Linked Life Data

7815927

Source:http://linkedlifedata.com/resource/pubmed/id/7815927

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1995-2-8
pubmed:databankReference
pubmed:abstractText
The genomes of homeothermic (warm-blooded) vertebrates are mosaic interspersions of homogeneously GC-rich and GC-poor regions (isochores). Evolution of genome compartmentalization and GC-rich isochores is hypothesized to reflect either selective advantages of an elevated GC content or chromosome location and mutational pressure associated with the timing of DNA replication in germ cells. To address the present controversy regarding the origins and maintenance of isochores in homeothermic vertebrates, newly obtained as well as published nucleotide sequences of the insulin and insulin-like growth factor (IGF) genes, members of a well-characterized gene family believed to have evolved by repeated duplication and divergence, were utilized to examine the evolution of base composition in nonconstrained (flanking) and weakly constrained (introns and fourfold degenerate sites) regions. A phylogeny derived from amino acid sequences supports a common evolutionary history for the insulin/IGF family genes. In cold-blooded vertebrates, insulin and the IGFs were similar in base composition. In contrast, insulin and IGF-II demonstrate dramatic increases in GC richness in mammals, but no such trend occurred in IGF-I. Base composition of the coding portions of the insulin and IGF genes across vertebrates correlated (r = 0.90) with that of the introns and flanking regions. The GC content of homologous introns differed dramatically between insulin/IGF-II and IGF-I genes in mammals but was similar to the GC level of noncoding regions in neighboring genes. Our findings suggest that the base composition of introns and flanking regions is determined by chromosomal location and the mutational pressure of the isochore in which the sequences are embedded. An elevated GC content at codon third positions in the insulin and the IGF genes may reflect selective constraints on the usage of synonymous codons.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0737-4038
pubmed:author
pubmed:issnType
Print
pubmed:volume
11
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
875-85
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Evolution of base composition in the insulin and insulin-like growth factor genes.
pubmed:affiliation
Center for Demographic and Population Genetics, University of Texas Health Science Center at Houston 77225.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't