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.
Project description:The expression of a very large number of genes changes as male germ cells pass through differentiation into spermatids and then sperm. Much of this transcriptional programme requires the activity of the meiotic arrest genes. We extracted RNA from wild type testes, as well as aly mutants and Nxt1 mutants, and used microarrays to compare gene expression profiles. We dissected testes from 0-1 day old Drosophila males, taking care to remove accessory glands and ejaculatory ducts. The control sample expressed a tin-RNAi construct, and had normal testes. The aly mutant were homozygous for aly[5]. The Nxt1 mutants were Nxt1[z2-0488]/Nxt1[DG05102].
Project description:The expression of a very large number of genes changes as male germ cells pass through differentiation into spermatids and then sperm. Much of this transcriptional programme requires the activity of the meiotic arrest genes. There are two principle classes, aly-class (including comr) and can-class, here we compare their effects on gene expression We extracted RNA from wild type testes, as well as comr mutants and can mutants, and used microarrays to compare gene expression profiles. We dissected testes from 0-1 day old Drosophila males, taking care to remove accessory glands and ejaculatory ducts. The control sample was red e, the background chromosome on which the can mutant was generated, and had normal testes. The comr mutants were comr[z1340] cn bw. The can mutants were w ; can[3] red e.
Project description:The expression of a very large number of genes changes as male germ cells pass through differentiation into spermatids and then sperm. Much of this transcriptional programme requires the activity of the meiotic arrest genes. We extracted RNA from wild type testes, as well as aly mutants and Nxt1 mutants, and used microarrays to compare gene expression profiles.
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:The expression of a very large number of genes changes as male germ cells pass through differentiation into spermatids and then sperm. Much of this transcriptional programme requires the activity of the meiotic arrest genes. There are two principle classes, aly-class (including comr) and can-class, here we compare their effects on gene expression We extracted RNA from wild type testes, as well as comr mutants and can mutants, and used microarrays to compare gene expression profiles.
Project description:The piRNA pathway is studied in great detail in Drosophila female germline. In this study we show that unlike the female germline where all Piwi proteins are expressed throughout oogenesis, Ago3 - a Piwi family protein shows a spatial expression male germline. To understand dynamics of piRNA pathway during spermatogonia and primary spermatocyte stages of male germline development, we used arrest mutants. The bag of marbles (bam) and benign gonial cell neoplasm (bgcn) mutants have only early mitotic dividing germline cells in the testes due to failure to progress to primary spermatocyte stage, the cannonball (can) and spermatocyte arrest (sa) mutant germline cells cannot progress beyond primary spermatocyte stage. To investigate the dynamics of the piRNA pathway during spermatogenesis in spermatogonia and primary spermatocyte stages, we used testicular tissues from these stage-specific arrested mutants. While we used entire bam and bgcn mutant testes for spermatogonia purification, we while we manually removed the apical regions of can and sa mutant testes to exclude mitotically dividing undifferentiated germline cells for primary spermatocytes purification. Our results show that piRNAs mapping to transposons are more abundant in spermatogonia, whereas those mapping to Suppressor of Stellate [Su(Ste)] and AT-chX are mostly expressed in primary spermatocytes. Furthermore we observed that transposon-mapping piRNAs with ping-pong signature are more abundant in spermatogonia albeit still detectable in primary spermatocytes where Ago3 is not expressed. These results suggest that robust piRNA production via ping-pong cycle takes place in spermatogonia, and to a lesser extent in primary spermatocytes even in the absence of Ago3. Consistently, piRNAs from ago3 mutant testes also exhibit the ping-pong signature, confirming that a non-canonical ping-pong cycle is acting during spermatogenesis. Our study provides a developmental dimension to the piRNA pathway and uncovers a new mechanism used in the male germline to silence transposons.