Li Keshuai, Østensen Mari-Ann, Attramadal Kari, Winge Per, Sparstad Torfinn, Bones Atle M, Vadstein Olav, Kjørsvik Elin, Olsen Yngvar
NTNU Norwegian University of Science and Technology, Department of Biology, NO-7491 Trondheim, Norway.
NTNU Norwegian University of Science and Technology, Department of Biology, NO-7491 Trondheim, Norway.
Comp Biochem Physiol B Biochem Mol Biol. 2015 Dec;190:16-26. doi: 10.1016/j.cbpb.2015.08.006. Epub 2015 Aug 23.
The mechanism of essentiality of dietary phospholipid (PL) for larval fish is not clear. The main objective of the present study was to determine if the PL requirement of Atlantic cod larvae was due to any genetic impairment caused by functional immaturity. Cod larvae were sampled at 1, 3, 8, 13, 17, 18, 30, 42 and 60 days post hatch (dph) for transcriptome analysis using a recently developed microarray. The fatty acid profile and gene expression levels of cod larvae at 17 dph were compared after feeding differently enriched rotifers, which contained different DHA levels in PL. No significant differences (p<0.05) were found for the two rotifer diets in the overall gene expression level of cod larvae, their growth and survival, and their DHA levels in total lipid and PL fraction. The fatty acid data suggested that dietary EPA was elongated to DPA by cod larvae, and a threshold DHA level in PL to maintain membrane fluidity and other functions may exist. There appeared to be no major effect of development on the expression of key genes of PL biosynthesis suggesting no genetic constrain in early developmental stages. Our overall data suggested that besides the possible limited de novo PC synthesis ability in the intestine, other metabolic constraints should also be considered, especially the possible low input of bile PC as a result of immature liver. Further studies are needed to elucidate the gene expression level and enzyme activity in the PL biosynthesis pathways for specific tissue or cells.
日粮磷脂（PL）对仔鱼的必需性机制尚不清楚。本研究的主要目的是确定大西洋鳕鱼仔鱼对PL的需求是否是由于功能不成熟导致的任何遗传损伤。在孵化后1、3、8、13、17、18、30、42和60天（dph）采集鳕鱼仔鱼样本，使用最近开发的微阵列进行转录组分析。在投喂不同富含程度的轮虫后，比较了17 dph时鳕鱼仔鱼的脂肪酸谱和基因表达水平，这些轮虫的PL中DHA水平不同。在鳕鱼仔鱼的总体基因表达水平、生长和存活以及它们在总脂质和PL组分中的DHA水平方面，两种轮虫日粮之间未发现显著差异（p<0.05）。脂肪酸数据表明，鳕鱼仔鱼可将日粮中的EPA延长为DPA，并且可能存在PL中维持膜流动性和其他功能的DHA阈值水平。发育对PL生物合成关键基因的表达似乎没有主要影响，这表明在早期发育阶段不存在遗传限制。我们的总体数据表明，除了肠道中可能有限的从头合成PC的能力外，还应考虑其他代谢限制，特别是由于肝脏不成熟导致胆汁PC输入可能较低。需要进一步研究以阐明特定组织或细胞在PL生物合成途径中的基因表达水平和酶活性。
