Expression of Transforming Growth Factor--Like Messenger Ribonucleic Acid Transcripts in the Bovine Mammary Gland

¹ Department of Animal and Food Sciences, University of Vermont, Burlington 05405

The objective of this study was to evaluate the expression of mRNA for transforming growth factor- in the bovine mammary gland. Total RNA from 23 cows at various stages of development was isolated from mammary parenchyma and subjected to Northern blot analysis using human transforming growth factor- ³²P-labeled deoxycytosine triphosphate cDNA probe. When blots were washed through 1x sodium chloride and sodium citrate plus 1% SDS at 60°C, a 4.8-kb band was observed in all RNA samples. When stringency was increased to .1x, mRNA transcripts were observed only for cows at d 233, 240, and 244 of gestation. After the high stringency washes, major bands were observed at 7.4 and 3.3 kb and minor bands on d 233 at 5.4, 2.3, and 1.6 kb. No additional transcripts were detected in RNA from mammary glands of nonpregnant cows during involution, lactating cows, or estrogen-treated heifers. These data indicate that transcripts similar to transforming growth factor- are present in the bovine mammary gland. The expression pattern could represent alternatively spliced transcripts that were produced during an important period of mammary development prior to parturition.

Key Words: transforming growth factor- • mammary gland • messenger ribonucleic acid • Northern blot analysis

Submitted on November 23, 1994
Accepted on May 1, 1995

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