MICROCYSTINS, NATURAL ENVIRONMENTAL TOXINS

微囊藻毒素是由蓝藻产生的多肽肝毒素 通常在包括饮用水供应在内的水体中形成浮渣， 构成环境公共健康危害。 我们的最终目标是充分解释这种化合物的毒性机制。 一组化合物。微囊藻毒素绝对是肝脏特异的，致命的 造成器官结构丧失的剂量(50-200毫微克/公斤ip) 和大量肝脏出血，随后在几个小时内死亡。 亚急性剂量被证明是非常有效的肿瘤促进剂，导致 大鼠肝脏恶性病变发生率增加 用二乙基亚硝胺。肝细胞是这些毒素的靶标。 因为这些细胞与其他细胞不同，它们有能力吸收这些 多肽。 因此，运输被认为是排他性的决定因素 微囊藻毒素的器官选择性毒性。为了达到一个完整的 了解微囊藻毒素肝毒性的性质。身份， 运输过程的属性和活动控制需要 这是本应用程序的重点。 具体目标是： 目的1.研究微囊藻毒素在大鼠肝窦中的转运特性 膜泡。 这些将被用来在分离有毒物质的情况下探索运输机制。 细胞间的相互作用。这些实验将定义传送器如何 在肝细胞的肝窦极的功能，并可能提示 改变其活动的战略，从而改变其面临的风险 毒素。 目的2.利用非洲爪哇卵母细胞表达系统对非洲爪哇卵母细胞进行鉴定 克隆了大鼠正弦微囊藻毒素转运蛋白。 运输机的性质和结构将由以下因素决定 通过注射大鼠肝脏RNA在非洲爪哇卵母细胞中表达， 确定一个单一物种的mRNA，即信息和测序 它。将有可能更好地定义运输的机制 分子水平，并确定其他外源物质或代谢物是什么 载体的基材。

Microcystins are peptide hepatotoxins produced by cyanobacteria that commonly form a scum in water bodies including potable water supplies, constituting an environmental public health hazard. Our ultimate goal is to fully explain the mechanism of toxicity of this group of compounds. Microcystins are absolutely liver specific, lethal doses (50-200 migiogram/kg ip) causing loss of the structure of the organ and massive hepatic hemorrhage, followed by death within a few hours. Subacute doses were shown to be very potent tumor promoters causing increased incidence of malignant changes in the liver of rats initiated with diethylnitrosamine. Liver cells are the target of these toxins because these cells, unlike others, have the capacity to take up these peptides. It is proposed that transport therefore is the determinant of the exclusive organ selective toxicity of microcystin. In order to reach a full understanding of microcystin hepatotoxicity the nature. the identity(ies), properties and the control of activity of the transport process need to be addressed which is the focus of this application. The specific aims are: Aim 1. To characterize microcystin transport in rat liver sinusoidal membrane vesicles. These will be used to probe the transport mechanism in isolation from toxic cellular interactions. These experiments will define how the transporter functions in the sinusoidal pole of the hepatocyte and possibly suggest strategies for altering its altering its activity and therefore exposure to the toxins. Aim 2. To use the Xenopus laevis oocyte expression system to characterize and clone the rat sinusoidal microcystin transporter. The nature and structure of the transporter will be determined by expressing it in Xenopus laevis oocytes by injection with rat liver RNA, identifying a the single species of mRNA that is the message and sequencing it. It will be possible to better define the mechanism of the transport at the molecular level and determine what other xenobiotics or metabolites are substrates for the carrier.