REGULATION OF OVINE BETA-LACTOGLOBULIN GENE-EXPRESSION DURING THE FIRST STAGE OF LACTOGENESIS

In the lactating mammary gland, expression of the ovine beta-lactoglob ulin gene correlates with the presence of a strong DNaseI hypersensiti ve site encompassing the promoter region. At this stage of lactogenesi s, prolactin is required for optimal expression. Using DNaseI as a pro be for formation of a transcription complex on the a-lactoglobulin pro moter, the temporal pattern of ovine beta-lactoglobulin expression dur ing pregnancy has been addressed. The appearance of nuclease hypersens itivity during pregnancy correlates with rising levels of placental la ctogen which suggests that this hormone may be the stimulus for expres sion during the first stage of lactogenesis. This raises the possibili ty that a different signalling pathway to that present in the lactatio n functions during pregnancy. (C) 1995 Academic Press, Inc.