INTESTINAL TRANSCRIPTOME
The intestine is one of the major organs in nematodes and it creates a key surface interface with the environment. While specific cellular characteristics can be diverse among nematode species, intestinal cells typically conform to polarized epithelial cells with an apical membrane composed of microvilli lining the digestive tube. This microvillous membrane is expected to confer an enormous capacity for nutrient digestion and absorption in nematodes. Furthermore, the intestine is expected to offer innate immunity against invasive pathogens. For parasitic nematodes, intestinal adaptations may be required to survive in context of the host immune systems with which the apical intestinal membrane interfaces. In addition, the nematode intestine has been suggested to be involved in other cellular process such as stress response, body size control, aging, etc. Previous studies have indicated that nematode intestine may be a prime target for parasite control.
In this study, we have produced the largest collections of nematode intestinal genes currently available from the clade V blood-feeding parasite Haemonchus contortus and the clade III nematode Ascaris suum, which is thought to feed on the semi-digested contents in the host intestine. Comparative studies were made among intestinal genes from the two parasites and the free-living bacterivore Caenorhabditis elegans. We have observed statistically significant conservation of intestinal gene expression at the tissue level, despite the evolutionary distance of ~350 million years separating species investigated. Numerous prospective proteins were identified that may represent core nematode intestinal functions, at least among the nematode lineages investigated here. Substantial diversification of intestinal genes was also indicated among species. The distinction of intestinal gene repertoires by clade and species may reflect the substantial differences in diet and metabolic requirements of different nematodes, especially parasites. Our study has thus contributed to a better understanding of nematode biology and laid foundations for the development of novel and more effective parasite controls.
Ascaris suum Intestinal Genes (3,121) |
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Haemonchus contortus Intestinal Genes (1,755) |
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Caenorhabditis elegans Intestinal Genes (5,065) |
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The Core IntFam-241 Protein Families (2,024) |
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Gene Ontology mappings: Default parameters for InterProScan v13.1 were used to search against InterPro database. Raw InterProScan results for the translated EST contigs were summarized at the EST cluster level. GO ontologies were further assigned and displayed graphically by AmiGO (ontology data from August 31, 2006) utilizing default parameters.
KEGG pathway analysis: An E-value cut-off of 1.0e-10 reported by WU-BLASTP against KEGG Genes Database Release 40.0 was used for pathway mapping, the top match and all the matches within a range of 30% of the top BLAST score, if meeting the cut-off, were accepted for KEGG association.
Complete KEGG Mappings in Microsoft Excel
