Intron C nucleotide sequences of the bovine MHC class I genes : evolutionary implications /
The vertebrate major histocompatibility complex (MHC) ofilm Inc. class I gene family contains a large number of related genes in most species, including humans, mice, and cattle. Classical class I proteins present immune system surveillance via play an important role in resistance to endogenous peps...
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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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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=733050381&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The vertebrate major histocompatibility complex (MHC) ofilm Inc. class I gene family contains a large number of related genes in most species, including humans, mice, and cattle. Classical class I proteins present immune system surveillance via play an important role in resistance to endogenous pepsines to cytologic T-lymphocytes and intercellular infection. Nonclassical class I proteins may have immune or developmental functions or may, with pseudogene and gene fragments, serve as a sequence reservoir for gene conversion of classical loci. The relationship of class I loci to one another within a species and the mechanisms by which these genes evolve are important questions that may facilitate our understanding of class gene function. Gene trees of BOLA (bovine MHC) CDNAS have been constructed to assess the number of loci and to evaluate the role of gene conversion. They have supported estimates of three transcribed class loci whose diversity is generated more by overdominance than by gene conversion. This investigation analyzed variation in a non-coding region, the third intros (intron C), in order to examine evolutionary relationships in regions that are presumably less subject to natural selection. Clones of PCR products and a plasmic subclone of a phage isolate were sequenced to provide 26 new IOLA class sequences for intros and surrounding partially sequenced ebons 3 and 4. Three were from lambda clones believed to encode nonclassical genes and represent the first BOLA intros sequences determined for nonclassical genes. Six groups of highly similar (>98A) sequences were identified, containing a total of 22, in addition to more distinct sequences. The intrans ranged in length from 571--1884 base pairs. Excluding central regions of 317--1301 base pairs from the longer intrans left sequences whose similarity to one another and to the shorter intrans ranged from 56%--100%. Gene trees of published CDNA coding regions and the new intros C sequences did not demonstrate different evolutionary histories for coding and non-coding regions. Transition/transversion ratios suggest that at least one locus may have duplicated in the bovine MHC class I genome after the separation of cattle and swine, about 55 million years ago. |
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| Item Description: | Vita. "Major Subject: Genetics". |
| Physical Description: | xi, 152 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 136-149). |