Real-time RT-PCR and cDNA macroarray to study the impact of the genetic polymorphism at the alphas1-casein locus on the expression of genes in the goat mammary gland during lactation.
Milk fat has a large effect on nutritional, technological and sensorial properties of milk products. The milk fat content and composition are modulated by genetics and nutritional factors and imply a large number of enzymes. The regulation of their gene expression in the mammary gland still needs to be clarified. An association between the extensive polymorphism at the alphas1-casein (alphas1-Cas) locus and both the lipid content and the characteristics of this fraction in caprine milk has been demonstrated. In order to decipher the mechanism responsible for this impact, a quantification of the transcripts of four lipogenic key enzymes (acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase and stearoyl-CoA desaturase) was performed using real-time RT-PCR, suggesting an absence of association between the alphas1-Cas genotype and expression variability of the studied genes. This approach has been completed by a more global analysis using a first generation of ruminant macroarray gathering 400 gene probes. The comparison of the expression profiles of lactating goat alphas1-Cas A/A (strong allele) and F/F (defective allele) mammary gland allowed to confirm the expected variability in the expression of known genes (such as those encoding the alphas1-casein) in ruminant mammary tissues as well as to identify up- and down-regulated genes. A second generation of ruminant cDNA macroarray extended to a few thousands of genes is currently in progress and will be applied to study different factors such as the nutritional regulation of gene expression in the mammary gland.
Leroux
Christine
C
Laboratoire de Génétique biochimique et de Cytogénétique, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy-en-Josas, France. cleroux@clermont.inra.fr
Le Provost
Fabienne
F
Petit
Elisabeth
E
Bernard
Laurence
L
Chilliard
Yves
Y
Martin
Patrice
P
D000483:Alleles; D000818:Animals; D002364:Caseins / Q000235:genetics*; D005223:Fats / Q000032:analysis; D005260:Female; D020869:Gene Expression Profiling / Q000662:veterinary*; D005786:Gene Expression Regulation; D006041:Goats / Q000502:physiology*; D008892:Milk / Q000737:chemistry*; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary*; D011110:Polymorphism, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*
D002364:Caseins; D005223:Fats