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Background: Caenorhabditis elegans has traditionally been used as a model for studying nematode biology, but its small size limits the ability for researchers to perform some experiments such as high-throughput tissue-specific gene expression studies. However, the dissection of individual tissues is possible in the parasitic nematode Ascaris suum due to its relatively large size. Here, we take advantage of the recent genome sequencing of Ascaris suum and the ability to physically dissect its separate tissues to produce a wide-scale tissue-specific nematode RNA-seq datasets, including data on three non-reproductive tissues (head, pharynx, and intestine) in both male and female worms, as well as four reproductive tissues (testis, seminal vesicle, ovary, and uterus). We obtained fundamental information about the biology of diverse cell types and potential interactions among tissues within this multicellular organism. Methodology/Principal Findings: Overexpression and functional enrichment analyses identified many putative biological functions enriched in each tissue studied, including functions which have not been previously studied in detail in nematodes. Putative tissue-specific transcriptional factors and corresponding binding motifs that regulate expression in each tissue were identified, including the intestine-enriched ELT-2 motif/transcription factor previously described in nematode intestines. Constitutively expressed and novel genes were also characterized, with the largest number of novel genes found to be overexpressed in the testis. Finally, a putative acetylcholine-mediated transcriptional network connecting biological activity in the head to the male reproductive system is described using co-expression networks, along with a similar ecdysone-mediated system in the female. Conclusions/Significance: The expression profiles, co-expression networks and co-expression regulation of the 10 tissues studied and the tissue-specific analysis presented here are a valuable resource for studying tissue-specific biological functions in nematodes. [ABSTRACT FROM AUTHOR]

Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent reinfection of host species. In addition, development of resistance to nematicides and anthelmintics by these parasites and reduced availability of some nematicides, for environmental protection, pose significant obstacles for current and future prospects of effective parasite control. Due to marked differences in host species, research on animal and plant parasitic nematodes often proceeds independently. Despite the differences between animals and plants, basic cellular properties are shared among these host organisms. Some common properties may be important for mechanisms [homologous or convergent (homoplastic)] by which nematodes successfully infect these diverse hosts or by which animal and plant hosts resist infections by these pathogens. Here we compare host/parasite interactions between plant parasitic nematodes (PPN) and animal parasitic nematodes, with an emphasis on mammalian hosts (MPN). Similarities and differences are considered in the context of progress on molecular dissection of these interactions. A comprehensive coverage is not possible in the space allotted. Instead, an illustrative approach is used to establish examples that, it is hoped, exemplify the value of the comparative approach. [ABSTRACT FROM AUTHOR]

The nematode Trichinella spiralis and related species are zoonotic food-borne pathogens of humans. The muscle larval stage of this parasite establishes a chronic infection in skeletal muscle cells of humans who acquire trichinellosis. Muscle larvae also reside in skeletal muscles of animals, swine in particular, and other food animals, including game animals. These muscle larvae are the source of zoonotic transmission to humans. Once established, muscle larvae become less susceptible to anthelmintics that are effective against other stages of the parasite. Very little information exists to guide discovery of new drug targets and improved methods of eliminating muscle larvae established in muscle cells of humans or food animals. Here we discuss progress that has been made on sequencing the genome of T. spiralis. This informational resource should prove valuable for dissecting molecular characteristics of this parasite that warrant investigation as targets for chemotherapy. The availability of the T. spiralis genome has made possible the comparison of genomes from nematodes that span the evolutionary extremes of the phylum Nematoda. We describe a pan-phylum comparison of genomes that is underway. This comparative genomics approach is expected to identify molecular characteristics that are conserved among all nematodes, and hence applicable to nematode pathogens throughout the phylum, including species from the genus Trichinella. T. spiralis expression data for muscle larvae has been integrated with genome sequences to identify specific genes and proteins with relevance to control of this stage of the parasite. Examples are discussed in which genomic information may advance understanding of T. spiralis biology and new methods for treating infections by this parasite.

Clade I nematode species in the genus Trichinella can cause infections in humans that lead to mortality and serious morbidity. There are currently eight recognized species or genotypes that comprise this genus. The species display diverse biological characteristics, the evolutionary significance of which recently has been extensively clarified. Some of that diversity translates into variable importance as zoonotic pathogens, with T. spiralis having the highest significance. Trichinellosis has re-emerged as an important zoonotic infection in various parts of the world, reminding us that control of this infection depends on persistent vigilance. Trichinella species display unique and biologically interesting complexity in interactions with host cells that they inhabit. Significant progress has been made toward understanding details of these interactions. Progress on transcriptomics, proteomics and now genomics offers exciting prospects for accelerating advances in future research. An overview of these parasites regarding biology, significance as zoonotic pathogens and selected research topics is presented here.