2010 Fiscal Year Final Research Report
Relationship between prevalence of a bacterial endosymbiont, Cardinium, and host immune response
| Project/Area Number |
19380032
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied entomology
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| Research Institution | Ibaraki University |
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Principal Investigator |
GOTOH Tetsuo Ibaraki University, 農学部, 教授 (60178449)
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| Co-Investigator(Kenkyū-buntansha) |
NODA Hiroaki 独)農業生物資源研究所, 昆虫・微生物相互作用研究ユニット (40343991)
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| Project Period (FY) |
2007 – 2010
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| Keywords | 細胞内共生細菌 / Cardinium / Wolbachia / マイクロアレイ / 細胞質不和合性 / 抗菌タンパク質 / 免疫応答 |
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| Research Abstract |
Cardinium and Wolbachia bacteria are intracellular symbionts in many arthropods. Both bacteria cause reproductive alterations to their hosts, such as cytoplasmic incompatibility, parthenogenesis, feminization and male killing. Of 47 spider mite species tested here, 38.3% (18 species) were infected with Cardinium and 36.2% (17 species) were infected with Wolbachia. Cardinium infection induced many immune-related genes, including antimicrobial peptides, pattern recognition receptors and a serine protease, whereas Wolbachia infection did not alter gene expression, i.e., Wolbachia neither induced nor suppressed immune responses of their hosts. The different cell wall structures between both bacteria are possibly responsible for the different immune responses. In Bm-aff3 silkworm cell cultures, Wolbachia proliferated faster than Cardinium, suggesting that proliferation rate has no relation with infection rates.
Double infection by Cardinium and Wolbachia was found in 5 out of 47 spider mite species (10.6%) tested in this study. To clarify the effect of both bacteria on the reproductive alterations of the infected spider mites, 16 cross combinations were carried out for two species, which harbored both Cardinium and Wolbachia. Co-infection by the two bacteria turned out to induce cytoplasmic incompatibility, and Wolbachia only was responsible for the cytoplasmic incompatibility. Cardinium seemed to have no effect on the Wolbachia-mediated reproductive incompatibility, suggesting that both bacteria independently affect on the reproduction of their hosts. However, the possibility of interaction between the two bacteria remains to be tested further.
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