Chinese Sturgeon Research Institute, China Three Gorges Corporation, Yichang, 443100, Hubei, China.
Hubei Key Laboratory of Three Gorges Project for Conservation of Fishes, Yichang, 443100, Hubei, China.
Sci Rep. 2020 Oct 15;10(1):17399. doi: 10.1038/s41598-020-74120-x.
In this study, the effects of different feeding frequencies on the growth and the expression of genes in the GH/IGF axis were assessed in juvenile Chinese sturgeon. The newly hatched Chinese sturgeons were bred for 38 days at three different feeding frequencies groups (feeding frequency of two times a day, TWD; three times a day, THD; and four times a day, FOD), and the expression levels of the GH/IGF axis responses to feeding frequency were determined by quantitative real-time PCR. In addition, the full-length of the Coding Sequences of IGF I and IGF II genes (489-bp and 660-bp, respectively), were cloned and analyzed from Chinese sturgeon the first time. Multiple sequence alignments of IGFs revealed that Chinese sturgeon are high sequence identity to IGFs from other species. The phylogenetic relationships based on the IGF I and IGF II amino acid sequences were consistent with the traditional classification. After 38 days of growth, the three different feeding frequencies groups of Chinese sturgeon had no significant difference of body length, body weight, specific growth rate, the survival rate, the rate of weight gain and the condition factor. However, the relative expression of Chinese sturgeon GH in the pituitary decreased with increasing feeding frequency. The relative expression of Chinese sturgeon GHR in liver and skeletal muscle was deceased with increasing feeding frequency, while the relative expression of GHR in stomach and intestines at THD group was significantly higher than that of at TWD group and FOD group (p < 0.05). The relative expression of Chinese sturgeon IGF I in liver increased significantly with increasing feeding frequency (p < 0.05). The relative expression of IGF I in stomach and skeletal muscle was similar at the three groups. The relative expression of IGF I in intestines was significantly higher at FOD group than at TWD group and THD group (p < 0.05). The relative expression of Chinese sturgeon IGF II in liver at TWD group was significantly higher than that at THD group and FOD group (p < 0.05). However, the relative expression of IGF II in stomach, intestines and skeletal muscle at THD group was higher than that at TWD group and FOD group. Based on these previous studies that liver IGF I is regarded as a biomarker of growth performance, this result suggested that the juvenile Chinese sturgeon is better for growth when feeding four times daily compared to twice and thrice daily.
在这项研究中，评估了不同投喂频率对幼龄中华鲟生长和 GH/IGF 轴基因表达的影响。将刚孵化的中华鲟饲养 38 天，分为三组不同的投喂频率（每天投喂两次，TWD；每天投喂三次，THD；每天投喂四次，FOD），通过定量实时 PCR 测定 GH/IGF 轴对投喂频率的反应表达水平。此外，首次从中华鲟中克隆并分析了 IGF I 和 IGF II 基因的全长编码序列（分别为 489-bp 和 660-bp）。IGFs 的多重序列比对显示，中华鲟与其他物种的 IGFs 具有高度的序列同一性。基于 IGF I 和 IGF II 氨基酸序列的系统发育关系与传统分类一致。生长 38 天后，三组中华鲟的体长、体重、特定生长率、成活率、增重率和体质量指数无显著差异。然而，垂体中华鲟 GH 的相对表达随投喂频率的增加而降低。肝和骨骼肌中中华鲟 GHR 的相对表达随投喂频率的增加而降低，而 THD 组胃和肠中的 GHR 相对表达明显高于 TWD 组和 FOD 组（p<0.05）。肝中中华鲟 IGF I 的相对表达随投喂频率的增加而显著增加（p<0.05）。三组胃和骨骼肌中 IGF I 的相对表达相似。肠中 IGF I 的相对表达在 FOD 组显著高于 TWD 组和 THD 组（p<0.05）。TWD 组肝中中华鲟 IGF II 的相对表达明显高于 THD 组和 FOD 组（p<0.05）。然而，THD 组胃、肠和骨骼肌中 IGF II 的相对表达高于 TWD 组和 FOD 组。基于之前的研究认为肝 IGF I 是生长性能的生物标志物，这一结果表明，与每天投喂两次和三次相比，每天投喂四次更有利于幼龄中华鲟的生长。
