• 综 述 •

### 昆虫共生菌的垂直传播

1. (中国计量大学生命科学学院, 浙江省生物计量与检验检疫技术重点实验室, 杭州 30018)
• 出版日期:2019-07-20 发布日期:2019-07-09

### Vertical transmission of insect symbionts

AN Peng#, XU Yi-Peng#,*, WU Jia-Min, ZHENG Rong-Er, YU Xiao-Ping*

1. (Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou 310018, China)
• Online:2019-07-20 Published:2019-07-09

共生菌普遍存在于昆虫体内，它们能够为宿主昆虫提供生长发育所必需的氨基酸、固醇类等营养物质，还能提高昆虫适应高温、寄生虫、病毒等不利环境因素的能力，昆虫则为共生菌提供稳定的生存环境和营养物质，昆虫与共生菌相互依存。多数情况下，共生菌通过垂直传播在宿主代次间进行传播，即共生菌由母代传递给子代。结合最近几年相关研究，本文综述了不同昆虫共生菌的垂直传播模式。除极少数肠道共生菌通过污染卵壳被宿主幼虫取食得以垂直传播外，垂直传播的共生菌多为经卵传播。根据侵染时期的不同，共生菌经卵传播模式多数可分为以下4种：侵染宿主昆虫幼虫中的生殖干细胞、侵染宿主昆虫年轻雌成虫中的生殖干细胞、侵染宿主昆虫雌成虫中的成熟卵母细胞以及侵染宿主昆虫囊胚期胚胎。其中，有些共生菌是以共生菌菌胞整体侵染的方式进入到宿主卵巢。另外，少数肠道共生菌也通过卵巢进行垂直传播，此类共生菌先侵染卵巢侧输卵管并在侧输卵管聚集，待卵排放至侧输卵管时再进入到卵中。在文中，我们也探讨了昆虫共生菌垂直传播过程中的细胞机制和免疫机制，包括共生菌避开宿主免疫反应、共生菌通过内吞作用进入卵巢以及不同共生菌间的协同作用等。

Abstract: Symbionts universally exist in insects, not only providing host insects with nutrients such as amino acids and sterols that are necessary for their growth and development, but also improving the adaptability of insects to external adverse environmental factors such as high temperature, parasites and viruses. Insects provide a stable living environment and nutrients for symbionts. Symbionts and host insects are interdependent. In most cases, symbionts are vertically transmitted between generations of their host insects, from the mother to its offsprings. In this article, based on the relevant studies in recent years we reviewed the vertical transmission modes of different insect symbionts. Except for a small number of intestinal symbionts that can be transmitted vertically through contaminated egg shells and then eaten by host larvae, most of vertically-transmitted symbionts are transovarially transmitted. According to different infection periods, most of the transovarial transmission modes of symbionts can be divided into the following four types: infecting germline stem cells in host insect larvae, infecting germline stem cells in the young female adult of host insect, infecting mature oocytes in the female adult of host insect, and infecting blastocyst embryos of host insect. Among them, some symbionts enter the host ovary in the form of bacteriocyte. In addition, a few intestinal symbionts are also vertically transmitted through the ovary. Such symbionts firstly infect the lateral oviduct and accumulate in it, and then enter the oocyte when the oocyte is discharged into the lateral oviduct. We also explored the cellular and immune mechanisms of vertical transmission of insect symbionts, including the avoidance of host immune responses by symbionts, the entry of symbionts into ovaries by endocytosis, and the synergistic effects between different symbionts.