菠萝型多细胞趋磁原核生物的适应性进化研究

Multicellular magnetotactic prokaryotes (MMPs) is a kind of distinctive magnetotactic bacteria (MTB). Two types of MMPs, mulberry-like and pineapple-like MMPs, have been reported. Compared with unicellular MTB, MMPs habitats in micro aerobic water or sediment, which is salty and rich in sulfur and. Distribution and abundance of MMPs are related to various environmental factors including temperature, iron, sulfur and salinity. Geochemical analysis reveals that the environmental conditions that mulberry-like MMPs habitats varied more than that of pineapple-like MMPs. Compared with the widely distributed mulberry-like MMPs, pineapple-like MMPs seems to prefer more stable habitats. Currently, Pineapple-like MMPs were found to be distributed only in Lake Yuehu (Rongcheng), Huiquan Bay (Qingdao), Tianya Haijiao (Sanya), Drummond Island (Xisha), and Mediterranean coast of Marseille (France), among which there are significant differences in the environmental factors, according to our preliminary observation. In this project, we propose (1) to screen the key genes driven by selective forces during evolution in four MMPs species from four different natural habitats in China, by integrating comparative genomics with variation in environmental factors, and (2) to explore the mechanism of adaptive evolution of pineapple-like MMPs.

多细胞趋磁原核生物（MMPs）是一类特殊的趋磁细菌，已发现有桑葚型和菠萝型两种形态。与单细胞趋磁细菌相比，MMPs生活环境都为富含硫且有一定盐浓度的微好氧水体或沉积物，其分布及丰度与温度、铁、硫、盐度等环境理化因子具有相关性。桑葚型MMPs有较好的适应能力，在世界范围内分布广泛，能够在变化剧烈的环境中生存；而菠萝型MMPs对环境条件的要求相对苛刻，需要更稳定的生存环境，目前只在我国荣成月湖、青岛汇泉湾、三亚天涯海角、西沙晋卿岛及法国马赛沿岸有发现。初步分析发现我国菠萝型MMPs四个自然分布区的环境因子具有明显的差异。本项目将以我国四个自然分布区的四个同属不同种的菠萝型MMPs为研究对象，将比较基因组学方法和环境因子的差异性分析相结合，筛查菠萝型MMPs进化过程中受环境压力选择的关键基因，进而探讨菠萝型MMPs对环境的适应性进化机制。

多细胞趋磁原核生物（MMPs）是一类特殊的趋磁细菌，主要桑葚型和菠萝型两种形态。其中，桑葚型MMPs有较好的适应能力，在世界范围内分布广泛，能够在变化剧烈的环境中生存；而菠萝型MMPs对环境条件的要求相对苛刻，需要更稳定的生存环境，目前只在我国荣成月湖、青岛汇泉湾、三亚天涯海角、西沙晋卿岛及法国马赛沿岸有发现。本项目以不同区域菠萝型MMPs为研究对象，通过显微操作、基因组扩增与高通量测序的方法获得其基因组，同时调查分布区的环境因子；通过基因组预测基因的注释，获得基因组基本信息；通过比较分析的方法，筛选菠萝型MMPs的特异基因，尝试获得其与环境适应相关的基因；通过对菠萝型MMPs的磁小体岛基因进行注释分析，解析菠萝型MMPs磁小体岛的编码类型，分析菠萝型MMPs的磁小体岛进化，进而探讨菠萝型MMPs对环境的适应性。