VIBRIO CHOLERAE PLANKTON COLONIZATION

人类病原体霍乱弧菌广泛分布在包括美国在内的许多海岸线上。环境因素在产毒霍乱弧菌的分布中起主要作用。例如，1991年第七次霍乱大流行传入拉丁美洲，有人认为这与厄尔尼诺现象等气候变化事件引发的海洋浮游生物大量繁殖有关。为了更好地了解影响霍乱传播的海洋媒介和条件，我们建议研究各种临床和环境霍乱弧菌菌株与海洋浮游生物的关系。将进行海洋中游实验，其中霍乱弧菌将通过用绿色荧光蛋白基因的修饰版本标记细胞来识别。利用细胞分裂频率技术结合图像分析方法，跟踪霍乱弧菌在中介体中的生长情况。在选定的海洋模式系统中，霍乱弧菌浮游生物的定植将被进一步研究，并将评估其趋化性在浮游生物或植物碎屑关联中的可能作用。我们还将分离和表征，或获得缺乏浮游生物定植的突变体。基因缺陷将被识别，浮游生物和哺乳动物之间的关系（如果有的话）将被确定。最后，确定生物和物理化学因素对霍乱弧菌在中生态系统中生长和分布的影响，探索海洋环境中霍乱毒素噬菌体产生和细胞间毒素基因交换的可能性。通过了解生物、化学和物理因素如何影响霍乱弧菌的分布、丰度和毒力，以及阐明其在沿海生态系统中与浮游生物持续存在的遗传要求，将有可能更好地预测环境变化何时可能带来霍乱公共卫生风险。

The human pathogen Vibrio cholerae is widely distributed along many coastlines including those of the United States. Environmental factors play a major role in determining the distribution of toxigenic V. cholerae. For example, the introduction of the seventh pandemic of cholera to Latin America in 1991 has been suggested to have been correlated with marine plankton blooms triggered by a climate change event such as that initiated by El Nino. In a effort to better understand marine vectors and conditions influencing the spread of cholera, we propose to examine the association of a variety of clinical and environmental strains of V. cholerae with marine plankton. Marine mesocosm experiments will be performed in which V. cholerae will be identified by marking cells with a modified version of the green fluorescent protein gene. growth of V. cholerae in the mesocosm will be followed using the frequency of dividing cells technique coupled to an image analysis method. Using selected marine model systems V. cholerae plankton colonization will be further examined, and the possible role of chemotaxis in plankton or phytodetritus association will be assessed. We will also isolate and characterize, or obtain mutants deficient in plankton colonization. The genetic defects will be identified, and the relationship, if any, between colonization of plankton and of mammals will be ascertained. Finally, the effect of biological and physiochemical factors on V. cholerae growth and distribution in mesocosms will be determined and the possibility of cholera toxin phage production and toxin gene exchange among cells in the marine environment will be explored. By understanding how biological, chemical, and physical factors influence the distribution, abundance and virulence of V. cholerae, together with the elucidation of the genetic requirements for its persistence with plankton in coastal ecosystems, it will be possible to better predict when environmental change is likely to present a cholera public health risk.