Thu, 21 Aug 2008 14:13:04 BST CiteULike: timothee's microbiology http://www.citeulike.org/user/timothee/tag/microbiology CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/timothee/article/1023162 <i>J Evol Biol, Vol. 17, No. 5. (September 2004), pp. 985-993.</i><br /><br />In this paper, we investigate the level of specialization of the symbiotic association between an entomopathogenic nematode (Steinernema carpocapsae) and its mutualistic native bacterium (Xenorhabdus nematophila). We made experimental combinations on an insect host where nematodes were associated with non-native symbionts belonging to the same species as the native symbiont, to the same genus or even to a different genus of bacteria. All non-native strains are mutualistically associated with congeneric entomopathogenic nematode species in nature. We show that some of the non-native bacterial strains are pathogenic for S. carpocapsae. When the phylogenetic relationships between the bacterial strains was evaluated, we found a clear negative correlation between the effect a bacterium has on nematode fitness and its phylogenetic distance to the native bacteria of this nematode. Moreover, only symbionts that were phylogenetically closely related to the native bacterial strain were transmitted. These results suggest that co-evolution between the partners has led to a high level of specialization in this mutualism, which effectively prevents horizontal transmission. The pathogenicity of some non-native bacterial strains against S. carpocapsae could result from the incapacity of the nematode to resist specific virulence factors produced by these bacteria. When mutualists are pathogens: an experimental study of the symbioses between Steinernema (entomopathogenic nematodes) and Xenorhabdus (bacteria). M Sicard JB Ferdy S Pagès N Le Brun B Godelle N Boemare C Moulia doi:10.1111/j.1420-9101.2004.00748.x J Evol Biol, Vol. 17, No. 5. (September 2004), pp. 985-993. 2007-01-03T10:34:33-00:00 2004 J Evol Biol 1010-061X 17 5 985 993 bacteriology microbiology mutualism nematodes parasitology pathogenicity symbiosis http://www.citeulike.org/user/timothee/article/1023160 <i>Curr Opin Microbiol, Vol. 9, No. 2. (April 2006), pp. 127-132.</i><br /><br />Photorhabdus is a genus of insect-pathogenic bacteria that also maintains a mutualistic interaction with Heterorhabditid nematodes. Bacteria in this genus are members of the family Enterobacteriaceae and are, therefore, closely related to many important mammalian pathogens. This bacteria-nematode complex has been exploited as a biocontrol agent that is active against several insect pests. However, this model system is also uniquely placed to address important fundamental questions about pathogenicity and mutualism. Indeed, recent genetic studies have suggested that there is a significant overlap in the genetic requirements of Photorhabdus for these contrasting interactions. In addition, the identification of key regulators of pathogenicity and symbiosis only serves to highlight the similarities between Photorhabdus, a genus of bacteria that infects invertebrate hosts, and closely related mammalian enteric pathogens. The regulation of pathogenicity and mutualism in Photorhabdus. SA Joyce RJ Watson DJ Clarke doi:10.1016/j.mib.2006.01.004 Curr Opin Microbiol, Vol. 9, No. 2. (April 2006), pp. 127-132. 2007-01-03T10:32:51-00:00 2006 Curr Opin Microbiol 1369-5274 9 2 127 132 bacteriology microbiology mutualism parasitology pathogenicity regulation