Fonseca-Madrigal Jorge, Navarro Juan C, Hontoria Francisco, Tocher Douglas R, Martínez-Palacios Carlos A, Monroig Óscar
Laboratorio de Acuicultura, Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH), Morelia 58330, Michoacán, Mexico.
Instituto de Acuicultura Torre de la Sal-Consejo Superior de Investigaciones Científicas (IATS-CSIC), Ribera de Cabanes 12595, Castellón, Spain.
J Lipid Res. 2014 Jul;55(7):1408-19. doi: 10.1194/jlr.M049791. Epub 2014 May 2.
Currently existing data show that the capability for long-chain PUFA (LC-PUFA) biosynthesis in teleost fish is more diverse than in other vertebrates. Such diversity has been primarily linked to the subfunctionalization that teleostei fatty acyl desaturase (Fads)2 desaturases have undergone during evolution. We previously showed that Chirostoma estor, one of the few representatives of freshwater atherinopsids, had the ability for LC-PUFA biosynthesis from C18 PUFA precursors, in agreement with this species having unusually high contents of DHA. The particular ancestry and pattern of LC-PUFA biosynthesis activity of C. estor make this species an excellent model for study to gain further insight into LC-PUFA biosynthetic abilities among teleosts. The present study aimed to characterize cDNA sequences encoding fatty acyl elongases and desaturases, key genes involved in the LC-PUFA biosynthesis. Results show that C. estor expresses an elongase of very long-chain FA (Elovl)5 elongase and two Fads2 desaturases displaying Δ4 and Δ6/Δ5 specificities, thus allowing us to conclude that these three genes cover all the enzymatic abilities required for LC-PUFA biosynthesis from C18 PUFA. In addition, the specificities of the C. estor Fads2 enabled us to propose potential evolutionary patterns and mechanisms for subfunctionalization of Fads2 among fish lineages.
目前已有的数据表明，硬骨鱼体内长链多不饱和脂肪酸（LC-PUFA）的生物合成能力比其他脊椎动物更为多样。这种多样性主要与硬骨鱼脂肪酸去饱和酶（Fads）2在进化过程中发生的亚功能化有关。我们之前发现，淡水银汉鱼科的少数代表物种之一埃氏奇脂鲤能够从C18多不饱和脂肪酸前体合成LC-PUFA，这与该物种中DHA含量异常高是一致的。埃氏奇脂鲤独特的谱系以及LC-PUFA生物合成活性模式，使其成为一个绝佳的研究模型，有助于进一步深入了解硬骨鱼的LC-PUFA生物合成能力。本研究旨在鉴定编码脂肪酸延长酶和去饱和酶的cDNA序列，这些是参与LC-PUFA生物合成的关键基因。结果表明，埃氏奇脂鲤表达一种极长链脂肪酸延长酶（Elovl）5以及两种具有Δ4和Δ6/Δ5特异性的Fads2去饱和酶，因此我们可以得出结论，这三个基因涵盖了从C18多不饱和脂肪酸合成LC-PUFA所需的所有酶促能力。此外，埃氏奇脂鲤Fads2的特异性使我们能够提出鱼类谱系中Fads2亚功能化的潜在进化模式和机制。
