Timmins-Schiffman Emma, Roberts Steven
School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105, USA.
BMC Res Notes. 2012 Sep 13;5:502. doi: 10.1186/1756-0500-5-502.
The lipid signaling molecule, ceramide, is a key component of the vertebrate stress response, however, there is limited information concerning its role in invertebrate species. In order to identify genes involved in ceramide metabolism in bivalve molluscs, Pacific oyster genomic resources were examined for genes associated with ceramide metabolism and signaling.
Several genes were identified including full-length sequences characterized for serine palmitoyltransferase-1, 3-ketodihydrosphingosine reductase, acid ceramidase, and ceramide glucosyltransferase. Genes involved in ceramide synthesis and metabolism are conserved across taxa in both form and function. Expression analysis as assessed by quantitative PCR indicated all genes were expressed at high levels in gill tissue. The role of the ceramide pathway genes in the invertebrate stress response was also explored by measuring expression levels in adult oysters exposed to Vibrio vulnificus. Two genes demonstrated increased expression during the bacterial challenge: a gene involved in hydrolytic breakdown of ceramide (acid ceramidase) and a gene involved in de novo generation of ceramide (3-ketodihydrosphingosine reductase), suggesting a possible role of ceramide in the invertebrate stress and immune responses.
In silico and laboratory results support that Pacific oysters have the basic components of the ceramide metabolism pathway. These results also indicate that ceramide may have analogous functions in vertebrates and invertebrates. The gene expression pattern of acid ceramidase and 3-kethodihydrosphingosine reductase in response to bacterial exposure especially supports that ceramide and sphingolipid metabolism may be involved in the oyster's stress and/or immune responses.
脂质信号分子神经酰胺是脊椎动物应激反应的关键组成部分，然而，关于其在无脊椎动物物种中的作用信息有限。为了鉴定双壳贝类中参与神经酰胺代谢的基因，研究人员检查了太平洋牡蛎的基因组资源，以寻找与神经酰胺代谢和信号传导相关的基因。
鉴定出了几个基因，包括丝氨酸棕榈酰转移酶-1、3-酮二氢鞘氨醇还原酶、酸性神经酰胺酶和神经酰胺葡糖基转移酶的全长序列。参与神经酰胺合成和代谢的基因在不同分类群中在形式和功能上都是保守的。通过定量PCR评估的表达分析表明，所有基因在鳃组织中均高水平表达。还通过测量暴露于创伤弧菌的成年牡蛎中的表达水平，探讨了神经酰胺途径基因在无脊椎动物应激反应中的作用。两个基因在细菌攻击期间表现出表达增加：一个参与神经酰胺水解分解的基因（酸性神经酰胺酶）和一个参与神经酰胺从头生成的基因（3-酮二氢鞘氨醇还原酶），这表明神经酰胺在无脊椎动物应激和免疫反应中可能发挥作用。
计算机模拟和实验室结果支持太平洋牡蛎具有神经酰胺代谢途径的基本组成部分。这些结果还表明神经酰胺在脊椎动物和无脊椎动物中可能具有类似的功能。酸性神经酰胺酶和3-酮二氢鞘氨醇还原酶对细菌暴露的基因表达模式尤其支持神经酰胺和鞘脂代谢可能参与牡蛎的应激和/或免疫反应。
