Transcriptomic signature of selenium versus zinc and iodine supplementation in sheep

Selenium (Se), zinc (Zn) and iodine (I) are significant elements in ruminant diet for their role on the immune system, fertility and hormone activity. In cattle and sheep, deficiencies of these elements have been confirmed under natural grazing conditions in many countries where soils produces pasture grasses and legumes low in content. Three different groups of 10 sheep each were administered for 40 days diets containing high supplementations (almost reaching the highest tolerated amounts according to EC restrictions) of Se (1.4 mg/ animal/day), Zn (212 mg/animal/day) and I (28 mg/animal/day). The effects of supplementation on whole blood transcriptome were investigated using microarray technology and a sheep custom microarray slides. In the group receiving Se, 942 and 244 mRNAs were shown to be up and down-regulated, respectively (1.5 ≥ FC ≤1.5; FDR<0.05). The functional annotation of these differentially expressed genes (DEGs) showed an involvement of immune system-related biological processes (lymphocyte and leukocyte activation, cytokine binding, T-cell differentiation) and pathways (cytokine and interleukin signalling). Then, we verified if the transcriptional effects induced by Se supplementation (in term of DEGs) were mirrored by the other two micronutrients. When we compared the transcriptional portrait of sheep given Zn and Se, a total of 231 and 20 mRNAs appeared to be commonly up-and down-regulated, respectively. Likewise, 166 and 13 mRNAs were commonly up and down-regulated in sheep provided with I and Se, respectively. In conclusion, these results show that micronutrient supplementation seems to affect the sheep blood transcriptome; moreover, some DEGs were proved to be similarly affected, particularly when we compared animals given Se and Zn. Clearly, further studies are needed to investigate more in depth the consequences of these effects on animal health and the possible presence of potential crosstalks between each micronutrient-related molecular pathways