title: An expressed sequence tag analysis of the life-cycle of the parasitic nematode Strongyloides ratti.
abstract: 14,761 expressed sequence tags (ESTs) were generated, representing five stages during the parasitic and free-living phases of the life-cycle of the parasitic nematode Strongyloides ratti. These ESTs formed 4152 clusters, of which 97% contained 10 or fewer ESTs and 66% were singletons. These 4152 clusters are likely to represent approximately 20% of S. ratti's genes. The clusters' consensus sequences were used to assign each cluster to one of three databases: (i) Caenorhabditis elegans and C. briggsae sequences; (ii) other nematode sequences; (iii) non-nematode sequences. This approach has identified putative nematode-specific genes, that may be targets for developing approaches for parasitic nematode control. Approximately 25% of the clusters have no significant alignments and may therefore represent novel genes. The EST representation between the libraries was used to analyse stage-specific or -biased expression in silico. This showed that 81% of clusters are present in only one library and 12% are present in any two libraries, indicating substantial stage-specificity of gene expression. The 30-most abundantly expressed clusters were analysed in further detail. Many of these have significantly different parasitic- or free-living-specific or -biased expression. Many of the parasitic-specific genes are, as yet, uncharacterised: one of these represents 25% of all ESTs obtained from the parasitic stage.
authors.affiliation: School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. f.thompson@bristol.ac.uk
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Thompson
authors.forename: Makedonka
authors.initials: M
authors.lastname: Mitreva
authors.forename: Gary L A
authors.initials: GL
authors.lastname: Barker
authors.forename: John
authors.initials: J
authors.lastname: Martin
authors.forename: Robert H
authors.initials: RH
authors.lastname: Waterston
authors.forename: Robert H
authors.initials: RH
authors.lastname: Waterson
authors.forename: James P
authors.initials: JP
authors.lastname: McCarter
authors.forename: Mark E
authors.initials: ME
authors.lastname: Viney
mesh_terms: D000818:Animals; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D005260:Female; D005786:Gene Expression Regulation; D015723:Gene Library; D023281:Genomics; D015801:Helminth Proteins / Q000235:genetics* / Q000378:metabolism*; D008018:Life Cycle Stages / Q000235:genetics*; D008969:Molecular Sequence Data; D051381:Rats; D017422:Sequence Analysis, DNA; D017170:Strongyloides ratti / Q000235:genetics / Q000254:growth & development*
chemical_list: D015801:Helminth Proteins