Embryo Defenses Against Toxins

这项为期一年的拨款将资助一个旨在了解胚胎如何抵御环境毒素的试点项目。埃佩尔博士假设，p糖蛋白药物转运体提供了这种保护，作为第一道防线，将毒素挡在细胞之外。它存在于一种泥栖蠕虫的胚胎和成虫中，它的活性保护其胚胎免受添加的试验毒素的侵害。这种保护可能解释了乌壁藻胚胎在孔隙水（泥滩沉积物的上清海水）中正常发育的能力。海星和海胆的胚胎不具有这种转运体，它们的胚胎不能在泥滩的孔隙水中发育。如果这种药物转运体确实能保护胚胎，那么在海胆或海星的胚胎中表达这种转运体应该能保护它们免受环境毒素的侵害。这项为期一年的初步研究的主要目标是利用从小鼠或线虫中克隆的基因，在海星或海胆的卵母细胞中表达这种转运蛋白，并确定由此产生的胚胎是否会发育。如果是这样，那么关于这种转运体在保护胚胎中的作用以及在一般海洋环境中防止毒素的作用，就可以提出和回答大量的问题。这种转运体在海洋环境中并不是普遍存在的，我们有限的调查表明它存在于滤食性和悬浮食性动物中，但在海胆和海星中没有。我们希望在这项初步研究中解决的第二个问题与这种转运体的分布有关。它存在于一种生活在沉积物中的针状虫体内。有这种转运体是肾上腺素的一般特征吗？还是说，只有那些生活方式暴露于毒素（比如栖息在沉积物中或滤食）的动物才会感染？为了回答这个问题，这项初步研究的一个小组成部分将确定在生活在清洁栖息地或生活方式不同的这一群体中，转运蛋白是否被表达或过度表达。提供这两个问题的答案，特别是关于克隆转运体基因在棘皮动物胚胎中的表达的信息，将表明将胚胎中表达的基因用于研究方法的可行性。如果可行，这些方法将为胚胎防御机制的生物学提供严格的信息，特别是这种药物转运体的作用

Epel 96-04354 This one year grant will fund a pilot project aimed at understanding how embryos defend themselves against environmental toxins. Dr. Epel hypothesizes that the P-glycoprotein drug transporters provide this protection, acting as a first line of defense to keep toxins out of the cell. It is present in embryos and adults of a mud-dwelling worm, Urechis caupo, and its activity protects its embryos against added test toxins. This protection might account for the ability of Urechis embryos to develop normally in pore water (the supernatant sea water from the mud flat sediments). The embryos of starfish and sea urchins do not possess this transporter and their embryos cannot develop in pore water from the mud flats. If this drug transporter in fact protects embryos, then expression of the transporter in the embryos of the sea urchin or starfish should confer protection against environmental toxins. The major goal of this one year pilot study is to express this transporter, using the gene cloned from the mouse or nematode worm, in starfish or sea urchins oocytes and to determine if the resultant embryos will develop. If so, a large number of questions can then be asked and answered about the role of this transporter in protection of embryos and also about protection against toxins in the marine environment in general. This transporter is not ubiquitous in the marine environment, and our limited survey indicates its presence in filter and suspension feeders but not in sea urchins or starfish. A second question we wish to address in this pilot study relates to the distribution of this transporter. It is present in an echiuroid worm which lives in sediments. Is having this transporter a general attribute of being an echiuroid? Or is it something restricted to animals whose lifestyle exposes them to toxins (such as sediment dwelling or filter feeding)? To provide an answer to this question, a minor component of this pilot study will determine whether the transport protein is ex pressed or over expressed in members of this group that live in clean habitats or have different lifestyles. Providing answers to these two questions, especially information about the expression of the cloned transporter gene in echinoderm embryos, will indicate will indicate the feasibility of research approaches using expressed genes in embyros. These approaches, if feasible, would provide rigorous information on the biology of embryo defense mechanisms in general and the role of this drug transporter in particular