Department of Entomology and Nematology, University of California Davis, Davis, CA, USA.
Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
Results Probl Cell Differ. 2020;69:497-536. doi: 10.1007/978-3-030-51849-3_19.
Tsetse flies (Glossina spp.) act as the sole vectors of the African trypanosome species that cause Human African Trypanosomiasis (HAT or African Sleeping Sickness) and Nagana in animals. These flies have undergone a variety of specializations during their evolution including an exclusive diet consisting solely of vertebrate blood for both sexes as well as an obligate viviparous reproductive biology. Alongside these adaptations, Glossina species have developed intricate relationships with specific microbes ranging from mutualistic to parasitic. These relationships provide fundamental support required to sustain the specializations associated with tsetse's biology. This chapter provides an overview on the knowledge to date regarding the biology behind these relationships and focuses primarily on four bacterial species that are consistently associated with Glossina species. Here their interactions with the host are reviewed at the morphological, biochemical and genetic levels. This includes: the obligate symbiont Wigglesworthia, which is found in all tsetse species and is essential for nutritional supplementation to the blood-specific diet, immune system maturation and facilitation of viviparous reproduction; the commensal symbiont Sodalis, which is a frequently associated symbiont optimized for survival within the fly via nutritional adaptation, vertical transmission through mating and may alter vectorial capacity of Glossina for trypanosomes; the parasitic symbiont Wolbachia, which can manipulate Glossina via cytoplasmic incompatibility and shows unique interactions at the genetic level via horizontal transmission of its genetic material into the genome in two Glossina species; finally, knowledge on recently observed relations between Spiroplasma and Glossina is explored and potential interactions are discussed based on knowledge of interactions between this bacterial Genera and other insect species. These flies have a simple microbiome relative to that of other insects. However, these relationships are deep, well-studied and provide a window into the complexity and function of host/symbiont interactions in an important disease vector.
采采蝇（舌蝇属）是唯一传播引起人类非洲锥虫病（昏睡病）和动物中的那加那病的非洲锥虫的媒介。这些苍蝇在进化过程中经历了各种特化，包括雌雄两性都仅以脊椎动物血液为食的特殊饮食，以及强制性的胎生生殖生物学。除了这些适应，舌蝇种类与特定的微生物建立了复杂的关系，从互利共生到寄生关系都有。这些关系为维持舌蝇生物学相关的特化提供了基本支持。本章概述了迄今为止关于这些关系背后的生物学的知识，并主要集中在与舌蝇种类密切相关的四个细菌物种上。这里在形态、生化和遗传水平上回顾了它们与宿主的相互作用。这包括：专性共生菌 Wigglesworthia，存在于所有舌蝇物种中，对血液特异性饮食的营养补充、免疫系统成熟和胎生生殖的促进至关重要；共生菌 Sodalis，这是一种经常与之共存的共生菌，通过营养适应在苍蝇中生存，通过交配进行垂直传播，并可能改变舌蝇对锥虫的媒介能力；寄生菌 Wolbachia，可以通过细胞质不相容性操纵舌蝇，并通过其遗传物质在两种舌蝇物种中的基因组中进行水平传播，在遗传水平上显示出独特的相互作用；最后，探索了最近在 Spiroplasma 和舌蝇之间观察到的关系，并根据这种细菌属与其他昆虫物种之间的相互作用的知识讨论了潜在的相互作用。与其他昆虫相比，这些苍蝇的微生物组相对简单。然而，这些关系是深入的、经过充分研究的，为了解重要病媒昆虫的宿主/共生体相互作用的复杂性和功能提供了一个窗口。
