@article {10496,
	title = {Long-term evolutionary stability of bacterial endosymbiosis in Curculionoidea: additional evidence of symbiont replacement in the Dryophthoridae family},
	journal = {Molecular Biology and Evolution},
	volume = {25},
	number = {5},
	year = {2008},
	month = {May},
	pages = {859-868},
	type = {Article},
	abstract = {Bacterial intracellular symbiosis ( endosymbiosis) is well documented in the insect world where it is believed to play a crucial role in adaptation and evolution. However, although Coleopteran insects are of huge ecological and economical interest, endosymbiont molecular analysis is limited to the Dryophthoridae family. Here, we have analyzed the intracellular symbiotic bacteria in 2 Hylobius species belonging to the Molytinae subfamily ( Curculionoidea superfamily) that exhibit different features from the Dryophthoridae insects in terms of their ecology and geographical spanning. Fluorescence in situ hybridization has shown that both Hylobius species harbor rod- shaped pleiomorphic symbiotic bacteria in the oocyte and in the bacteria- bearing organ ( the bacteriome), with a shape and location similar to those of the Dryophthoridae bacteriome. Phylogenetic analysis of the 16S ribosomal DNA gene sequences, using the heterogeneous model of DNA evolution, has placed the Hylobius spp. endosymbionts ( H- group) at the basal position of the ancestral Rclade of Dryophthoridae endosymbionts named Candidatus Nardonella but relatively distant from the S- clade of Sitophilus spp. endosymbionts. Endosymbionts from the H- group and the R- clade evolved more quickly compared with free- living enteric bacteria and endosymbionts from the S- and D- clades of Dryophthoridae. They are AT biased ( 58.3\% A + T), and they exhibit AT- rich insertions at the same position as previously described in the Candidatus Nardonella 16S rDNA sequence. Moreover, the host phylogenetic tree based on the mitochondrial COI gene was shown to be highly congruent with the H- group and the R- clade, the divergence of which was estimated to be around 125 MYA. These new molecular data show that endosymbiosis is old in Curculionids, going back at least to the common ancestor of Molytinae and Dryophthoridae, and is evolutionary stable, except in 2 Dryophthoridae clades, providing additional and independent supplementary evidence for endosymbiont replacement in these taxa.},
	keywords = {Dryophthoridae, Hylobius abietis, Hylobius transversovittatus},
	isbn = {0737-4038},
	author = {Conord, Cyrille and Despres, Laurence and Vallier, Agnes and Balmand, Severine and Miquel, Christian and Zundel, Stephanie and Lemperiere, Guy and Heddi, Abdelaziz}
}
@article {5470,
	title = {Identification of the weevil immune genes and their expression in the bacteriome tissue},
	journal = {BMC Biology},
	volume = {6},
	number = {43},
	year = {2008},
	month = {16 October},
	pages = {1-13},
	type = {Article},
	abstract = {Background: Persistent infections with mutualistic intracellular bacteria (endosymbionts) are well represented in insects and are considered to be a driving force in evolution. However, while pathogenic relationships have been well studied over the last decades very little is known about the recognition of the endosymbionts by the host immune system and the mechanism that limits their infection to the bacteria-bearing host tissue (the bacteriome). Results: To study bacteriome immune specificity, we first identified immune-relevant genes of the weevil Sitophilus zeamais by using suppressive subtractive hybridization (SSH) and then analyzed their full-length coding sequences obtained by RACE-PCR experiments. We then measured immune gene expression in the bacteriome, and in the aposymbiotic larvae following S. zeamais primary endosymbiont (SZPE) injection into the hemolymph, in order to consider the questions of bacteriome immune specificity and the insect humoral response to symbionts. We show that larval challenge with the endosymbiont results in a significant induction of antibacterial peptide genes, providing evidence that, outside the bacteriome, SZPE are recognized as microbial intruders by the host. In the bacteriome, gene expression analysis shows the overexpression of one antibacterial peptide from the coleoptericin family and, intriguingly, homologs to genes described as immune modulators (that is, PGRP-LB, Tollip) were also shown to be highly expressed in the bacteriome. Conclusion: The current data provide the first description of immune gene expression in the insect bacteriome. Compared with the insect humoral response to SZPE, the bacteriome expresses few genes among those investigated in this work. This local immune gene expression may help to maintain the endosymbiont in the bacteriome and prevent its invasion into insect tissues. Further investigations of the coleoptericin, the PGRP and the Tollip genes should elucidate the role of the host immune system in the maintenance and regulation of endosymbiosis.},
	keywords = {Sitophilus zeamais},
	isbn = {1741-7007},
	url = {http://www.biomedcentral.com/bmcbiol/},
	author = {Anselme, Caroline and Perez-Brocal, Vicente and Vallier, Agnes and Vincent-Monegat, Carole and Charif, Delphine and Latorre, Amparo and Moya, Andres and Heddi, Abdelaziz}
}
