Sexual dimorphism in mammals is mostly attributable to sex-related hormonal differences in fetal and adult tissues; however, this may not be the sole determinant. Though genetically-identical for autosomal chromosomes, male and female preimplantation embryos could display sex-specific transcriptional regulation which can only be attributted to the differences in sexual chromosome dosage.
Sex determines the expression level of one third of the actively expressed genes in bovine blastocysts.
Sex, Specimen part
View SamplesTemporal changes in the embryo transcriptome between the blastocyst stage (Day 7) and initiation of elongation (Day 13) differ between in vivo- and in vitro-derived embryos and are reflective of subsequent developmental fate.
Transcriptome changes at the initiation of elongation in the bovine conceptus.
Specimen part
View SamplesThe aim of this study was to compare the transcriptome of the different regions of the oviduct between pregnant and cyclic heifers. After synchronizing crossbred beef heifers, those in standing oestrus (=Day 0) were randomly assigned to cyclic (non bred, n=6), or pregnant (artificially inseminated, n=11) groups. They were slaughtered on Day 3 and both oviducts from each animal were isolated and cut in half to separate ampulla and isthmus. Each portion was flushed to confirm the presence of an oocyte/embryo and was then opened longitudinally and scraped to obtain epithelial cells which were snap-frozen. Oocytes and embryos were located in the isthmus of the oviduct ipsilateral to the corpus luteum. Microarray analysis of oviductal cells revealed that proximity to the corpus luteum did not affect the transcriptome of the isthmus, irrespective of pregnancy status. However, 2287 genes were differentially expressed (P<0.01) between the ampulla and isthmus of the oviduct ipsilateral to the corpus luteum. Gene ontology revealed that the main biological processes overrepresented in the isthmus were synthesis of nitrogen, lipids, nucleotides, steroids and cholesterol as well as vesicle-mediated transport, cell cycle, apoptosis, endocytosis and exocytosis, whereas cell motion, motility and migration, DNA repair, calcium ion homeostasis, carbohydrate biosynthesis and regulation of cilium movement and beat frequency were overrepresented in the ampulla. In conclusion, large differences in gene expression were observed between the isthmus and ampulla that reflect morphological and functional characteristics of each segment.
Spatial differences in gene expression in the bovine oviduct.
Specimen part
View SamplesIn cattle, almost all fully grown vesicle stage oocytes (GV) have the ability to resume meisos, develop to Metaphase II stage (MII), support fertilization and progress through the early embryonic cycles in vitro. Yet without intensive selection, the majority fail to develop to the blastocyst stage.
Sequential analysis of global gene expression profiles in immature and in vitro matured bovine oocytes: potential molecular markers of oocyte maturation.
Specimen part
View SamplesThe objective of this study was to examine the effect of the presence of a single or multiple embryo(s) on the transcriptome of the bovine oviduct. In Experiment 1, cyclic (non-bred, n = 6) and pregnant (artificially inseminated, n = 11) heifers were slaughtered on Day 3 after estrus, and the ampulla and isthmic regions of the oviduct ipsilateral to the corpus luteum were separately flushed. Oviductal epithelial cells from the isthmus region, in which all oocytes/embryos were located, were snap-frozen for microarray analysis. In Experiment 2, heifers were divided into cyclic (non-bred, n = 6) or pregnant (multiple embryo transfer, n = 10) groups. In vitro-produced presumptive zygotes were transferred endoscopically to the ipsilateral oviduct on Day 1.5 post estrus (n = 50 zygotes per heifer). Heifers were slaughtered on Day 3 and oviductal isthmus epithelial cells were recovered for RNA sequencing. Microarray analysis in Experiment 1 failed to detect any difference in the transcriptome of the oviductal isthmus induced by the presence of a single embryo. In Experiment 2, following multiple embryo transfer, RNA sequencing revealed 278 differentially expressed genes of which 123 were up- and 155 were down-regulated in pregnant heifers. Most of the down-regulated genes were related to immune function. Overall design: Transcriptional profiles of oviductal isthmus epithelial cells from cyclic and pregnant heifers were generated by sequencing of total RNA on the Illumina HiSeq 2500 platform
Oviduct-Embryo Interactions in Cattle: Two-Way Traffic or a One-Way Street?
Specimen part, Treatment, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Oviduct-Embryo Interactions in Cattle: Two-Way Traffic or a One-Way Street?
Specimen part, Treatment
View SamplesThe objective of this study was to examine the effect of the presence of a single or multiple embryo(s) on the transcriptome of the bovine oviduct. In Experiment 1, cyclic (non-bred, n = 6) and pregnant (artificially inseminated, n = 11) heifers were slaughtered on Day 3 after estrus, and the ampulla and isthmic regions of the oviduct ipsilateral to the corpus luteum were separately flushed. Oviductal epithelial cells from the isthmus region, in which all oocytes/embryos were located, were snap-frozen for microarray analysis. In Experiment 2, heifers were divided into cyclic (non-bred, n = 6) or pregnant (multiple embryo transfer, n = 10) groups. In vitro-produced presumptive zygotes were transferred endoscopically to the ipsilateral oviduct on Day 1.5 post estrus (n = 50 zygotes per heifer). Heifers were slaughtered on Day 3 and oviductal isthmus epithelial cells were recovered for RNA sequencing. Microarray analysis in Experiment 1 failed to detect any difference in the transcriptome of the oviductal isthmus induced by the presence of a single embryo. In Experiment 2, following multiple embryo transfer, RNA sequencing revealed 278 differentially expressed genes of which 123 were up- and 155 were down-regulated in pregnant heifers. Most of the down-regulated genes were related to immune function.
Oviduct-Embryo Interactions in Cattle: Two-Way Traffic or a One-Way Street?
Specimen part
View SamplesThis study relates to embryo-maternal interaction. The aim was to compare the transcriptome and ability of the ipsilateral and contralateral uterine horns to support preimplantation conceptus survival and growth to Day 14. Although differences in gene expression exist between the endometrium of uterine horns ipsilateral and contralateral to the CL in cattle, they do not impact conceptus survival or length between Days 7 and 14. Overall design: The endometrial samples from both uterine horns were collected from synchronized heifers slaughtered on Day 5, 7, 13 or 16 post-estrus (n = 5 per time) and subjected to RNA sequencing.
Do differences in the endometrial transcriptome between uterine horns ipsilateral and contralateral to the corpus luteum influence conceptus growth to day 14 in cattle?
Specimen part, Subject, Time
View SamplesOur hypothesis was that genes differentially expressed in the endometrium and corpus luteum on day 13 of the estrous cycle between cows with either good or poor genetic merit for fertility would be enriched for genetic variants associated with fertility. We combined a unique genetic model of fertility (cattle which have been selected for high and low fertility and show substantial difference in fertility), with gene expression data from these cattle, and genome-wide association study (GWAS) results in ~20,000 cattle, to identify quantitative trait loci (QTL) regions and sequence variants associated with genetic variation in fertility. Overall design: 26 samples total; 8 Fert+ (high fertility) endometrium, 6 Fert- (low fertility) endometrium; 7 Fert+ corpus luteum, 5 Fert- corpus luteum; Fert+ Fert- differential gene expression analysis
Differentially Expressed Genes in Endometrium and Corpus Luteum of Holstein Cows Selected for High and Low Fertility Are Enriched for Sequence Variants Associated with Fertility.
Specimen part, Subject, Time
View SamplesAn increase in circulating progesterone (P4) concentrations is associated with increased pregnancy success in beef and dairy cattle. Our objective was to ascertain differential effects of elevated P4 concentrations following conception on endometrial gene expression in beef heifers on Days 5, 7, 13 and 16 of pregnancy, corresponding to the morula, blastocyst, elongation and maternal recognition of pregnancy stages, respectively. Estrus was synchronized in beef heifers (N=263). Two-thirds (N=140) were inseminated (Day 0), and all animals were randomly assigned to one of the following treatments: (i) pregnant, high P4; (ii) pregnant, normal P4; (iii) cycling, high P4; (iv) and cycling, normal P4. All high P4 groups received a P4 release intravaginal device (PRID) on Day 3 post-estrus/mating. Tissue was collected on Days 5, 7, 13 or 16 of the cycle or pregnancy, and pregnancy was confirmed by the presence of an appropriately developed embryo/conceptus. PRID insertion elevated (P<0.05) P4 concentrations from Day 3.5 to 8 compared with untreated animals and conceptus size was larger (P<0.05) in animals with elevated P4 on Days 13 and 16 compared with normal P4. Total RNA was extracted from predominantly intercaruncular endometria from the ipsilateral uterine horn. Samples from individual heifers were selected on the basis of their P4 profiles and gene expression was analyzed using bovine Affymetrix microarrays (N=5 per treatment per time point). Microarray data from analyses using Bioconductor GCRMA and Limma packages were subjected to a modified t-test and P-values were adjusted for multiple testing using the Benjamin and Hochberg false discovery rate method. Differentially expressed genes were selected on the basis of an adjusted P-value of <0.01. There were no detectable differences in gene expression in endometria from pregnant and cyclic heifers on Days 5, 7 and 13 post-estrus, but, the expression of 764 genes was altered due to the presence of the conceptus at maternal recognition of pregnancy (Day 16). On Days 5 and 7, elevated P4 in pregnant heifers, altered the expression of 36 and 124 genes respectively but on Days 13 and 16 there were relatively few DEG between high and normal P4 heifers (15 and 25). Of the genes that were differentially regulated by P4, the majority were unique to a specific day of the estrous cycle/early pregnancy. In conclusion, gene expression in endometria did not differ between pregnant and cycling heifers until Day 16 of pregnancy (i.e. the time of maternal recognition of pregnancy and production of interferon tau by conceptus trophectoderm); however, elevating P4 in early pregnancy programmed changes in gene expression in endometria that are hypothesized to impact early conceptus growth and development. Thus, on Days 5, 7 and 13 differential gene expression was affected by P4, but on Day 16 the conceptus primarily influenced gene expression in uterine endometria of heifers.
Conceptus-induced changes in the endometrial transcriptome: how soon does the cow know she is pregnant?
Specimen part, Time
View Samples