SPECIFIC DETECTION OF INTRACELLULAR SYMBIOTIC BACTERIA OF APHIDS BY OLIGONUCLEOTIDE-PROBED IN-SITU HYBRIDIZATION

Oligonucleotide-probed in situ hybridization targeted to bacterial rRN As was attempted to detect, visualize and characterize the intracellul ar symbiotic bacteria of aphids. Using the EUB338 probe that hybridize s universally with 16S rRNA of eubacteria, the primary and secondary i ntracellular symbionts of various aphids were successfully stained on tissue thin sections. When in situ hybridization was conducted with GA M42A and BET42A probes that are targeted to 23S rRNA of gamma- and P-s ubdivision of the Proteobacteria, respectively, it was shown that the secondary symbionts of Cinara pini and Nippolachnus piri belong to the gamma-subdivision of the Proteobacteria whereas that of Tetraneura ra dicicola is a member of the beta-subdivision of the Proteobacteria. Th is is the first report on the phylogenetic affinity of the secondary i ntracellular symbionts of aphids. Because insect tissues have strong a utofluorescence in general, non-fluorescent in situ hybridization usin g biotin- and digoxigenin-labelled probes was more suitable for detect ing symbiotic bacteria in aphid tissue sections.