X Chromosome Inactivation during Grasshopper Spermatogenesis.

Area of Science:

• Reproductive biology
• Genetics
• Molecular biology

Background:

• Transcriptional regulation during meiosis is linked to chromosome synapsis.
• Mammalian male meiosis shows dynamic transcriptional changes, with sex chromosomes often inactivated.
• Limited knowledge exists on synapsis-transcription relationships in non-mammalian species.

Purpose of the Study:

• To investigate the relationship between synapsis and transcription in grasshopper (Eyprepocnemis plorans) spermatocytes.
• To compare transcriptional patterns in grasshoppers with those in mammals.

Main Methods:

• Immunolabeling of RNA polymerase II phosphorylated at serine 2 to assess transcriptional activity.
• Analysis of epigenetic modifications (H3K9 methylation, H2AX phosphorylation) on the X chromosome.
• Microscopic examination of spermatocytes and spermatogonia.

Main Results:

• Autosomes in E. plorans are transcriptionally active from leptotene to diakinesis.
• The unsynapsed X chromosome is transcriptionally inactive throughout meiosis.
• X chromosome inactivation is associated with repressive epigenetic marks (H3K9me, H2AXpS139) and occurs in premeiotic spermatogonia.

Conclusions:

• Transcriptional regulation in E. plorans spermatogenesis differs from the typical mammalian pattern.
• X chromosome inactivation in E. plorans likely involves pre-meiotic heterochromatinization.