Global gene expression profiling following a dietary selenium supplementation in sheep (Ovis aries).

In the present study, we studied the effect of dietary selenium (Se) supplementation on the transcriptomic profile of sheep. The main objective was to evaluate the effect of Se-supplementation on the overall transcriptome of sheep, the altered pathways, and the biological processes related to it . A custom oligo microarray platform (AMADID: 070119) was designed, then used to profile gene expression from 20 samples from 10 sheep at two time points (T0; before Se-supplementation, and T40; at the end of a 40-d Se-supplementation period). Isolated and purified total RNAs were individually hybridized to the custom (4x44k) DNA microarray. The comparison of control and treated animal transcriptomes revealed a large set of differentially expressed genes. After functional analysis and qPCR validation, the result showed several pathways and biological processes that have been altered following Se-supplementation to the diet. Ten lactating crossbred ewes (3 to 4 y of age and 55 to 65 kg BW) were assigned to a before-and-after experimental design, where each animal served as its own control. The sheep have been acclimatized (4-wk) on a basal diet containing a maintenance level of Se (0.13 mg Se/kg DM). At the end of the 4-wk acclimatization period the sheep started to receive the supra Se-supplemented diet (0.45 mg Se/kg DM) for a 40-d period. Blood samples were collected at 2 time points [T0; one day before the supra Se-supplementation, and T40; at the end of the 40-d supra Se-supplementation phase]. Blood samples were collected from each individual animal directly into Paxgene blood collection tubes, processed and stored at -20˚C till further analyses. All samples yielded high quality RNA that was tested prior the microarray setup.