Mydlarz Laura D, Harvell C Drew
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca NY 14853 USA.
Comp Biochem Physiol A Mol Integr Physiol. 2007 Jan;146(1):54-62. doi: 10.1016/j.cbpa.2006.09.005. Epub 2006 Sep 16.
The enzymatic defense mechanisms of Gorgonia ventalina to the fungal pathogen Aspergillus sydowii may play important roles in colony resistance to infection. In this study, we examined the role of the superfamily of peroxidase enzymes in the coral response to a naturally occurring pathogen. We examined the inducibility of peroxidases by experimentally exposing corals to A. sydowii and found that peroxidase activity was induced after an 8 day incubation period. In contrast, naturally infected corals collected from the reef had lower peroxidase activity when compared to healthy corals. Infected sea fans from the field also had less measurable protein in their tissues and increased purple sclerites near infection sites and it is likely that these infections are months old. Using native-PAGE activity gels, we detected 5 peroxidase isozymes in healthy corals, indicating that multiple isoforms of peroxidase with a plurality of possible functions are present in this coral. The role of the peroxidase enzymes in disease resistance was examined by testing anti-fungal activity of commercially available and partially purified sea fan peroxidases. In both cases there was significant, dose-dependent anti-fungal activity. While peroxidases are ubiquitous enzymes involved in many cellular pathways, we also hypothesize that G. ventalina utilizes these enzymes as an integral component in disease resistance pathways. As such, they may also contribute to the initiation of physiochemical defenses such as melanization and lipid soluble anti-fungal metabolites.
紫柳珊瑚对真菌病原体烟曲霉的酶促防御机制可能在群体抗感染中发挥重要作用。在本研究中，我们研究了过氧化物酶超家族在珊瑚对自然存在的病原体的反应中的作用。我们通过实验将珊瑚暴露于烟曲霉来检测过氧化物酶的诱导性，发现在8天的潜伏期后过氧化物酶活性被诱导。相比之下，从珊瑚礁采集的自然感染珊瑚与健康珊瑚相比，过氧化物酶活性较低。从野外采集的受感染海扇组织中的可测量蛋白质也较少，并且在感染部位附近有更多的紫色骨片，这些感染可能已有数月之久。使用天然聚丙烯酰胺凝胶活性电泳，我们在健康珊瑚中检测到5种过氧化物酶同工酶，表明这种珊瑚中存在具有多种可能功能的多种过氧化物酶同工型。通过测试市售和部分纯化的海扇过氧化物酶的抗真菌活性来研究过氧化物酶在抗病性中的作用。在这两种情况下，都有显著的、剂量依赖性的抗真菌活性。虽然过氧化物酶是参与许多细胞途径的普遍存在的酶，但我们也推测紫柳珊瑚利用这些酶作为抗病途径的一个组成部分。因此，它们也可能有助于启动物理化学防御，如黑化和脂溶性抗真菌代谢产物。
