Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Poster: Sequencing & EST
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Expressed Sequence Tags (ESTs) obtained through the sequencing of cDNA clones provide a valuable source of information for the screening of BAC libraries, RH panels and the physical mapping of genes. ESTs have been used extensively as a tool for gene mapping in various prokaryotes, plants, animals and humans. Thousands of single-pass sequences have been established in databases using this method. Currently, there are approximately 400 unique reports of mRNA and 200 microsatellite sequences from the domestic horse (Equus caballus) deposited in Genbank, but there is no EST or repository of cDNA libraries. In an effort to increase the number of ESTs of Type I markers in the horse, we have sequenced randomly chosen clones from a cDNA library of a 60-day old foetus. Of the 1181 clones sequenced, 672 (56.9%) showed homology to known sequences in Genbank, 459 (38.8%) represented either novel transcripts or matched sequences with unknown identity in the database and 32 (2.7%), 24 (2%) and 17 (1.4%) were repetitive, ribosomal and mitochondrial sequences respectively. A number of sequences occurred at high frequency, including albumin (50, 4.2%), alpha-fetoprotein (30, 2.5%), elongation factor 1-alpha (14, 1.2%), tubulin (8, 0.7%), actin (alpha, beta or gamma) (7, 0.6%) and collagen 1A2 (6, 0.5%). The Australian Equine Blood Typing Research Laboratory has already developed 81 primer pairs for specific ESTs which are currently being mapped. These ESTs will assist in future horse gene mapping projects.