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bioRxiv · 10.1101/205211

Gender- and gamete-specific patterns of X chromosome segregation in a three-gendered nematode

Tandonnet, S.·Farrell, M. C.·Koutsovoulos, G.·Blaxter, M.·Parihar, M.·Sadler, P. L.·Shakes, D.·Pires da Silva, A.
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Abstract

Meiosis is at the core of sexual reproduction and alterations to its program can have dramatic effects. In this study, we investigate the segregation pattern of the X chromosome in Auanema rhodensis, a three-gendered nematode. This species has an atypical pattern of X chromosome segregation during male spermatogenesis that results in the exclusive production of haplo-X sperm. Here we use a combination of genetic and cytological approaches to show that while XX females undergo conventional meiosis to produce mostly haplo-X oocytes, hermaphrodites undergo atypical meiosis to produce nullo-X oocytes and mostly diplo-X sperm. Gender- and gamete-specific alterations of the normal meiotic program include non-pairing of the X homologs and precocious separation of X chromatids. Given these intra-species, intra-individual and intra-gametogenesis variations in meiotic program of A. rhodensis, we argue that it is an ideal model to study the plasticity of meiosis and how it can be modulated.\n\nHighlights- Matings between A. rhodensis hermaphrodites and males generate only male crossprogeny.\n- Hermaphrodites generate mostly nullo-X oocytes and diplo-X sperm.\n- Following normal Mendelian genetics, XX females produce haplo-X oocytes.\n- In cross-progeny, sons always inherit the X chromosome from the father.

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Tandonnet, S., Farrell, M. C., Koutsovoulos, G., Blaxter, M., Parihar, M., Sadler, P. L., Shakes, D., Pires da Silva, A.. 2017-10-18. Gender- and gamete-specific patterns of X chromosome segregation in a three-gendered nematode. https://doi.org/10.1101/205211

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