Current knowledge of steroid nutrition, metabolism, and function in free-living, plant-parasitic and animal-parasitic nematodes is reviewed, with emphasis upon recent investigation of Caenorhabditis elegans. A number of 4-desmethylsterols with a trans-A/B ring configuration can satisfy the steroid nutritional requirement in C. elegans, but sterols with a cis-A/B ring configuration or trans-A/B ...

Plant parasitic nematodes which are highly successful parasites evolved a very specialized feeding relationship with the host plant to cause the destructive root-knot disease. They initiate their parasitic relationship with the host by releasing their secretions into root cells which in turn stimulate the root cells of the host to become specialized feeding cells which are considered as the sin...

Wolbachia is an endosymbiotic bacterium widely present in arthropods and animal-parasitic nematodes. Despite previous efforts, it has never been identified in plant-parasitic nematodes. Random sequencing of genes expressed by the burrowing nematode Radopholus similis resulted in several sequences with similarity to Wolbachia genes. The presence of a Wolbachia-like endosymbiont in this plant-par...

The sensitivity of acetylcholinesterases (ACHE) isolated from the plant-parasitic nematodes Meloidogyne arenaria, M. incognita, and Heterodera glycines and the free-living nematode Caenorhabditis elegans to carbamate and organophosphate nematicides was examined. The AChE from plant-parasitic nematode species were more sensitive to carbamate inhibitors than was AChE from C. elegans, but response...

Plant-parasitic nematodes are major constraints to the productivity of tropical farming operations. Intensive land use and climatic conditions favorable to nematode development contribute to increased crop losses due to these pests. Many farmers in developing tropical countries have limited resources and management options. Cropping systems research is a relatively low-cost, low-input method of...

The family Orobanchaceae includes many parasitic plant species. Parasitic plants invade host vascular tissues and form organs called haustoria, which are used to obtain water and nutrients. Haustorium formation is initiated by host-derived chemicals including quinones and flavonoids. Two types of quinone oxidoreductase (QR) are involved in signal transduction leading to haustorium formation; QR...

A PCR-DGGE primer pair, Tyl2F-Tyl4R, specific to plant parasitic and fungivorous nematodes was designed based on the 18S rRNA gene. The results of community analysis using the primers showed that they are specific to the order Tylenchida. This primer pair detected species belonging to Tylenchida with high sensitivity and high resolution. The number of detected species of plant parasitic and fun...

The self-splicing RNAs known as group I introns exist in many organisms, but their distribution is difficult to explain. We hypothesize that group I introns have been transferred between a parasite and its host. We describe here the discovery of a common group I intron sequence between a plant-parasitic fungus, Protomyces inouyei, and its host, Youngia japonica. It strongly supports our theory ...

Haemonchus contortus and Trichostrongylus colubriformis are among the most important parasitic nematodes of small ruminants. Caenorhabditis elegans, a free-living nematode, is used as a model for evaluating anthelmintic activity of a variety of test substances. Extracts of several medicinal plants are useful in vitro and in vivo against nematode development. Extracts of Curtisia dentata, a Sout...

The most evolutionary advanced adaptations for plant parasitism by nematodes are the products of parasitism genes expressed in their esophageal gland cells and secreted through their stylet into host tissue to control the complex process of parasitism. Molecular analyses of nematode parasitism genes are revealing the complexity of the tools that enable the nematode to attack plants, and the res...