Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal; Centre for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal.
CSIRO Agriculture and Food, Queensland Biosciences Precinct, St Lucia, QLD 4067, Australia; School of Agricultural and Food Sciences, The University of Queensland, St Lucia, QLD, 4067, Australia.
Comp Biochem Physiol A Mol Integr Physiol. 2019 May;231:170-176. doi: 10.1016/j.cbpa.2019.02.025. Epub 2019 Feb 25.
In aquaculture, there is high interest in substituting marine-derived with vegetable-based ingredients as energy source. Farmed carnivorous fish under high carbohydrate diets tend to increase adiposity but it remains unclear if this happens by increased lipid retention/accumulation, promotion of lipogenic pathways, or both. In order to determine the response of extrahepatic tissue to dietary starch, European (Dicentrarchus labrax) and Asian (Lates calcarifer) seabass were fed a control (low starch; LS) or experimental (high starch; HS) diet, for at least 21 days and then transferred for 6 days to saltwater enriched with deuterated water HO. Incorporation of H-labelling follows well-defined metabolic steps, and analysis of triacylglycerols (TAG) H-enrichment by HNMR allowed evaluation of de novo lipogenesis (DNL) in muscle and visceral adipose tissue (VAT). Fractional synthetic rates for TAG-bound fatty acids and glycerol were quantified separately providing a detailed lipogenic profile. The FA profile differed substantially between muscle and VAT in both species, but their lipogenic fluxes revealed even greater differences. In European seabass, HS promoted DNL of TAG-bound FA, in muscle and VAT. High H-enrichment also found in muscle TAG-bound glycerol was indicative of its role on lipid cycling. In Asian seabass, HS had no effect on muscle FA composition and lipogenic flux, with no H-enriched TAG being detected. VAT on the other hand revealed a strong enhancement of DNL in HS-fed fish along with high TAG-bound glycerol cycling. This study consolidated the use of HO as tracer for fish lipid metabolism in different tissues, under different dietary conditions and suitable to use in different fish models.
在水产养殖中，人们对用植物性成分替代海洋衍生成分作为能源非常感兴趣。在高碳水化合物饮食下养殖的肉食性鱼类往往会增加脂肪含量，但目前尚不清楚这是通过增加脂质保留/积累、促进脂肪生成途径还是两者兼而有之。为了确定肝外组织对膳食淀粉的反应，欧洲鲈鱼（Dicentrarchus labrax）和亚洲尖吻鲈（Lates calcarifer）分别用对照（低淀粉；LS）或实验（高淀粉；HS）饮食喂养至少 21 天，然后再转移到富含氘水 HO 的海水中 6 天。H 标记的掺入遵循明确的代谢步骤，通过 HNMR 分析三酰基甘油(TAG)的 H 富集，可以评估肌肉和内脏脂肪组织 (VAT)中的从头脂肪生成 (DNL)。TAG 结合脂肪酸和甘油的分数合成率分别进行量化，提供了详细的脂肪生成谱。在两种物种中，肌肉和 VAT 之间的 FA 谱差异很大，但它们的脂肪生成通量差异更大。在欧洲鲈鱼中，HS 促进了肌肉和 VAT 中 TAG 结合 FA 的 DNL。在肌肉 TAG 结合甘油中也发现了高 H 富集，表明其在脂质循环中的作用。在亚洲尖吻鲈中，HS 对肌肉 FA 组成和脂肪生成通量没有影响，没有检测到富含 H 的 TAG。另一方面，VAT 显示出 HS 喂养的鱼中 DNL 的强烈增强，同时伴随着高的 TAG 结合甘油循环。这项研究巩固了 HO 在不同组织中作为鱼类脂质代谢示踪剂的使用，适用于不同的饮食条件和鱼类模型。
