scholarly journals An Integrated Transcriptome-Wide Analysis of Cave and Surface Dwelling Astyanax mexicanus

PLoS ONE ◽  
2013 ◽  
Vol 8 (2) ◽  
pp. e55659 ◽  
Author(s):  
Joshua B. Gross ◽  
Allison Furterer ◽  
Brian M. Carlson ◽  
Bethany A. Stahl
Keyword(s):  
Astyanax Mexicanus ◽  
Surface Dwelling

scholarly journals A hypomorphic cystathionine ß-synthase gene contributes to cavefish eye loss by disrupting optic vasculature

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Ma ◽  
Aniket V. Gore ◽  
Daniel Castranova ◽  
Janet Shi ◽  
Mandy Ng ◽  
...  
Keyword(s):  
Circulatory System ◽  
Astyanax Mexicanus ◽  
Transsulfuration Pathway ◽  
Key Enzyme ◽  
Surface Dwelling ◽  
Blind Cave ◽  
Vestigial Structures ◽  
Key Indicators ◽  
Evolutionary Descent ◽  
Eye Formation

Abstract Vestigial structures are key indicators of evolutionary descent, but the mechanisms underlying their development are poorly understood. This study examines vestigial eye formation in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling morph and multiple populations of blind cave morphs. Cavefish embryos initially develop eyes, but they subsequently degenerate and become vestigial structures embedded in the head. The mutated genes involved in cavefish vestigial eye formation have not been characterized. Here we identify cystathionine ß-synthase a (cbsa), which encodes the key enzyme of the transsulfuration pathway, as one of the mutated genes responsible for eye degeneration in multiple cavefish populations. The inactivation of cbsa affects eye development by increasing the transsulfuration intermediate homocysteine and inducing defects in optic vasculature, which result in aneurysms and eye hemorrhages. Our findings suggest that localized modifications in the circulatory system may have contributed to the evolution of vestigial eyes in cavefish.

scholarly journals Genetic analysis reveals candidate genes for activity QTL in the blind Mexican tetra,Astyanax mexicanus

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5189 ◽  
Author(s):  
Brian M. Carlson ◽  
Ian B. Klingler ◽  
Bradley J. Meyer ◽  
Joshua B. Gross
Keyword(s):  
Candidate Genes ◽  
Genetic Basis ◽  
Activity Patterns ◽  
Potential Candidate ◽  
Behavioral Phenotypes ◽  
Astyanax Mexicanus ◽  
Broad Array ◽  
Patterns Of Behavior ◽  
Surface Dwelling

Animal models provide useful tools for exploring the genetic basis of morphological, physiological and behavioral phenotypes. Cave-adapted species are particularly powerful models for a broad array of phenotypic changes with evolutionary, developmental and clinical relevance. Here, we explored the genetic underpinnings of previously characterized differences in locomotor activity patterns between the surface-dwelling and Pachón cave-dwelling populations ofAstyanax mexicanus.We identified multiple novel QTL underlying patterns in overall levels of activity (velocity), as well as spatial tank use (time spent near the top or bottom of the tank). Further, we demonstrated that different regions of the genome mediate distinct patterns in velocity and tank usage. We interrogated eight genomic intervals underlying these activity QTL distributed across six linkage groups. In addition, we employed transcriptomic data and draft genomic resources to generate and evaluate a list of 36 potential candidate genes. Interestingly, our data support the candidacy of a number of genes, but do not suggest that differences in the patterns of behavior observed here are the result of alterations to certain candidate genes described in other species (e.g., teleost multiple tissue opsins, melanopsins or members of the core circadian clockwork). This study expands our knowledge of the genetic architecture underlying activity differences in surface and cavefish. Future studies will help define the role of specific genes in shaping complex behavioral phenotypes inAstyanaxand other vertebrate taxa.

scholarly journals Cavefish cope with environmental hypoxia by developing more erythrocytes and overexpression of hypoxia inducible genes

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Corine M van der Weele ◽  
William R Jeffery
Keyword(s):  
Normal Development ◽  
Hypoxia Inducible Factor ◽  
Hypoxia Tolerance ◽  
Astyanax Mexicanus ◽  
Hypoxia Inducible Factor 1 ◽  
Primitive Hematopoiesis ◽  
Cave Environment ◽  
Surface Dwelling ◽  
Inducible Genes ◽  
Lateral Mesoderm

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.

scholarly journals A Hypomorphic Cystathionine ß-Synthase Gene Contributes to Cavefish Eye Loss by Disrupting Optic Vasculature

2019 ◽  
Author(s):  
Li Ma ◽  
Aniket V. Gore ◽  
Daniel Castranova ◽  
Janet Shi ◽  
Mandy Ng ◽  
...  
Keyword(s):  
Oxygen Deficiency ◽  
Circulatory System ◽  
Astyanax Mexicanus ◽  
Transsulfuration Pathway ◽  
Key Enzyme ◽  
Surface Dwelling ◽  
Blind Cave ◽  
Different Populations ◽  
Key Indicators ◽  
Blind Cavefish

AbstractVestigial structures are key indicators of evolutionary descent but the mechanisms underlying their development are poorly understood. This study examines vestigial eye formation in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling morph and different populations of blind cave morphs. Cavefish embryos initially develop optic primordia but vestigial eyes are formed during larval development. Multiple genetic factors are involved in cavefish eye loss but none of the mutated genes have been identified. Here we identify cystathionine ß-synthase (cbsa), which encodes the key enzyme of the transsulfuration pathway, as a mutated gene responsible for eye degeneration in multiple cavefish populations. The inactivation of cbsa affects eye development by inducing accumulation of the transsulfuration intermediate homocysteine and defects in optic vasculature, including aneurysms and eye hemorrhages, leading to oxygen deficiency. Our findings suggest that localized modifications in the circulatory system and hypoxia had important roles in the evolution of vestigial eyes in blind cavefish.

scholarly journals Maternal control of visceral asymmetry evolution in Astyanax cavefish

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Ma ◽  
Mandy Ng ◽  
Janet Shi ◽  
Aniket V. Gore ◽  
Daniel Castranova ◽  
...  
Keyword(s):  
Heart Development ◽  
Nodal Signaling ◽  
Lateral Plate Mesoderm ◽  
Visceral Organ ◽  
Maternal Control ◽  
Lateral Plate ◽  
Astyanax Mexicanus ◽  
Evolutionary Changes ◽  
Liver And Pancreas ◽  
Surface Dwelling

AbstractThe 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.

scholarly journals Developmental evolution of the forebrain in cavefish, from natural variations in neuropeptides to behavior

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Alexandre Alié ◽  
Lucie Devos ◽  
Jorge Torres-Paz ◽  
Lise Prunier ◽  
Fanny Boulet ◽  
...  
Keyword(s):  
Basal Forebrain ◽  
Neuronal Development ◽  
Cell Types ◽  
Extreme Environment ◽  
Neuronal System ◽  
Normal Surface ◽  
Astyanax Mexicanus ◽  
Developmental Evolution ◽  
Surface Dwelling ◽  
Natural Variations

The fish Astyanax mexicanus comes in two forms: the normal surface-dwelling and the blind depigmented cave-adapted morphs. Comparing the development of their basal forebrain, we found quantitative differences in numbers of cells in specific clusters for six out of nine studied neuropeptidergic cell types. Investigating the origins of these differences, we showed that early Shh and Fgf signaling impact on the development of NPY and Hypocretin clusters, via effect on Lhx7 and Lhx9 transcription factors, respectively. Finally, we demonstrated that such neurodevelopmental evolution underlies behavioral evolution, linking a higher number of Hypocretin cells with hyperactivity in cavefish. Early embryonic modifications in signaling/patterning at neural plate stage therefore impact neuronal development and later larval behavior, bridging developmental evolution of a neuronal system and the adaptive behavior it governs. This work uncovers novel variations underlying the evolution and adaptation of cavefish to their extreme environment.

scholarly journals Liver-derived cell lines from cavefish Astyanax mexicanus as an in vitro model for studying metabolic adaptation

2022 ◽  
Author(s):  
Jaya Krishnan ◽  
Yan Wang ◽  
Olga Kenzior ◽  
Huzaifa Hassan ◽  
Luke Olsen ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cost Effective ◽  
Science Research ◽  
Model Systems ◽  
Metabolic Adaptation ◽  
Astyanax Mexicanus ◽  
Surface Dwelling ◽  
Vitro Model

Cell lines have become an integral resource and tool for conducting biological experiments ever since the Hela cell line was first developed (1). They not only allow detailed investigation of molecular pathways but are faster and more cost-effective than most in vivo approaches. The last decade saw many emerging model systems strengthening basic science research. However, lack of genetic and molecular tools in these newer systems pose many obstacles. Astyanax mexicanus is proving to be an interesting new model system for understanding metabolic adaptation. To further enhance the utility of this system, we developed liver-derived cell lines from both surface-dwelling and cave-dwelling morphotypes. In this study, we provide detailed methodology of the derivation process along with a comprehensive biochemical and molecular characterization of the cell lines, which reflects key metabolic traits of cavefish adaptation. We anticipate these cell lines to become a useful resource for the Astyanax community as well as researchers investigating fish biology, comparative physiology, and metabolism.

Regressive Evolution of Pigmentation in the Cavefish Astyanax

2006 ◽  
Vol 52 (3-4) ◽  
pp. 405-422 ◽  
Author(s):  
William R. Jeffery
Keyword(s):  
Neural Crest ◽  
Single Gene ◽  
Pigment Cells ◽  
Loss Of Function ◽  
Coding Region ◽  
Protein Coding ◽  
Regressive Evolution ◽  
Astyanax Mexicanus ◽  
Key Enzyme ◽  
Surface Dwelling

Many cave animals are colorless due to loss of pigment cells. Here, we review recent progress on how and why pigmentation has disappeared in Astyanax mexicanus, a single teleost species with conspecific surface-dwelling (surface fish) and many different cave-dwelling (cavefish) forms. During surface fish development, migratory neural crest cells form three types of pigment cells: silver iridophores, orange xanthophores, and black melanophores. Cavefish have eliminated or substantially reduced their complement of melanophores and exhibit albinism, loss of the capacity to synthesize melanin. Cell tracing, immunolocalization, and neural tube explant cultures show that cavefish have retained a colorless pre-melanophore (melanoblast) lineage derived from the neural crest. Thus, the cavefish neural crest produces melanoblasts that migrate normally but are blocked in differentiation and show defective melanogenesis. Cavefish melanoblasts can convert exogenous L-DOPA into melanin and therefore have active tyrosinase, the key enzyme in melanogenesis. In contrast, cavefish melanoblasts are unable to convert L-tyrosine to L-DOPA (and melanin), although this reaction is also catalyzed by tyrosinase. Thus, cavefish are tyrosinase-positive albinos that have a deficiency in L-tyrosine transport or utilization within the melanosome, the organelle in which melanin is synthesized. At least five different types of Astyanax cavefish show the same defect in melanogenesis. Genetic analysis shows that cavefish albinism is caused by loss of function mutations in a single gene, p/oca2, which encodes a large protein that probably spans the melanosome membrane. Different deletions in the p/oca2 protein-coding region are responsible for loss of function in at least two different cavefish populations, suggesting that albinism evolved by convergence. Based on current understanding of the genetic basis of albinism, we discuss potential mechanisms for regressive evolution of cavefish pigmentation.

scholarly journals A chromosome-level genome of Astyanax mexicanus surface fish for comparing population-specific genetic differences contributing to trait evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wesley C. Warren ◽  
Tyler E. Boggs ◽  
Richard Borowsky ◽  
Brian M. Carlson ◽  
Estephany Ferrufino ◽  
...  
Keyword(s):  
Complex Traits ◽  
Fish Genome ◽  
Genetic Studies ◽  
Astyanax Mexicanus ◽  
Eye Size ◽  
Genome Wide ◽  
Surface Dwelling ◽  
Trait Locus ◽  
Chromosome Level

AbstractIdentifying the genetic factors that underlie complex traits is central to understanding the mechanistic underpinnings of evolution. Cave-dwelling Astyanax mexicanus populations are well adapted to subterranean life and many populations appear to have evolved troglomorphic traits independently, while the surface-dwelling populations can be used as a proxy for the ancestral form. Here we present a high-resolution, chromosome-level surface fish genome, enabling the first genome-wide comparison between surface fish and cavefish populations. Using this resource, we performed quantitative trait locus (QTL) mapping analyses and found new candidate genes for eye loss such as dusp26. We used CRISPR gene editing in A. mexicanus to confirm the essential role of a gene within an eye size QTL, rx3, in eye formation. We also generated the first genome-wide evaluation of deletion variability across cavefish populations to gain insight into this potential source of cave adaptation. The surface fish genome reference now provides a more complete resource for comparative, functional and genetic studies of drastic trait differences within a species.

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