title: Coexistence of Wolbachia with Buchnera aphidicola and a secondary symbiont in the aphid Cinara cedri.
abstract: Intracellular symbiosis is very common in the insect world. For the aphid Cinara cedri, we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboring Buchnera aphidicola, the primary endosymbiont of aphids, C. cedri harbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an alpha-proteobacterium that belongs to the Wolbachia genus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA sequences, we have shown that Wolbachia was represented by only a few minute bacteria surrounding the S symbionts. Moreover, the observed B. aphidicola and the S symbionts had similar sizes and were housed in separate specific bacterial cells, the bacteriocytes. Interestingly, in contrast to the case for all aphids examined thus far, the S symbionts were shown to occupy a similarly sized or even larger bacteriocyte space than B. aphidicola. These findings, along with the facts that C. cedri harbors the B. aphidicola strain with the smallest bacterial genome and that the S symbionts infect all Cinara spp. analyzed so far, suggest the possibility of bacterial replacement in these species.
authors.affiliation: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, València, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez-Valero
authors.forename: Mario
authors.initials: M
authors.lastname: Soriano-Navarro
authors.forename: Vicente
authors.initials: V
authors.lastname: Pérez-Brocal
authors.forename: Abdelaziz
authors.initials: A
authors.lastname: Heddi
authors.forename: Andrés
authors.initials: A
authors.lastname: Moya
authors.forename: José Manuel
authors.initials: JM
authors.lastname: García-Verdugo
authors.forename: Amparo
authors.initials: A
authors.lastname: Latorre
mesh_terms: D000818:Animals; D001042:Aphids / Q000382:microbiology*; D020635:Buchnera / Q000235:genetics / Q000302:isolation & purification*; D004275:DNA, Ribosomal / Q000737:chemistry; D008854:Microscopy, Electron; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013559:Symbiosis; D020577:Wolbachia / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S