Project description:Two-thirds of gene promoters in mammals are associated with regions of non-methylated DNA, called CpG islands (CGIs), which counteract the repressive effects of DNA methylation. In lower vertebrates, computational CGI predictions often reside away from gene promoters, suggesting a major divergence in gene promoter architecture across vertebrates. By experimentally identifying non-methylated DNA in the genomes of seven diverse vertebrates, we instead reveal that non-methylated islands (NMIs) of DNA are a central feature of vertebrate gene promoters. Furthermore, NMIs are present at orthologous genes across vast evolutionary distances, revealing a surprising level of conservation in this epigenetic feature. By profiling NMIs in different tissues and developmental stages we uncover a unifying set of features that are central to the function of NMIs in vertebrates. Together these findings demonstrate an ancient logic for NMI usage at gene promoters and reveal an unprecedented level of epigenetic conservation across vertebrate evolution. Bio-CAP was used to identify non-methylated regions of the genome in seven diverse vertebrates (human, mouse, platypus, chicken, lizard, frog and zebrafish) across a number of tissues.
Project description:We carried out a cross species cattle-sheep array comparative genome hybridization (aCGH) experiment in order to identify copy number variations (CNVs) in the sheep genome analysing animals of Italian dairy breeds (Sarda, Bagnolese, Laticauda, Massese and Valle del Belice) using a tiling oligonucleotide array with ~385,000 probes designed on the bovine genome. We identified 135 CNV regions (CNVRs) covering about 10.5 Mb of the virtual sheep genome referred to the bovine genome (0.398%) with a mean and median equal to 77.6 kb and 55.9 kb, respectively. A comparative analysis between the identified sheep CNVRs and those reported in the cattle and goat genomes indicated that overlaps between sheep and goat and sheep and cattle CNVRs are highly significant (P<0.0001) suggesting that several chromosome regions might contain recurrent interspecies CNVRs. Many sheep CNVs affect genes with important biological functions. Further studies are needed to evaluate the functional relevance of these CNVs.
Project description:The sheep (Ovis aries) plays a major socio-economic role in the world. Copy number variations (CNVs) are increasingly recognized as a key and potent source of genetic variation and phenotypic diversity, but little is known about the extent to which CNVs contribute to genetic variation in Chinese sheep breeds. Analyses of CNVs in the genomes of eight sheep breeds were performed using the sheep SNP50 BeadChip genotyping array. A total of 111 CNV regions (CNVRs) were obtained from 160 Chinese sheep breeds. These CNVRs covered 13.75 Mb of the sheep genome sequence. A total of 22 Go terms and 17 candidate genes were obtained from the functional analysis. Ten CNVRs were selected for validation, of which 7 CNVRs were further experimentally confirmed by quantitative PCR. Four candidate genes were selected to confirm the results of the functional analysis. These results provide a resource for furthering understanding of ruminant biology, and for further improving the genetic quality of sheep breeds.