Project description:Genomic imprinting is an epigenetic mechanism that leads to parental-allele-specific gene expression. Approximately 150 imprinted genes have been identified in humans and mice but less than 30 genes have been described as imprinted in cattle. For the purpose of de novo identification of imprinted genes in bovine, we determined global monoallelic gene expression in brain, skeletal muscle, liver, kidney and placenta of day ~105 Bos taurus indicus X Bos taurus taurus F1 conceptuses using RNA sequencing. For this, we developed a bioinformatics pipeline to identify parental-specific SNPs after filtering A-to-I RNA editing sites. We identified 53 genes subject to monoallelic expression. A total of 23 are genes known to be imprinted in the cow and 7 are previously-characterized imprinted genes in human and/or mouse that have not be reported to be imprinted in cattle. Of the remaining 23 genes, we found that 10 are uncharacterized or unannotated transcripts located in known imprinting clusters, whereas the other 13 genes are distributed across the bovine genome and not close to any known imprinting clusters. To exclude potential cis-eQTL effects on allelic expression, we corroborated the parental specificity of monoallelic expression in day 86 Bos taurus taurus X Bos taurus taurus F1s and identified eight novel imprinted genes in bovine. Further, we identified 671 candidate A-to-I RNA editing sites and describe imprinted X inactivation in the bovine trophectoderm-derived CT1 cell line. Our results expand the imprinted gene list in bovine and demonstrate that monoallelic gene expression can be the result of cis-eQTL effect.
Project description:During maternal-to-embryonic transition control of embryonic development gradually switches from maternal RNAs and proteins stored in the oocyte to gene products generated after embryonic genome activation (EGA). Detailed insight into the onset of embryonic transcription is obscured by the presence of maternal transcripts. Using the bovine model system, we established by RNA sequencing a comprehensive catalogue of transcripts in germinal vesicle and metaphase II oocytes, and in embryos at the 4-cell, 8-cell, 16-cell and blastocyst stages. These were produced by in vitro fertilization of Bos t. taurus oocytes with sperm from a Bos t. indicus bull to facilitate parent-specific transcriptome analysis. Transcripts from 12.4 to 13.7 M-CM-^W 10^3 different genes were detected in the various developmental stages. EGA was analyzed by i) detection of embryonic transcripts which are not present in oocytes; ii) detection of transcripts from the paternal allele; and iii) detection of primary transcripts with intronic sequences. These strategies revealed (i) 220, (ii) 937, and (iii) 6,848 genes to be activated from the 4-cell to the blastocyst stage. The largest proportion of gene activation, i.e. (i) 59%, (ii) 42%, and (iii) 58%, was found in 8-cell embryos, indicating major EGA at this stage. Gene ontology analysis of genes activated at the 4-cell stage identified categories related to translation, RNA processing and transport, consistent with preparation for major EGA. Our study provides the largest transcriptome data set of bovine oocyte maturation and early embryonic development and new insight into the timing of embryonic activation of specific genes. RNA-Seq profiles from pools of 10 ooytes/embryos from bovine Bos t. taurus GV and MII oocytes and a cross-breed of Bos t. taurus x Bos t. indicus from 4-cell, 8-cell, 16-cell and blastocysts generated using Illumina GAIIx
Project description:Here we describe a genome-wide analysis of copy number variations (CNVs) in Chinese domestic cattle by using array comparative genomic hybridization (array CGH) and quantitative PCR (qPCR). We conducted array CGH analysis on 30 male cattle individuals, animals from consisting of 12 breeds of Bos taurus/Bos indicus, 1 Bos grunniens and and two ones of Bubalus bubalis breeds for with beef, and/or dairy or dual purpose. We identified over 470 candidate CNV regions (CNVRs) in Bos B. taurus/B. indicus; 118 candidate CNV regions (CNVRs) in B. grunniens, 139 CNVRs in B. bubalis. Furthermore, based on the Y haplotypes of B. taurus/ B. indicus, Wwe also identified 69, 337, and 251 candidate CNV regions (CNVRs) in the sub-groups of Y1, Y2 and Y3 haplotypes.
Project description:The objective was to study the transcriptomic changes in adipose tissue in the early stages of lactation, specifically in Bos Taurus, Holstein dairy cattle as a function of milk production and genetic merit. Chip quality backgrounds averaged below 50 units, and 3’/5’ bias on control genes < 2.0. Correlations among replicates were > 0.85.
Project description:Copy number variations (CNVs) have been demonstrated as crucial substrates for evolution, adaptation and breed formation. Chinese indigenous cattle breeds exhibit a broad geographical distribution and diverse environmental adaptability. Here, we analyzed the population structure and adaptation to high altitude of Chinese indigenous cattle based on genome-wide CNVs derived from the high-density BovineHD SNP array. We successfully detected the genome-wide CNVs of 318 individuals from 24 Chinese indigenous cattle breeds and 37 yaks as outgroups. A total of 5,818 autosomal CNV regions (683 bp - 4,477,860 bp in size), covering ~14.34% of the bovine genome (UMD3.1), were identified, showing abundant CNV resources. Neighbor-joining clustering, principal component analysis (PCA), and population admixture analysis based on these CNVs support that most Chinese cattle breeds are hybrids of Bos taurus taurus (hereinafter to be referred as Bos taurus) and Bos taurus indicus (Bos indicus). The distribution patterns of the CNVs could to some extent be related to the geographical backgrounds of the habitat of the breeds, and admixture among cattle breeds from different districts. We analyzed the selective signatures of CNVs positively involved in high-altitude adaptation using pairwise Fst analysis within breeds with a strong Bos taurus background (taurine-type breeds) and within Bos taurus×Bos indicus hybrids, respectively. CNV-overlapping genes with strong selection signatures (at top 0.5% of Fst value), including LETM1 (Fst = 0.490), TXNRD2 (Fst=0.440) and STUB1 (Fst=0.420) within taurine-type breeds, and NOXA1 (Fst = 0.233), RUVBL1 (Fst=0.222) and SLC4A3 (Fst=0.154) within hybrids, were potentially involved in the adaptation to hypoxia. Thus, we provide a new profile of population structure from the CNV aspects of Chinese indigenous cattle and new insights into high-altitude adaptation in cattle.