Meiosis is a basic process of most eukaryotes, as it forms with conjugation the basis of sexual reproduction. As sex seems to be present in the vast majority of eukaryotes, the origin of meiosis is presently unknown. Protists having optional or alternative sexual and asexual cycles seem to be the best targets for research on the evolution of meiosis. While the budding yeast Saccharomyces cerevisiae shows an elaborate and well-known meiotic process, the fission yeast Schizosaccharomyces pombe, has a much simpler meiosis, which may show some of the most primitive features of meiotic mechanisms. The present availability of whole genome sequences of many bacteria and some protists is revealing that eukaryotic sexual reproduction has recruited some prokaryotic processes for its own development. Some of these processes are analyzed and the basic role of chromosome linearity and telomere constitution in the development of meiosis is underlined.
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Sci Rep
January 2025
Department of Ecology, Faculty of Science, Charles University, Viničná 7, Prague, 128 44, Czech Republic.
Obligatory parthenogenesis in vertebrates is restricted to squamate reptiles and evolved through hybridisation. Parthenogens can hybridise with sexual species, resulting in individuals with increased ploidy levels. We describe two successive hybridisations of the parthenogenetic butterfly lizards (genus Leiolepis) in Vietnam with a parental sexual species.
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January 2025
Sex Chromosome Biology Laboratory, The Francis Crick Institute, London, UK.
The mammalian Y chromosome is essential for male fertility, but which Y genes regulate spermatogenesis is unresolved. We addressed this by generating 13 Y-deletant mouse models. In , , and deletants, spermatogenesis was impaired.
View Article and Find Full Text PDFPLoS Genet
January 2025
Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
The synaptonemal complex (SC) is a protein-rich structure essential for meiotic recombination and faithful chromosome segregation. Acting like a zipper to paired homologous chromosomes during early prophase I, the complex is a symmetrical structure where central elements are connected on two sides by the transverse filaments to the chromatin-anchoring lateral elements. Despite being found in most major eukaryotic taxa implying a deeply conserved evolutionary origin, several components of the complex exhibit unusually high rates of sequence turnover.
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January 2025
Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
The abundance and sequence of satellite DNA at and around centromeres is evolving rapidly despite the highly conserved and essential process through which the centromere directs chromosome inheritance. The impact of such rapid evolution is unclear. Here we find that sequence-dependent DNA shape dictates packaging of pericentromeric satellites in female meiosis through a conserved DNA-shape-recognizing chromatin architectural protein, high mobility group AT-hook 1 (HMGA1).
View Article and Find Full Text PDFGigascience
January 2025
Centre for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou 310058, China.
Background: A thorough analysis of genome evolution is fundamental for biodiversity understanding. The iconic monotremes (platypus and echidna) feature extraordinary biology. However, they also exhibit rearrangements in several chromosomes, especially in the sex chromosome chain.
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