Positional cloning of candidate genes affecting growth in Bos taurus x Bos indicus /
The positional candidate gene approach was utilized in this study to identify QTLs affecting growth in the Angleton resource herd comprising 701 animals from Angus x Brahman F₂ and backcrosses. The specific objectives of this research were: 1) to screen a bovine bacterial artificial chromosome (BAC)...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=845702731&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The positional candidate gene approach was utilized in this study to identify QTLs affecting growth in the Angleton resource herd comprising 701 animals from Angus x Brahman F₂ and backcrosses. The specific objectives of this research were: 1) to screen a bovine bacterial artificial chromosome (BAC) library for candidate genes potentially associated with growth QTL; 2) to physically and genetically map these candidate genes, and; 3) to identify DNA sequence variation associated with phenotypic variation when the candidate gene was putatively identified to be the QTL. Successful primers were designed for twenty six candidate genes affecting growth and were used to screen the bovine BAC library. Positive clones were identified in the bovine BAC library for twenty four genes and one gene was identified in the ovine BAC library. Twenty six BAC clones, representing thirteen candidate genes, mapped to their predicted chromosomal locations based on FISH. Microsatellites were isolated from BAC clones containing genes which localized to subchromosomal regions of interest as identified in interval analyses for the Angleton population. Microsatellite markers for SST, PIT1, MGDF, NPY3R, and GDF-8 were integrated into the existing genetic maps for bovine chromosomes 1 and 2. Interval analyses identified major genes and QTL on bovine chromosomes 1 and 2. Myostatin (GDF-8), a potential QTL for growth on bovine chromosome 2, was not identified as a QTL in this population. PIT1 mapped within the 1-LOD interval of a yield grade and ribeye area QTL. Somatostatin (SST), a principal gene in the growth hormone axis, was identified as a QTL for marbling and quality grade with LOD support of 4.78 and 4.70, respectively. Sequencing of the somatostatin gene in four individuals each from Angus and Brahman identified ten DNA sequence polymorphisms. Angus and Brahman alleles were identified in these sequences. A significant polymorphism was identified which resulted in an amino acid change (Glu-Lys) in the first codon of exon 2 in two Angus individuals. This creates a potential monobasic cleavage site in the prohormone which may affect posttranslational modifications. Further study is needed to determine the specific effects of somatostatin in this and other cattle populations. |
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| Item Description: | Vita. "Major Subject: Genetics". |
| Physical Description: | xiii, 150 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 118-128). |