A study was conducted to investigate the effects of dietary n‐3 LC‐PUFA on the growth performance, fatty acid profile, transcription of related genes and intestinal microflora in adult sea urchin (Strongylocentrotus intermedius). Kelp (Laminaria japonica) and four formulated feeds with graded levels of n‐3 LC‐PUFA (0%, 0.5%, 0.8% and 1.0% dry diet) were prepared as the experimental diets. Each diet was randomly allocated to ten adult sea urchin individuals. The feeding period lasted for 90 days. Results showed that gonadosomatic index (GSI) of adult S. intermedius fed formulated feeds was significantly higher than that fed kelp (p < 0.05), while weight gain rate (WGR) showed no significance between kelp and feed groups (p > 0.05). Neither WGR nor GSI showed significant differences among the four feed treatments (p > 0.05). Notably, ARA and EPA in the gonads of S. intermedius fed the feeds devoid of n‐3 LC‐PUFA were comparable to that fed the feeds with 0.5% n‐3 LC‐PUFA (p > 0.05). Transcription of Elovl4 and Δ5‐desaturase in the intestine and gonad significantly decreased as dietary n‐3 LC‐PUFA increased (p < 0.05). Proteobacteria and Bacteroidetes (phylum level) and Psychromonas and Sulfurimonas (genus level) were the most abundant bacteria species in the intestine of S. intermedius. The abundance of Sulfurimonas was comparable in the S. intermedius fed kelp and the feed with 0% n‐3 LC‐PUFA, which was significantly higher than that fed the other formulated feeds (p < 0.05). These results indicated that S. intermedius seems to have a low requirement for n‐3 LC‐PUFA to sustain its normal growth and gonad development. The increased transcription of rate‐limiting enzymes (Elovl4 and Δ5‐desaturase) could be responsible for the considerable amounts of EPA and ARA in the gonads of S. intermedius when fed feeds without LC‐PUFA. The intestinal microflora were affected to a certain extent by the die categories and the n‐3 LC‐PUFA in the formulated feeds. It is speculated that some unknown bacteria in the genus of Sulfurimonas could participate in the synthesis of LC‐PUFA.

中文翻译：

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日粮n-3 LC-PUFA对成年海胆（Strongylocentrotus intermedius）生长性能，性腺发育，脂肪酸谱，相关基因转录和肠道菌群的影响

进行了一项研究，以研究日粮n-3 LC-PUFA对成年海胆（Strongylocentrotus intermedius）的生长性能，脂肪酸谱，相关基因的转录和肠道菌群的影响。准备了海带（Laminaria japonica）和四种配方饲料，其中n-3 LC-PUFA的分级水平为干饲料（0％，0.5％，0.8％和1.0％）作为实验饲料。每种饮食被随机分配给十个成年海胆个体。喂养期持续90天。结果表明成人的那性腺指数（GSI）S.中间型馈配方饲料比馈海带（显著更高P <  0.05），而增重率（WGR）显示海带和饲料组之间没有显着性（p  > 0.05）。在四种饲料处理中，WGR和GSI均未显示出显着差异（p  > 0.05）。值得注意的是，在不含n-3 LC-PUFA的饲料中，中间链球菌性腺中的ARA和EPA与添加0.5％n-3 LC-PUFA的饲料中的ARA和EPA相当（p  > 0.05）。随着日粮n-3 LC-PUFA的增加，肠和性腺中Elovl4和Δ5-去饱和酶的转录显着降低（p <  0.05）。变形菌和拟杆菌（门级）和Psychromonas和Sulfurimonas（属级）是在肠道内最丰富的菌种S.中间型。丰富的在中间链球菌饲喂的海带和含0％n-3 LC-PUFA的饲料中，磺脲类具有可比性，明显高于其他配方饲料（p <  0.05）。这些结果表明，中间链球菌对n-3 LC-PUFA维持其正常生长和性腺发育的要求较低。当饲喂不添加LC-PUFA的饲料时，间质链球菌性腺中限速酶（Elov14和Δ5-去饱和酶）的转录增加可能是导致EPA和ARA含量增加的原因。肠道微生物区系在一定程度上受模具类型和配制饲料中n-3 LC-PUFA的影响。据推测，一些不明细菌属磺脲类可能参与LC-PUFA的合成。