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Pensabene E, Augstenová B, Kratochvíl L, Rovatsos M. Differentiated sex chromosomes, karyotype evolution, and spontaneous triploidy in carphodactylid geckos. J Hered 2024; 115:262-276. [PMID: 38366660 DOI: 10.1093/jhered/esae010] [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: 11/02/2023] [Accepted: 02/13/2024] [Indexed: 02/18/2024] Open
Abstract
Geckos exhibit derived karyotypes without a clear distinction between macrochromosomes and microchromosomes and intriguing diversity in sex determination mechanisms. We conducted cytogenetic analyses in six species from the genera Nephrurus, Phyllurus, and Saltuarius of the gecko family Carphodactylidae. We confirmed the presence of a female heterogametic system with markedly differentiated and heteromorphic sex chromosomes in all examined species, typically with the W chromosome notably larger than the Z chromosome. One species, Nephrurus cinctus, possesses unusual multiple Z1Z1Z2Z2/Z1Z2W sex chromosomes. The morphology of the sex chromosomes, along with repetitive DNA content, suggests that the differentiation or emergence of sex chromosomes occurred independently in the genus Phyllurus. Furthermore, our study unveils a case of spontaneous triploidy in a fully grown individual of Saltuarius cornutus (3n = 57) and explores its implications for reproduction in carphodactylid geckos. We revealed that most carphodactylids retain the putative ancestral gekkotan karyotype of 2n = 38, characterized by predominantly acrocentric chromosomes that gradually decrease in size. If present, biarmed chromosomes emerge through pericentric inversions, maintaining the chromosome (and centromere) numbers. However, Phyllurus platurus is a notable exception, with a karyotype of 2n = 22 chromosomes. Its eight pairs of biarmed chromosomes were probably formed by Robertsonian fusions of acrocentric chromosomes. The family underscores a remarkable instance of evolutionary stability in chromosome numbers, followed by a profound transformation through parallel interchromosomal rearrangements. Our study highlights the need to continue generating cytogenetic data in order to test long-standing ideas about reproductive biology and the evolution of genome and sex determination.
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Affiliation(s)
- Eleonora Pensabene
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Augstenová
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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Yurchenko A, Pšenička T, Mora P, Ortega JAM, Baca AS, Rovatsos M. Cytogenetic Analysis of Satellitome of Madagascar Leaf-Tailed Geckos. Genes (Basel) 2024; 15:429. [PMID: 38674364 PMCID: PMC11049218 DOI: 10.3390/genes15040429] [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: 03/04/2024] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Satellite DNA (satDNA) consists of sequences of DNA that form tandem repetitions across the genome, and it is notorious for its diversity and fast evolutionary rate. Despite its importance, satDNA has been only sporadically studied in reptile lineages. Here, we sequenced genomic DNA and PCR-amplified microdissected W chromosomes on the Illumina platform in order to characterize the monomers of satDNA from the Henkel's leaf-tailed gecko U. henkeli and to compare their topology by in situ hybridization in the karyotypes of the closely related Günther's flat-tail gecko U. guentheri and gold dust day gecko P. laticauda. We identified seventeen different satDNAs; twelve of them seem to accumulate in centromeres, telomeres and/or the W chromosome. Notably, centromeric and telomeric regions seem to share similar types of satDNAs, and we found two that seem to accumulate at both edges of all chromosomes in all three species. We speculate that the long-term stability of all-acrocentric karyotypes in geckos might be explained from the presence of specific satDNAs at the centromeric regions that are strong meiotic drivers, a hypothesis that should be further tested.
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Affiliation(s)
- Alona Yurchenko
- Department of Ecology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic; (A.Y.); (T.P.)
| | - Tomáš Pšenička
- Department of Ecology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic; (A.Y.); (T.P.)
| | - Pablo Mora
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas s/n, E-23071 Jaen, Spain; (P.M.); (J.A.M.O.); (A.S.B.)
| | - Juan Alberto Marchal Ortega
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas s/n, E-23071 Jaen, Spain; (P.M.); (J.A.M.O.); (A.S.B.)
| | - Antonio Sánchez Baca
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaén, Campus Las Lagunillas s/n, E-23071 Jaen, Spain; (P.M.); (J.A.M.O.); (A.S.B.)
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, 128 44 Prague, Czech Republic; (A.Y.); (T.P.)
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3
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Lisachov A, Tishakova K, Romanenko S, Lisachova L, Davletshina G, Prokopov D, Kratochvíl L, O Brien P, Ferguson-Smith M, Borodin P, Trifonov V. Robertsonian fusion triggers recombination suppression on sex chromosomes in Coleonyx geckos. Sci Rep 2023; 13:15502. [PMID: 37726346 PMCID: PMC10509250 DOI: 10.1038/s41598-023-39937-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 08/02/2023] [Indexed: 09/21/2023] Open
Abstract
The classical hypothesis proposes that the lack of recombination on sex chromosomes arises due to selection for linkage between a sex-determining locus and sexually antagonistic loci, primarily facilitated by inversions. However, cessation of recombination on sex chromosomes could be attributed also to neutral processes, connected with other chromosome rearrangements or can reflect sex-specific recombination patterns existing already before sex chromosome differentiation. Three Coleonyx gecko species share a complex X1X1X2X2/X1X2Y system of sex chromosomes evolved via a fusion of the Y chromosome with an autosome. We analyzed synaptonemal complexes and sequenced flow-sorted sex chromosomes to investigate the effect of chromosomal rearrangement on recombination and differentiation of these sex chromosomes. The gecko sex chromosomes evolved from syntenic regions that were also co-opted also for sex chromosomes in other reptiles. We showed that in male geckos, recombination is less prevalent in the proximal regions of chromosomes and is even further drastically reduced around the centromere of the neo-Y chromosome. We highlight that pre-existing recombination patterns and Robertsonian fusions can be responsible for the cessation of recombination on sex chromosomes and that such processes can be largely neutral.
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Affiliation(s)
- Artem Lisachov
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand.
- Institute of Environmental and Agricultural Biology (X-BIO), University of Tyumen, Tyumen, 625003, Russia.
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia.
| | - Katerina Tishakova
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Svetlana Romanenko
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
| | - Lada Lisachova
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
- Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Guzel Davletshina
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
| | - Dmitry Prokopov
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, 12844, Prague, Czech Republic
| | - Patricia O Brien
- Department of Veterinary Medicine, Cambridge Resource Centre for Comparative Genomics, University of Cambridge, Cambridge, CB3 0ES, UK
| | - Malcolm Ferguson-Smith
- Department of Veterinary Medicine, Cambridge Resource Centre for Comparative Genomics, University of Cambridge, Cambridge, CB3 0ES, UK
| | - Pavel Borodin
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
| | - Vladimir Trifonov
- Institute of Molecular and Cellular Biology, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090, Russia
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Mezzasalma M, Brunelli E, Odierna G, Guarino FM. Chromosome Diversity and Evolution of the Endemic Malagasy Velvet Geckos of the Genus Blaesodactylus (Reptilia, Gekkonidae). Animals (Basel) 2023; 13:2068. [PMID: 37443866 DOI: 10.3390/ani13132068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 06/15/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
We performed a molecular and phylogenetic analysis and a comparative cytogenetic study with standard karyotyping, silver staining (Ag-NOR) and sequential C-banding + Giemsa, + fluorochromes on several Blaesodactylus samples. The phylogenetic inference retrieved two main clades, the first comprises B. victori, B. microtuberculatus and B. boivini, while the second includes B. sakalava, B. antongilensis and B. ambonihazo. The available samples of B. sakalava form two different clades (here named B. sakalava clade A and clade B), which probably deserve a taxonomic re-evaluation. We found a karyological variability in Blaesodactylus in terms of chromosome number (2n = 40-42), morphology, location of NORs, and heterochromatin distribution pattern. Blaesodactylus antongilensis and B. sakalava clade A and B showed a karyotype of 2n = 40 mostly telocentric chromosomes. Pairs 1 and 6 were metacentric in B. sakalava clade A and B, while pair 1 was composed of subtelocentric/submetacentric elements in B. antongilensis. In contrast, B. boivini displayed a karyotype with 2n = 42 only telocentric chromosomes. NORs were on the first chromosome pair in B. boivini, and on the second pair in B. antongilensis. Adding our data to those available from the literature on evolutionarily related species, we highlight that the chromosome diversification in the genus probably proceeded towards a progressive reduction in the chromosome number and the formation of metacentric elements.
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Affiliation(s)
- Marcello Mezzasalma
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende, Italy
| | - Elvira Brunelli
- Department of Biology, Ecology and Earth Science, University of Calabria, Via P. Bucci 4/B, 87036 Rende, Italy
| | - Gaetano Odierna
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy
| | - Fabio Maria Guarino
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy
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Cytogenetic Analysis of Seven Species of Gekkonid and Phyllodactylid Geckos. Genes (Basel) 2023; 14:genes14010178. [PMID: 36672918 PMCID: PMC9859368 DOI: 10.3390/genes14010178] [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: 11/28/2022] [Revised: 12/24/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Geckos (Gekkota), the species-rich clade of reptiles with more than 2200 currently recognized species, demonstrate a remarkable variability in diploid chromosome numbers (2n = 16-48) and mode of sex determination. However, only a small fraction of gekkotan species have been studied with cytogenetic methods. Here, we applied both conventional (karyotype reconstruction and C-banding) and molecular (fluorescence in situ hybridization with probes for rDNA loci and telomeric repeats) cytogenetic analyses in seven species of geckos, namely Blaesodactylus boivini, Chondrodactylus laevigatus, Gekko badenii, Gekko cf. lionotum, Hemidactylus sahgali, Homopholis wahlbergii (Gekkonidae) and Ptyodactylus togoensis (Phyllodactylidae), in order to provide further insights into the evolution of karyotypes in geckos. Our analysis revealed the presence of interstitial telomeric repeats in four species, but we were not able to conclude if they are remnants of previous chromosome rearrangements or were formed by an accumulation of telomeric-like satellite motifs. Even though sex chromosomes were previously identified in several species from the genera Hemidactylus and Gekko by cytogenetic and/or genomic methods, they were not detected by us in any examined species. Our examined species either have poorly differentiated sex chromosomes or, possibly, environmental sex determination. Future studies should explore the effect of temperature and conduct genome-wide analyses in order to identify the mode of sex determination in these species.
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Widespread chromosomal rearrangements preceded genetic divergence in a monitor lizard, Varanus acanthurus (Varanidae). Chromosome Res 2023; 31:9. [PMID: 36745262 PMCID: PMC9902428 DOI: 10.1007/s10577-023-09715-x] [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: 09/02/2022] [Revised: 11/12/2022] [Accepted: 11/28/2022] [Indexed: 02/07/2023]
Abstract
Chromosomal rearrangements are often associated with local adaptation and speciation because they suppress recombination, and as a result, rearrangements have been implicated in disrupting gene flow. Although there is strong evidence to suggest that chromosome rearrangements are a factor in genetic isolation of divergent populations, the underlying mechanism remains elusive. Here, we applied an integrative cytogenetics and genomics approach testing whether chromosomal rearrangements are the initial process, or a consequence, of population divergence in the dwarf goanna, Varanus acanthurus. Specifically, we tested whether chromosome rearrangements are indicators of genetic barriers that can be used to identify divergent populations by looking at gene flow within and between populations with rearrangements. We found that gene flow was present between individuals with chromosome rearrangements within populations, but there was no gene flow between populations that had similar chromosome rearrangements. Moreover, we identified a correlation between reduced genetic variation in populations with a higher frequency of homozygous submetacentric individuals. These findings suggest that chromosomal rearrangements were widespread prior to divergence, and because we found populations with higher frequencies of submetacentric chromosomes were associated with lower genetic diversity, this could indicate that polymorphisms within populations are early indicators of genetic drift.
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7
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Marín-Gual L, González-Rodelas L, M. Garcias M, Kratochvíl L, Valenzuela N, Georges A, Waters PD, Ruiz-Herrera A. Meiotic chromosome dynamics and double strand break formation in reptiles. Front Cell Dev Biol 2022; 10:1009776. [PMID: 36313577 PMCID: PMC9597255 DOI: 10.3389/fcell.2022.1009776] [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: 08/02/2022] [Accepted: 09/23/2022] [Indexed: 11/13/2022] Open
Abstract
During meiotic prophase I, tightly regulated processes take place, from pairing and synapsis of homologous chromosomes to recombination, which are essential for the generation of genetically variable haploid gametes. These processes have canonical meiotic features conserved across different phylogenetic groups. However, the dynamics of meiotic prophase I in non-mammalian vertebrates are poorly known. Here, we compare four species from Sauropsida to understand the regulation of meiotic prophase I in reptiles: the Australian central bearded dragon (Pogona vitticeps), two geckos (Paroedura picta and Coleonyx variegatus) and the painted turtle (Chrysemys picta). We first performed a histological characterization of the spermatogenesis process in both the bearded dragon and the painted turtle. We then analyzed prophase I dynamics, including chromosome pairing, synapsis and the formation of double strand breaks (DSBs). We show that meiosis progression is highly conserved in reptiles with telomeres clustering forming the bouquet, which we propose promotes homologous pairing and synapsis, along with facilitating the early pairing of micro-chromosomes during prophase I (i.e., early zygotene). Moreover, we detected low levels of meiotic DSB formation in all taxa. Our results provide new insights into reptile meiosis.
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Affiliation(s)
- Laia Marín-Gual
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Laura González-Rodelas
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Maria M. Garcias
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Nicole Valenzuela
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, United States
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia
| | - Paul D. Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, UNSW, Sydney, NSW, Australia
| | - Aurora Ruiz-Herrera
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
- *Correspondence: Aurora Ruiz-Herrera,
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8
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Keating SE, Greenbaum E, Johnson JD, Gamble T. Identification of a cis-sex chromosome transition in banded geckos (Coleonyx, Eublepharidae, Gekkota). J Evol Biol 2022; 35:1675-1682. [PMID: 35665979 DOI: 10.1111/jeb.14022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 04/13/2022] [Accepted: 04/28/2022] [Indexed: 12/24/2022]
Abstract
Sex-determination systems are highly variable amongst vertebrate groups, and the prevalence of genomic data has greatly expanded our knowledge of how diverse some groups truly are. Gecko lizards are known to possess a variety of sex-determination systems, and each new study increases our knowledge of this diversity. Here, we used RADseq to identify male-specific markers in the banded gecko Coleonyx brevis, indicating this species has a XX/XY sex-determination system. Furthermore, we show that these sex-linked regions are not homologous to the XX/XY sex chromosomes of two related Coleonyx species, C. elegans and C. mitratus, suggesting that a cis-sex chromosome turnover-a change in sex chromosomes without a concomitant change in heterogamety-has occurred within the genus. These findings demonstrate the utility of genome-scale data to uncover novel sex chromosomes and further highlight the diversity of gecko sex chromosomes.
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Affiliation(s)
- Shannon E Keating
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Eli Greenbaum
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
| | - Jerry D Johnson
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA.,Milwaukee Public Museum, Milwaukee, Wisconsin, USA.,Bell Museum of Natural History, University of Minnesota, St. Paul, Minnesota, USA
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Sex Chromosomes and Master Sex-Determining Genes in Turtles and Other Reptiles. Genes (Basel) 2021; 12:genes12111822. [PMID: 34828428 PMCID: PMC8622242 DOI: 10.3390/genes12111822] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/12/2021] [Accepted: 11/16/2021] [Indexed: 11/24/2022] Open
Abstract
Among tetrapods, the well differentiated heteromorphic sex chromosomes of birds and mammals have been highly investigated and their master sex-determining (MSD) gene, Dmrt1 and SRY, respectively, have been identified. The homomorphic sex chromosomes of reptiles have been the least studied, but the gap with birds and mammals has begun to fill. This review describes our current knowledge of reptilian sex chromosomes at the cytogenetic and molecular level. Most of it arose recently from various studies comparing male to female gene content. This includes restriction site-associated DNA sequencing (RAD-Seq) experiments in several male and female samples, RNA sequencing and identification of Z- or X-linked genes by male/female comparative transcriptome coverage, and male/female transcriptomic or transcriptome/genome substraction approaches allowing the identification of Y- or W-linked transcripts. A few putative master sex-determining (MSD) genes have been proposed, but none has been demonstrated yet. Lastly, future directions in the field of reptilian sex chromosomes and their MSD gene studies are considered.
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Augstenová B, Pensabene E, Veselý M, Kratochvíl L, Rovatsos M. Are Geckos Special in Sex Determination? Independently Evolved Differentiated ZZ/ZW Sex Chromosomes in Carphodactylid Geckos. Genome Biol Evol 2021; 13:evab119. [PMID: 34051083 PMCID: PMC8290109 DOI: 10.1093/gbe/evab119] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 12/20/2022] Open
Abstract
Amniotes possess astonishing variability in sex determination ranging from environmental sex determination (ESD) to genotypic sex determination (GSD) with highly differentiated sex chromosomes. Geckos are one of the few amniote groups with substantial variability in sex determination. What makes them special in this respect? We hypothesized that the extraordinary variability of sex determination in geckos can be explained by two alternatives: 1) unusual lability of sex determination, predicting that the current GSD systems were recently formed and are prone to turnovers; and 2) independent transitions from the ancestral ESD to later stable GSD, which assumes that geckos possessed ancestrally ESD, but once sex chromosomes emerged, they remain stable in the long term. Here, based on genomic data, we document that the differentiated ZZ/ZW sex chromosomes evolved within carphodactylid geckos independently from other gekkotan lineages and remained stable in the genera Nephrurus, Underwoodisaurus, and Saltuarius for at least 15 Myr and potentially up to 45 Myr. These results together with evidence for the stability of sex chromosomes in other gekkotan lineages support more our second hypothesis suggesting that geckos do not dramatically differ from the evolutionary transitions in sex determination observed in the majority of the amniote lineages.
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Affiliation(s)
- Barbora Augstenová
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Eleonora Pensabene
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Milan Veselý
- Department of Zoology, Faculty of Science, Palacký University, Olomouc, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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11
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Lisachov A, Andreyushkova D, Davletshina G, Prokopov D, Romanenko S, Galkina S, Saifitdinova A, Simonov E, Borodin P, Trifonov V. Amplified Fragments of an Autosome-Borne Gene Constitute a Significant Component of the W Sex Chromosome of Eremias velox (Reptilia, Lacertidae). Genes (Basel) 2021; 12:779. [PMID: 34065205 PMCID: PMC8160951 DOI: 10.3390/genes12050779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 01/30/2023] Open
Abstract
Heteromorphic W and Y sex chromosomes often experience gene loss and heterochromatinization, which is frequently viewed as their "degeneration". However, the evolutionary trajectories of the heterochromosomes are in fact more complex since they may not only lose but also acquire new sequences. Previously, we found that the heterochromatic W chromosome of a lizard Eremias velox (Lacertidae) is decondensed and thus transcriptionally active during the lampbrush stage. To determine possible sources of this transcription, we sequenced DNA from a microdissected W chromosome sample and a total female DNA sample and analyzed the results of reference-based and de novo assembly. We found a new repetitive sequence, consisting of fragments of an autosomal protein-coding gene ATF7IP2, several SINE elements, and sequences of unknown origin. This repetitive element is distributed across the whole length of the W chromosome, except the centromeric region. Since it retained only 3 out of 10 original ATF7IP2 exons, it remains unclear whether it is able to produce a protein product. Subsequent studies are required to test the presence of this element in other species of Lacertidae and possible functionality. Our results provide further evidence for the view of W and Y chromosomes as not just "degraded" copies of Z and X chromosomes but independent genomic segments in which novel genetic elements may arise.
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Affiliation(s)
- Artem Lisachov
- Institute of Environmental and Agricultural Biology (X-BIO), University of Tyumen, Lenina str. 23, 625003 Tyumen, Russia;
- Institute of Cytology and Genetics SB RAS, Acad. Lavrentiev Ave. 10, 630090 Novosibirsk, Russia; (G.D.); (P.B.)
| | - Daria Andreyushkova
- Institute of Molecular and Cellular Biology SB RAS, Acad. Lavrentiev Ave. 8/2, 630090 Novosibirsk, Russia; (D.A.); (D.P.); (S.R.); (V.T.)
| | - Guzel Davletshina
- Institute of Cytology and Genetics SB RAS, Acad. Lavrentiev Ave. 10, 630090 Novosibirsk, Russia; (G.D.); (P.B.)
- Institute of Molecular and Cellular Biology SB RAS, Acad. Lavrentiev Ave. 8/2, 630090 Novosibirsk, Russia; (D.A.); (D.P.); (S.R.); (V.T.)
| | - Dmitry Prokopov
- Institute of Molecular and Cellular Biology SB RAS, Acad. Lavrentiev Ave. 8/2, 630090 Novosibirsk, Russia; (D.A.); (D.P.); (S.R.); (V.T.)
| | - Svetlana Romanenko
- Institute of Molecular and Cellular Biology SB RAS, Acad. Lavrentiev Ave. 8/2, 630090 Novosibirsk, Russia; (D.A.); (D.P.); (S.R.); (V.T.)
| | - Svetlana Galkina
- Department of Genetics and Biotechnology, Saint Petersburg State University, Universitetskaya Emb. 7–9, 199034 Saint Petersburg, Russia;
| | - Alsu Saifitdinova
- Department of Human and Animal Anatomy and Physiology, Herzen State Pedagogical University of Russia, Moyka Emb. 48, 191186 Saint Petersburg, Russia;
| | - Evgeniy Simonov
- Institute of Environmental and Agricultural Biology (X-BIO), University of Tyumen, Lenina str. 23, 625003 Tyumen, Russia;
| | - Pavel Borodin
- Institute of Cytology and Genetics SB RAS, Acad. Lavrentiev Ave. 10, 630090 Novosibirsk, Russia; (G.D.); (P.B.)
- Novosibirsk State University, Pirogova str. 3, 630090 Novosibirsk, Russia
| | - Vladimir Trifonov
- Institute of Molecular and Cellular Biology SB RAS, Acad. Lavrentiev Ave. 8/2, 630090 Novosibirsk, Russia; (D.A.); (D.P.); (S.R.); (V.T.)
- Novosibirsk State University, Pirogova str. 3, 630090 Novosibirsk, Russia
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12
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Pensabene E, Kratochvíl L, Rovatsos M. Independent Evolution of Sex Chromosomes in Eublepharid Geckos, A Lineage with Environmental and Genotypic Sex Determination. Life (Basel) 2020; 10:E342. [PMID: 33322017 PMCID: PMC7763811 DOI: 10.3390/life10120342] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/28/2022] Open
Abstract
Geckos demonstrate a remarkable variability in sex determination systems, but our limited knowledge prohibits accurate conclusions on the evolution of sex determination in this group. Eyelid geckos (Eublepharidae) are of particular interest, as they encompass species with both environmental and genotypic sex determination. We identified for the first time the X-specific gene content in the Yucatán banded gecko, Coleonyx elegans, possessing X1X1X2X2/X1X2Y multiple sex chromosomes by comparative genome coverage analysis between sexes. The X-specific gene content of Coleonyx elegans was revealed to be partially homologous to genomic regions linked to the chicken autosomes 1, 6 and 11. A qPCR-based test was applied to validate a subset of X-specific genes by comparing the difference in gene copy numbers between sexes, and to explore the homology of sex chromosomes across eleven eublepharid, two phyllodactylid and one sphaerodactylid species. Homologous sex chromosomes are shared between Coleonyx elegans and Coleonyx mitratus, two species diverged approximately 34 million years ago, but not with other tested species. As far as we know, the X-specific gene content of Coleonyx elegans / Coleonyx mitratus was never involved in the sex chromosomes of other gecko lineages, indicating that the sex chromosomes in this clade of eublepharid geckos evolved independently.
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Affiliation(s)
| | | | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, 12844 Prague, Czech Republic; (E.P.); (L.K.)
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13
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Straková B, Rovatsos M, Kubička L, Kratochvíl L. Evolution of Sex Determination in Amniotes: Did Stress and Sequential Hermaphroditism Produce Environmental Determination? Bioessays 2020; 42:e2000050. [DOI: 10.1002/bies.202000050] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 07/15/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Barbora Straková
- Department of Ecology, Faculty of Science Charles University Viničná 7 Praha 2 12844 Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science Charles University Viničná 7 Praha 2 12844 Czech Republic
| | - Lukáš Kubička
- Department of Ecology, Faculty of Science Charles University Viničná 7 Praha 2 12844 Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science Charles University Viničná 7 Praha 2 12844 Czech Republic
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14
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Iannucci A, Altmanová M, Ciofi C, Ferguson-Smith M, Milan M, Pereira JC, Pether J, Rehák I, Rovatsos M, Stanyon R, Velenský P, Ráb P, Kratochvíl L, Johnson Pokorná M. Conserved sex chromosomes and karyotype evolution in monitor lizards (Varanidae). Heredity (Edinb) 2019; 123:215-227. [PMID: 30670841 PMCID: PMC6781170 DOI: 10.1038/s41437-018-0179-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/10/2018] [Accepted: 12/14/2018] [Indexed: 11/08/2022] Open
Abstract
Despite their long history with the basal split dating back to the Eocene, all species of monitor lizards (family Varanidae) studied so far share the same chromosome number of 2n = 40. However, there are differences in the morphology of the macrochromosome pairs 5-8. Further, sex determination, which revealed ZZ/ZW sex microchromosomes, was studied only in a few varanid species and only with techniques that did not test their homology. The aim of this study was to (i) test if cryptic interchromosomal rearrangements of larger chromosomal blocks occurred during the karyotype evolution of this group, (ii) contribute to the reconstruction of the varanid ancestral karyotype, and (iii) test homology of sex chromosomes among varanids. We investigated these issues by hybridizing flow sorted chromosome paints from Varanus komodoensis to metaphases of nine species of monitor lizards. The results show that differences in the morphology of the chromosome pairs 5-8 can be attributed to intrachromosomal rearrangements, which led to transitions between acrocentric and metacentric chromosomes in both directions. We also documented the first case of spontaneous triploidy among varanids in Varanus albigularis. The triploid individual was fully grown, which demonstrates that polyploidization is compatible with life in this lineage. We found that the W chromosome differs between species in size and heterochromatin content. The varanid Z chromosome is clearly conserved in all the analyzed species. Varanids, in addition to iguanas, caenophidian snakes, and lacertid lizards, are another squamate group with highly conserved sex chromosomes over a long evolutionary time.
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Affiliation(s)
- Alessio Iannucci
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino, FI, Italy
| | - Marie Altmanová
- Department of Ecology, Charles University, Viničná 7, 128 00, Prague, Czech Republic
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
| | - Claudio Ciofi
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino, FI, Italy
| | - Malcolm Ferguson-Smith
- Cambridge Resource Centre for Comparative Genomics, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom
| | - Massimo Milan
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020, Legnaro, PD, Italy
| | - Jorge Claudio Pereira
- Cambridge Resource Centre for Comparative Genomics, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom
| | - James Pether
- Reptilandia Park, Galdar, 35460, Gran Canaria, Spain
| | - Ivan Rehák
- Prague Zoological Garden, U Trojského zámku 120/3, 171 00, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Charles University, Viničná 7, 128 00, Prague, Czech Republic
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
| | - Roscoe Stanyon
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino, FI, Italy
| | - Petr Velenský
- Prague Zoological Garden, U Trojského zámku 120/3, 171 00, Prague, Czech Republic
| | - Petr Ráb
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Charles University, Viničná 7, 128 00, Prague, Czech Republic.
| | - Martina Johnson Pokorná
- Department of Ecology, Charles University, Viničná 7, 128 00, Prague, Czech Republic
- Institute of Animal Physiology and Genetics, The Czech Academy of Sciences, Rumburská 89, 277 21, Liběchov, Czech Republic
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15
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Alam SMI, Sarre SD, Gleeson D, Georges A, Ezaz T. Did Lizards Follow Unique Pathways in Sex Chromosome Evolution? Genes (Basel) 2018; 9:E239. [PMID: 29751579 PMCID: PMC5977179 DOI: 10.3390/genes9050239] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 02/02/2023] Open
Abstract
Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata) which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways.
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Affiliation(s)
| | - Stephen D Sarre
- Institute for Applied Ecology, University of Canberra, Canberra 2616, Australia.
| | - Dianne Gleeson
- Institute for Applied Ecology, University of Canberra, Canberra 2616, Australia.
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra 2616, Australia.
| | - Tariq Ezaz
- Institute for Applied Ecology, University of Canberra, Canberra 2616, Australia.
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16
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Frynta D, Jančúchová-Lásková J, Frýdlová P, Landová E. A comparative study of growth: different body weight trajectories in three species of the genus Eublepharis and their hybrids. Sci Rep 2018; 8:2658. [PMID: 29422546 PMCID: PMC5805741 DOI: 10.1038/s41598-018-19864-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 01/09/2018] [Indexed: 02/03/2023] Open
Abstract
An extensive research effort is devoted to the evolution of life-histories and processes underlying the variation in adult body weight; however, in this regard, some animal taxa remain neglected. Here we report rates and timing of growth recorded in two wild-derived populations of a model lizard species, Eublepharis macularius (M, W), other two related species, i.e., E. angramainyu (A) and E. sp. (D), and their between-species hybrids. We detected clear differences among the examined species/populations, which can be interpreted in the terms of "fast - slow" continuum of life-history strategies. The mean asymptotic body size was the highest in A and further decreased in the following order: M, W, and D. In contrast, the growth rate showed an opposite pattern. Counter-intuitively, the largest species exhibited the slowest growth rates. The final body size was determined mainly by the inflexion point. This parameter reflecting the duration of exponential growth increased with mean asymptotic body size and easily overcompensated the effect of decreasing growth rates in larger species. Compared to the parental species, the F1 and backcross hybrids exhibited intermediate values of growth parameters. Thus, except for the case of the F2 hybrid of MxA, we failed to detect deleterious effects of hybridization in these animals with temperature sex determination.
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Affiliation(s)
- Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, CZ-12844, Prague 2, Czech Republic
| | - Jitka Jančúchová-Lásková
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, CZ-12844, Prague 2, Czech Republic
| | - Petra Frýdlová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, CZ-12844, Prague 2, Czech Republic.
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, CZ-12844, Prague 2, Czech Republic
- National Institute of Mental Health, Topolová 748, CZ-25067, Klecany, Czech Republic
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17
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Tracking the evolutionary pathway of sex chromosomes among fishes: characterizing the unique XX/XY1Y2 system in Hoplias malabaricus (Teleostei, Characiformes). Chromosoma 2017; 127:115-128. [DOI: 10.1007/s00412-017-0648-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/16/2017] [Accepted: 10/17/2017] [Indexed: 10/18/2022]
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18
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Rovatsos M, Vukić J, Lymberakis P, Kratochvíl L. Evolutionary stability of sex chromosomes in snakes. Proc Biol Sci 2017; 282:20151992. [PMID: 26702042 DOI: 10.1098/rspb.2015.1992] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Amniote vertebrates possess various mechanisms of sex determination, but their variability is not equally distributed. The large evolutionary stability of sex chromosomes in viviparous mammals and birds was believed to be connected with their endothermy. However, some ectotherm lineages seem to be comparably conserved in sex determination, but previously there was a lack of molecular evidence to confirm this. Here, we document a stability of sex chromosomes in advanced snakes based on the testing of Z-specificity of genes using quantitative PCR (qPCR) across 37 snake species (our qPCR technique is suitable for molecular sexing in potentially all advanced snakes). We discovered that at least part of sex chromosomes is homologous across all families of caenophidian snakes (Acrochordidae, Xenodermatidae, Pareatidae, Viperidae, Homalopsidae, Colubridae, Elapidae and Lamprophiidae). The emergence of differentiated sex chromosomes can be dated back to about 60 Ma and preceded the extensive diversification of advanced snakes, the group with more than 3000 species. The Z-specific genes of caenophidian snakes are (pseudo)autosomal in the members of the snake families Pythonidae, Xenopeltidae, Boidae, Erycidae and Sanziniidae, as well as in outgroups with differentiated sex chromosomes such as monitor lizards, iguanas and chameleons. Along with iguanas, advanced snakes are therefore another example of ectothermic amniotes with a long-term stability of sex chromosomes comparable with endotherms.
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Affiliation(s)
- Michail Rovatsos
- Faculty of Science, Department of Ecology, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic
| | - Jasna Vukić
- Faculty of Science, Department of Ecology, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic
| | - Petros Lymberakis
- Natural History Museum of Crete, University of Crete, Knossou Avenue, 71409 Irakleio, Crete, Greece
| | - Lukáš Kratochvíl
- Faculty of Science, Department of Ecology, Charles University in Prague, Viničná 7, 12844 Praha 2, Czech Republic
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19
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Symonová R, Majtánová Z, Arias-Rodriguez L, Mořkovský L, Kořínková T, Cavin L, Pokorná MJ, Doležálková M, Flajšhans M, Normandeau E, Ráb P, Meyer A, Bernatchez L. Genome Compositional Organization in Gars Shows More Similarities to Mammals than to Other Ray-Finned Fish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2016; 328:607-619. [DOI: 10.1002/jez.b.22719] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 11/13/2016] [Accepted: 11/22/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Radka Symonová
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
- Department of Zoology; Faculty of Science; Charles University; Prague 2 Czech Republic
- Research Institute for Limnology; University of Innsbruck; Mondsee Austria
| | - Zuzana Majtánová
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
- Department of Zoology; Faculty of Science; Charles University; Prague 2 Czech Republic
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas; Universidad Juárez Autónoma de Tabasco (UJAT); Villahermosa Tabasco México
| | - Libor Mořkovský
- Department of Zoology; Faculty of Science; Charles University; Prague 2 Czech Republic
| | - Tereza Kořínková
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
| | - Lionel Cavin
- Muséum d'Histoire Naturelle; Geneva 6 Switzerland
| | - Martina Johnson Pokorná
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
- Department of Ecology; Faculty of Science; Charles University; Prague 2 Czech Republic
| | - Marie Doležálková
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
- Department of Zoology; Faculty of Science; Charles University; Prague 2 Czech Republic
| | - Martin Flajšhans
- Faculty of Fisheries and Protection of Waters; South Bohemian Research Centre of Aquaculture and Biodiversity of Hydrocenoses; University of South Bohemia in České Budějovice; Vodňany Czech Republic
| | - Eric Normandeau
- IBIS, Department of Biology, University Laval, Pavillon Charles-Eugène-Marchand; Avenue de la Médecine Quebec City; Canada
| | - Petr Ráb
- Laboratory of Fish Genetics; Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
| | - Axel Meyer
- Chair in Zoology and Evolutionary Biology; Department of Biology; University of Konstanz; Konstanz Germany
| | - Louis Bernatchez
- IBIS, Department of Biology, University Laval, Pavillon Charles-Eugène-Marchand; Avenue de la Médecine Quebec City; Canada
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20
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Rovatsos M, Johnson Pokorná M, Altmanová M, Kratochvíl L. Mixed-Up Sex Chromosomes: Identification of Sex Chromosomes in the X1X1X2X2/X1X2Y System of the Legless Lizards of the Genus Lialis (Squamata: Gekkota: Pygopodidae). Cytogenet Genome Res 2016; 149:282-289. [DOI: 10.1159/000450734] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2016] [Indexed: 11/19/2022] Open
Abstract
Geckos in general show extensive variability in sex determining systems, but only male heterogamety has been demonstrated in the members of their legless family Pygopodidae. In the pioneering study published more than 45 years ago, multiple sex chromosomes of the type X1X1X2X2/X1X2Y were described in Burton's legless lizard (Lialisburtonis) based on conventional cytogenetic techniques. We conducted cytogenetic analyses including comparative genomic hybridization and fluorescence in situ hybridization (FISH) with selected cytogenetic markers in this species and the previously cytogenetically unstudied Papua snake lizard (Lialis jicari) to better understand the nature of these sex chromosomes and their differentiation. Both species possess male heterogamety with an X1X1X2X2/X1X2Y sex chromosome system; however, the Y and one of the X chromosomes are not small chromosomes as previously reported in L. burtonis, but the largest macrochromosomal pair in the karyotype. The Y chromosomes in both species have large heterochromatic blocks with extensive accumulations of GATA and AC microsatellite motifs. FISH with telomeric probe revealed an exclusively terminal position of telomeric sequences in L. jicari (2n = 42 chromosomes in females), but extensive interstitial signals, potentially remnants of chromosomal fusions, in L.burtonis (2n = 34 in females). Our study shows that even largely differentiated and heteromorphic sex chromosomes might be misidentified by conventional cytogenetic analyses and that the application of more sensitive cytogenetic techniques for the identification of sex chromosomes is beneficial even in the classical examples of multiple sex chromosomes.
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21
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Rovatsos M, Vukić J, Altmanová M, Johnson Pokorná M, Moravec J, Kratochvíl L. Conservation of sex chromosomes in lacertid lizards. Mol Ecol 2016; 25:3120-6. [DOI: 10.1111/mec.13635] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 03/07/2016] [Accepted: 03/22/2016] [Indexed: 01/26/2023]
Affiliation(s)
- Michail Rovatsos
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7 128 44 Prague Czech Republic
| | - Jasna Vukić
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7 128 44 Prague Czech Republic
| | - Marie Altmanová
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7 128 44 Prague Czech Republic
| | - Martina Johnson Pokorná
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7 128 44 Prague Czech Republic
- Institute of Animal Physiology and Genetics; The Czech Academy of Sciences; Liběchov Czech Republic
| | - Jiří Moravec
- Department of Zoology; National Museum; Václavské nám. 68 115 79 Prague Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7 128 44 Prague Czech Republic
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22
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Discovery of the youngest sex chromosomes reveals first case of convergent co-option of ancestral autosomes in turtles. Chromosoma 2016; 126:105-113. [DOI: 10.1007/s00412-016-0576-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 11/27/2022]
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23
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Jančúchová-Lásková J, Landová E, Frynta D. Experimental Crossing of Two Distinct Species of Leopard Geckos, Eublepharis angramainyu and E. macularius: Viability, Fertility and Phenotypic Variation of the Hybrids. PLoS One 2015; 10:e0143630. [PMID: 26633648 PMCID: PMC4669172 DOI: 10.1371/journal.pone.0143630] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/07/2015] [Indexed: 12/01/2022] Open
Abstract
Hybridization between distinct species of animals and subsequent genetic introgression plays a considerable role in the speciation process and the emergence of adaptive characters. Fitness of between-species hybrids usually sharply decreases with the divergence time of the concerned species and the divergence depth, which still allows for a successful crossing differs among principal clades of vertebrates. Recently, a review of hybridization events among distinct lizard species revealed that lizards belong to vertebrates with a highly developed ability to hybridize. In spite of this, reliable reports of experimental hybridizations between genetically fairly divergent species are only exceptional. Here, we show the results of the crossing of two distinct allopatric species of eyelid geckos possessing temperature sex determination and lacking sex chromosomes: Eublepharis macularius distributed in Pakistan/Afghanistan area and E. angramainyu, which inhabits Mesopotamia and adjacent areas. We demonstrated that F1 hybrids were viable and fertile, and the introgression of E. angramainyu genes into the E. macularius genome can be enabled via a backcrossing. The examined hybrids (except those of the F2 generation) displayed neither malformations nor a reduced survival. Analyses of morphometric and coloration traits confirmed phenotypic distinctness of both parental species and their F1 hybrids. These findings contrast with long-term geographic and an evolutionary separation of the studied species. Thus, the occurrence of fertile hybrids of comparably divergent species, such as E. angramainyu and E. macularius, may also be expected in other taxa of squamates. This would violate the current estimates of species diversity in lizards.
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Affiliation(s)
| | - Eva Landová
- Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - Daniel Frynta
- Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
- * E-mail:
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24
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Interstitial Telomeric Motifs in Squamate Reptiles: When the Exceptions Outnumber the Rule. PLoS One 2015; 10:e0134985. [PMID: 26252002 PMCID: PMC4529230 DOI: 10.1371/journal.pone.0134985] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 07/15/2015] [Indexed: 12/19/2022] Open
Abstract
Telomeres are nucleoprotein complexes protecting the physical ends of linear eukaryotic chromosomes and therefore helping to ensure their stability and integrity. Additionally, telomeric sequences can be localized in non-terminal regions of chromosomes, forming so-called interstitial telomeric sequences (ITSs). ITSs are traditionally considered to be relics of chromosomal rearrangements and thus very informative in the reconstruction of the evolutionary history of karyotype formation. We examined the distribution of the telomeric motifs (TTAGGG)n using fluorescence in situ hybridization (FISH) in 30 species, representing 17 families of squamate reptiles, and compared them with the collected data from another 38 species from literature. Out of the 68 squamate species analyzed, 35 possess ITSs in pericentromeric regions, centromeric regions and/or within chromosome arms. We conclude that the occurrence of ITSs is rather common in squamates, despite their generally conserved karyotypes, suggesting frequent and independent cryptic chromosomal rearrangements in this vertebrate group.
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25
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Srikulnath K, Uno Y, Nishida C, Ota H, Matsuda Y. Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis, Gekkonidae): The Process of Microchromosome Disappearance in Gekkota. PLoS One 2015; 10:e0134829. [PMID: 26241471 PMCID: PMC4524605 DOI: 10.1371/journal.pone.0134829] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 07/15/2015] [Indexed: 01/12/2023] Open
Abstract
The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.
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Affiliation(s)
- Kornsorn Srikulnath
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- Laboratory of Animal Cytogenetics and Comparative Genomics, Department of Genetics, Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, Thailand
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University (CASTNAR, NRU-KU), Kasetsart University, Bangkok, Thailand
| | - Yoshinobu Uno
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Chizuko Nishida
- Department of Natural History Sciences, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido, Japan
| | - Hidetoshi Ota
- Institute of Natural and Environmental Sciences, University of Hyogo, and Museum of Nature and Human Activities, Sanda, Hyogo, Japan
| | - Yoichi Matsuda
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
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Golinski A, Kubička L, John-Alder H, Kratochvíl L. Androgenic control of male-typical behavior, morphology and sex recognition is independent of the mode of sex determination: A case study on Lichtenfelder's gecko (Eublepharidae: Goniurosaurus lichtenfelderi). Horm Behav 2015; 72:49-59. [PMID: 25967849 DOI: 10.1016/j.yhbeh.2015.04.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 04/10/2015] [Accepted: 04/11/2015] [Indexed: 11/21/2022]
Abstract
Previous work on lizards has shown that many sexually dimorphic traits depend on testosterone (T), but the details of this control can vary among species. Here, we tested the role of T on the expression of morphological, physiological, and behavioral traits in Lichtenfelder's gecko (Goniurosaurus lichtenfelderi), from the lizard family Eublepharidae notable for interspecific variation in sexually dimorphic traits and the mode of sex determination. Experiments included three groups of males (intact control, surgically castrated, castrated with T replacement) and two groups of females (intact control, T supplemented). In males, castration caused reductions in 1) the size of hemipenes, 2) offensive aggression, 3) male sexual behavior in a neutral arena, 4) activity of precloacal glands, and 5) loss of male chemical cues for sex recognition. These reductions were not observed in castrated males with T replacement. Interestingly, castrated males performed sexual behavior in their home cages, which shows that the effect of T depends on the environmental context. Notably, tail vibration, previously reported as a courtship behavior in other eublepharids, is displayed by males of G. lichtenfelderi during interactions with conspecifics of both sexes, suggesting an evolutionary shift in the meaning of this signal. In females, T induced growth of hemipenes and male-typical courtship but did not induce precloacal pore activity, aggression, or mounting. In comparison to previous reports on Eublepharis macularius, our results indicate that effects of T do not depend on the mode of sex determination. Further, our results extend our understanding of the complexity of control of male traits and illustrate how lability in the effects of T can be a general mechanism causing evolutionary changes in the components of suites of functionally correlated traits.
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Affiliation(s)
- Alison Golinski
- Graduate Program in Endocrinology and Animal Biosciences, Rutgers University, 84 Lipman Drive, New Brunswick, NJ 08901, USA
| | - Lukáš Kubička
- Faculty of Science, Charles University in Prague, Department of Ecology, Viničná 7, 128 44 Praha 2, Czech Republic
| | - Henry John-Alder
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Lukáš Kratochvíl
- Faculty of Science, Charles University in Prague, Department of Ecology, Viničná 7, 128 44 Praha 2, Czech Republic.
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Johnson Pokorná M, Trifonov VA, Rens W, Ferguson-Smith MA, Kratochvíl L. Low rate of interchromosomal rearrangements during old radiation of gekkotan lizards (Squamata: Gekkota). Chromosome Res 2015; 23:299-309. [PMID: 25665924 DOI: 10.1007/s10577-015-9468-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 01/21/2023]
Abstract
Gekkotan lizards are a highly specious (∼1600 described species) clade of squamate lizards with nearly cosmopolitan distribution in warmer areas. The clade is primarily nocturnal and forms an ecologically dominant part of the world nocturnal herpetofauna. However, molecular cytogenetic methods to study the evolution of karyotypes have not been widely applied in geckos. Our aim here was to uncover the extent of chromosomal rearrangements across the whole group Gekkota and to search for putative synapomorphies supporting the newly proposed phylogenetic relationships within this clade. We applied cross-species chromosome painting with the recently derived whole-chromosomal probes from the gekkonid species Gekko japonicus to members of the major gekkotan lineages. We included members of the families Diplodactylidae, Carphodactylidae, Pygopodidae, Eublepharidae, Phyllodactylidae and Gekkonidae. Our study demonstrates relatively high chromosome conservatism across the ancient group of gekkotan lizards. We documented that many changes in chromosomal shape across geckos can be attributed to intrachromosomal rearrangements. The documented rearrangements are not totally in agreement with the recently newly erected family Phyllodactylidae. The results also pointed to homoplasy, particularly in the reuse of chromosome breakpoints, in the evolution of gecko karyotypes.
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Affiliation(s)
- Martina Johnson Pokorná
- Department of Ecology, Faculty of Science, Charles University in Prague, Viničná 7, Praha 2, Czech Republic
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Pokorná MJ, Kratochvíl L. What was the ancestral sex-determining mechanism in amniote vertebrates? Biol Rev Camb Philos Soc 2014; 91:1-12. [DOI: 10.1111/brv.12156] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 10/01/2014] [Accepted: 10/15/2014] [Indexed: 01/15/2023]
Affiliation(s)
- Martina Johnson Pokorná
- Department of Ecology; Faculty of Science, Charles University in Prague; Viničná 7 Praha 2 Czech Republic
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic; Rumburská 89 Liběchov Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology; Faculty of Science, Charles University in Prague; Viničná 7 Praha 2 Czech Republic
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Pokorná MJ, Rovatsos M, Kratochvíl L. Sex chromosomes and karyotype of the (nearly) mythical creature, the Gila monster, Heloderma suspectum (Squamata: Helodermatidae). PLoS One 2014; 9:e104716. [PMID: 25119263 PMCID: PMC4131918 DOI: 10.1371/journal.pone.0104716] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 07/15/2014] [Indexed: 12/31/2022] Open
Abstract
A wide variety of sex determination systems exist among squamate reptiles. They can therefore serve as an important model for studies of evolutionary transitions among particular sex determination systems. However, we still have only a limited knowledge of sex determination in certain important lineages of squamates. In this respect, one of the most understudied groups is the family Helodermatidae (Anguimorpha) encompassing the only two venomous species of lizards which are potentially lethal to human beings. We uncovered homomorphic ZZ/ZW sex chromosomes in the Gila monster (Heloderma suspectum) with a highly heterochromatic W chromosome. The sex chromosomes are morphologically similar to the ZZ/ZW sex chromosomes of monitor lizards (Varanidae). If the sex chromosomes of helodermatids and varanids are homologous, female heterogamety may be ancestral for the whole Anguimorpha group. Moreover, we found that the karyotype of the Gila monster consists of 2n = 36 chromosomes (14 larger metacentric chromosomes and 22 acrocentric microchromosomes). 2n = 36 is the widely distributed chromosomal number among squamates. In his pioneering works representing the only previous cytogenetic examination of the family Helodermatidae, Matthey reported the karyotype as 2n = 38 and suggested a different chromosomal morphology for this species. We believe that this was probably erroneously. We also discovered a strong accumulation of telomeric sequences on several pairs of microchromosomes in the Gila monster, which is a trait documented relatively rarely in vertebrates. These new data fill an important gap in our understanding of the sex determination and karyotype evolution of squamates.
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Affiliation(s)
- Martina Johnson Pokorná
- Department of Ecology, Faculty of Science, Charles University in Prague, Praha, Czech Republic
- Institute of Animal Physiology and Genetics, Academy of the Sciences of the Czech Republic, Liběchov, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University in Prague, Praha, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University in Prague, Praha, Czech Republic
- * E-mail:
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Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable? Chromosome Res 2014; 22:441-52. [PMID: 25056523 DOI: 10.1007/s10577-014-9430-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 06/04/2014] [Accepted: 06/12/2014] [Indexed: 01/09/2023]
Abstract
Among amniote vertebrates, geckos represent a clade with exceptional variability in sex determination; however, only a minority of species of this highly diverse group has been studied in this respect. Here, we describe for the first time a female heterogamety in the genus Paroedura, the group radiated in Madagascar and adjacent islands. We identified homomorphic ZZ/ZW sex chromosomes with a highly heterochromatic W chromosome in Paroedura masobe, Paroedura oviceps, Paroedura karstophila, Paroedura stumpffi, and Paroedura lohatsara. Comparative genomic hybridization (CGH) revealed that female-specific sequences are greatly amplified in the W chromosome of P. lohatsara and that P. gracilis seems to possess a derived system of multiple sex chromosomes. Contrastingly, neither CGH nor heterochromatin visualization revealed differentiated sex chromosomes in the members of the Paroedura picta-Paroedura bastardi-Paroedura ibityensis clade, which is phylogenetically nested within lineages with a heterochromatic W chromosome. As a sex ratio consistent with genotypic sex determination has been reported in P. picta, it appears that the members of the P. picta-P. bastardi-P. ibityensis clade possess homomorphic, poorly differentiated sex chromosomes and may represent a rare example of evolutionary loss of highly differentiated sex chromosomes. Fluorescent in situ hybridization (FISH) with a telomeric probe revealed a telomere-typical pattern in all species and an accumulation of telomeric sequences in the centromeric region of autosomes in P. stumpffi and P. bastardi. Our study adds important information for the greater understanding of the variability and evolution of sex determination in geckos and demonstrates how the geckos of the genus Paroedura provide an interesting model for studying the evolution of the sex chromosomes.
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Rovatsos M, Altmanová M, Pokorná M, Kratochvíl L. CONSERVED SEX CHROMOSOMES ACROSS ADAPTIVELY RADIATEDANOLISLIZARDS. Evolution 2014; 68:2079-85. [DOI: 10.1111/evo.12357] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 01/08/2014] [Indexed: 12/17/2022]
Affiliation(s)
- Michail Rovatsos
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7, 12844 Praha 2 Czech Republic
| | - Marie Altmanová
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7, 12844 Praha 2 Czech Republic
| | - Martina Pokorná
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7, 12844 Praha 2 Czech Republic
- Department of Vertebrate Evolutionary Biology and Genetics; Institute of Animal Physiology and Genetics; Academy of Sciences of the Czech Republic; Rumburská 89 277 21 Liběchov Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology; Faculty of Science; Charles University in Prague; Viničná 7, 12844 Praha 2 Czech Republic
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Pokorná M, Altmanová M, Kratochvíl L. Multiple sex chromosomes in the light of female meiotic drive in amniote vertebrates. Chromosome Res 2014; 22:35-44. [DOI: 10.1007/s10577-014-9403-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Pokorná M, Rens W, Rovatsos M, Kratochvíl L. A ZZ/ZW Sex Chromosome System in the Thick-Tailed Gecko ( Underwoodisaurus milii; Squamata: Gekkota: Carphodactylidae), a Member of the Ancient Gecko Lineage. Cytogenet Genome Res 2014; 142:190-6. [DOI: 10.1159/000358847] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2013] [Indexed: 11/19/2022] Open
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Conservation of chromosomes syntenic with avian autosomes in squamate reptiles revealed by comparative chromosome painting. Chromosoma 2012; 121:409-18. [DOI: 10.1007/s00412-012-0371-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 04/05/2012] [Accepted: 04/10/2012] [Indexed: 01/06/2023]
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35
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Main H, Scantlebury DP, Zarkower D, Gamble T. Karyotypes of two species of Malagasy ground gecko (Paroedura: Gekkonidae). AFR J HERPETOL 2012. [DOI: 10.1080/21564574.2012.667837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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36
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Angelopoulou R, Lavranos G, Manolakou P. Sex determination strategies in 2012: towards a common regulatory model? Reprod Biol Endocrinol 2012; 10:13. [PMID: 22357269 PMCID: PMC3311596 DOI: 10.1186/1477-7827-10-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Accepted: 02/22/2012] [Indexed: 12/21/2022] Open
Abstract
Sex determination is a complicated process involving large-scale modifications in gene expression affecting virtually every tissue in the body. Although the evolutionary origin of sex remains controversial, there is little doubt that it has developed as a process of optimizing metabolic control, as well as developmental and reproductive functions within a given setting of limited resources and environmental pressure. Evidence from various model organisms supports the view that sex determination may occur as a result of direct environmental induction or genetic regulation. The first process has been well documented in reptiles and fish, while the second is the classic case for avian species and mammals. Both of the latter have developed a variety of sex-specific/sex-related genes, which ultimately form a complete chromosome pair (sex chromosomes/gonosomes). Interestingly, combinations of environmental and genetic mechanisms have been described among different classes of animals, thus rendering the possibility of a unidirectional continuous evolutionary process from the one type of mechanism to the other unlikely. On the other hand, common elements appear throughout the animal kingdom, with regard to a) conserved key genes and b) a central role of sex steroid control as a prerequisite for ultimately normal sex differentiation. Studies in invertebrates also indicate a role of epigenetic chromatin modification, particularly with regard to alternative splicing options. This review summarizes current evidence from research in this hot field and signifies the need for further study of both normal hormonal regulators of sexual phenotype and patterns of environmental disruption.
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Affiliation(s)
- Roxani Angelopoulou
- Experimental Embryology Unit, Department of Histology and Embryology, Medical School, Athens University, Athens, Greece
| | - Giagkos Lavranos
- Experimental Embryology Unit, Department of Histology and Embryology, Medical School, Athens University, Athens, Greece
| | - Panagiota Manolakou
- Experimental Embryology Unit, Department of Histology and Embryology, Medical School, Athens University, Athens, Greece
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37
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Pokorná M, Kratochvíl L, Kejnovský E. Microsatellite distribution on sex chromosomes at different stages of heteromorphism and heterochromatinization in two lizard species (Squamata: Eublepharidae: Coleonyx elegans and lacertidae: Eremias velox). BMC Genet 2011; 12:90. [PMID: 22013909 PMCID: PMC3215666 DOI: 10.1186/1471-2156-12-90] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 10/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The accumulation of repetitive sequences such as microsatellites during the differentiation of sex chromosomes has not been studied in most squamate reptiles (lizards, amphisbaenians and snakes), a group which has a large diversity of sex determining systems. It is known that the Bkm repeats containing tandem arrays of GATA tetranucleotides are highly accumulated on the degenerated W chromosomes in advanced snakes. Similar, potentially homologous, repetitive sequences were found on sex chromosomes in other vertebrates. Using FISH with probes containing all possible mono-, di-, and tri-nucleotide sequences and GATA, we studied the genome distribution of microsatellite repeats on sex chromosomes in two lizard species (the gecko Coleonyx elegans and the lacertid Eremias velox) with independently evolved sex chromosomes. The gecko possesses heteromorphic euchromatic sex chromosomes, while sex chromosomes in the lacertid are homomorphic and the W chromosome is highly heterochromatic. Our aim was to test whether microsatellite distribution on sex chromosomes corresponds to the stage of their heteromorphism or heterochromatinization. Moreover, because the lizards lie phylogenetically between snakes and other vertebrates with the Bkm-related repeats on sex chromosomes, the knowledge of their repetitive sequence is informative for the determination of conserved versus convergently evolved repetitive sequences across vertebrate lineages. RESULTS Heteromorphic sex chromosomes of C. elegans do not show any sign of microsatellite accumulation. On the other hand, in E. velox, certain microsatellite sequences are extensively accumulated over the whole length or parts of the W chromosome, while others, including GATA, are absent on this heterochromatinized sex chromosome. CONCLUSION The accumulation of microsatellite repeats corresponds to the stage of heterochromatinization of sex chromosomes rather than to their heteromorphism. The lack of GATA repeats on the sex chromosomes of both lizards suggests that the Bkm-related repeats on sex chromosomes in snakes and other vertebrates evolved convergently. The comparison of microsatellite sequences accumulated on sex chromosomes in E. velox and in other eukaryotic organisms suggests that historical contingency, not characteristics of particular sequences, plays a major role in the determination of which microsatellite sequence is accumulated on the sex chromosomes in a particular lineage.
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Affiliation(s)
- Martina Pokorná
- Department of Ecology, Charles University in Prague, Viničná 7, 128 44 Praha 2, Czech Republic
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Strong conservation of the bird Z chromosome in reptilian genomes is revealed by comparative painting despite 275 million years divergence. Chromosoma 2011; 120:455-68. [PMID: 21725690 DOI: 10.1007/s00412-011-0322-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 04/18/2011] [Accepted: 04/25/2011] [Indexed: 01/20/2023]
Abstract
The divergence of lineages leading to extant squamate reptiles (lizards, snakes, and amphisbaenians) and birds occurred about 275 million years ago. Birds, unlike squamates, have karyotypes that are typified by the presence of a number of very small chromosomes. Hence, a number of chromosome rearrangements might be expected between bird and squamate genomes. We used chromosome-specific DNA from flow-sorted chicken (Gallus gallus) Z sex chromosomes as a probe in cross-species hybridization to metaphase spreads of 28 species from 17 families representing most main squamate lineages and single species of crocodiles and turtles. In all but one case, the Z chromosome was conserved intact despite very ancient divergence of sauropsid lineages. Furthermore, the probe painted an autosomal region in seven species from our sample with characterized sex chromosomes, and this provides evidence against an ancestral avian-like system of sex determination in Squamata. The avian Z chromosome synteny is, therefore, conserved albeit it is not a sex chromosome in these squamate species.
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