Project description:Chromatin organization undergoes drastic reprogramming during gametogenesis . However, the three-dimensional chromatin structure and its reprogramming remain largely unknown, with even less known for primates. Here, by using a low-input Hi-C method we developed recently, we examined re-organization of 3D chromatin architecture during spermatogenesis in rhesus monkey (Macaca mulatta). Interestingly, we found that topologically associating domains (TADs) are partially dissolved in spermatogonia and are further depleted at the pachytene stage, before they gradually become consolidated in round spermatids and mature sperm. Strikingly, in local regions, pachytene chromatin is uniquely characterized by highly refined compartments that alternate between transcribing regions (Refined-A) and non-transcribed regions (Refined-B). Refined A/B occurs genomewide except for the X chromosome, which is inactivated at this stage. Interestingly, such chromatin organization remains intact upon transcription inhibition but is disrupted in spermatocytes deficient in SYCP2, a core component of synaptonemal complex. Strikingly, this is accompanied by the restoration of TADs in these mutant cells, suggesting that synaptonemal complex may restrict TADs and permit the emergence of strong local compartments. Taken together, these data reveal extensive reprogramming of higher-order meiotic chromatin architecture during mammalian gametogenesis.
Project description:We conducted a genome-wide expression analysis of wild-type males using three cell populations isolated from mitotic, meiotic and post-meiotic phases of spermatogenesis in Drosophila melanogaster. Our approach was to directly isolate testis regions enriched with RNAs from each of the three specific germline phases. We used microarrays to detail the global gene expression profile in spermatogenesis and identified up- and down-regulated genes between two different spermatogenic phases in pairwise comparisons Experiment Overall Design: Cell types present at various stages of spermatogenesis are generally located in a gradient along the proximal-distal axis of the testis, however most are not exclusively restricted to any one geographic region. Cells enriched for mitotic, meiotic and post-meiotic phases were obtained by dissection of apical, proximal and distal regions of the testis, respectively
Project description:We conducted a genome-wide expression analysis of wild-type males using three cell populations isolated from mitotic, meiotic and post-meiotic phases of spermatogenesis in Drosophila melanogaster. Our approach was to directly isolate testis regions enriched with RNAs from each of the three specific germline phases. We used microarrays to detail the global gene expression profile in spermatogenesis and identified up- and down-regulated genes between two different spermatogenic phases in pairwise comparisons
Project description:Investigation of whole genome gene expression level changes of testes in the meiotic drive system in aedes aegypti during spermatogenesis compared to non drive strain. The meiotic drive system in Aedes aegypti causes the female determining chromosome to fragment during spermatogenesis. A six chip study using total RNA from three separately extracted non driving strain testes of Aedes aegypti and three separately extracted meiotic drive strain testes of Aedes aegypti.
Project description:Investigation of whole genome gene expression level changes of testes in the meiotic drive system in aedes aegypti during spermatogenesis compared to non drive strain. The meiotic drive system in Aedes aegypti causes the female determining chromosome to fragment during spermatogenesis.
Project description:We comprehensively compared the chromatin structures and transcriptomes in successive substages of female and male mouse meiotic prophase by using sisHi-C and RNA-Seq methods. Interestingly, the transcriptional change happened earlier than chromatin structures reprograming that chromatin structures largely maintained the pre-meiotic condition in leptotene. Also, compartments and TADs gradually disappeared and then slowly recovered in both oocytes and spermatocytes. We characterized the events of homologous chromosomes pairing and found homologues adopted two sex-conserved pairing strategies prior to and after leptotene-to-zygotene transition, which firstly contacted more frequently in LINE enriched compartment B and then switched to SINE enriched compartment A. The sexual difference of transcriptome was most obvious in late meiotic prophase, which reflected in gamete morphology and function differences. We also complemented marker genes for each substage of oocytes and spermatocytes meiotic prophase, and predicted the sex-specific meiotic functional genes, whose mutation or deletion may cause sex different effects on fertility. In summary, this study revealed the sexual similarities and dimorphic of higher-order chromatin architecture, homologous pairing and transcriptome during meiotic prophase of both oogenesis and spermatogenesis.
Project description:The Piwi protein Mili and the Piwi-interacting RNA (piRNA) pathway are required to establish L1 DNA methylation during epigenetic reprogramming that accompanies male germ cell development. Although Mili is expressed throughout most of adult spermatogenesis, its function therein remains unknown. We find that Mili displays a hitherto unappreciated dynamic expression profile during spermatogenesis, expressed in the mitotic spermatogonia but absent at the early meiotic stages only to reappear in late zygotene spermatocytes. Here we show using conditional mutagenesis that Mili's endonuclease activity post-transcriptionally cleaves L1 transcripts commencing upon its reappearance in late zygotene spermatocytes even in the presence of normal L1 DNA methylation
Project description:In mammals, a key transition in spermatogenesis is the exit from spermatogonial differentiation and mitotic proliferation and the entry into spermatocyte differentiation and meiosis. Although several genes that regulate this transition have been identified, how it is controlled and coordinated remains poorly understood. Here we examine the role in male gametogenesis of the Doublesex-related gene Dmrt6 (Dmrtb1) and find that Dmrt6 plays a critical role in directing germ cells through the mitotic to meiotic germ cell transition. DMRT6 protein is expressed in late mitotic spermatogonia. In mice of the C57BL/6J strain a null mutation in Dmrt6 disrupts spermatogonial differentiation, causing expression in inappropriate cell types of spermatogonial differentiation factors including SOHLH1, SOHLH2 and DMRT1 and the meiotic initiation factor STRA8 and causing most late spermatogonia to undergo apoptosis. In mice of the 129Sv background, most Dmrt6 mutant spermatogonia can complete differentiation and enter meiosis, but they show defects in chromosome pairing, establishment of the XY body, and processing of recombination foci, and mainly arrest in mid-pachynema. mRNA profiling of Dmrt6 mutant testes together with DMRT6 ChIP-seq suggest that DMRT6 represses genes involved in spermatogonial differentiation and activates genes required for meiotic prophase. Our results indicate that Dmrt6 plays a key role in coordinating the transition in gametogenic programs from spermatogonial differentiation and mitosis to spermatocyte development and meiosis. Six samples for RNA-Seq with three biological replicates in each group. Two samples for ChIP-Seq (one input and one ChIP).
Project description:In mammals, the X and Y chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during prophase I in the male germline, but their status thereafter is currently unclear. An abundance of X-linked spermatogenesis genes has spawned the view that the X must be active [1-8]. On the other hand, the idea that the imprinted paternal X of the early embryo may be pre-inactivated by MSCI suggests that silencing may persist longer [9-12]. To clarify this issue, we establish a comprehensive X-expression profile during mouse spermatogenesis. Here, we discover that the X and Y occupy a novel compartment in the post-meiotic spermatid and adopt a non-Rabl configuration. We demonstrate that this post-meiotic sex chromatin (PMSC) persists throughout spermiogenesis into mature sperm and exhibits epigenetic similarity to the XY body. In the spermatid, 87% of X-linked genes remain suppressed post-meiotically, while autosomes are largely active. We conclude that chromosome-wide X-silencing continues from meiosis to the end of spermiogenesis and discuss implications for proposed mechanisms of imprinted X-inactivation. Independent germ cell preps were used for array analysis. Duplicates were provided for each sample.
Project description:During meiosis, chromosomes undergo extensive changes in structure and intranuclear positioning. How these chromosome organization changes occur and how they influence meiosis-specific chromosome events are not fully understood. Using Hi-C, we characterized chromosome architecture throughout mouse spermatogenesis at high temporal resolution. Our study revealed an intimate link between chromosome organization features and homolog pairing and alignment. We found that the meiotic chromosomes progressively reshape from TAD-like domains into linearly arranged loop arrays during prophase I. The transcriptionally active and inactive genomic regions exhibit distinct dynamics of loop growth, resulting in alternating domains consisting of shorter and longer chromosome loops. Such a domanial organization along meiotic chromosome axes is tightly correlated with the strength and precision of inter-homolog alignment. We further showed that a significant fraction of chromosomes near chromosome ends exhibit elevated inter-chromosomal association upon entering zygotene stage, while also exhibiting a higher degree of inter-homolog alignment. Using a mouse model defective in LINC complex component SUN1, we demonstrated that the prominent alignment of chromosome ends is dependent on the association of telomeres with the mechano-transducing LINC complex, but not the tethering of telomeres to the nuclear periphery. Taken together, our results suggest the 3D chromosome organization may provide a structural framework for the regulation of meiotic chromosome processes in higher eukaryotes.