Permalink : http://hdl.handle.net/2115/45200

抗菌ペプチドはショウジョウバエにおいて主要な生体防御機構の一つであり, キイロショウジョウバエでは, これまでに7種類が同定されている. これら抗菌ペプチドは種類によって活性を示す対象の微生物が異なり, バクテリアに対して強い抗菌活性を示すものや真菌類に強い抗菌活性を示すものが知られている. 様々な研究から, 抗菌ペプチドは, 個体レベルでは個体の微生物に対する抵抗性に大きく影響することが, 遺伝子レベルでは種類によってその分子進化パターンが異なることが明らかとなっている. そこで, 本稿では抗菌ペプチドの分子進化と抗菌活性や個体での抵抗性との関わりについて論じる.
Antimicrobial peptides (AMPs) are essential components for Drosophila innate immune systems against microorganisms. Seven antimicrobial peptides have been identified in D. melanogaster, in which some AMPs show strong anti-bacterial activity, but others show anti-fungal activity. Repertoire of AMPs and their expression patterns are important for individual fly to survive under infection of Gram-negative, Gram-positive bacteria and fungi. Many molecular evolutionary analyses show different AMP genes have evolved in different manner. Cecropin and Drosomycin genes, for example, have evolved under frequent gene duplication and deletion event, so-called birth-and-death evolution, while Metchnikwin and Drosocin genes have kept only one copy in their host genome through Drosophila evolution. Ecologically, Drosophila is distributed among various environments from Tropical to Polar Zone, and some species have more resistance to bacteria or fungi than others have. However, the molecular-based mechanisms which affect a resistance to microorganisms still have not been elucidated clearly. In this paper, we introduce functions of Drosophila AMPs and their molecular evolution, and then discuss evolutionary relationship between them.