Novel screens to identify genes regulating global chromatin structure during female meiotic prophase
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Date
2010Author
Loh, Benjamin Jia Hui
Metadata
Abstract
During female meiotic prophase in many organisms, a specialized chromatin
structure is formed in the oocyte nucleus. This structure is known as the karyosome,
and has been proposed to be important for the formation of the female meiotic
bipolar spindle. However, how the karyosome is formed and maintained is not very
well understood.
To identify proteins involved in the formation and maintenance of the
karyosome, I carried out a cytological screen on a collection of 220 mutant fly lines
for mutants that were defective in karyosome morphology. The screen identified 46
mutants on the X and 2nd chromosome with abnormal karyosomes. Genetic analysis
of these 46 mutants, followed by molecular analysis of one mutant, identified SRPK
(SR Protein Kinase) as a protein that is important for the proper formation of the
karyosome.
NHK-1 (Nucleosomal Histone Kinase 1) was previously identified as a
protein that is essential for the formation of the karyosome via its phosphorylation of
BAF (Barrier-to-Autointegration Factor). NHK-1 phosphorylation of BAF leads to the
release of chromatin from the nuclear membrane, an essential step for the formation
of the karyosome, however, the regulation of this process is unclear.
In order to identify genes that interact with NHK-1, I carried out a genetic
modifier screen using a semi-lethal allele of NHK-1, NHK-1trip. After screening a
collection of 44 deficiencies located on the 2nd chromosome, I identified a genetic
region (44B8-44D1) containing a gene that interacts with NHK-1 and, when gene
dosage is halved, enhanced the semi-lethal phenotype of NHK-1trip.