title: Histone H3 phosphorylation and elimination of paternal X chromosomes at early cleavages in sciarid flies.
abstract: In sciarid flies (Diptera, Sciaridae), one or two paternally derived X chromosomes are discarded from the soma at early cleavages to determine the sex of the embryo (XX, females; X0, males). X chromosome(s) elimination is achieved by an abnormal anaphase segregation so that X sister chromatids do not reach the poles and are not included in the daughter nuclei. A cis-acting locus (CE) within the heterochromatin proximal to the centromere is known to regulate X chromosome elimination. By immunofluorescence analysis in early embryos from Sciara ocellaris and Sciara coprophila, we investigated histone H3 phosphorylation at Ser10, Ser28 and Thr3 prior to, and during, the X elimination process. We found that the regular syncytial nuclear divisions are characterized by a gradual loss of H3S10 phosphorylation along the chromosome arms at anaphase. Importantly, the eliminating X chromosomes show a retardation in anaphase chromatid segregation and high levels of H3S10 phosphorylation in the chromosome arms. In the present study, we provide the first evidence linking the hyper-phosphorylated H3 status of the X chromosome with a delay in sister chromatid separation at anaphase. Our findings support the idea that the CE induces a deficiency in H3 dephosphorylation in the paternal X chromosomes to be eliminated.
authors: Centro de Investigaciones Biológicas, Departamento de Biología Celular y Molecular, CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors: M Carmen
authors: MC
authors: Escribá
authors: Clara
authors: C
authors: Goday
mesh_terms: D000705:Anaphase / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D004175:Diptera / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian; D005260:Female; D005455:Fluorescent Antibody Technique; D006570:Heterochromatin / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008297:Male; D010766:Phosphorylation; D019849:Sex Determination Processes / Q000235:genetics; D014960:X Chromosome / Q000378:metabolism*
chemical_list: D006570:Heterochromatin; D006657:Histones
keywords: Chromosome elimination; H3 phosphorylation; Sciara; Syncytial divisions