Molecular Analysis of the Agouti Gene in Livestock

Author

Marcus Dale Johansen

Document Type

Thesis - University Access Only

Award Date

1998

Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology

Abstract

Agouti alleles regulate pigmentation in mouse melanocytes causing the production of black and/or yellow coat color. Yellow allelic mutations result in the dysregulated overexpression of the agouti gene and promote a number of systemic disorders (lethal yellow syndrome) of great interest to human health and animal productivity. The objectives of this study were to 1) identify a bovine agouti homo log, 2) sequence the bovine agouti homolog, and 3) characterize agouti expression in bovine tissues. Bovine genomic DNA was isolated and either digested with restriction enzymes for Southern analysis or used for Polymerase Chain Reaction (PCR) to amplify specific regions of the bovine agouti coding region. Amplified PCR products were cloned and sequenced. Bovine total RNA was isolated and either used for Northern analysis or Reverse Transcriptase (RT)-PCR. In both Southern (DNA) and Northern (RNA) analyses, hybridization was detected using a ³²P labeled murine agouti cDNA as the probe. Southern hybridizations showed that cattle possess an agouti gene. Sequence analysis of cloned PCR products revealed a 161 bp product that hybridized to murine agouti cDNA and resembled agouti exon 2. The nucleotide sequence of bovine agouti exon 2 was 75, 82, and 88% similar to murine, human, and porcine agouti nucleic acid sequences. Furthermore, the predicted amino acid sequence was 60, 73, and 81 % similar to murine, human, and porcine agouti predicted amino acid sequences. RT-PCR on bovine liver tissue produced a 336 bp product that did not resemble murine agouti cDNA, but rather a region in the bovine mitochondrial genome. Northern hybridizations indicate that the bovine agouti gene produces transcripts (expression) in liver, heart, and kidney. A molecular understanding of the bovine agouti homolog may enable cattle producers to select agouti alleles beneficial for rapid growth, high protein/low fat carcasses, enhanced reproduction, and greater vigor. Work funded by SDSU-AES (HD089), Eagles' Ehrmann Cancer Fund, and NIH (AR42757).

Library of Congress Subject Headings

Cattle -- Molecular genetics
Lethal mutation
Pigments (Biology)

Format

application/pdf

Number of Pages

82

Publisher

South Dakota State University

Recommended Citation

Johansen, Marcus Dale, "Molecular Analysis of the Agouti Gene in Livestock" (1998). Electronic Theses and Dissertations. 426.
https://openprairie.sdstate.edu/etd2/426