Among amniotes, squamate reptiles are especially variable in their mechanisms of sex determination; however, based largely on cytogenetic data, some lineages possess highly evolutionary stable sex chromosomes. The still very limited knowledge of the genetic content of squamate sex chromosomes precludes a reliable reconstruction of the evolutionary history of sex determination in this group and consequently in all amniotes. Female heterogamety with a degenerated W chromosome typifies the lizards of the family Lacertidae, the widely distributed Old World clade including several hundreds of species. From the liver transcriptome of the lacertid Takydromus sexlineatus female, we selected candidates for Z-specific genes as the loci lacking single-nucleotide polymorphisms. We validated the candidate genes through the comparison of the copy numbers in the female and male genomes of T. sexlineatus and another lacertid species, Lacerta agilis, by quantitative PCR that also proved to be a reliable technique for the molecular sexing of the studied species. We suggest that this novel approach is effective for the detection of Z-specific and X-specific genes in lineages with degenerated W, respectively Y chromosomes. The analyzed gene content of the Z chromosome revealed that lacertid sex chromosomes are not homologous with those of other reptiles including birds, but instead the genes have orthologs in the X-conserved region shared by viviparous mammals. It is possible that this part of the vertebrate genome was independently co-opted for the function of sex chromosomes in viviparous mammals and lacertids because of its content of genes involved in gonad differentiation.

Department of Ecology Faculty of Science Charles University Prague Prague Czech Republic

Zobrazit více v PubMed

Alföldi J, Di Palma F, Grabherr M, Williams C, Kong L, Mauceli E et al. (2011). The genome of the green anole lizard and a comparative analysis with birds and mammals. Nature 477: 587–591. PubMed PMC

Andres C, Franke F, Bleidorn C, Bernhard D, Schlegel M. (2014). Phylogenetic analysis of the Lacerta agilis subspecies complex. Syst Biodivers 12: 43–54.

Bachtrog D, Mank JE, Peichel CL, Kirkpatrick M, Otto SP, Ashman TL et al. (2014). Sex determination: why so many ways of doing it? PLoS Biol 12: e1001899. PubMed PMC

Danielyan F, Arakelyan M, Stepanyan I. (2008). Hybrids of Darevskia valentiniD. armeniaca and D. unisexualis from a sympatric population in Armenia. Amphibia-Reptilia 29: 487–504.

Delgado CLR, Waters PD, Gilbert C, Robinson TJ, Graves JAM. (2009). Physical mapping of the elephant X chromosome: conservation of gene order over 105 million years. Chromosome Res 17: 917–926. PubMed

Eckalbar WL, Hutchins ED, Markov GJ, Allen AN, Corneveaux JC, Lindblad-Toh K et al. (2013). Genome reannotation of the lizard Anolis carolinensis based on 14 adult and embryonic deep transcriptomes. BMC Genomics 14: 49. PubMed PMC

Fujii J, Kodama M, Oike A, Matsuo Y, Min M-S, Hasebe T et al. (2014). Involvement of androgen receptor in sex determination in an amphibian species. PLoS One 9: e93655. PubMed PMC

Gamble T, Geneva AJ, Glor RE, Zarkower D. (2014). Anolis sex chromosomes are derived from a single ancestral pair. Evolution 68: 1027–1041. PubMed PMC

Gamble T, Coryell J, Ezaz T, Lynch J, Scantlebury DP, Zarkower D. (2015). Restriction site-associated DNA sequencing (RAD-seq) reveals an extraordinary number of transitions among gecko sex-determining systems. Mol Biol Evol 32: 1296–1309. PubMed

Gullberg A, Olsson M, Tegelström H. (1998). Colonization, genetic diversity, and evolution in the Swedish sand lizard, Lacerta agilis (Reptilia, Squamata). Biol J Linn Soc 65: 257–277.

Holleley CE, O'Meally D, Sarre SD, Marshall Graves JAM, Ezaz T, Matsubara K et al. (2015). Sex reversal triggers the rapid transition from genetic to temperature-dependent sex. Nature 523: 79–82. PubMed

Johnson Pokorná M, Kratochvíl L. (2016). What was the ancestral sex-determining mechanism in amniote vertebrates? Biol Rev 91: 1–12. PubMed

Johnson Pokorná M, Trifonov VA, Rens W, Ferguson-Smith MA, Kratochvíl L. (2015). Low rate of interchromosomal rearrangements during old radiation of gekkotan lizards (Squamata: Gekkota). Chromosome Res 23: 299–309. PubMed

Kawagoshi T, Nishida C, Matsuda Y. (2012). The origin and differentiation process of X and Y chromosomes of the black marsh turtle (Siebenrockiella crassicollis, Geoemydidae, Testudines). Chromosome Res 20: 95–110. PubMed

Kawagoshi T, Uno Y, Nishida C, Matsuda Y. (2014). The Staurotypus turtles and aves share the same origin of sex chromosomes but evolved different types of heterogametic sex determination. PLoS One 9: e105315. PubMed PMC

Kawai A, Ishijima J, Nishida C, Kosaka A, Ota H, Kohno SI et al. (2009). The ZW sex chromosomes of Gekko hokouensis (Gekkonidae, Squamata) represent highly conserved homology with those of avian species. Chromosoma 118: 43–51. PubMed

Kearse M, Moir R, Wilson A, Stones-Havas S, Cheung M, Sturrock S et al. (2012). Geneious Basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 28: 1647–1649. PubMed PMC

Kikuchi K, Hamaguchi S. (2013). Novel sex-determining genes in fish and sex chromosome evolution. Dev Dyn 242: 339–353. PubMed

Kohn M, Kehrer-Sawatzki H, Vogel W, Graves JAM, Hameister H. (2004). Wide genome comparisons reveal the origins of the human X chromosome. Trends Genet 20: 598–603. PubMed

Lambeth LS, Raymond CS, Roeszler KN, Kuroiwa A, Nakata T, Zarkower D et al. (2014). Over-expression of DMRT1 induces the male pathway in embryonic chicken gonads. Dev Biol 389: 160–172. PubMed PMC

Literman R, Badenhorst D, Valenzuela N. (2014). qPCR-based molecular sexing by copy number variation in rRNA genes and its utility for sex identification in soft-shell turtles. Methods Ecol Evol 9: 872–880.

Matsubara K, Tarui H, Toriba M, Yamada K, Nishida-Umehara C, Agata K et al. (2006). Evidence for different origin of sex chromosomes in snakes, birds, and mammals and step-wise differentiation of snake sex chromosomes. Proc Natl Acad Sci USA 103: 18190–18195. PubMed PMC

Mácha J, Teichmanová R, Sater AK, Wells DE, Tlapáková T, Zimmerman LB et al. (2012). Deep ancestry of mammalian X chromosome revealed by comparison with the basal tetrapod Xenopus tropicalis. BMC Genomics 13: 315. PubMed PMC

Nguyen P, Sýkorová M, Šíchová J, Kůta V, Dalíková M, Čapková Frydrychová R et al. (2013). Neo-sex chromosomes and adaptive potential in tortricid pests. Proc Natl Acad Sci USA 110: 6931–6936. PubMed PMC

Odierna G, Olmo E, Cobror O. (1985). C-band variability in some Lacertidae (Sauria, Reptilia). Experientia 41: 944–946.

Olmo E, Signorino GG. (2005). Chromorep: a reptile chromosomes database. Retrieved from http://chromorep.univpm.it (Accessed 21 March 2015).

Olmo E, Cobror O, Morescalchi G. (1984). Homomorphic sex chromosomes in the lacertid lizard Takydromus sexlineatus. Heredity 53: 457–459.

Olmo E, Odierna G, Cobror O. (1986). C-band variability and phylogeny of Lacertidae. Genetica 71: 63–74.

O'Meally D, Ezaz T, Georges A, Sarre SD, Graves JAM. (2012). Are some chromosomes particularly good at sex? Insights from amniotes. Chromosome Res 20: 7–19. PubMed

Pokorná M, Kratochvíl L. (2009). Phylogeny of sex-determining mechanisms in squamate reptiles: are sex chromosomes an evolutionary trap? Zool J Linn Soc 156: 168–183.

Pokorná M, Giovannotti M, Kratochvíl L, Kasai F, Trifonov VA, O'Brien PC et al. (2011. a). Strong conservation of the bird Z chromosome in reptilian genomes is revealed by comparative painting despite 275 million years divergence. Chromosoma 120: 455–468. PubMed

Pokorná M, Kratochvíl L, Kejnovský E. (2011. b). 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 Genetics 12: 90. PubMed PMC

Pokorná M, Giovannotti M, Kratochvíl L, Caputo V, Olmo E, Ferguson-Smith MA et al. (2012). Conservation of chromosomes syntenic with avian autosomes in squamate reptiles revealed by comparative chromosome painting. Chromosoma 121: 409–418. PubMed

Pyron RA, Burbrink FT, Wiens JJ. (2013). A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evol Biol 13: 93. PubMed PMC

Quinn AE, Georges A, Sarre SD, Guarino F, Ezaz T, Graves JAM. (2007). Temperature sex reversal implies sex gene dosage in a reptile. Science 316: 411. PubMed

Rens W, O'Brien PC, Grutzner F, Clarke O, Graphodatskaya D, Tsend-Ayush E et al. (2007). The multiple sex chromosomes of platypus and echidna are not completely identical and several share homology with the avian Z. Genome Biol 8: R243. PubMed PMC

Rovatsos M, Pokorná M, Altmanová M, Kratochvíl L. (2014. a). Cretaceous park of sex determination: sex chromosomes are conserved across iguanas. Biol Lett 10: 20131093. PubMed PMC

Rovatsos M, Altmanová M, Pokorná M, Kratochvíl L. (2014. b). Conserved sex chromosomes across adaptively radiated Anolis lizards. Evolution 68: 2079–2085. PubMed

Rovatsos M, Altmanova M, Pokorna MJ, Kratochvil L. (2014. c). Novel X-lnked genes revealed by quantitative polymerase chain reaction in the green anole, Anolis carolinensis. G3 (Bethesda) 4: 2107–2113. PubMed PMC

Rovatsos M, Vukić J, Lymberakis P, Kratochvíl L. (2015). Evolutionary stability of sex chromosomes in snakes. Proc R Soc B 282: 20151992. PubMed PMC

Shabsovich D, Tirado CA. (2014). Genes, chromosomes, and disorders of sex development: an update. J Assoc Genet Technol 40: 124–140. PubMed

Smeds L, Kawakami T, Burri R, Bolivar P, Husby A, Qvarnström A et al. (2014). Genomic identification and characterization of the pseudoautosomal region in highly differentiated avian sex chromosomes. Nat Commun 5: 5448. PubMed PMC

Smith CA, Roeszler KN, Ohnesorg T, Cummins DM, Farlie PG, Doran TJ et al. (2009). The avian Z-linked gene DMRT1 is required for male sex determination in the chicken. Nature 461: 267–271. PubMed

Srikulnath K, Matsubara K, Uno Y, Nishida C, Olsson M, Matsuda Y. (2014). Identification of the linkage group of the Z sex chromosomes of the sand lizard (Lacerta agilis, Lacertidae) and elucidation of karyotype evolution in lacertid lizards. Chromosoma 123: 563–575. PubMed

Takehana Y, Matsuda M, Myosho T, Suster ML, Kawakami K, Shin-I T et al. (2014). Co-option of Sox3 as the male-determining factor on the Y chromosome in the fish Oryzias dancena. Nat Commun 5: 4157. PubMed

Uetz P, Hošek J (eds). (2014) The Reptile Database. Retrieved from http://www.reptile-database.org (Accessed 21 March 2015).

Vicoso B, Emerson JJ, Zektser Y, Mahajan S, Bachtrog D. (2013). Comparative sex chromosome genomics in snakes: differentiation, evolutionary strata, and lack of global dosage compensation. PLoS Biol 11: e1001643. PubMed PMC

Ye J, Coulouris G, Zaretskaya I, Cutcutache I, Rozen S, Madden T. (2012). Primer-BLAST: A tool to design target-specific primers for polymerase chain reaction. BMC Bioinformatics 13: 134. PubMed PMC

Zhou Q, Zhang J, Bachtrog D, An N, Huang Q, Jarvis ED et al. (2014). Complex evolutionary trajectories of sex chromosomes across bird taxa. Science 346: 1246338. PubMed PMC

Zhang J, Li C, Zhou Q, Zhang G. (2015). Improving the ostrich genome assembly using optical mapping data. GigaScience 4: 24. PubMed PMC

Heteromorphic ZZ/ZW sex chromosomes sharing gene content with mammalian XX/XY are conserved in Madagascan chameleons of the genus Furcifer

Sex chromosome evolution among amniotes: is the origin of sex chromosomes non-random?

Evolutionary Variability of W-Linked Repetitive Content in Lacertid Lizards

Escaping the evolutionary trap? Sex chromosome turnover in basilisks and related lizards (Corytophanidae: Squamata)

Little evidence for switches to environmental sex determination and turnover of sex chromosomes in lacertid lizards

Stable Cretaceous sex chromosomes enable molecular sexing in softshell turtles (Testudines: Trionychidae)