Primavera-Tirol Y H, Coloso R M, Quinitio G F, Ordonio-Aguilar R, Laureta L V
Southeast Asian Fisheries Development Center-Aquaculture Department, 5021, Tigbauan, Iloilo, Philippines,
Fish Physiol Biochem. 2014 Apr;40(2):607-24. doi: 10.1007/s10695-013-9870-y. Epub 2013 Oct 2.
Enterocytes of the anterior to midsection of the intestine in grouper Epinephelus coioides larvae were compared among different treatments: unfed to the point-of-no-return (PNR), fed natural food only, and co-fed natural food and artificial diet. On day 3, the nutritional condition of unfed grouper larvae regressed with its reduced enterocyte heights which were further degraded on day 4, the PNR, when all the enterocytes were in advanced stages of apoptosis. The apoptosis appeared to be internally directed via the mitochondria. Among day 3 fed larvae, enterocyte heights of those fed artificial diet did not differ from those fed natural food only. Dietary phospholipid deficiency was indicated in larvae co-fed artificial diet on day 3 with an unusually large chylomicron opening into the inter-enterocyte space, and on days 6 and 33 by intestinal steatosis. On day 19, scant to absent lipid droplets in enterocytes of larvae disclosed heightened nutritional requirement preparatory to metamorphosis. As observed in unfed day 3 and premetamorphic day 19 E. coioides, larvae undergoing critical periods and starvation during development employ apoptosis to dispose of degenerated enterocytes that are phagocytosed by adjacent healthy enterocytes without causing inflammatory distress. Upon metamorphosis, grouper larval gut develops better immunity fitness with eosinophilic granule cells observed in the intestinal epithelia of day 33 larvae. Future studies on grouper larval nutrition may consider the appropriate dietary phospholipid levels and larval competence to biosynthesize highly unsaturated fatty acid from linoleic acid vis-à-vis the use of plant ingredients in artificial diet formulations. In vivo challenge tests may validate appropriate dietary nutrient supplementation and lead to better feed formulation, matching the varying energetic demands and digestive capacities of developing E. coioides larvae.
饥饿至不可逆点（PNR）、仅投喂天然食物以及同时投喂天然食物和人工饲料。在第3天，饥饿的石斑鱼仔鱼营养状况变差，肠上皮细胞高度降低，在第4天即PNR时进一步退化，此时所有肠上皮细胞都处于凋亡晚期。凋亡似乎是通过线粒体由内部引发的。在第3天投喂的仔鱼中，投喂人工饲料的仔鱼肠上皮细胞高度与仅投喂天然食物的仔鱼没有差异。在第3天同时投喂人工饲料的仔鱼中，膳食磷脂缺乏表现为异常大的乳糜微粒进入肠上皮细胞间隙，在第6天和第33天则表现为肠道脂肪变性。在第19天，仔鱼肠上皮细胞中脂质小滴稀少或没有，这表明在变态前营养需求增加。正如在未投喂的第3天和变态前的第19天的斜带石斑鱼中观察到的那样，在发育过程中经历关键时期和饥饿的仔鱼利用凋亡来清除退化的肠上皮细胞，这些细胞被相邻的健康肠上皮细胞吞噬，不会引起炎症反应。变态后，石斑鱼仔鱼肠道的免疫适应性增强，在第33天仔鱼的肠道上皮中观察到嗜酸性粒细胞。未来关于石斑鱼仔鱼营养的研究可能会考虑合适的膳食磷脂水平以及仔鱼从亚油酸生物合成高度不饱和脂肪酸的能力，以及在人工饲料配方中使用植物成分的情况。体内攻毒试验可以验证合适的膳食营养补充，并有助于制定更好的饲料配方，以满足发育中的斜带石斑鱼仔鱼不同的能量需求和消化能力。
