噬藻体是特异性侵染蓝藻的DNA病毒，广泛分布于海洋和淡水水体中。它参与调控蓝藻种群的丰度和分布，在蓝藻的种群演替过程中发挥着重要作用，因此是一种潜在的新型控制蓝藻水华的手段。相对于噬菌体或海洋噬藻体，淡水噬藻体的研究非常少。我们从巢湖水华爆发区分离筛选到一株侵染铜绿微囊藻的长尾噬藻体Mic1，并解析了头部衣壳的三维结构，测定了含有98个开放阅读框的全基因组序列，但仍有57个未知基因无法注释。本项目将利用转录组学、生物化学、分子生物学和X-射线晶体学等手段系统鉴定Mic1侵染宿主的裂解周期全过程中与宿主互作的重要蛋白质，同时利用冷冻电镜技术解析Mic1的尾部整体结构。基于上述研究结果，我们将对Mic1的基因组进行重注释，以期揭示淡水长尾噬藻体与宿主蓝藻互作的完整通路及其分子机制。该研究将为将来利用噬藻体检测和干预蓝藻水华的季节性爆发提供理论基础。

In recent years, due to the eutrophication and high temperature of fresh and marine waterbodies, the quickly proliferation of cyanobacteria triggers the seasonal outbreak of cyanobacterial bloom all over the world, which has become a severe ecological and environmental problem. Viruses that specifically infect cyanobacteria are called cyanophages, which are widespread in all types of aquatic environments. Cyanophages play an essential role in regulating the abundancy, distribution, diversity and homeostasis of cyanobacteria populations, thus may be viewed as a potential biological agent to temporarily control cyanobacterial blooms. Compared to the well-studied bacteriophages and marine cyanophages, little information is available concerning the freshwater cyanophages. A systematic screening of water samples in the Lake Chaohu enabled us to isolate a freshwater long-tailed cyanophage Mic1 that specifically infects the cyanobacteria Microcystis aeruginosa. We have set up a robust system to amplify and purify Mic1, which enabled us to sequence its complete genome and solve its capsid structure at 3.5 Å. However, there remain 57 hypothetical genes out of 98 putative open reading frames to be annotated. In this project, we will apply technologies of transcriptomics, biochemistry, molecular biology and X-ray crystallography, to systematically identify the key proteins that are involved in the interactions between Mic1 and its host in the complete lytic cycle from recognition to the release of progeny viruses. Moreover, we will solve the 3-D structure of the cyanophage tail using cryo-electron microscopy. These findings will not only elucidate the molecular mechanism of interactions between freshwater long-tailed cyanophage Mic1 and its host, but also help us re-annotate the complete genome of Mic1, and provide hints for developing novel approaches to control the seasonal outbreak of cyanobacterial blooms.