Tissue distribution of lipid and fatty acid metabolism and transcription factors genes in adult Atlantic bluefin tuna (Thunnus thynnus L.)

To determine expression of the major lipid pathways in tissues of adult bluefin tuna 8 individualswere used for collecting samples for tissue expression of key lipid metabolism genes. Triplicatesets of samples of brain, gills, heart, kidney, spleen, liver, intestine, white muscle, red muscle,adipose tissue ovary and testis were collected. Expression of genes was determined by qPCR.Tissue expression profiles showed that PUFA biosynthetic pathway genes were expressed in alltissues examined, highest expression in brain, liver and testis. Elongase elovl5 showed higherexpression than desaturase fads2d6 in all other tissues, with low expression of in red muscle andovaries.Transcription factors, pparα and pparγ showed parallel expression, with adipose tissue with thehighest relative copy number, followed by intestine>testis>liver. The expression of lxr was low inliver, with highest expression in testis, brain and kidney. Similarly, rxr was poorly expressed in liverwith higher expression in muscle, spleen and brain. The rank order of expression of srebp1 wasbrain, testis, ovary, intestines, kidney, gill, liver, white muscle, spleen, heart and red muscle. Forsrebp2 the highest expression was shown in brain, testis and adipose with lowest expression inheart and white muscle. Expression of fabp2 was highest in intestine, brain and heart with lowerlevels in liver, red muscle, adipose and kidney. fabp4 showed highest expression in ovaries withliver showing the lowest. fabp7 showed highest expression levels in brain and testis with lowestvalues in liver. cptI expression was highest in brain and lowest in liver. Similarly, the relative copynumber for fas was highest in brain followed by gonads, gill and liver, with white muscle showinglowest expression. The expression of aco was highest in adipose and intestine, followed byliver, kidney and brain. The expression of hmgcl was highest in ovary followed by adipose, brainand testis, with lowest expression in liver. Expression of lpl was highest in testis and lowest inovary, with liver and white muscle, adipose, heart, gills and red muscle, kidney, intestine showingintermediate levels of expression.This research was supported by projects from the Junta de Andalucía, Proyecto de Excelencia dePromoción General del Conocimiento Ref. RNM 0733, and Programa Estatal de Investigación delMinisterio de Economía y Competitividad Ref. AGL2014-52003-C2-1-R.AQUACULTURE, ENDOCRINOLOGY AND TOXICOLOGY 218. VI IBERIAN CONGRESS OF ICHTHYOLOGY MURCIA, SPAIN 21st · 24th June P-040