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Evolution of multigene families: Hi...

Piontkivska, Olena.

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Evolution of multigene families: Histone and major histocompatibility complex genes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Evolution of multigene families: Histone and major histocompatibility complex genes./
Author:	Piontkivska, Olena.
Description:	141 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3075.
Contained By:	Dissertation Abstracts International64-07B.
Subject:	Biology, Genetics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3098240

Evolution of multigene families: Histone and major histocompatibility complex genes.
Piontkivska, Olena.

Evolution of multigene families: Histone and major histocompatibility complex genes. - 141 p.

Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3075.

Thesis (Ph.D.)--The Pennsylvania State University, 2003.

To understand the mode and mechanism of multigene families evolution, I studied the evolutionary pattern of highly conserved historic H3 and H4 and highly divergent MHC gene families. (1) Histone H3 genes were investigated to determine whether this gene family has evolved following the model of concerted evolution as was claimed by previous authors. Phylogenetic analysis indicated that although H3 protein sequences are highly conserved even between different kingdoms, the level of synonymous sites divergence is generally very high and often close to the saturation level. Thus, high degree of H3 protein conservation is caused by purifying selection, while nucleotide sequences evolve following the model of birth-and-death evolution. My study also suggested that replication-dependent genes evolved from replication-independent-like H3 genes. (2) Phylogenetic analysis of the most highly conserved histone H4 showed that the evolutionary pattern of this gene family is essentially the same as that of the H3 gene family. That is, H4 nucleotide sequences evolve following the birth-and-death model of evolution, while protein sequence homogeneity is maintained by purifying selection. Five classes of histone genes (H1, H2A, H2B, H3 and H4) diverged at nearly the same time before the separation of eukaryotic kingdoms. (3) MHC genes were suggested to be subject to birth-and-death evolution with a high rate of gene turnover, but the rate of gene turnover has never been studied. To obtain some insight into this problem, I estimated the divergence times of MHC class I loci in primates. My results showed that locus F diverged from the other loci about 46--66 MYA. Classical locus C in great apes and duplicated B locus in macaques have appeared about 21--28 WA. The major diversification of class I loci was estimated to have occurred about 35--49 MYA, which is before the separation of Catarrhini and Platyrrhini clades. The most recent common ancestors of allelic lineages at HLA-A, B and C loci were estimated to have appeared at least 14--19, 10--15 and 13--17 MYA, respectively. These results suggest that the rate of gene turnover in primate MHC class I genes is indeed quite rapid, as was previously conjectured.Subjects--Topical Terms:

1017730
Biology, Genetics.

Evolution of multigene families: Histone and major histocompatibility complex genes.
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100 1 $a Piontkivska, Olena. $3 1948136
245 1 0 $a Evolution of multigene families: Histone and major histocompatibility complex genes.
300 $a 141 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3075.
500 $a Adviser: M. Nei.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2003.
520 $a To understand the mode and mechanism of multigene families evolution, I studied the evolutionary pattern of highly conserved historic H3 and H4 and highly divergent MHC gene families. (1) Histone H3 genes were investigated to determine whether this gene family has evolved following the model of concerted evolution as was claimed by previous authors. Phylogenetic analysis indicated that although H3 protein sequences are highly conserved even between different kingdoms, the level of synonymous sites divergence is generally very high and often close to the saturation level. Thus, high degree of H3 protein conservation is caused by purifying selection, while nucleotide sequences evolve following the model of birth-and-death evolution. My study also suggested that replication-dependent genes evolved from replication-independent-like H3 genes. (2) Phylogenetic analysis of the most highly conserved histone H4 showed that the evolutionary pattern of this gene family is essentially the same as that of the H3 gene family. That is, H4 nucleotide sequences evolve following the birth-and-death model of evolution, while protein sequence homogeneity is maintained by purifying selection. Five classes of histone genes (H1, H2A, H2B, H3 and H4) diverged at nearly the same time before the separation of eukaryotic kingdoms. (3) MHC genes were suggested to be subject to birth-and-death evolution with a high rate of gene turnover, but the rate of gene turnover has never been studied. To obtain some insight into this problem, I estimated the divergence times of MHC class I loci in primates. My results showed that locus F diverged from the other loci about 46--66 MYA. Classical locus C in great apes and duplicated B locus in macaques have appeared about 21--28 WA. The major diversification of class I loci was estimated to have occurred about 35--49 MYA, which is before the separation of Catarrhini and Platyrrhini clades. The most recent common ancestors of allelic lineages at HLA-A, B and C loci were estimated to have appeared at least 14--19, 10--15 and 13--17 MYA, respectively. These results suggest that the rate of gene turnover in primate MHC class I genes is indeed quite rapid, as was previously conjectured.
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773 0 $t Dissertation Abstracts International $g 64-07B.
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