Nematode-bacterial

Blinova SL, Ivanova ES. Culturing the nematode-bacterial complex of Neoaplectana carpocapsae in insects. In Sonin MD, editor. Helminths of insects. New Delhi Amerind Publishing 1987. 

Enhanced nutrient cycling in both the rhizosphere and bulk soil may depend on the bacterial grazing by protozoa or nematodes with release of inorganic N. Nematodes appear to be the primary consumers of bacteria in the rhizosphere, whereas protozoa are equally prevalent in rhizosphere and bulk soil (41,97). Estimated C-to-N ratios of bacterial-feeding nematodes range from 5 1 to 10 1 (98,99) and are generally higher than those of their bacterial food source thus the excess N is excreted as ammonia (100,101) by nematodes. The estimated... 

The rate of progression of signs and symptoms varies depending on the infecting organism. A differential diagnosis for keratitis must include viral, fungal, and nematodal infections in addition to bacterial causes.19... 

Intracellular symbiosis is extremely widespread in invertebrates. For example, mutualistic symbioses with intracellular bacteria can be found in almost all animal phyla, including sponges, cnidaria, nematodes, anellids, mollusca and arthropoda. Buchner (1965) thoroughly reviews most information published on bacterial symbiosis in animals up to 1964. After this monumental work, various reviews on more specific subjects have been published (e.g. Baumann, 1998, and references therein) including some recent reviews on Wolbachia (O Neill et al., 1997 Werren, 1997). In most of these papers, the term symbiosis is apparently used with a broad meaning the intracellular bacterium is usually referred to as an endosymbiont even in the absence of data on effects on host fitness. Here only key points on intracellular symbiosis and Wolbachia will be summarized, so as to put the information available on symbiosis in filarial nematodes into a broader context. 

The effectors of the mammalian host immune attack against filaria include reactive oxygen intermediates. Filarial nematodes express glutathione peroxidase, thioredoxin peroxidase and superoxide dismutase at their surface - enzymes believed to protect the nematode from this attack (Selkirk et al., 1998). A bacterial catalase gene has been identified that most probably derives from the endosymbiont genome (Henkle-Duhrsen et al., 1998) this enzyme may contribute with other enzymes to the protection of both Wolbachia and its nematode host from oxygen radicals. 

This chapter focuses on Wolbachia in filarial nematodes. EM studies have also revealed intracellular bacteria in other nematodes (e.g. Shepperd et al., 1973 Marti et al., 1995) and the bacterial endosymbionts of plant pathogenic nematodes belonging to the genus Xiphinema have recently been identified as belonging to the verrucomicrobia group (Vandekerckhove et al., 2000). However, most nematode bacteria are still to be identified. These may also play important roles in nematode biology. 

Marti, O.G., Rogers, C.E. and Styer, E.L. (1995) Report on intracellular bacterial symbiont in Noctuidonema guayanense, an ectoparasitic nematode of Spodoptera frugiperda. Journal of Invertebrate Pathology 66, 94-96. 

The most intimate of the bacterial-nematode associations involves Wolbachia, a genus of rickettsia-like, alpha proteobacteria found in obligate intracellular association with a wide variety of arthropods, and a now well-characterized association with B. malayi and Dirofilaria immitis (Chapter 2). Although not formally identified as Wolbachia, the presence of rickett-sia-like organisms has been observed, principally in the reproductive tracts of Globodera females (Shepherd et al., 1973) and males (Walsh et al., 1983) and in Heterodera larvae (Endo, 1979). 

Several of the postulated roles for nematode-secreted AChEs assume that they gain access to the intestinal mucosa. Several possibilities exist for transport of parasite AChE across the epithelial cell barrier, such as (i) utilization of existing pathways for receptor-mediated transcytosis (ii) a paracellular route facilitated by parasite-secreted proteases as observed for a bacterial elastase (Azghani et al., 1993) and (iii) increased paracellular permeability resulting from inflammatory events in the mucosa. We consider the latter suggestion most likely, as this has been duplicated by ex vivo perfusion with rat mast cell protease II (Scudamore et al., 1995). Moreover, cholinergic stimulation attenuates epithelial barrier properties to macromolecules in rat ileal crypts (Phillips et al., 1987). 

Jan ND, Mahar GM, Mahar AN, Hullio MH, Lanjar AG, Gower SR. Susceptibility of different insect pupae to the bacterial symbiont, Xenorhabdus nematophila, isolated from the entomopathogenic nematode, Steinemema carpocapsae. Pak J Nematol. 2008 26 59-67. 

Shapiro-Ilan DI, Gaugler R. Production technology for entomopathogenic nematodes and their bacterial symbionts. J Indust Micro Biotech. 2002 28 137-146. 

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