There has been a tremendous amount of information produced on peroxisome proliferator-activated receptors (PPARs). The interest on PPAR was originally driven largely by their role in hypolipidemia and hepatocarcinogenesis, but it soon became evident that they played important roles in the metabolic syndrome and overall health of organisms including regeneration of tissues, differentiation, insulin signaling, overall lipid metabolism, and immune response. From a nutritional standpoint, the PPARs are of extreme importance because of their ability to bind and be activated by long-chain fatty acids and their metabolites. Therefore, the PPARs are recognized as ideal candidates for therapeutic use in order to improve metabolism and overall health through diet. At present there is substantial interest on therapeutic applications tailored to regulate PPAR via synthetic drugs but the exploitation of dietary approaches is not a reality yet.

Most of our knowledge on PPAR has been produced by studies carried out in rodents and humans and little from other species, bovine and pig being the most studied among livestock species. Despite the substantial degree of protein and functional conservation of PPAR among species, there also are some important differences some of which, for instance, preclude the translation of findings in one species to another. This is an important obstacle in translating findings from animal models to human.

The multitude of roles of PPARs and the possibility of regulating them through dietary approaches also are of interest in animal food production. Among livestock scientists there is an increasing interest on PPARs, but the amount of information generated to date is relatively small.

Therefore, a comparative approach to bring together physiological and nutritional roles of PPARs across species appears critical.

We are interested in the current status and advancement of research on PPARs isotypes as it relates to physiology and nutrition across livestock species or model organisms and encourages authors to submit original papers and review articles on the subject. Potential topics include, but are not limited to:

• Direct comparative studies of PPARs isotypes between two or more species (including in silico analysis, epigenetics, 3D structure, target genes, nutritional responses, and physiological or inflammatory responses)
• Studies on the roles or adaptation of PPARs isotypes to physiological state, development, specific agonists, or nutrition in livestock species or model organisms

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/ppar/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/submit/journals/ppar/cpn/ according to the following timetable: