THE IDENTIFICATION OF NUCLEAR AND MITOCHONDRIAL GENES BY SEQUENCING RANDOMLY CHOSEN CLONES FROM A MARSUPIAL MAMMARY-GLAND CDNA LIBRARY

To increase the number of genes that can be mapped to the genome of th e tammar wallaby (Macropus eugenii), we sequenced 100 randomly chosen clones from a mammary gland cDNA library. Provisional identifications were made of seven nuclear genes and one mitochondrial gene encoding t wo caseins,beta-galactosidase, acetyl-coenzyme A synthetase, lipoprote in lipase, inorganic pyrophosphatase, an ATP-dependent RNA helicase, a nd cytochroome c oxidase I. Highly conserved genes, such as that encod ing acetyl-coenzyme A synthetase, were easily identified even from cro ss-kingdom matches. Genes which ai e highly divergent, however, such a s those encoding the mature casein peptides, could not be aligned with homologues in the databases. Even in an organ where there is high mRN A species redundancy, the sequence characterization of expressed seque nce tags provides a rapid means of gene identification for mapping pur poses.