Differential allele-specific accumulation of bovine kappa-casein mRNA throughout lactation.
A differential allele-specific accumulation of kappa-casein mRNA that is not linked to the kappa-casein protein variants is described in Holstein cows. Actually, cows genotyped kappa-casein AB were a mixed population. For the first group of kappa-casein AB cows, allele A-specific kappa-casein mRNA contents within mammary epithelial cells were lower than the allele B-specific ones (cows LH), suggesting that the allele A-specific kappa-casein gene was expressed with lower efficiency in mRNA. For the other group of kappa-casein AB cows, allele A- and B-specific kappa-casein mRNA accumulated to a similar level within mammary epithelial cells (cows HH). The objective of this study was to determine whether the accumulation of allele-specific kappa-casein mRNA remained constant throughout lactation for the two groups of cows. Quantitative RT-PCR was used to monitor Holstein cows kappa-casein AB genotyped HH and LH throughout lactation for the proportion of allele B-specific mRNA accumulation relative to the total kappa-casein encoded mRNA within mammary epithelial cells: RNA was extracted from milk somatic cells known to contain a small proportion of mammary epithelial cells. Mean values of allele B-specific mRNA content were 50.6+/-0.5 and 54.0+/-0.9%, for cows HH and cows LH, respectively, and did not vary during lactation (P> 0.10). This suggests that the phenotypic expression of the genetic mutation that causes the differential allele-specific accumulation of kappa-casein mRNA was not affected by physiological and environmental factors, which tend to vary considerably throughout lactation.
Vachon
Dominic
D
Sherbrooke University, Sherbrooke, Canada.
Britten
Michel
M
Morisset
Jean
J
Petitclerc
Denis
D
Robitaille
Gilles
G
D000483:Alleles; D000818:Animals; D002364:Caseins / Q000235:genetics*; D002417:Cattle / Q000378:metabolism*; D004847:Epithelial Cells / Q000737:chemistry; D005260:Female; D007774:Lactation; D008321:Mammary Glands, Animal / Q000737:chemistry*; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002364:Caseins; D012333:RNA, Messenger