Submitted to: American Society of Parasitologists
Publication Type: Abstract Only
Publication Acceptance Date: March 18, 2003
Publication Date: N/A
Technical Abstract: The protozoan Eimeria tenella, is one of the species which causes coccidiosis in poultry. This is an economically important disease, costing the U.S. poultry industry millions of dollars annually. While the life-cycle of this parasite has been described, little is known about the genetic mechanisms that control its progression. To identify genes that are differentially expressed between unsporulated and sporulated oocysts of E. tenella, subtracted cDNA libraries were constructed from these two stages of E. tenella life-cycle. One hundred and sixty seven random clones were sequenced from subtracted cDNAs of unsporulated oocysts. These clones represent sequences from up to 69 different genes, of which 63% share no significant homology to sequences in the GenBank database. Clones which share significant homology to known genes are those encoding: prolyl endopeptidase, aspartyl protease, transhydrogenase, calcium dependent protein kinase, histones, 5.8s rRNA, as well as several hypothetical proteins predicted from genome sequence of other protozoans. Fifty-four clones were sequenced from subtracted cDNAs of sporulated oocysts. These clones represent sequences from up to 22 different genes. Of these, 39% share no significant homology to sequences in the GenBank database. Clones that share significant homology to known genes are those encoding: heat shock protein 90, serine protease inhibitor, microneme protein, glucosamine fructose 6-P aminotransferase, aminopeptidase, as well as 5.8s rRNA. Currently, the only clones found in both libraries are those encoding 5.8s rRNA, indicating that subtraction was successful. Allelic diversity was observed in genes for which multiple clones were identified. This data provides information on gene expression patterns in two development stages of E. tenella, however, it may also be used to measure genetic diversity. Altogether, subtractive hybridization is a powerful technique for studying organisms with complex life-cycles, such as the protozoans, whose gene expression profiles change significantly between developmental stages.