PgmNr W4010: Sex specific differences in C. elegans meiosis.

Authors:
S. Fielder; W. G. Kelly


Institutes
Emory University, Atlanta, GA.


Keyword: Gametogenesis, Fertilization, Egg-embryo transition

Abstract:

Meiotic synapsis is a conserved process that is required for proper segregation of homologous chromosomes in both oogenesis and spermatogenesis. In early prophase I, homolog sets are connected together by a bridge-like complex of synapsis proteins that keep them in close proximity to facilitate crossing over. If a chromosome is unable to pair and synapse, such as the lone X in C. elegans males, it is targeted for heterochromatin assembly in a process called meiotic silencing. This process has been observed in numerous organisms, including in mammals. I have observed in C. elegans, meiotic silencing, measured by histone H3 lysine 9 dimethylation accumulation (H3K9me2), occurs in both male and hermaphrodite mutants that are unable to pair and synapse one or two sets of homologs (e.g., zim-2 mutants, which are unable to pair chromosome V). Consistent with this trend, male mutants that completely lack synapsis show accumulation of H3K9me2 on all chromosomes. However, this pattern is strikingly different in hermaphrodites that lack synapsis: they do not show any increased accumulation of H3K9me2. This indicates that there may be a previously undescribed checkpoint that recognizes a failure to initiate synapsis and bypasses meiotic silencing in hermaphrodites. The global H3K9me2 enrichment in males indicates that this proposed checkpoint is sex specific or regulated differently in males. Analysis of this sex specific difference will be presented.



Wormbase Genetic Index
1. syp-1
2. zim-2