Project description:Here we present a high-density in situ synthesized microarray for Ovis aries, named Aristaeus, designed by means of a pipeline of software instruments that, starting from non-annotated redundant EST sequences, selects oligonucleotides suitable for in situ generation on chip. The chip was tested by comparing the gene expression profiles of two sheep breeds with different phenotype, Sarda and Gentile di Puglia. We carried out microarray experiments on liver and udder tissues from lactating individuals and identified a relevant number of differentially expressed genes, all involved in metabolism pathways. The results are consistent with literature knowledge, while selected differential gene expressions have been confirmed by quantitative real-time polymerase chain reaction analyses. Tissue samples of liver were collected from 4 lactating individuals of two sheep (Ovis aries) breeds, Gentile di Puglia and Sarda. Biopsies of liver tissue were taken at second lactation stage (first record, stage 01: 6 days after lambing; second record, stage 02: 44 days after lambing) in both breeds. Tissues from liver were immersed in RNAlater (Sigma) immediately after biopsy and stored at -20°C. Samples were pooled by breed and then reverse labeled (cy5 and cy3), resulting in four raw data sets.
Project description:Background:The Marco Polo Sheep (Ovis ammon polii), a subspecies of argali (Ovis ammon) that is distributed mainly in the Pamir Mountains, provides a mammalian model to study high altitude adaptation mechanisms. Due to over-hunting and subsistence poaching, as well as competition with livestock and habitat loss, O. ammon has been categorized as an endangered species on several lists. It can have fertile offspring with sheep. Hence, a high-quality reference genome of the Marco Polo Sheep will be very helpful in conservation genetics and even in exploiting useful genes in sheep breeding. Findings:A total of 1022.43 Gb of raw reads resulting from whole-genome sequencing of a Marco Polo Sheep were generated using an Illumina HiSeq2000 platform. The final genome assembly (2.71 Gb) has an N50 contig size of 30.7 Kb and a scaffold N50 of 5.49 Mb. The repeat sequences identified account for 46.72% of the genome, and 20 336 protein-coding genes were predicted from the masked genome. Phylogenetic analysis indicated a close relationship between Marco Polo Sheep and the domesticated sheep, and the time of their divergence was approximately 2.36 million years ago. We identified 271 expanded gene families and 168 putative positively selected genes in the Marco Polo Sheep lineage. Conclusions:We provide the first genome sequence and gene annotation for the Marco Polo Sheep. The availability of these resources will be of value in the future conservation of this endangered large mammal, for research into high altitude adaptation mechanisms, for reconstructing the evolutionary history of the Caprinae, and for the future conservation of the Marco Polo Sheep.