Quality over quantity: unraveling the contributions to cytoplasmic incompatibility caused by two coinfecting Cardinium symbionts

Cardinium hertigii is a common maternally-inherited bacterial endosymbiont of arthropods. Some Cardinium strains spread by increasing female fitness through the induction of cytoplasmic incompatibility (CI), which kills offspring of crosses between infected males and uninfected female hosts. CI is a two-step manipulation: first, sperm from male hosts are modified by the symbiont in a manner that causes offspring death. Second, when females are also infected, the symbiont reverses sperm modification in the egg cytoplasm, allowing offspring of infected females to survive and spread the symbiont. While Cardinium causes CI in many arthropod hosts, most of what is known about Cardinium CI stems from the symbiosis between the Cardinium strain cEper1 and its minute parasitoid host, Encarsia suzannae. Here, we study a second Cardinium CI system in the wasp Encarsia partenopea. Encarsia partenopea harbors two Cardinium strains, cEina2 and cEina3, with the cEina3 present at a much lower density t...赫尔蒂格卡迪纳菌（Cardinium hertigii）是一类常见的节肢动物母系遗传细菌内共生体。部分卡迪纳菌菌株可通过诱导细胞质不相容（cytoplasmic incompatibility, CI）提升雌性宿主适合度，该机制会导致感染雄性与未感染雌性宿主交配所产生的子代死亡。细胞质不相容是一种两步操控过程：首先，共生体对雄性宿主的精子进行修饰，进而引发子代死亡；其次，若雌性宿主同样被该共生体感染，其卵细胞质中的共生体可逆转精子的修饰状态，使感染雌性的子代得以存活并传播共生体。尽管卡迪纳菌在众多节肢动物宿主中均可诱发细胞质不相容，但目前学界对卡迪纳菌细胞质不相容的认知大多源于cEper1菌株与其小型寄生蜂宿主苏珊娜恩蚜小蜂（Encarsia suzannae）的共生体系。本研究聚焦于菲氏恩蚜小蜂（Encarsia partenopea）体内的第二类卡迪纳菌细胞质不相容体系。菲氏恩蚜小蜂体内携带两种卡迪纳菌菌株：cEina2与cEina3，其中cEina3的菌体密度显著更低...