Project description:Co-ordinated regulation of endometrial gene expression is essential for successful pregnancy establishment. A non-receptive uterine environment may be a key contributor to pregnancy loss, as the majority of pregnancy losses occur prior to embryo implantation. DNA methylation has been highlighted as a potential contributor in regulating early pregnancy events in the uterus. It was hypothesized that DNA methylation regulates expression of key genes in the uterus during pregnancy. To gain support for this hypothesis the correlation between DNA methylation and gene expression was tested. Endometrial samples from fertile and sub-fertile dairy cow strains were obtained at day 17 of pregnancy or the reproductive cycle. Microarrays were used to characterize genome-wide DNA methylation profiles and data compared with transcription profiles which have been previously reported. 39% of DNA methylation probes assayed mapped to RefSeq genes with transcription measurements. The 1,000 most significant correlations were used for subsequent analysis. Of these, 52% percent were negatively correlated with gene expression. When this gene list was compared with previously reported gene expression studies on the same tissues, 42% were differentially expressed when comparing pregnant and cycling animals and 11% were differentially expressed comparing pregnant fertile and sub-fertile animals. DNA methylation status was correlated with gene expression in several pathways implicated in early pregnancy events. Although these data do not provide direct evidence of a causative association between DNA methylation and gene expression, this study provides critical support for an effect of DNA methylation in early pregnancy events and highlights candidate genes for future studies.
Project description:Gene expression profiles in the bovine corpus luteum (CL) of the estrous cycle and pregnancy: Possible roles of chemokines in regulating CL function during pregnancy
Project description:Co-ordinated regulation of endometrial gene expression is essential for successful pregnancy establishment. A non-receptive uterine environment may be a key contributor to pregnancy loss, as the majority of pregnancy losses occur prior to embryo implantation. DNA methylation has been highlighted as a potential contributor in regulating early pregnancy events in the uterus. It was hypothesized that DNA methylation regulates expression of key genes in the uterus during pregnancy. To gain support for this hypothesis the correlation between DNA methylation and gene expression was tested. Endometrial samples from fertile and sub-fertile dairy cow strains were obtained at day 17 of pregnancy or the reproductive cycle. Microarrays were used to characterize genome-wide DNA methylation profiles and data compared with transcription profiles which have been previously reported. 39% of DNA methylation probes assayed mapped to RefSeq genes with transcription measurements. The 1,000 most significant correlations were used for subsequent analysis. Of these, 52% percent were negatively correlated with gene expression. When this gene list was compared with previously reported gene expression studies on the same tissues, 42% were differentially expressed when comparing pregnant and cycling animals and 11% were differentially expressed comparing pregnant fertile and sub-fertile animals. DNA methylation status was correlated with gene expression in several pathways implicated in early pregnancy events. Although these data do not provide direct evidence of a causative association between DNA methylation and gene expression, this study provides critical support for an effect of DNA methylation in early pregnancy events and highlights candidate genes for future studies. The estrous cycles of 24 lactating dairy cows were synchronized (at 58.8 (SEM 3.77) and 60.2 (SEM 1.51) days post calving in dairy cows of sub-fertile and fertile strains, respectively) and 14 received a single embryo transferred on day 7 of the estrous cycle. Animals were slaughtered at day 17 of the reproductive cycle and endometrial tissues (both caruncular and intercaruncular) were sampled. Selection criteria for the study included strain and calving date, and health postcalving was an exclusion criterion (cows with severe uterine infections or mastitis were excluded before being enrolled in the embryo transfer round). Cows in each strain were matched for calving number and age. A total of 10 cycling and 12 pregnant animals enrolled in the study were utilized, due to the associated costs of slaughtering the cows. These animals represented fertile (six pregnant and five cycling Holstein-Friesian cows with New Zealand ancestry/M-bM-^IM-$30% North American genetics, n=11, NZ) and sub-fertile (six pregnant and five cycling Holstein-Friesian cows with >87% North American ancestry, n=11, NA) phenotypes of Holstein-Friesian dairy cows
Project description:The liver of dairy cows naturally displays a series of metabolic adaptation during the periparturient period in response to the increasing nutrient requirement of lactation. The hepatic adaptation is partly regulated by insulin resistance and it is affected by the prepartal energy intake level of cows. We aimed to investigate the metabolic changes in the liver of dairy cows during the periparturient at gene expression level and to study the effect of prepartal energy level on the metabolic adaptation at gene expression level.B13:N13
Project description:The Toll-like receptor (TLR) and peptidoglycan recognition protein 1 (PGLYRP1) genes play key roles in the innate immune systems of mammals. While the TLRs recognize a variety of invading pathogens and induce innate immune responses, PGLYRP1 is directly microbicidal. We used custom allele-specific assays to genotype and validate 220 diallelic variants, including 54 nonsynonymous SNPs in 11 bovine innate immune genes (TLR1-TLR10, PGLYRP1) for 37 cattle breeds. Bayesian haplotype reconstructions and median joining networks revealed haplotype sharing between Bos taurus taurus and Bos taurus indicus breeds at every locus, and we were unable to differentiate between the specialized B. t. taurus beef and dairy breeds, despite an average polymorphism density of one locus per 219 bp. Ninety-nine tagSNPs and one tag insertion-deletion polymorphism were sufficient to predict 100% of the variation at all 11 innate immune loci in both subspecies and their hybrids, whereas 58 tagSNPs captured 100% of the variation at 172 loci in B. t. taurus. PolyPhen and SIFT analyses of nonsynonymous SNPs encoding amino acid replacements indicated that the majority of these substitutions were benign, but up to 31% were expected to potentially impact protein function. Several diversity-based tests provided support for strong purifying selection acting on TLR10 in B. t. taurus cattle. These results will broadly impact efforts related to bovine translational genomics.