Date of Completion

Spring 5-8-2011

Thesis Advisor(s)

Kristen Govoni

Honors Major

Animal Science

Disciplines

Animal Sciences | Dairy Science

Abstract

In American society, dairy products are vital for nutrition and the economy. Optimizing the process of producing milk can benefit the consumers, producers, and the animals involved. Understanding the mechanisms of the development of the mammary gland can increase the efficiency of milk production, as well as improve animal health.

Mammary epithelial cells (MEC) are the functional unit of the mammary gland. Although, there is a well-established MEC cell line, known as MAC-T, the use of a primary cell line is preferred because it more closely mimics an in vivo model. To better understand how mammary cell differentiation is regulated, it is vital to understand key mechanisms involved. One of the key genes involved in differentiation of MEC is the casein gene, which is expressed during mammary development and can be used to indicate differentiation of MEC. The main goal of this research is to establish the optimal methods for differentiation of primary bovine MEC in culture.

Previous studies suggest that growth hormone (GH), also known as bovine somatotropin, is a promoter of MEC differentiation.

Therefore, we hypothesize that GH will promote differentiation in MEC in culture. To test our hypothesis, we isolated and cultured bovine MEC from lactating dairy cows postmortem. Cells were cultured in standard media (DMEM + 10% FBS) and bovine insulin, prolactin, and dexamethasone were added to induce differentiation. In addition, cells were cultured in the absence (DMEM + 0.2% BSA) or presence of GH (DMEM + 0.2% BSA + 10ng/mL GH) for 8 days. To evaluate differentiation of the cells, we determined the expression of the α-casein gene by real-time reverse transcriptase-polymerase chain reaction (PCR) analysis at 0, 2, 4, 6, and 8 days of culture.

The expression in primary MEC cultured was low or not detectable, indicating that the cells have not differentiated into mature MEC.

In addition, cells treated with GH did not have greater expression of α-casein at day 8 compared to the controls, suggesting that GH did not further differentiate MEC. Further studies are needed to identify optimal conditions to differentiate primary bovine MEC in culture.

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