Chromosome mapping of genes in mammals and birds and its applcation for animal resource sciences

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Cloning of a human cDNA encoding the trifunctional glycinamide ribonucleotide synthetase (GARS) -aminoimidazole ribonucleotide synthetase (AIRS) -glycinamide ribonucleotide transformylase (GART) enzyme by functional complementation in E.coli and in yeast has been reported previously. In this study, we demonstrates the isolation of a novel cDNA clone encoding only the GARS domain from a human fetal brain cDNA library using the 5' region of the human GARS-AIRS-GART cDNA as a probe. Analysis of the nucleotide sequence reveals that the coding region of this cDNA is identical to that of the GARS domain of the GARS-AIRS-GART gene cDNA.Analysis of the expression patterns of the two transcripts in normal human brains of various ages demonstrates that each is transcribed at different overall levels depending upon age. We concluded that the human GARS-AIRS-GART gene produces the trifunctional enzyme and the human gene encoding only the GARS domain produced the enzyme showing the activity of only GARS.In addition, the connecting region of GARS and AIRS in the GARS-AIRS-GART gene were completely preserved between the primates. On the contrary, in the 3' untranslate region of the GARS gene we observed a few replacements, inserts as well as deletion of nucleic acids between human and other primates. In conclusion, these results strongly suggested that the GARS-AIRS-GART gene is fused from the independent GARS,AIRS,GART genes evolutionally. Using the chromosome mapping techniques, we continuously intend to analyze other important genes for animal resource sciences.