Micronutrients are essential for optimal human health. However, in some cases,raising intake by supplementation has not proven to be beneficial and there iseven some evidence that supplementation may increase disease risk, highlightingthe importance of assessing the functional status of micronutrients. Techniquessuch as gene microarrays and single-nucleotide polymorphism analysis have thepotential to examine effects of micronutrient intake on patterns of geneexpression and inter-individual variation in micronutrient metabolism. Recentgenomic research related to selenium (Se) provides examples illustrating howstudies of functional single-nucleotide polymorphism and gene expressionpatterns can reveal novel biomarkers of micronutrient function. Both invitro and in vivo experiments show that there arefunctionally relevant polymorphisms in genes encoding glutathione peroxidases 1,3 and 4, selenoprotein P, selenoprotein S and the 15 kDa selenoprotein. Diseaseassociation studies investigating these gene variants have so far beenrelatively small but an association of a polymorphism in the selenoprotein Sgene with colorectal cancer risk has been replicated in two distinctpopulations. Future disease association studies should examine effects ofmultiple variants in combination with nutritional status. Gene microarraystudies indicate that changes in Se intake alter expression of components ofinflammatory, stress response and translation pathways. Our hypothesis is thatSe intake and genetic factors have linked effects on stress response,inflammation and apoptotic pathways. Combining such data in a systems biologyapproach has the potential to identify both biomarkers of micronutrients statusand sub-group populations at particular risk.

The expression of many genes encoding secreted and non-secreted factors have been studied in human and rodent adipose tissue with cDNA microarrays, but few such studies in adipose tissue from growing pigs have been reported. Total RNA was collected at slaughter from outer subcutaneous adipose tissue (OSQ) and middle subcutaneous adipose tissue (MSQ) samples from gilts at 90, 150 and 210 days (n = 5/age). Dye-labeled cDNA probes were hybridized to custom microarrays (70-mer oligonucleotides) representing about 600 pig genes involved in growth and reproduction. Gene expression intensity ratios changed little with age for 100 transcription factors, nuclear receptors, enzymes and other regulatory proteins in OSQ and MSQ from pigs between 90 and 210 days of age. However, the relative expression of 13 genes distinguished OSQ and MSQ depots in growing pigs. The expression of several genes were influenced by age including an increase in CCND3, HSF1 and PTGR1 expression in MSQ and a decrease in UCP2 and REA (prohibitin-2) expression in OSQ. These studies demonstrate for the first time the expression of several key regulatory genes in pig adipose tissue. Simple linear regression analysis showed that leptin gene expression was associated with expression of some of these regulatory genes. Negative associations between expression of some regulatory factors and leptin gene expression indicated that local leptin may decrease or antagonize adipogenesis.