Molecular evolution of bovine major histocompatibility complex (BoLA) class I genes : concerted evolution does not occur among the five BoLA class I loci /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1993.
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| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | To explore the genetic mechanisms responsible for major histocompatibility complex (MHC) class I evolution in artiodactyls (order Artiodactyla, suborder Ruminantia), MHC class I cDNAs were cloned and sequenced from three species: cattle (Bos taurus, family Bovidae), sheep (Ovis aries, family Bovidae) and red deer (Cervis elaphus, family Cervidae). The first goal was to ascertain the number of transcribed MHC class I genes in cattle. Six unique cDNAs w ere cloned from a Bos taurus bull indicating the presence of at least three MHC class I loci. Comparisons made among these cDNAs suggested that there may be four loci represented by these six cDNAs. Additional comparisons made with previously published bovine MHC class I cDNAs suggested that there may be five transcribed MHC class I loci in cattle, one of which may be a nonclassical gene. The second goal was to compare these cattle MHC class I sequences with sequences from other artiodacytls to determine sequence similarity and orthology among all artiodactyl MHC class I genes. Three unique MHC class I cDNAs were isolated from a sheep. Comparisons of these ovine cDNAs and other published ovine cDNAs with cattle MHC class I cDNAs suggested that duplication of MHC class I lo d occurred before the ovine and bovine lineages split in the Middle Miocene. These duplications resulted in ortnologous relationships between these two species so that some of the BoLA class I cDNAs had more sequence similarity with some sheep cDNAs than to other cattle cDNAs. Partial length MHC class I cDNAs from the conserved 3' domains were recovered from a red deer and were compared with the same regions of cattle and sheep cDNAs. Two of these red deer cDNAs had significant sequence similarity with a sheep cDNA demonstrating possible orthology between sheep and red deer MHC class I genes. MHC class I sequences from pigs (Suis scrofa, suborder Suiformes) were also included in all interspecies analysis. No single cDNA of cattle, sheep, or red deer was more similar to any pig cDNA. Suiforms diverged from the common artiodactyl lineage during the early Oligocene 55 - 50 million years ago (MYA), and thus represents a much older phylogenetic lineage than the ruminants Cervidae and Bovidae, which had their origins between 15 and 25 MYA during the Lower to Middle Miocene... |
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| Item Description: | Vita. "Major subject: Genetics." |
| Physical Description: | ix, 77 leaves : illustrations ; 28 cm |
| Bibliography: | Includes bibliographical references. |