The Role of Cell-to-Cell Communication in Microcystis Aeruginosa Blooms

[1438622]裴若。细胞间通讯在铜绿微囊藻华中的作用铜绿微囊藻是世界范围内湖泊和河口水体中造成有害藻华的主要蓝藻种。这些水华释放出强大的毒素，对用水的人类造成严重的公共健康危害，包括疾病和死亡。尽管具有毁灭性的影响，但目前对铜绿假单胞菌调节水华形成和毒素产生的生物学知之甚少。因此，在了解基础生物学的基础上，研究铜绿假单胞菌的有效控制策略是十分必要的。该研究的重点是群体感应，这是细胞间通过化学“语言”进行沟通的关键机制，它控制着各种细菌的群体行为，如毒素产生和细胞生长，但在铜绿假单胞菌中却知之甚少。了解微囊藻群体感应的基本生物学原理将为通过调节群体感应途径控制铜绿假单胞菌在各种水体中的繁殖提供新的策略。这个教育项目的目标是当地的高中生和德克萨斯大学圣安东尼奥分校的本科生和研究生，这是一所西班牙裔的大学，其中约有60%的少数族裔未被充分代表。初步结果鉴定出两种化学“语言”，也称为自诱导剂，包括n -酰基同丝氨酸内酯和自诱导剂-2。在这些发现的基础上，将进行拟议的研究，以阐明群体感应在调节华花形成和毒素产生中的机制。PI将通过阐明M. aeruginosa的n -酰基同丝氨酸内酯和自诱导剂2诱导的群体感应途径来进行这些研究。具体而言，将克隆合成n -酰基高丝氨酸内酯和自诱导剂-2的合酶基因，并鉴定n -酰基高丝氨酸内酯和自诱导剂-2调控的生理反应。然后PI将确定群体感应、毒素产生和细胞聚集之间是否存在串扰。将通过阻塞每个功能来验证串扰，并检查对其他两个功能的影响。最后，PI将研究群体感应在铜绿假单胞菌繁殖过程中的作用。重点是研究群体感应在铜绿假单胞菌和其他异养细菌之间的相互作用中的作用，这是形成水华的重要组成部分。在研究结束时，将更好地了解铜绿假单胞菌繁殖的生物学机制。本文将确定铜绿假单胞菌群体感应的途径，包括鉴定自诱导剂的化学结构和合成自诱导剂的基因。毒素的产生、细胞聚集、细胞生长和细胞浮力是否在群体感应自诱导体调节的社会行为中，将被确定。更重要的是，群体感应是否有助于M. aeruginosa和异养细菌之间的相互作用，从而导致M. aeruginosa华的发展，将被确定。总的来说，这将有助于回答长期困扰该领域的问题“是什么导致了铜绿假单胞菌的大量繁殖”。

1438622Pei, RuotingThe role of cell-to-cell communication in Microcystis aeruginosa bloomsMicrocystis aeruginosa is the dominant cyanobacterial species causing harmful algal blooms in lakes and estuarine water bodies worldwide. The blooms release potent toxins and pose severe public health hazards to humans using the water, including sickness and death. Despite the devastating effects, currently there is remarkably little understanding of the M. aeruginosa biology regulating bloom formation and toxin production. Thus research is much needed to develop more effective controlling strategies for M. aeruginosa blooms based on the understanding of basic biology. The focus of the proposed research is quorum sensing, the key cell-cell communication mechanism via chemical "languages", which control population behaviors such as toxin production and cell growth in diverse bacteria, but is poorly understood in M. aeruginosa. The understanding of the basic biology of Microcystis quorum sensing will lead to novel strategies for controlling M. aeruginosa blooms in various water bodies by modulating the quorum sensing pathways. The education program targets local high school students and the undergraduate and graduate students at the University of Texas at San Antonio, a Hispanic serving institution with about 60 % underrepresented minorities. Preliminary results have identified two chemical "languages", also called autoinducers, including N-acyl homoserine lactones and autoinducer-2 in M. aeruginosa. Building on these findings, the proposed research will be performed to elucidate the mechanisms of quorum sensing in regulating bloom formation and toxin production. The PI will approach these studies by elucidating the N-acyl homoserine lactones and autoinducer-2-induced quorum sensing pathways in M. aeruginosa. Specifically, the synthase genes responsible for synthesis of N-acyl homoserine lactones and autoinducer-2 will be cloned and the physiological responses regulated by N-acyl homoserine lactones and autoinducer-2 will be identified. Then the PI will dDetermine whether there is crosstalk among quorum sensing, toxin production and cell aggregation. The crosstalk will be validated by blocking each function and examine the effects on the other two functions. And, finally the PI will examine the role of quorum sensing in the development of M. aeruginosa blooms. The focus is on examining the role of quorum sensing in the interaction between M. aeruginosa and other heterotrophic bacteria, an important component of bloom formation. At the conclusion of the study, a better understanding of biological mechanisms of M. aeruginosa blooms will be achieved. The pathways of quorum sensing in M. aeruginosa will be determined including identification the chemical structures of the autoinducers and the genes responsible for synthesizing the autoinducers. Whether toxin production, cell aggregation, cell growth and cell buoyancy are among the social behaviors regulated by the quorum sensing autoinducers will be determined. More importantly, whether quorum sensing contributes to the interaction between M. aeruginosa and heterotrophic bacteria and hence the development of M. aeruginosa blooms will be determined. Overall, this will contribute to answering the question "what causes M. aeruginosa blooms" that has long puzzled the field.