Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli, Italy.
PLoS One. 2013 Aug 27;8(8):e73281. doi: 10.1371/journal.pone.0073281. eCollection 2013.
Oxylipins are low-molecular weight secondary metabolites derived from the incorporation of oxygen into the carbon chains of polyunsaturated fatty acids (PUFAs). Oxylipins are produced in many prokaryotic and eukaryotic lineages where they are involved in a broad spectrum of actions spanning from stress and defense responses, regulation of growth and development, signaling, and innate immunity. We explored the diversity in oxylipin patterns in the marine planktonic diatom Pseudo-nitzschia. This genus includes several species only distinguishable with the aid of molecular markers. Oxylipin profiles of cultured strains were obtained by reverse phase column on a liquid chromatograph equipped with UV photodiode detector and q-ToF mass spectrometer. Lipoxygenase compounds were mapped on phylogenies of the genus Pseudo-nitzschia inferred from the nuclear encoded hyper-variable region of the LSU rDNA and the plastid encoded rbcL. Results showed that the genus Pseudo-nitzschia exhibits a rich and varied lipoxygenase metabolism of eicosapentaenoic acid (EPA), with a high level of specificity for oxylipin markers that generally corroborated the genotypic delineation, even among genetically closely related cryptic species. These results suggest that oxylipin profiles constitute additional identification tools for Pseudo-nitzschia species providing a functional support to species delineation obtained with molecular markers and morphological traits. The exploration of the diversity, patterns and plasticity of oxylipin production across diatom species and genera will also provide insights on the ecological functions of these secondary metabolites and on the selective pressures driving their diversification.
氧化脂类是由多不饱和脂肪酸（PUFAs）的碳链中掺入氧而衍生的低分子量次生代谢物。氧化脂类在许多原核和真核生物谱系中产生，它们参与了从应激和防御反应、生长和发育调节、信号转导和先天免疫等广泛的作用。我们探索了海洋浮游硅藻拟菱形藻中氧化脂类模式的多样性。这个属包括几种仅借助分子标记才能区分的物种。通过配备紫外光电二极管检测器和 q-ToF 质谱仪的液相色谱仪的反相柱，获得了培养菌株的氧化脂类图谱。脂氧合酶化合物被映射到基于 LSU rDNA 的核编码超可变区和质体编码 rbcL 推断的拟菱形藻属系统发育树上。结果表明，拟菱形藻属表现出丰富多样的二十碳五烯酸（EPA）脂氧合酶代谢，对氧化脂类标志物具有高度特异性，通常与基因型划分相符，即使在遗传上密切相关的隐种之间也是如此。这些结果表明，氧化脂类图谱构成了拟菱形藻种的附加鉴定工具，为通过分子标记和形态特征获得的物种划分提供了功能支持。对不同硅藻物种和属的氧化脂类产生的多样性、模式和可塑性的探索也将为这些次生代谢物的生态功能以及驱动它们多样化的选择压力提供见解。
