@article{NandaSchoriesSimeonovetal.2022,
  author    = {Nanda, Indrajit and Schories, Susanne and Simeonov, Ivan and Adolfi, Mateus Contar and Du, Kang and Steinlein, Claus and Alsheimer, Manfred and Haaf, Thomas and Schartl, Manfred},
  title     = {Evolution of the degenerated Y-chromosome of the swamp guppy, Micropoecilia picta},
  series = {Cells},
  volume    = {11},
  journal   = {Cells},
  number    = {7},
  issn      = {2073-4409},
  doi       = {10.3390/cells11071118},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-267242},
  year      = {2022},
  abstract  = {The conspicuous colour sexual dimorphism of guppies has made them paradigmatic study objects for sex-linked traits and sex chromosome evolution. Both the X- and Y-chromosomes of the common guppy (Poecilia reticulata) are genetically active and homomorphic, with a large homologous part and a small sex specific region. This feature is considered to emulate the initial stage of sex chromosome evolution. A similar situation has been documented in the related Endler's and Oropuche guppies (P. wingei, P. obscura) indicating a common origin of the Y in this group. A recent molecular study in the swamp guppy (Micropoecilia. picta) reported a low SNP density on the Y, indicating Y-chromosome deterioration. We performed a series of cytological studies on M. picta to show that the Y-chromosome is quite small compared to the X and has accumulated a high content of heterochromatin. Furthermore, the Y-chromosome stands out in displaying CpG clusters around the centromeric region. These cytological findings evidently illustrate that the Y-chromosome in M. picta is indeed highly degenerated. Immunostaining for SYCP3 and MLH1 in pachytene meiocytes revealed that a substantial part of the Y remains associated with the X. A specific MLH1 hotspot site was persistently marked at the distal end of the associated XY structure. These results unveil a landmark of a recombining pseudoautosomal region on the otherwise strongly degenerated Y chromosome of M. picta. Hormone treatments of females revealed that, unexpectedly, no sexually antagonistic color gene is Y-linked in M. picta. All these differences to the Poecilia group of guppies indicate that the trajectories associated with the evolution of sex chromosomes are not in parallel.},
  language  = {en}
}
@article{KottlerSchartl2018,
  author    = {Kottler, Verena A. and Schartl, Manfred},
  title     = {The colorful sex chromosomes of teleost fish},
  series = {Genes},
  volume    = {9},
  journal   = {Genes},
  number    = {5},
  doi       = {10.3390/genes9050233},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176587},
  pages     = {233},
  year      = {2018},
  abstract  = {Teleost fish provide some of the most intriguing examples of sexually dimorphic coloration, which is often advantageous for only one of the sexes. Mapping studies demonstrated that the genetic loci underlying such color patterns are frequently in tight linkage to the sex-determining locus of a species, ensuring sex-specific expression of the corresponding trait. Several genes affecting color synthesis and pigment cell development have been previously described, but the color loci on the sex chromosomes have mostly remained elusive as yet. Here, we summarize the current knowledge about the genetics of such color loci in teleosts, mainly from studies on poeciliids and cichlids. Further studies on these color loci will certainly provide important insights into the evolution of sex chromosomes.},
  language  = {en}
}
@article{TomaszkiewiczChalopinSchartletal.2014,
  author    = {Tomaszkiewicz, Marta and Chalopin, Domitille and Schartl, Manfred and Galiana, Delphine and Volff, Jean-Nicolas},
  title     = {A multicopy Y-chromosomal SGNH hydrolase gene expressed in the testis of the platyfish has been captured and mobilized by a Helitron transposon},
  series = {BMC Genetics},
  volume    = {15},
  journal   = {BMC Genetics},
  number    = {44},
  doi       = {10.1186/1471-2156-15-44},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116746},
  year      = {2014},
  abstract  = {Background: Teleost fish present a high diversity of sex determination systems, with possible frequent evolutionary turnover of sex chromosomes and sex-determining genes. In order to identify genes involved in male sex determination and differentiation in the platyfish Xiphophorus maculatus, bacterial artificial chromosome contigs from the sex-determining region differentiating the Y from the X chromosome have been assembled and analyzed. Results: A novel three-copy gene called teximY (for testis-expressed in Xiphophorus maculatus on the Y) was identified on the Y but not on the X chromosome. A highly related sequence called texim1, probably at the origin of the Y-linked genes, as well as three more divergent texim genes were detected in (pseudo) autosomal regions of the platyfish genome. Texim genes, for which no functional data are available so far in any organism, encode predicted esterases/lipases with a SGNH hydrolase domain. Texim proteins are related to proteins from very different origins, including proteins encoded by animal CR1 retrotransposons, animal platelet-activating factor acetylhydrolases (PAFah) and bacterial hydrolases. Texim gene distribution is patchy in animals. Texim sequences were detected in several fish species including killifish, medaka, pufferfish, sea bass, cod and gar, but not in zebrafish. Texim-like genes are also present in Oikopleura (urochordate), Amphioxus (cephalochordate) and sea urchin (echinoderm) but absent from mammals and other tetrapods. Interestingly, texim genes are associated with a Helitron transposon in different fish species but not in urochordates, cephalochordates and echinoderms, suggesting capture and mobilization of an ancestral texim gene in the bony fish lineage. RT-qPCR analyses showed that Y-linked teximY genes are preferentially expressed in testis, with expression at late stages of spermatogenesis (late spermatids and spermatozeugmata). Conclusions: These observations suggest either that TeximY proteins play a role in Helitron transposition in the male germ line in fish, or that texim genes are spermatogenesis genes mobilized and spread by transposable elements in fish genomes.},
  language  = {en}
}