Project description:Prototypical micro RNAs (miRNAs) are 21~25-base-pair RNAs that regulate differentiation, carcinogenesis and pluripotency by eliminating mRNAs or blocking their translation, processes collectively termed RNA interference (RNAi). RNAi mediated by miRNAs regulates early development in zebrafish, and mouse embryos lacking the miRNA precursor processor, Dicer, are inviable. However, the role of miRNAs during mammalian fertilization is unknown. We here show using microarrays that miRNAs are present in mouse sperm structures that enter the oocyte at fertilization. Sperm contained a broad profile of miRNAs and a subset of potential mRNA targets were expressed in fertilizable, metaphase II (mII) oocytes. Oocytes contained transcripts for the RNAinduced silencing complex (RISC) catalytic subunit, EIF2C3 (formerly AGO3). However, levels of sperm-borne miRNA (measured by quantitative PCR) were apparently low relative to those of unfertilized, mII oocytes, and fertilization did not alter the part of the mII oocyte miRNA landscape that included the most abundant sperm-borne miRNAs. Coinjection of mII oocytes with sperm heads plus anti-miRNAs - to suppress miRNA function - did not perturb pronuclear activation or preimplantation development. Contrastingly, we provide evidence that nuclear transfer by microinjection alters the miRNA profile of enucleated oocytes. These data argue that sperm-borne prototypical miRNAs play a limited role, if any, in mammalian fertilization or early preimplantation development. Keywords: miRNA profiling Seven samples were analyzed for the study.
Project description:Prototypical micro RNAs (miRNAs) are 21~25-base-pair RNAs that regulate differentiation, carcinogenesis and pluripotency by eliminating mRNAs or blocking their translation, processes collectively termed RNA interference (RNAi). RNAi mediated by miRNAs regulates early development in zebrafish, and mouse embryos lacking the miRNA precursor processor, Dicer, are inviable. However, the role of miRNAs during mammalian fertilization is unknown. We here show using microarrays that miRNAs are present in mouse sperm structures that enter the oocyte at fertilization. Sperm contained a broad profile of miRNAs and a subset of potential mRNA targets were expressed in fertilizable, metaphase II (mII) oocytes. Oocytes contained transcripts for the RNAinduced silencing complex (RISC) catalytic subunit, EIF2C3 (formerly AGO3). However, levels of sperm-borne miRNA (measured by quantitative PCR) were apparently low relative to those of unfertilized, mII oocytes, and fertilization did not alter the part of the mII oocyte miRNA landscape that included the most abundant sperm-borne miRNAs. Coinjection of mII oocytes with sperm heads plus anti-miRNAs - to suppress miRNA function - did not perturb pronuclear activation or preimplantation development. Contrastingly, we provide evidence that nuclear transfer by microinjection alters the miRNA profile of enucleated oocytes. These data argue that sperm-borne prototypical miRNAs play a limited role, if any, in mammalian fertilization or early preimplantation development. Keywords: miRNA profiling
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven M-bM-^@M-^Xhotspots,M-bM-^@M-^Y seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a M-bM-^@M-^XfertileM-bM-^@M-^Y subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. Gene expression was measured in whole testis in males aged 70(M-BM-15) days. Samples include 294 WSB/EiJ x PWD/PhJ F2s, 11 PWD/PhJ x WSB/EiJ F2s, 8 WSB/EiJ, 8 PWD/PhJ, 6 PWD/PhJ x WSB/EiJ F1s and 4 WSB/EiJ x PWD/PhJ F1s.