|Evolutionary forces in the human and mouse genomes|
|Researchers compare human chromosome 19 and related regions in the mouse|
Edward R. Winstead
July 9, 2001
comparison of human and mouse chromosomes suggests that familial clusters of genes evolve differently than do single-copy genes. In a study of evolutionary history, researchers compared human chromosome 19 to its corresponding regions of the mouse genome. Many unique human genes from chromosome 19 have counterparts in mice, but clustered families of genes differ extensively in number, coding capacity and organization between the two species, the analysis showed.
"The mammalian single-copy gene repertoire is relatively static, changing slowly over evolutionary time," the researchers write in Science. "However, against this stably conserved background, lineage-specific changes continue at a rapid pace within gene families."
The duplication and loss of genes are possible explanations for the differences observed in homologous mouse and human gene families, according to the researchers. Lisa Stubbs, of the Lawrence Livermore National Laboratory, in Livermore, California, and colleagues sequenced 15 chromosomal segments in the mouse genome that are homologous to human chromosome 19, one of the smallest but most gene-dense human chromosomes.
Based on the chromosome 19 data, the researchers write, "we can expect to find hundreds of new and lost lineage-specific genes as human and mouse genomes are compared."
The researchers conclude from their analysis that only a small number of genes will by found uniquely through cross-species comparisons. However, comparative analyses of human and mouse sequences will be important, they write, for the further characterization of known genes and confirmation of hypothetical genes predicted by other methods.
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