Project description:Aneuploidy, and especially the presence of unpaired chromosomal axes during meiosis, can cause infertility. However, it is not known if extra, unpaired autosomal chromosome segments acquire characteristic protein modifications and undergo transcriptional silencing (meiotic silencing of unpaired chromatin, or MSUC) similar to the unpaired regions of the X and Y chromosomes during spermatogenesis. We used three mouse models of Down syndrome, involving either an extra chromosome or translocation trisomy, to test requirements and consequences of meiotic protein modification and gene silencing in spermatocytes. These models reveal that copy number alone is not sufficient for up-regulation of genes in the trisomic interval, and that MSUC-promoting modifications are not sufficient for down-regulation of genes that reside in unpaired chromatin during meiosis. The position of a trisomic region relative to a centromere, the pairing status of the centromere, and the physical extent of the unpaired chromosomal region all affected assembly of meiotic protein modifications typical of MSUC. One key determinant to modification of unpaired chromatin and infertility in trisomy male mice appears to be proximity of unpaired chromatin to a centromere. Furthermore, the presence of an extra, unpaired centromere, but not translocation trisomy, causes global misregulation of transcription in spermatocytes. Thus, neither trisomy per se, nor chromatin modifications of unpaired chromosomal segments, have major effects on gene expression or meiotic success, but an intact unpaired chromosome has profoundly negative effects on meiotic gene expression.
Project description:SPO11-promoted DNA double-strand breaks (DSBs) formation is a crucial step for meiotic recombination, and it is indispensable to detect the broken DNA ends accurately for dissecting the molecular mechanisms behind. Here, we report a novel technique, named DEtail-seq (DNA End tailing followed by sequencing), that can directly and quantitatively capture the meiotic DSB 3’ overhang hotspots at single-nucleotide resolution.
Project description:PURPOSE: To provide a detailed gene expression profile of the normal postnatal mouse cornea. METHODS: Serial analysis of gene expression (SAGE) was performed on postnatal day (PN)9 and adult mouse (6 week) total corneas. The expression of selected genes was analyzed by in situ hybridization. RESULTS: A total of 64,272 PN9 and 62,206 adult tags were sequenced. Mouse corneal transcriptomes are composed of at least 19,544 and 18,509 unique mRNAs, respectively. One third of the unique tags were expressed at both stages, whereas a third was identified exclusively in PN9 or adult corneas. Three hundred thirty-four PN9 and 339 adult tags were enriched more than fivefold over other published nonocular libraries. Abundant transcripts were associated with metabolic functions, redox activities, and barrier integrity. Three members of the Ly-6/uPAR family whose functions are unknown in the cornea constitute more than 1% of the total mRNA. Aquaporin 5, epithelial membrane protein and glutathione-S-transferase (GST) omega-1, and GST alpha-4 mRNAs were preferentially expressed in distinct corneal epithelial layers, providing new markers for stratification. More than 200 tags were differentially expressed, of which 25 mediate transcription. CONCLUSIONS: In addition to providing a detailed profile of expressed genes in the PN9 and mature mouse cornea, the present SAGE data demonstrate dynamic changes in gene expression after eye opening and provide new probes for exploring corneal epithelial cell stratification, development, and function and for exploring the intricate relationship between programmed and environmentally induced gene expression in the cornea. Keywords: other