Gene Expression profile in preimplantation in vitro embryos derived from Prepubertal heifers and Adult Cattle
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ABSTRACT: Age of the donor animal has a significant influence on the oocyte’s ability to complete maturation and acquire the mRNA and proteins required for normal embryonic development. It is well known that developmental competence is reduced in oocytes derived from juvenile animals when compared to that derived from adults. However, the molecular mechanisms associated with these differences are not well elucidated. The aim of this study was to analyze the transcriptome differences between adult versus prepubertal derived preimplantation embryos and to identify genes associated with oocyte developmental potential. We performed cDNA microarray analysis on populations of preimplantation embryos (8- to 16-cell and Day 7 blastocysts) derived from adult versus prepubertal Japanese Black cattle. Total RNA was extracted and amplified in a linear fashion and then subjected to the microarray hybridization using the Affymetrix GeneChip Bovine Genome Array. The Bovine Array contains 24 072 probe sets representing over 23000 transcripts and 19000 UniGene clusters. Following normalization of the microarray data, analysis revealed differences in gene expression abundance in 8- to 16-cell and blastocysts harvested from adult versus prepubertal heifers. Results indicated that a total of 591 and 490 genes were differentially expressed (≥2-fold) in 8- to 16-cell and blastocyst respectively between the two groups (p<0.01). In 8- to 16-cell stage, 373 genes were up-regulated and 218 gens down-regulated in adult when compared to the prepubertal heifer group. In case of blastocyst stage embryos, 242 genes were up-regulated and 248 genes were down-regulated in adult when compared to prepubertal group.
Project description:Age of the donor animal has a significant influence on the oocyteM-bM-^@M-^Ys ability to complete maturation and acquire the mRNA and proteins required for normal embryonic development. It is well known that developmental competence is reduced in oocytes derived from juvenile animals when compared to that derived from adults. However, the molecular mechanisms associated with these differences are not well elucidated. The aim of this study was to analyze the transcriptome differences between adult versus prepubertal derived preimplantation embryos and to identify genes associated with oocyte developmental potential. We performed cDNA microarray analysis on populations of preimplantation embryos (8- to 16-cell and Day 7 blastocysts) derived from adult versus prepubertal Japanese Black cattle. Total RNA was extracted and amplified in a linear fashion and then subjected to the microarray hybridization using the Affymetrix GeneChip Bovine Genome Array. The Bovine Array contains 24 072 probe sets representing over 23000 transcripts and 19000 UniGene clusters. Following normalization of the microarray data, analysis revealed differences in gene expression abundance in 8- to 16-cell and blastocysts harvested from adult versus prepubertal heifers. Results indicated that a total of 591 and 490 genes were differentially expressed (M-bM-^IM-%2-fold) in 8- to 16-cell and blastocyst respectively between the two groups (p<0.01). In 8- to 16-cell stage, 373 genes were up-regulated and 218 gens down-regulated in adult when compared to the prepubertal heifer group. In case of blastocyst stage embryos, 242 genes were up-regulated and 248 genes were down-regulated in adult when compared to prepubertal group. The ovaries of adult cows (Japanese black cattle) were collected from local abattoir while ovaries of prepubertal Japanese black heifers (9 to 12 months old) were collected by spay device at several commercial farms. The ovaries were transported to the research laboratory in 0.67% (w/v) NaCl solution containing 100 mg/L kanamycin sulfate. COC were placed in 200 M-BM-5L drop of the maturation medium (TCM 199 + 10% FBS) and cultured at 38.5M-BM-0C in a humidified atmosphere of 5% CO2 in air for 20 to 22 h for in vitro maturation (IVM). After 20 to 22 h IVM, the COC were fertilized in vitro with frozenM-bM-^@M-^Sthawed semen of Japanese Black bull in BO medium. Six hours after IVF, oocytes were denuded of surrounding cumulus cells by gentle pipetting in a solution of 0.1% (w/v) hyaluronidase. The presumptive zygotes were cultured in CR1aa medium supplemented with fatty acid-free BSA (Sigma) for 2 days and cultured in CR1aa medium supplemented with 10% (v/v) fetal bovine serum (FBS) for next 5 days at 38.5 M-BM-0C in 5% CO2, 5% O2 and 90% N2 with high humidity (15 to 20 zygotes per 50 M-BM-5l microdrop). 8- to 16-cell refers to day 3, 70 to 72 hours post insemination( hpi) preimplantation embryo stage containing 8 to 16 cells, while blastocyst refer to pre-hatching day 7 expanded blastocysts. Pools of 8- to 16- cell embryos (50 in each sample) and blastocysts (10 in each sample) from prepubertal and adult groups were used for cDNA microarray.
Project description:Preimplantation stages of mouse embryo development involve temporal and spatial specification and segregation of three late blastocyst cell lineages; trophectoderm (TE), primitive endoderm (PrE) and epiblast (EPI). Spatial separation of the outer TE lineage from the two inner-cell-mass (ICM) lineages (PrE and EPI) starts with the 8- to 16-cell transition and concludes following transit through the 16- to 32-cell stages. This results in a nascent early blastocyst ICM derived from descendants of primary founding inner cells and a secondarily contributed population; of which subsequent relative EPI versus PrE potencies are subject to debate. We showed that generation of primary but not the secondary ICM populations is highly dependent on temporally discreet activation of the mammalian target of rapamycin (mTOR – specifically mTORC1) around 8-cell stage M-phase entry. Moreover, that this role is mediated via the regulated function of the 7-methylguanosine- (7mG) cap binding initiation complex (EIF4F) and potentiating the translation of a subset of key but otherwise intransigent mRNAs containing 5’ UTR terminal oligopyrimidine (TOP-) sequence motifs. To find out translation of which mRNAs is regulated by mTOR during 8- to 16-cell transition, we analysed proteomes of control and mTOR-inhibited embryos during this time window.
Project description:The hypothesis that CSF2 plays a role in the preimplantation development of the bovine embryo was tested by evaluating consequences of deletion of CSF2RA (the functional receptor in the embryo) for development of embryos in utero. CRISPR/Cas9 was used to delete exon 5 and intron 5 of CSF2RA on chromosome 3. Control embryos were injected with Cas9 mRNA only. Embryos > 16 cells at day 5 after insemination were transferred to synchronized recipient females in groups of 7 to 24. Embryos were flushed from the uterus two days later. The proportion of recovered embryos that developed to the blastocyst stage was lower for knockout embryos (39%) than for control embryos (63%). RNA sequencing of individual morulae and blastocysts indicated a total of 27 (morula) or 15 (blastocyst) differentially-expressed genes (false discovery rate <0.05). Differentially-expressed genes as well as regulated gene sets identified by gene set enrichment analysis indicated that knockout affected genes playing roles in several functions including cell signaling and glycosylation. It was concluded that signaling through CSF2RA is not obligatory for development of the bovine preimplantation embryo to the blastocyst stage but that CSF2 signaling does enhance the likelihood that the embryo can become a blastocyst and result in specific changes in gene expression.
Project description: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. We used microarrays to analyze sex-related transcriptional differences at the blastocyst stage. Day 7 bovine in vitro produced bovine blastocysts produced with sorted semen from 3 different bulls. Pooled RNA from 60 blastocysts of one sex and produced with one bull was used per chip. Three replicates of each sex per bull. In total, 18 Bovine GeneChip (Affymetrix) were used (3 replicates X 3 bulls X 2 sexes).
Project description:Delayed implantation occurs in many mammals, but the underlying mechanisms that direct this process remain largely unknown. In mice, ovariectomy prior to the preimplantation ovarian estrogen secretion on day 4 of pregnancy initiates blastocyst dormancy, which can be maintained for more than 200 days by continued progesterone treatment. An injection of estrogen activates blastocysts rapidly and makes them to implant in the progesterone-primed uterus. Recent establishment of a 60-mer oligo microarray platform, enriched for genes expressed in stem cells and early embryos including preimplantation embryos (7), fulfills this objective. With an optimized labeling reaction for a small amount of RNA with two rounds of cRNA linear amplification, we compared gene expression differences between dormant and activated blastocysts with validation of microarray data of several key genes at protein expression level using immunohistochemistry.
Project description:In their attempt to fulfill the wish of having children, women who suffer from fertility issues often undergo assisted reproductive technologies (ART) such as ovarian stimulation, which has been associated with adverse health outcomes and imprinting disorders in children. However, given the crucial role of exogenous hormone stimulation in improving human infertility treatments, a more comprehensive analysis of the potential impacts on DNA methylation in embryos following ovarian stimulation is needed. Here, we provide genome-wide DNA methylation profiles of blastocysts generated after superovulation of prepubertal or adult mice, compared with blastocysts derived from non-stimulated adult mice. Additionally, we assessed the impact of the in vitro growth and maturation of oocytes on methylation in blastocysts.
Project description:Developmental competences of oocytes derived from prepubertal heifers are lower than those derived from adult counterparts. The objective of this study was to identify a range of genes associated with reduced oocyte competence that are differentially expressed between adult versus prepubertal donors. Microarray experiments were conducted using total RNA isolated from GV and MII stages oocytes collected from adult and prepubertal animals using Affymetrix GeneChip Bovine Genome Array containing 24,072 probe sets representing over 23,000 transcripts. A total of 549 and 333 genes were differentially expressed between prepubertal versus adult bovine MII and GV stages oocytes respectively. Out of these, 312 and 176 genes were up-regulated, while 237 and 157 were down-regulated in prepubertal when compared with adult MII and GV oocytes respectively. Ontological classification of the differentially expressed genes revealed that up-regulated genes in adult oocytes were involved in signal transduction, regulation of transcription DNA-dependent, and transport. Results from the present study indicated that significant number of genes were differentially expressed (>2-fold, p<0.01) between the two groups. Thus the decreased developmental competence of oocytes from prepubertal heifers may be induced due to difference in gene expression abundance as observed in our study. In conclusion, transcript abundance analyses of oocytes using microarray approach have been carried out in bovine and several other species. However, to our knowledge, this is the first study carried out to examine genes expression differential abundance in oocytes derived from perpubertal versus adult Japanese Black Cattle. Bovine 4b PP biological rep1, Bovine 78b PP biological rep2, Bovine 79 PP biological rep3 represents GV stage oocytes derived from Prepubertal (PP) heifer group, while Bovine 74b A biological rep1, Bovine 80b A biological rep2, Bovine 81 A biological rep3 represents GV stage oocytes derived from Adult (A) cow group. Bovine 7 PP biological rep1, Bovine 53 PP biological rep2, Bovine 57 PP biological rep3 represents MII stage oocytes derived from Prepubertal heifer group, while Bovine 59 A biological rep1, Bovine 70 A biological rep2, Bovine 71 A biological rep3 represents MII stage oocytes from Adult cow group.
Project description:Preimplantation embryos experience profound resetting of epigenetic information. Genome-wide analysis at single-base resolution had shown relevant species differences between human and mouse preimplantation embryos. Thus, we have extended such analysis to two key livestock species, the pig and the cow. We generated data showing the genome-wide DNA methylation landscape and whole-transcriptomes from gametes to blastocysts in both species. Detailed analysis revealed species specific differences and new insights in biological paradigms. An oocyte-like pattern of methylation in the cleavage stages, albeit with some reduction in methylation level, appears to persist even in cow blastocysts. Hypermethylated domains were prevalent over hypomethylated domains in pigs and cows, similar to human, while in the mouse the pattern is reversed. Interestingly, the behaviour of the oocyte hypo-domains in cleavage embryos revealed a complex dynamic of methylation reprogramming. It shows a pronounced increase in methylation at the 8-16 cell stage in pigs, similar to human, concomitant with ZFP57 expression. Even it is widely accepted that imprinted genes are established in the parental germline and robustly maintained through early development, our data show a greater dynamic of methylation in germline differentially methylated regions and few appear to maintain the expected 50% methylation from the 2-4 cell stage to blastocyst stage. It reveals that an active period of imprint stabilization until the blastocyst stage is required
Project description:Preimplantation embryos experience profound resetting of epigenetic information. Genome-wide analysis at single-base resolution had shown relevant species differences between human and mouse preimplantation embryos. Thus, we have extended such analysis to two key livestock species, the pig and the cow. We generated data showing the genome-wide DNA methylation landscape and whole-transcriptomes from gametes to blastocysts in both species. Detailed analysis revealed species specific differences and new insights in biological paradigms. An oocyte-like pattern of methylation in the cleavage stages, albeit with some reduction in methylation level, appears to persist even in cow blastocysts. Hypermethylated domains were prevalent over hypomethylated domains in pigs and cows, similar to human, while in the mouse the pattern is reversed. Interestingly, the behaviour of the oocyte hypo-domains in cleavage embryos revealed a complex dynamic of methylation reprogramming. It shows a pronounced increase in methylation at the 8-16 cell stage in pigs, similar to human, concomitant with ZFP57 expression. Even it is widely accepted that imprinted genes are established in the parental germline and robustly maintained through early development, our data show a greater dynamic of methylation in germline differentially methylated regions and few appear to maintain the expected 50% methylation from the 2-4 cell stage to blastocyst stage. It reveals that an active period of imprint stabilization until the blastocyst stage is required
Project description:Background: In vitro culture of preimplantation mouse embryos is associated with changes in gene expression. It is however not known if the method of fertilization affects the global pattern of gene expression. Method: We compared gene expression and development of mouse blastocysts produced by intra-cytoplasmic sperm injection and cultured in Whitten’s medium (ICSIWM) or KSOM medium with amino acids (ICSIKSOMaa) with control blastocysts flushed out of the uterus on post coital day 3.5 (In vivo). Global pattern of gene expression was assessed using the Affymetrix 430 2.0 chip. In addition we compared gene expression in embryos generated in IVF or ICSI using WM. Results: Blastocysts resulting from ICSI fertilization have a reduction in the number of trophoblastic and inner cell mass cells compared to in vivo generated embryos. Approximately 1000 genes are different between ICSI blastocyst and in vivo blastocysts; proliferation, apoptosis and morphogenetic pathways are the most common pathways altered after in vitro culture. Unexpectedly, only 41 genes were statistically different between embryo cultured in suboptimal conditions (WM) or optimal conditions (KSOMaa). Conclusion: The method of fertilization plays a more important role in shaping the transcriptome of the developing mouse embryo than the culture media used. 16 samples were used in 4 treatment groups (4 replicate samples per treatment)