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.
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
Christine
C
Leroux
Fabienne
F
Le Provost
Elisabeth
E
Petit
Laurence
L
Bernard
Yves
Y
Chilliard
Patrice
P
Martin
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