1% of C. oncophora and 57. 9% of O. ostertagi polypeptides when compared with free living nematodes. The slightly higher percentages observed in this study can be attributed to the better coverage of the Cooperia and Ostertagia transcriptomes using pyrosequencing relative to the coverage obtained from conventional EST libraries in previous Inhibitors,Modulators,Libraries investigations. Because of differences in the environments Inhibitors,Modulators,Libraries and living requirements between the free living and parasitic stages, it is expected that some pathways and enzymes will be unique to these two phases of development and coincide with the requirements and challenges imposed by the different environments. Comparisons of domains and pathways present in the free living stages to those in the parasitic stages revealed many of these differences.
Given the similarities between C. oncophora and O. ostertagi, it was not unexpected that there would be sig nificant overlap Drug_discovery in the domains found in up regulated peptides in the various stages. For example, among the 20 most abundant domains in all stages, ten were identi cal in both organisms. The domains that were prevalent in the free living vs. parasitic stages may provide clues to the lifestyles and environments in which these organisms live. In the free living stages, domains previ ously implicated in growth and development tended to dominate. In C. oncophora three different chromo domains and the MADF domain were enriched. Chromo domains are often found in association with heterochromatin protein 1 which functions in germline and vulval development in C. elegans.
The MADF domain is a transcription factor in Drosophila that activates genes necessary for develop ment. Chromo domains and MADF domains were found in proteins that predominate in the egg as would be expected. Interestingly, the chromo domain and MADF domain were also found elevated in adult O. ostertagi. Two Inhibitors,Modulators,Libraries domains identified as basic leucine zippers were up regulated in the free living stages of O. ostertagi. As the organisms transition to L1, the domain preva lence shifts as well. In C. oncophora, the most prevalent domain was EF hand like domain. This domain tends to be found in calcium binding proteins. In contrast, the most prevalent domain in O. ostertagi was globin. Globin and saposin domains were prevalent in the L2 of both species. Both of these domains were found in secreted peptides of both species.
Saposin domains are expressed in all stages of Ancylostoma caninum. While they were not found in enriched peptides in every stage of C. Inhibitors,Modulators,Libraries oncophora or O. ostertagi, these domain containing peptides were expressed in all stages. During the L3sh, the worms both protect themselves from environmental stress as well as prepare for uptake by and development within the host. Among the most prevalent domains in the L3sh were protease inhibitor I8 and late embryogenesis abundant protein in C. oncophora and O. ostertagi, respectively.