School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, Shandong 266237, China.
School of Agriculture, Ludong University, Yantai, Shandong 264025, China.
J Agric Food Chem. 2021 Dec 15;69(49):14802-14809. doi: 10.1021/acs.jafc.1c04731. Epub 2021 Dec 1.
Compound-specific stable isotope analysis of individual amino acids (AAs) has been widely used in studies on food webs, resource tracing, and biochemical cycling. In the present study, juvenile sea cucumbers were fed the microalga (CF) or (ST) during a 130-day experiment. The δC values of individual AAs in the experimental diet and body wall of sea cucumbers were determined to calculate the variability in carbon isotopic fractionation (ΔC) and elucidate the isotopic routing of essential AAs and biosynthesis of nonessential AAs. The results showed that the sea cucumbers fed with diet CF had higher specific growth and ingestion rates but relatively lower feed conversion efficiency compared to those fed with diet ST. The experimental diets were generally less abundant in nonessential AAs (i.e., glycine, serine, aspartic acid, and arginine) but more abundant in essential AAs (i.e., isoleucine, leucine, lysine, phenylalanine, and histidine) than body walls. The fluctuations in the δC values of total AAs analyzed were 19.8 ± 4.6‰ for diets and 21.3 ± 2.7‰ for body walls. Serine and threonine were C-enriched AAs, while leucine and phenylalanine were C-depleted AAs. The diet ST treatment exhibited more positive ΔC values of nonessential AAs (e.g., glycine, alanine, aspartic acid, and proline) compared to diet CF. There were significant negative relationships between ΔC values and differences in nonessential AA percent abundance between the experimental diets and body walls of sea cucumber (for diet CF: = -0.79 - 0.56, = 0.47; diet ST: = 0.75 - 0.29, = 0.51), which implied the flexibility in the routing of various dietary macronutrients (protein, lipids, and carbohydrates) by sea cucumber. This study can greatly provide a new understanding of nutrient utilization and metabolism routing during juvenile sea cucumber culturing.
对单个氨基酸 (AAs) 的稳定同位素组成进行的化合物特异性分析已广泛应用于食物网研究、资源追踪和生物化学循环。在本研究中，在 130 天的实验中，幼海参被喂食微藻 (CF) 或 (ST)。测定实验饲料和海参体壁中单个 AAs 的 δC 值，以计算碳同位素分馏 (ΔC) 的可变性，并阐明必需 AAs 的同位素路径和非必需 AAs 的生物合成。结果表明，与喂食 ST 饲料的海参相比，喂食 CF 饲料的海参具有更高的特定生长率和摄食率，但相对较低的饲料转化率。实验饲料一般比体壁含有较少的非必需 AAs（即甘氨酸、丝氨酸、天冬氨酸和精氨酸），但含有更多的必需 AAs（即异亮氨酸、亮氨酸、赖氨酸、苯丙氨酸和组氨酸）。分析的总 AAs 的 δC 值波动范围为饲料 19.8 ± 4.6‰，体壁 21.3 ± 2.7‰。丝氨酸和苏氨酸是 C 富集的 AAs，而亮氨酸和苯丙氨酸是 C 耗尽的 AAs。与 CF 饲料处理相比，ST 饲料处理的非必需 AAs（如甘氨酸、丙氨酸、天冬氨酸和脯氨酸）的 ΔC 值更呈正相关。ΔC 值与实验饲料和海参体壁中非必需 AA 百分丰度之间的差异呈显著负相关（对于 CF 饲料： = -0.79 - 0.56， = 0.47；ST 饲料： = 0.75 - 0.29， = 0.51），这意味着海参对各种饲料宏量营养素（蛋白质、脂肪和碳水化合物）的路由具有灵活性。本研究可以极大地为幼海参养殖过程中营养利用和代谢路由提供新的认识。
