第11回共生進化機構国際セミナー

講師: Prof. Steve Perlman（University of Victoria, Canada）
演題: A tale of two symbionts: Hidden players in interactions between Drosophila and their nematode parasites
日時: 2022年2月25日（金）10:00 (JST)～

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Abstract： Multicellular organisms commonly harbour microbes that protect them against natural enemies, and these defensive symbionts are important players in host-parasite evolution and ecology. On the other hand, natural enemies themselves may employ microbial symbionts that help them to successfully infect hosts; these types of symbioses have generally received less attention than defensive ones.

We have been studying how beneficial microbes affect interactions between Drosophila and their natural enemies. In particular, Drosophila are infected by diverse parasitic nematodes that vary widely in virulence and host specificity. We have found that D. neotestacea, a common N. American woodland species, harbours a maternally inherited bacterial symbiont called Spiroplasma that protects it against the virulent sterilizing nematode, Howardula aoronymphium, and that the benefit conferred by Spiroplasma is so great that symbiont-infected flies have replaced their uninfected counterparts across the continent. Protection appears to involve toxins called ribosome-inactivating proteins (RIPs). Spiroplasma genomes encode a diverse repertoire of RIP toxins, and we speculate that toxin diversity and evolution play an important role in specificity against different enemies. Finally, we have also recently found that Howardula nematodes have themselves recently acquired a bacterial symbiont that is allied with a lineage of plant-pathogenic bacteria, and we speculate on this symbiont’s role in infection and nematode fitness.

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連絡先: 深津 武馬（生物プロセス研究部門首席研究員、t-fukatsu@aist.go.jp)
ERATO深津共生進化機構プロジェクト
参照記事: https://www.jst.go.jp/erato/fukatsu/news/2022/220225.html