Project description:The oocytes of many species, both invertebrate and vertebrate, contain a large collection of localized determinants in the form of proteins and translationally inactive maternal mRNAs. However, it is unknown whether mouse oocytes contain localized MmRNA determinants and what mechanisms might be responsible for their control. We collected intact MII oocytes, enucleated MII oocyte cytoplasts (with the spindle removed), and spindle-chromosome complexes which had been microsurgically removed. RNA was extracted, amplified, labeled, and applied to microarrays to determine if any MmRNA determinants were localized to the SCC. We used microarrays to determine whether maternal mRNAs in mouse oocytes are enriched in the meiotic spindle
Project description:MicroRNAs (miRNAs) have been shown to have important functions in a variety of cellular processes. Here we report on miRNA expression and their dynamic regulation during mouse oogenesis and early embryos. We show that following specific deletion of Dicer from growing oocytes, the mutant oocytes cease development and were unable to progress through the first cell division. While the mutant mature oocytes seemed morphologically normal, they had disorganized spindle. Using detailed single cell cDNA microarray analysis of normal versus mutant oocytes, we found that a large proportion of maternal genes, including C-mos, are under the control of miRNAs. This study provides strong evidence that maternal miRNAs are essential for the earliest stages of mouse embryonic development. mRNA expression was compared with miRNA expression in dicer knockout and wild-type mouse mature oocyte.
Project description:Chromosome aneuploidy increases in oocytes with maternal age, and is considered the leading cause for the increased incidence of infertility, miscarriage, and birth defects. Using mRNA-Sequencing of oocytes from 12 month old mouse versus 3 month young mouse, we identified a spindle assembly checkpoint gene, BubR1, whose expression was significantly decreased. We employed a mRNA microinjection based approach to increase BubR1 expression in aging oocytes. We find that increased expression of BubR1 protects against aneuploidy and chromosome misalignment in aging oocytes. After in vitro fertilization, the embryos derived from BubR1 increased expression aging oocytes exhibited chromosome stability as robust as those of the young ones. Furthermore, following embryo transfer, these embryos showed greatly improved developmental competency, with comparable levels of full-term development to those of the young ones. These results indicate that the decline in oocyte quality may be reversible and could lead to treatments that prolong female fertility. Examination of the effect of maternal aging on the mRNA expression in the mature oocytes of the female mice. Naturally ovulated mature oocytes (MII stage) were collected from 6 young (3 month) and 6 aging (12 month) female mice (3 oocytes per mice, 18 oocytes for each group).
Project description:MicroRNAs (miRNAs) have been shown to have important functions in a variety of cellular processes. Here we report on miRNA expression and their dynamic regulation during mouse oogenesis and early embryos. We show that following specific deletion of Dicer from growing oocytes, the mutant oocytes cease development and were unable to progress through the first cell division. While the mutant mature oocytes seemed morphologically normal, they had disorganized spindle. Using detailed single cell cDNA microarray analysis of normal versus mutant oocytes, we found that a large proportion of maternal genes, including C-mos, are under the control of miRNAs. This study provides strong evidence that maternal miRNAs are essential for the earliest stages of mouse embryonic development. Keywords: mRNA and miRNA expression comparison
Project description:The oocytes of many species, both invertebrate and vertebrate, contain a large collection of localized determinants in the form of proteins and translationally inactive maternal mRNAs. However, it is unknown whether mouse oocytes contain localized MmRNA determinants and what mechanisms might be responsible for their control. We collected intact MII oocytes, enucleated MII oocyte cytoplasts (with the spindle removed), and spindle-chromosome complexes which had been microsurgically removed. RNA was extracted, amplified, labeled, and applied to microarrays to determine if any MmRNA determinants were localized to the SCC.
Project description:The long-standing view of 'immortal germ line versus mortal soma' poses a fundamental question in biology concerning how oocytes age in molecular terms. A mainstream hypothesis is that maternal aging of oocytes has its roots in gene transcription. Investigating the proteins resulting from mRNA translation would reveal how far the levels of functionally available proteins correlate with mRNAs, and would offer novel insight into the changes oocytes undergo during maternal aging. Gene ontology semantic analysis reveals the high similarity of the detected proteome (2,324 proteins) to the transcriptome (22,334 mRNAs), though not all proteins have a cognate mRNA. Concerning their dynamics, 4-fold changes of abundance are more frequent in the proteome (3%) than the transcriptome (0.05%), with correlation. Whereas proteins associated with the nucleus (e.g. structural maintenance of chromosomes, spindle-assembly checkpoints) are largely represented among those that change in oocytes during maternal aging; proteins associated with oxidative stress/damage (e.g. superoxide dismutase) are infrequent. These quantitative alterations are either impoverishing or enriching. Using gene ontology analysis, these alterations do not relate in any simple way to the classic signature of aging known from somatic tissues. We conclude that proteome analysis of mouse oocytes may not be surrogated with transcriptome analysis, given the lack of correlation. Furthermore, we conclude that the classic features of aging may not be transposed from somatic tissues to oocytes in a one-to-one fashion. Overall, there is more to the maternal aging of oocytes than mere cellular deterioration exemplified by the notorious increase of meiotic aneuploidy. Three pools of 20 zona-enclosed B6C3F1 oocytes from each age group were subjected for experiment.
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
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Chromosome aneuploidy increases in oocytes with maternal age, and is considered the leading cause for the increased incidence of infertility, miscarriage, and birth defects. Using mRNA-Sequencing of oocytes from 12 month old mouse versus 3 month young mouse, we identified a spindle assembly checkpoint gene, BubR1, whose expression was significantly decreased. We employed a mRNA microinjection based approach to increase BubR1 expression in aging oocytes. We find that increased expression of BubR1 protects against aneuploidy and chromosome misalignment in aging oocytes. After in vitro fertilization, the embryos derived from BubR1 increased expression aging oocytes exhibited chromosome stability as robust as those of the young ones. Furthermore, following embryo transfer, these embryos showed greatly improved developmental competency, with comparable levels of full-term development to those of the young ones. These results indicate that the decline in oocyte quality may be reversible and could lead to treatments that prolong female fertility.