VIBRIO CHOLERAE PLANKTON COLONIZATION

人类病原体霍乱弧菌广泛分布于沿着许多海岸线，包括美国的海岸线。环境因素在决定霍乱弧菌的分布中起主要作用。例如，有人认为，1991年第七次霍乱大流行病传入拉丁美洲与厄尔尼诺等气候变化事件引发的海洋浮游生物大量繁殖有关。为了更好地了解海洋媒介和影响霍乱传播的条件，我们建议研究各种临床和环境菌株的霍乱弧菌与海洋浮游生物的关联。将进行海洋围隔生态系统实验，其中将通过用绿色荧光蛋白基因的修改版本标记细胞来识别霍乱弧菌。将使用与图像分析方法结合的细胞分裂频率技术来跟踪围隔中霍乱弧菌的生长。使用选定的海洋模型系统五. cholesterium浮游生物定殖将进一步研究，并在浮游生物或植物碎屑协会的趋化性可能发挥的作用将进行评估。我们还将分离和表征，或获得缺乏浮游生物定殖的突变体。将查明遗传缺陷，并查明浮游生物和哺乳动物之间的关系（如果有的话）。 最后，将确定生物和物理化学因素对围隔生态系统中霍乱弧菌生长和分布的影响，并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造成霍乱公共卫生风险。

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.