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 regulation of endometrial inflammation has important consequences for the resumption of bovine fertility post-partum. All cows experience bacterial influx into the uterus after calving; however a significant proportion fail to clear infection leading to the development of cytological endometritis (CE) and compromised fertility. We hypothesised that early immunological changes could not only act as potential prognostic biomarkers for the subsequent development of disease but also shed light on the pathogenesis of endometritis in the post-partum dairy cow. Here, next-generation sequencing from endometrial biopsies taken at 7 days post-partum (DPP) identified significant expression of inflammatory genes in all cows. Despite the common inflammatory profile and enrichment of the Toll-like receptor, NF?B and TNF signalling pathways, 73 genes and 31 miRNAs differentiated between healthy cows (HC, n=9) and cows which subsequently developed CE at 7 DPP (n=6, FDR<0.1). In healthy cows, 4197 differentially expressed genes between 7 and 21 DPP whereas only 31 genes were differentially expressed in samples from cows with CE. At 21 DPP, a further 1167 genes were differentially expressed between HC cows and cows diagnosed with CE (FDR<0.1). These changes in host gene expression reflected culture-independent microbiological analysis which showed significant differences in uterine bacterial profiles between groups. Inflammatory activity was not confined to the uterus; decreased circulating granulocytes and increased Acute Phase Protein (SAA and HP) plasma expression levels were detected at 7 DPP in cows that developed CE. In conclusion, our data suggests that the major inflammatory cascade activated early post-partum is resolved thereby restoring homeostasis in healthy cows by 21 DPP, but this transition fails to occur in cows which develop CE. Despite a common inflammatory profile, differential expression of specific immune genes may identify cows at risk of prolonged inflammation and the development of CE post-partum. Sixteen Holstein Friesian cows, of mixed parity, within the same university dairy herd were sampled 7 and 21 days postpartum (DPP) in the morning after milking, over an eight week period.

Project description:The regulation of endometrial inflammation has important consequences for the resumption of bovine fertility post-partum. All cows experience bacterial influx into the uterus after calving; however a significant proportion fail to clear infection leading to the development of cytological endometritis (CE) and compromised fertility. We hypothesised that early immunological changes could not only act as potential prognostic biomarkers for the subsequent development of disease but also shed light on the pathogenesis of endometritis in the post-partum dairy cow. Here, next-generation sequencing from endometrial biopsies taken at 7 days post-partum (DPP) identified significant expression of inflammatory genes in all cows. Despite the common inflammatory profile and enrichment of the Toll-like receptor, NFκB and TNF signalling pathways, 73 genes and 31 miRNAs differentiated between healthy cows (HC, n=9) and cows which subsequently developed CE at 7 DPP (n=6, FDR<0.1). In healthy cows, 4197 differentially expressed genes between 7 and 21 DPP whereas only 31 genes were differentially expressed in samples from cows with CE. At 21 DPP, a further 1167 genes were differentially expressed between HC cows and cows diagnosed with CE (FDR<0.1). These changes in host gene expression reflected culture-independent microbiological analysis which showed significant differences in uterine bacterial profiles between groups. Inflammatory activity was not confined to the uterus; decreased circulating granulocytes and increased Acute Phase Protein (SAA and HP) plasma expression levels were detected at 7 DPP in cows that developed CE. In conclusion, our data suggests that the major inflammatory cascade activated early post-partum is resolved thereby restoring homeostasis in healthy cows by 21 DPP, but this transition fails to occur in cows which develop CE. Despite a common inflammatory profile, differential expression of specific immune genes may identify cows at risk of prolonged inflammation and the development of CE post-partum. Sixteen Holstein Friesian cows, of mixed parity, within the same university dairy herd were sampled 7 and 21 days postpartum (DPP) in the morning after milking, over an eight week period.

Project description:In high yielding dairy cows the liver undergoes extensive physiological and biochemical changes during the early postpartum period in an effort to re-establish metabolic homeostasis and to counteract the adverse effects of negative energy balance (NEB). These adaptations are likely to be mediated by significant alterations in hepatic gene expression. To gain new insights into these events an EB model was created using differential feeding and milking regimes to produce two groups of cows with either a mild (MNEB) (n=5) or severe NEB (SNEB) (n=6) status. Cows were slaughtered and liver tissues collected on days 6-7 of the first follicular wave postpartum. Using an AffymetrixM-BM-. 23k oligonucleotide bovine array to determine global gene expression in hepatic tissue of these cows, a total of 416 genes (189 up- and 227 down-regulated) were found to be altered by SNEB. Network analysis using Ingenuity Pathway Analysis revealed that SNEB was associated with widespread changes in gene expression classified into 36 gene networks including those associated with lipid metabolism, connective tissue development and function, cell signalling, cell cycle and metabolic diseases. Severe NEB cows displayed reduced expression of transcription activators and signal transducers that regulate the expression of genes and gene networks associated with cell signalling and tissue repair. These alterations are linked with increased expression of abnormal cell cycle and cellular proliferation associated pathways. This study provides new information and insights on the effect of SNEB on gene expression in high yielding Holstein Friesian dairy cows in the early postpartum period. Multiparous Holstein-Friesian cows (n=24) were blocked 2 weeks prior to expected calving date according to parity, body condition score, and previous lactation yield (average lactation 6477M-BM-1354kg) and randomly allocated to mild (MNEB; n=12) or severe (SNEB; n=12) NEB groups. MNEB cows were fed ad lib grass silage and 8 kg day-1 concentrates and milked once daily; SNEB cows were fed 25 kg day-1 silage and 4kg day-1 concentrate and milked three times daily. Measurements of body condition score and EB were used to select cows which showed extremes in EB from each group (MNEB, n=5; SNEB, n=6). Cows were slaughtered on days 6-7 of the first follicular wave after calving (mean number of days post-partum: MNEB mean 13.6 M-BM-1 0.75, range 11M-bM-^@M-^S15; SNEB mean 14.3 M-BM-1 0.56, range 13M-bM-^@M-^S16), based on daily transrectal ultrasonography.The entire liver was removed within 15 to 30 min after slaughter and weighed. Samples weighing approximately 1 g were dissected, rinsed in RNase free phosphate buffer, snap frozen in liquid nitrogen and stored at -80M-BM-:C.

Dataset Information

Bos taurus

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets