Mueller Casey A, Doyle Liam, Eme John, Manzon Richard G, Somers Christopher M, Boreham Douglas R, Wilson Joanna Y
Department of Biological Sciences, California State University San Marcos, San Marocs, CA, USA.
Medical Sciences, Northern Ontario School of Medicine, Laurentian University, Sudbury, ON, Canada.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Jan;203:201-209. doi: 10.1016/j.cbpa.2016.09.018. Epub 2016 Sep 28.
Lipids serve as energy sources, structural components, and signaling molecules during fish embryonic development, and utilization of lipids may vary with temperature. Embryonic energy utilization under different temperatures is an important area of research in light of the changing global climate. Therefore, we examined percent lipid content and fatty acid profiles of lake whitefish (Coregonus clupeaformis) throughout embryonic development at three incubation temperatures. We sampled fertilized eggs and embryos at gastrulation, eyed and fin flutter stages following chronic incubation at temperatures of 1.8, 4.9 and 8.0°C. Hatchlings were also sampled following incubation at temperatures of 3.3, 4.9 and 8.0°C. Fertilized eggs had an initial high percentage of dry mass composed of lipid (percent lipid content; ~29%) consisting of ~20% saturated fatty acids (SFA), ~32% monounsaturated fatty acids (MUFA), ~44% polyunsaturated fatty acids (PUFA), and 4% unidentified. The most abundant fatty acids were 16:0, 16:1, 18:1(n-9c), 20:4(n-6), 20:5(n-3) and 22:6(n-3). This lipid profile matches that of other cold-water fish species. Percent lipid content increased during embryonic development, suggesting protein or other yolk components were preferentially used for energy. Total percentage of MUFA decreased during development, which indicated MUFA were the primary lipid catabolized for energy during embryonic development. Total percentage of PUFA increased during development, driven largely by an increase in 22:6(n-3). Temperature did not influence percent lipid content or percent MUFA at any development stage, and had inconsistent effects on percent SFA and percent PUFA during development. Thus, lake whitefish embryos appear to be highly adapted to low temperatures, and do not alter lipids in response to temperature within their natural incubation conditions.
在鱼类胚胎发育过程中，脂质充当能量来源、结构成分和信号分子，并且脂质的利用可能随温度而变化。鉴于全球气候的变化，不同温度下胚胎的能量利用是一个重要的研究领域。因此，我们在三个孵化温度下，研究了湖白鲑（Coregonus clupeaformis）胚胎发育全过程中的脂质含量百分比和脂肪酸谱。我们在1.8、4.9和8.0°C的温度下长期孵化后，在原肠胚形成期、眼点期和鳍摆动期采集了受精卵和胚胎样本。在3.3、4.9和8.0°C的温度下孵化后，也采集了幼体样本。受精卵的初始干物质中脂质所占百分比很高（脂质含量百分比；约29%），其中约20%为饱和脂肪酸（SFA），约32%为单不饱和脂肪酸（MUFA），约44%为多不饱和脂肪酸（PUFA），还有4%未鉴定。最丰富的脂肪酸是16:0、16:1、18:1(n - 9c)、20:4(n - 6)、20:5(n - 3)和22:6(n - 3)。这种脂质谱与其他冷水鱼类物种的脂质谱相匹配。脂质含量百分比在胚胎发育过程中增加，这表明蛋白质或其他卵黄成分被优先用于提供能量。发育过程中单不饱和脂肪酸的总百分比下降，这表明单不饱和脂肪酸是胚胎发育过程中主要用于能量代谢的脂质。多不饱和脂肪酸的总百分比在发育过程中增加，这主要是由22:6(n - 3)的增加所驱动。温度在任何发育阶段都不影响脂质含量百分比或单不饱和脂肪酸百分比，并且在发育过程中对饱和脂肪酸百分比和多不饱和脂肪酸百分比的影响不一致。因此，湖白鲑胚胎似乎高度适应低温，并且在其自然孵化条件下不会因温度变化而改变脂质。
