Analysis of expressed sequence tags from the ectoparasitic nematode Xiphinema index

We report the results of a small-scale expressed sequence tag project performed on the ectoparasitic nematode Xiphinema index. Approximately 1400 genes were sequenced, 70% from a cDNA library generated from dissected basal bulbs (containing the pharyngeal gland cells) and 30% from cDNA libraries generated from whole mixed stage nematodes. A large portion of the bulb library (48%) was composed of proteins with no matches in the database. Further analysis of these genes revealed that a total of 51 contigs were present, half of which encoded novel secreted proteins. By contrast, the whole nematode library contained more housekeeping and nematode-specific genes. Only one of the novel genes from the whole nematode library had a predicted signal peptide at the N-terminus. Genes encoding transthyretin-like proteins were abundant in the bulb library and in situ hybridisation confirmed that one of these is expressed in the basal bulb. Genes encoding a variety of proteases, which were shown using in situ hybridisation to be expressed in the gut, were also identified.