Science：壶菌病菌使蛙类致命原因

新的研究表明，导致全世界蛙类数量减损的皮肤真菌是通过阻碍通过皮肤的钠及其它电解质的流动而造成损害并导致心脏衰竭的。这种皮肤病叫壶菌病，它是由蛙壶菌（Batrachochytrium dendrobatidis）这种真菌引起的。图片来源： Jamie Voyles'' Alex Hyatt 和 Frank Fillipi.

据10月23日的《科学》杂志报道说，导致全世界蛙类数量减损的皮肤真菌是通过阻碍通过皮肤的钠及其它电解质的流动而造成损害并导致心脏衰竭的。这些发现可以在未来给研发新的挽救濒临灭绝的生物种群的方法建立一个基础。

这种皮肤病叫壶菌病，它是由蛙壶菌（Batrachochytrium dendrobatidis）这种真菌引起的。这种真菌被认为是近些年中全球两栖类动物数量下降的重要原因之一。但是，这种真菌是如何导致死亡的一直是一个谜，因为死亡的动物总体上看显得是健康的，它们除了有皮肤损伤之外没有其它的疾病征兆。

Jamie Voyles及其同僚报告说，在感染了该真菌的绿色树蛙中，跨皮肤电解质的转运被抑制了50%以上，而蛙血浆中的钠和钾浓度分别减少了20%及50%。濒死的蛙的心电图显示其心跳减慢并最终完全停止跳动，其最可能的原因是电解质失衡。为了证实这种想法，文章的作者发现，喂饲电解质补充剂的病蛙比那些没有喂饲电解质的病蛙要活得更长，尽管它们最终也会死于感染。人们需要做更多的研究以弄清该真菌究竟是如何破坏蛙类的经皮肤的渗透压平衡。（生物谷Bioon.com）

生物谷推荐原始出处：

Science 23 October 2009:DOI: 10.1126/science.1176765

Pathogenesis of Chytridiomycosis'' a Cause of Catastrophic Amphibian Declines

Jamie Voyles''1''* Sam Young''1 Lee Berger''1 Craig Campbell''2 Wyatt F. Voyles''3 Anuwat Dinudom''2 David Cook''2 Rebecca Webb''1 Ross A. Alford''4 Lee F. Skerratt''1 Rick Speare1

The pathogen Batrachochytrium dendrobatidis (Bd)'' which causes the skin disease chytridiomycosis'' is one of the few highly virulent fungi in vertebrates and has been implicated in worldwide amphibian declines. However'' the mechanism by which Bd causes death has not been determined. We show that Bd infection is associated with pathophysiological changes that lead to mortality in green tree frogs (Litoria caerulea). In diseased individuals'' electrolyte transport across the epidermis was inhibited by >50%'' plasma sodium and potassium concentrations were respectively reduced by ~20% and ~50%'' and asystolic cardiac arrest resulted in death. Because the skin is critical in maintaining amphibian homeostasis'' disruption to cutaneous function may be the mechanism by which Bd produces morbidity and mortality across a wide range of phylogenetically distant amphibian taxa.

1 School of Public Health'' Tropical Medicine and Rehabilitation Sciences'' Amphibian Disease Ecology Group'' James Cook University'' Townsville'' QLD 4811'' Australia.
2 Discipline of Physiology'' Bosch Institute'' Faculty of Medicine'' University of Sydney'' Sydney'' NSW 2006'' Australia.
3 School of Medicine'' Division of Cardiology'' University of New Mexico'' Albuquerque'' NM 87131'' USA.
4 School of Marine and Tropical Biology'' Amphibian Disease Ecology Group'' James Cook University'' Townsville'' QLD 4811'' Australia.