides the acellular yolk, the teleost-specific yolk syncytial layer (YSL) and the superficial epithelial enveloping layer are recognized as extraembryonic structures that play critical roles throughout embryonic development. They provide enriched microenvironments in which molecular feedback loops, cellular interactions and mechanical signals emerge to sculpt, among other things, embryonic patterning along the dorsoventral and left-right axes, mesendodermal specification and the execution of morphogenetic movements in the early embryo and during organogenesis. An emerging concept points to a critical role of extraembryonic structures in reinforcing early genetic and morphogenetic programmes in reciprocal coordination with the embryonic blastoderm, providing the necessary boundary conditions for development to proceed. In addition, the role of the enveloping cell layer in providing mechanical, osmotic and immunological protection during early stages of development, and the autonomous nutritional support provided by the yolk and YSL, have probably been key aspects that have enabled the massive radiation of teleosts to colonize every ecological niche on the Earth. This article is part of the theme issue 'Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom'.
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Affiliation(s)
- Miguel L. Concha
- Integrative Biology Program, Institute of Biomedical Sciences (ICBM), Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
- Biomedical Neuroscience Institute (BNI), Santiago 8380453, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago 7800003, Chile
| | - Germán Reig
- Escuela de Tecnología Médica y del Centro Integrativo de Biología y Química Aplicada (CIBQA), Universidad Bernardo O’Higgins, Santiago 7800003, Chile
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8
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Rétaux S. [The toolbox of developmental evolution or how Mexican cave fishes lost their eyes]. Biol Aujourdhui 2022; 216:49-53. [PMID: 35876521 DOI: 10.1051/jbio/2022011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Indexed: 06/15/2023]
Abstract
The fish Astyanax mexicanus comes in two very different forms: a "normal" river morph, and a blind, depigmented cave morph, living in the total and permanent darkness of Mexican caves. This species is on the way to becoming a model of choice in evolutionary and comparative biology, both for the study of the evolution of behavior, physiology or morphology, and for molecular genetics or population genetics. Here, I present the advancement of knowledge in the field of the developmental evolution of the eye of the cave morph. By rewinding back in time its development from the eye of the larva to the retinal field at the end of gastrulation, the cave-dwelling Astyanax embryo reveals mechanisms and processes likely to contribute to evolutionary variations between species, but also to pathological variations in the morphogenesis of the optic region.
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9
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Agnès F, Torres-Paz J, Michel P, Rétaux S. A 3D molecular map of the cavefish neural plate illuminates eye-field organization and its borders in vertebrates. Development 2022; 149:274971. [DOI: 10.1242/dev.199966] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 03/18/2022] [Indexed: 01/21/2023]
Abstract
ABSTRACT
The vertebrate retinas originate from a specific anlage in the anterior neural plate called the eye field. Its identity is conferred by a set of ‘eye transcription factors’, whose combinatorial expression has been overlooked. Here, we use the dimorphic teleost Astyanax mexicanus, which develops proper eyes in the wild type and smaller colobomatous eyes in the blind cavefish embryos, to unravel the molecular anatomy of the eye field and its variations within a species. Using a series of markers (rx3, pax6a, cxcr4b, zic1, lhx2, emx3 and nkx2.1a), we draw a comparative 3D expression map at the end of gastrulation/onset of neurulation, which highlights hyper-regionalization of the eye field into sub-territories of distinct sizes, shapes, cell identities and combinatorial gene expression levels along the three body axes. All these features show significant variations in the cavefish natural mutant. We also discover sub-domains within the prospective telencephalon and characterize cell identities at the frontiers of the eye field. We propose putative fates for some of the characterized eye-field subdivisions, and suggest the existence of a trade-off between some subdivisions in the two Astyanax morphs on a micro-evolutionary scale.
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Affiliation(s)
- François Agnès
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Jorge Torres-Paz
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Pauline Michel
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Sylvie Rétaux
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
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10
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van der Weele CM, Jeffery WR. Cavefish cope with environmental hypoxia by developing more erythrocytes and overexpression of hypoxia-inducible genes. eLife 2022; 11:69109. [PMID: 34984980 PMCID: PMC8765751 DOI: 10.7554/elife.69109] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 12/31/2021] [Indexed: 12/24/2022] Open
Abstract
Dark caves lacking primary productivity can expose subterranean animals to hypoxia. We used the surface-dwelling (surface fish) and cave-dwelling (cavefish) morphs of Astyanax mexicanus as a model for understanding the mechanisms of hypoxia tolerance in the cave environment. Primitive hematopoiesis, which is restricted to the posterior lateral mesoderm in other teleosts, also occurs in the anterior lateral mesoderm in Astyanax, potentially pre-adapting surface fish for hypoxic cave colonization. Cavefish have enlarged both hematopoietic domains and develop more erythrocytes than surface fish, which are required for normal development in both morphs. Laboratory-induced hypoxia suppresses growth in surface fish but not in cavefish. Both morphs respond to hypoxia by overexpressing hypoxia-inducible factor 1 (hif1) pathway genes, and some hif1 genes are constitutively upregulated in normoxic cavefish to similar levels as in hypoxic surface fish. We conclude that cavefish cope with hypoxia by increasing erythrocyte development and constitutive hif1 gene overexpression.
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Affiliation(s)
| | - William R Jeffery
- Department of Biology, University of Maryland, College Park, United States
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11
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Devos L, Agnès F, Edouard J, Simon V, Legendre L, El Khallouki N, Barbachou S, Sohm F, Rétaux S. Eye morphogenesis in the blind Mexican cavefish. Biol Open 2021; 10:bio059031. [PMID: 34590124 PMCID: PMC8565469 DOI: 10.1242/bio.059031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 01/13/2023] Open
Abstract
The morphogenesis of the vertebrate eye consists of a complex choreography of cell movements, tightly coupled to axial regionalization and cell type specification processes. Disturbances in these events can lead to developmental defects and blindness. Here, we have deciphered the sequence of defective events leading to coloboma in the embryonic eye of the blind cavefish of the species Astyanax mexicanus. Using comparative live imaging on targeted enhancer-trap Zic1:hsp70:GFP reporter lines of both the normal, river-dwelling morph and the cave morph of the species, we identified defects in migratory cell behaviours during evagination that participate in the reduced optic vesicle size in cavefish, without proliferation defect. Further, impaired optic cup invagination shifts the relative position of the lens and contributes to coloboma in cavefish. Based on these results, we propose a developmental scenario to explain the cavefish phenotype and discuss developmental constraints to morphological evolution. The cavefish eye appears as an outstanding natural mutant model to study molecular and cellular processes involved in optic region morphogenesis.
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Affiliation(s)
- Lucie Devos
- Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, 91198 Gif sur Yvette, France
| | - François Agnès
- Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, 91198 Gif sur Yvette, France
| | - Joanne Edouard
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Victor Simon
- Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, 91198 Gif sur Yvette, France
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Laurent Legendre
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Naima El Khallouki
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Sosthène Barbachou
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Frédéric Sohm
- AMAGEN, CNRS, INRA, Université Paris-Saclay, 91198, Gif sur Yvette, France
| | - Sylvie Rétaux
- Paris-Saclay Institute of Neuroscience, CNRS, Université Paris-Saclay, 91198 Gif sur Yvette, France
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12
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Busby L, Steventon B. Tissue tectonics and the multi-scale regulation of developmental timing. Interface Focus 2021; 11:20200057. [PMID: 34055304 PMCID: PMC8086930 DOI: 10.1098/rsfs.2020.0057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2021] [Indexed: 12/17/2022] Open
Abstract
Development encompasses processes that occur at multiple length scales, including gene-regulatory interactions, cell movements and reorganization, cell signalling and growth. It is essential that the timing of events in all of these different processes is coordinated to generate well-patterned tissues and organs. However, how the timing of intrinsic cell state changes is coordinated with events occurring at the multi-tissue and whole-organism level is unknown. Here, we argue that an important mechanism that accounts for the integration of timing across levels of organization is provided by tissue tectonics, i.e. how morphogenetic events driving tissue shape changes result in the relative displacement of signalling and responding tissues and coordinate developmental timing across scales. In doing so, tissue tectonics provides a mechanism by which the cell specification events intrinsic to cells can be modulated by the temporal exposure to extracellular signals. This exposure is in turn regulated by higher-order properties of the embryo, such as their physical properties, rates of growth and the combination of dynamic cell behaviours, impacting tissue morphogenesis. Tissue tectonics creates a downward flow of information from higher to lower levels of biological organization, providing an instance of downward causation in development.
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Affiliation(s)
- Lara Busby
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
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13
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Maternal control of visceral asymmetry evolution in Astyanax cavefish. Sci Rep 2021; 11:10312. [PMID: 33986376 PMCID: PMC8119719 DOI: 10.1038/s41598-021-89702-6] [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] [Received: 12/07/2020] [Accepted: 04/29/2021] [Indexed: 11/08/2022] Open
Abstract
The direction of visceral organ asymmetry is highly conserved during vertebrate evolution with heart development biased to the left and pancreas and liver development restricted to opposing sides of the midline. Here we show that reversals in visceral organ asymmetry have evolved in Astyanax mexicanus, a teleost species with interfertile surface-dwelling (surface fish) and cave-dwelling (cavefish) forms. Visceral organ asymmetry is conventional in surface fish but some cavefish have evolved reversals in heart, liver, and pancreas development. Corresponding changes in the normally left-sided expression of the Nodal-Pitx2/Lefty signaling system are also present in the cavefish lateral plate mesoderm (LPM). The Nodal antagonists lefty1 (lft1) and lefty2 (lft2), which confine Nodal signaling to the left LPM, are expressed in most surface fish, however, lft2, but not lft1, expression is absent during somitogenesis of most cavefish. Despite this difference, multiple lines of evidence suggested that evolutionary changes in L-R patterning are controlled upstream of Nodal-Pitx2/Lefty signaling. Accordingly, reciprocal hybridization of cavefish and surface fish showed that modifications of heart asymmetry are present in hybrids derived from cavefish mothers but not from surface fish mothers. The results indicate that changes in visceral asymmetry during cavefish evolution are influenced by maternal genetic effects.
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Torres-Paz J, Rétaux S. Pescoids and Chimeras to Probe Early Evo-Devo in the Fish Astyanax mexicanus. Front Cell Dev Biol 2021; 9:667296. [PMID: 33928092 PMCID: PMC8078105 DOI: 10.3389/fcell.2021.667296] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/25/2021] [Indexed: 12/31/2022] Open
Abstract
The fish species Astyanax mexicanus with its sighted and blind eco-morphotypes has become an original model to challenge vertebrate developmental evolution. Recently, we demonstrated that phenotypic evolution can be impacted by early developmental events starting from the production of oocytes in the fish ovaries. A. mexicanus offers an amenable model to test the influence of maternal determinants on cell fate decisions during early development, yet the mechanisms by which the information contained in the eggs is translated into specific developmental programs remain obscure due to the lack of specific tools in this emergent model. Here we describe methods for the generation of pescoids from yolkless-blastoderm explants to test the influence of embryonic and extraembryonic tissues on cell fate decisions, as well as the production of chimeric embryos obtained by intermorph cell transplantations to probe cell autonomous or non-autonomous processes. We show that Astyanax pescoids have the potential to recapitulate the main ontogenetic events observed in intact embryos, including the internalization of mesodermal progenitors and eye development, as followed with zic:GFP reporter lines. In addition, intermorph cell grafts resulted in proper integration of exogenous cells into the embryonic tissues, with lineages becoming more restricted from mid-blastula to gastrula. The implementation of these approaches in A. mexicanus will bring new light on the cascades of events, from the maternal pre-patterning of the early embryo to the evolution of brain regionalization.
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Affiliation(s)
- Jorge Torres-Paz
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Gif-sur-Yvette, France
| | - Sylvie Rétaux
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Gif-sur-Yvette, France
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Abstract
The small teleost fish Astyanax mexicanus has emerged as an outstanding model for studying many biological topics in the context of evolution. A major attribute is conspecific surface dwelling (surface fish) and blind cave dwelling (cavefish) morphs that can be raised in the laboratory and spawn large numbers of transparent and synchronously developing embryos. More than 30 cavefish populations have been discovered, mostly in northeastern Mexico, and some are thought to have evolved independently from surface fish ancestors, providing excellent models of parallel and convergent evolution. Cavefish have evolved eye and pigmentation regression, as well as modifications in brain morphology, behaviors, heart regenerative capacity, metabolic processes, and craniofacial organization. Thus, the Astyanax model provides researchers with natural "mutants" to study life in the challenging cave environment. The application of powerful genetic approaches based on hybridization between the two morphs and between the different cavefish populations are key advantages for deciphering the developmental and genetic mechanisms regulating trait evolution. QTL analysis has revealed the genetic architectures of gained and lost traits. In addition, some cavefish traits resemble human diseases, offering novel models for biomedical research. Astyanax research is supported by genome assemblies, transcriptomes, tissue and organ transplantation, gene manipulation and editing, and stable transgenesis, and benefits from a welcoming and interactive research community that conducts integrated community projects and sponsors the International Astyanax Meeting (AIM).
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Affiliation(s)
- William R. Jeffery
- Department of Biology, University of Maryland, College Park, MD 20742 USA
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