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Identification, for ruminants, of genes and gene networks involved in differentiation and activity of the mammary gland

Felicie Faucon
Abstract : Biosynthesis and secretion activity by the ruminant mammary gland is settled by terminal differentiation of mammary structures and the expression of many genes. In this work, microarray technology was used to determine genes that participate to the goat mammary gland differentiation and that explain variation of milk composition observed with the K232A mutation at the bovine DGAT1 locus. Our study showed that the gene expression profile of the goat mammary tissues undergo considerable changes during pregnancy: i) triggering off differentiation before the 1st third of pregnancy; ii) tissue remodelling enhanced by expression of immune response genes; iii) acquisition of the secretory phenotype and triggering off lipid synthesis at the parturition. Transcriptomic comparison of mammary tissues from cows with homozygous and opposite genotype at the DGAT1 locus (K232 vs. A232) help to determine cellular mechanisms underlying variation of milk composition observed between these two genotypes. We have confirmed a reduction of fat percentage (-10g/kg) and middle chain unsaturated fatty acids (FA), an increase of middle chain saturated FA and long chain unsaturated FA and a reduction of milk fat globule size with the A232 genotype. Transcriptomic analysis with total RNA extracted from mammary tissues revealed that genes implicated in synthesis of lactose, lipids and proteins were up-regulated with A232 individuals. For the lipids, these genes partially explain the difference in milk FA composition and suggest alternative metabolic pathways of the diacylglycerol.
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Submitted on : Wednesday, February 24, 2010 - 8:00:00 AM
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Felicie Faucon. Identification, for ruminants, of genes and gene networks involved in differentiation and activity of the mammary gland. Life Sciences [q-bio]. AgroParisTech, 2009. English. ⟨NNT : 2009AGPT0013⟩. ⟨pastel-00005545⟩

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