Rosenblum Erica Bree, Stajich Jason E, Maddox Nicole, Eisen Michael B
Departments of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):17034-9. doi: 10.1073/pnas.0804173105. Epub 2008 Oct 13.
Amphibians around the world are being threatened by an emerging pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Bd). Despite intensive ecological study in the decade since Bd was discovered, little is known about the mechanism by which Bd kills frogs. Here, we compare patterns of global gene expression in controlled laboratory conditions for the two phases of the life cycle of Bd: the free-living zoospore and the substrate-embedded sporangia. We find zoospores to be transcriptionally less complex than sporangia. Several transcripts more abundant in zoospores provide clues about how this motile life stage interacts with its environment. Genes with higher levels of expression in sporangia provide new hypotheses about the molecular pathways involved in metabolic activity, flagellar function, and pathogenicity in Bd. We highlight expression patterns for a group of fungalysin metallopeptidase genes, a gene family thought to be involved in pathogenicity in another group of fungal pathogens that similarly cause cutaneous infection of vertebrates. Finally we discuss the challenges inherent in developing a molecular toolkit for chytrids, a basal fungal lineage separated by vast phylogenetic distance from other well characterized fungi.
全球两栖动物正受到一种新出现的病原体——蛙壶菌（Batrachochytrium dendrobatidis，简称Bd）的威胁。尽管自发现Bd以来的十年里进行了深入的生态学研究，但对于Bd杀死青蛙的机制仍知之甚少。在此，我们在可控的实验室条件下，比较了Bd生命周期两个阶段——自由生活的游动孢子和包埋于基质中的孢子囊——的全球基因表达模式。我们发现游动孢子在转录上比孢子囊更简单。游动孢子中几种丰度更高的转录本为这个游动生活阶段如何与环境相互作用提供了线索。孢子囊中表达水平更高的基因对参与Bd代谢活动、鞭毛功能和致病性的分子途径提出了新的假说。我们着重介绍了一组真菌溶素金属肽酶基因的表达模式，该基因家族被认为在另一组同样导致脊椎动物皮肤感染的真菌病原体的致病性中发挥作用。最后，我们讨论了为壶菌开发分子工具包所固有的挑战，壶菌是一个基部真菌谱系，与其他特征明确的真菌在系统发育上相距甚远。
