Project description:Genome wide localization of Kumgang, dMi-2, and Aly in Drosophila melanogaster testes were evaluated by ChIP-Seq in wild-type and kmg knock down testes. / Title: Blocking promiscuous activation at cryptic promoters directs cell type–specific gene expression / Abstract: To selectively express cell type–specific transcripts during development, it is critical to maintain genes required for other lineages in a silent state. Here, we show in the Drosophila male germline stem cell lineage that a spermatocyte-specific zinc finger protein, Kumgang (Kmg), working with the chromatin remodeler dMi-2 prevents transcription of genes normally expressed only in somatic lineages. By blocking transcription from normally cryptic promoters, Kmg restricts activation by Aly, a component of the testis-meiotic arrest complex, to transcripts for male germ cell differentiation. Our results suggest that as new regions of the genome become open for transcription during terminal differentiation, blocking the action of a promiscuous activator on cryptic promoters is a critical mechanism for specifying precise gene activation.
Project description:Drosophila melanogaster is a well-studied genetic model organism with several large-scale transcriptome resources. Here we investigate 7,952 proteins during the fly life cycle from embryo to adult and also provide a high-resolution temporal time course proteome of 5,458 proteins during embryogenesis. We use our large scale data set to compare transcript/protein expression, uncovering examples of extreme differences between mRNA and protein abundance. In the embryogenesis proteome, the time delay in protein synthesis after transcript expression was determined. For some proteins, including the transcription factor lola, we monitor isoform specific expression levels during early fly development. Furthermore, we obtained firm evidence of 268 small proteins, which are hard to predict by bioinformatics. We observe peptides originating from non-coding regions of the genome and identified Cyp9f3psi as a protein-coding gene. As a powerful resource to the community, we additionally created an interactive web interface (http://www.butterlab.org) advancing the access to our data.
Project description:Spermiogenesis in Drosophila melanogaster is a highly conserved process and essential for male fertility. In this haploid phase of spermatogenesis, motile sperm are assembled from round cells, flagella are assembled, and needle-shaped nuclei with highly compacted genomes are formed. We aimed at identifying proteins relevant for the maturation phase from spermatids to sperm. As transcription takes place mainly in spermatocytes, and transcripts with relevance for post-meiotic sperm development are translationally repressed for days, we comparatively analysed the prote-ome of larval testes (stages before meiotic divisions), of testes of 1–2-day-old pupae (meiotic and early spermatid stages) and adult flies (late spermatids and sperm). We identified 6677 pro-teins, with 422 solely detected in larval testes, 623 in pupal testes and 634 in adult testes. We analysed a few so far uncharacterized proteins with repect to stage specific expression and im-portance for male fertility. For example, Mst84B (gene CG1988), a very basic cysteine- and lysine-rich nuclear protein, was present in the phase of transition from a histone-based to a pro-tamine-based chromatin structure. CG6332 encodes d-Theg, which is related to the mouse tHEG and human THEG proteins. Mutants of d-Theg lacked sperm in the seminal vesicles and were sterile. The identification of numerous predicted proteins underscores the high potential of pro-teome analysis for future analyses of spermatogenesis.