ADAPTATION TO ENVIRONMENTAL STRESSES AND DENTAL CARIES

在菌斑中，细菌通常会受到下列酸胁迫 宿主对可发酵碳水化合物的摄取。致龋菌 如变形链球菌等能在生理上适应酸胁迫。 这种适应可以在不到一代细胞的时间内发生，并涉及 质子转运F-ATPase活性增加以及其他， 目前，应对酸化的机制定义不清。因此， 致龋菌不仅具有较高的基础或构成水平 对酸胁迫的抵抗力，但可以通过 可诱导的自适应机制。类似类型的酸适应也发生在 肠道细菌，并用于增强对杀戮的抵抗力 吞噬小体的酸化环境。这件事的主要焦点是 应用将在生理和分子表征方面。 变形链球菌对酸胁迫的适应性反应 与对其他压力的反应重叠，如导致斑块。 变形链球菌酸适应细胞能在pH条件下进行糖酵解 值低于未适应单元格的最小值，并且此能力在 斑块将转化为更强的脱矿潜力，即。 即增强的致龋性。除变形链球菌外的菌斑细菌 可以适应酸胁迫，而这种适应，包括去抑制 链球菌等生物体中精氨酸脱亚胺酶系统的研究 Sanguis，很可能在整个斑块生态中具有重要意义。 然而，此应用程序中的定位主要是针对变种人 链球菌。 该项目的三个具体目标是：L)开发一个更完整的 变种对酸胁迫适应的生理学定义 链球菌和密切相关细菌，2)鉴定和鉴定 变形链球菌的酸性调节蛋白和基因，以及3)携带 Out分子遗传学分析对大黄素的调节作用 变形链球菌中的应激反应蛋白。 参与该项目的三个实验室的协调努力 将由计划内的交互来补充，特别是在 重金属和唾液肽对人体健康影响的关系 致龋性。这项工作的一个长期目标是设计方法来 打乱反应，从而降低斑块的致龋性。

In plaque, bacteria are routinely subjected to acid stresses following ingestion of fermentable carbohydrates by the host. Cariogenic organisms such as the mutans streptococci can adapt physiologically to acid stress. This adaptation can occur in less than a cell generation and involves increased activities of proton-translocating F-ATPases as well as other, currently ill-defined mechanisms of coping with acidification. Thus, cariogenic bacteria not only have a high basal or constitutive level of resistance to acid stress but can increase their resistance through inducible adaptive mechanisms. Similar types of acid adaptation occur in enteric bacteria and serve to enhance resistance to killing in the acidified environment of the phagolysosome. The major focus of this application will be on physiologic and molecular characterization of the adaptive responses of mutans streptococci to acid stress, which are likely to overlap with responses to other stresses such as to lead in plaque. Acid-adapted cells of mutans streptococci can carry out glycolysis at pH values lower than the minimum for unadapted cells, and this ability in plaque would translate into enhanced potential for demineralization, i. e., enhanced cariogenicity. Plaque bacteria other than mutans streptococci can adapt to acid stress, and this adaptation, which includes derepression of the arginine deiminase system in organisms such as Streptococcus sanguis, is likely to be of major importance in overall plaque ecology. However, the orientation in this application is primarily to mutans streptococci. The three specific aims of the project are: l) to develop a more complete physiological definition of adaptation to acid stress in mutans streptococci and closely related bacteria, 2) to identify and characterize acid-regulated proteins and genes of mutans streptococci, and 3) to carry out molecular genetic analysis of the regulation and function of major stress response proteins in mutans streptococci. The coordinated efforts of the three laboratories involved in this project will be supplemented by interactions within the program, especially in relation to effects of heavy metals and salivary peptides on cariogenicity. A long term objective of the work is to design means to upset the responses and thereby to lower plaque cariogenicity.