Immunostimulants are key molecules in aquaculture since they heighten defensive responses and protection against pathogens. The present study investigated the treatment of Senegalese sole larvae with a whole-cell crude extract of the microalgae Nannochloropsis gaditana (Nanno) and programming of growth and the immune system. Larvae at hatch were treated with the Nanno extracts for 2 h and thereafter were cultivated for 32 days post-hatch (dph) in parallel with an untreated control group (CN). Dry weight and length at 21 days post-hatch (dph) were higher in post-larvae of the Nanno than CN group. These differences in weight were later confirmed at 32 dph. To evaluate changes in the immune response associated with Nanno-programming treatments, the Nanno and CN post-larvae were supplied with two bioactive compounds yeast β-glucan (Y) and a microalga extract from the diatom Phaeodactylum tricornutum (MAe). The bioactive treatments were administrated to the treatment groups through the live prey (artemia metanauplii, 200 artemia mL⁻¹) enriched for 30 min with MAe or Y (at 2 mg mL⁻¹ SW) or untreated prey in the case of the negative control (SW). The effect of the treatments was assessed by monitoring gene expression, enzyme activity and mortality over 48 h. The post-larvae sole supplied with the bioactive compounds Y and MAe had increased mortality at 48 h compared to the SW group. Moreover, mortality was higher in Nanno-programmed than CN post-larvae. Lysozyme and total anti-protease enzymatic activities at 6 and 24 h after the start of the trial were significantly higher in the Nanno and MAe supplied post-larvae compared to their corresponding control (CN and SW, respectively). Immune gene transcripts revealed that il1b, cxc10 and mx mRNAs were significantly different between Nanno and CN post-larvae at 6 and 24 h. Moreover, the expression of il1b, tnfa, cxc10, irf3, irf7 and mx was modified by bioactive treatments but with temporal differences. At 48 h after bioactive treatments, Y and SW post-larvae were challenged with the lymphocystis disease virus (LCDV). No difference existed in viral copy number between programming or bioactive treatment groups at 3, 6 and 24 h after LCDV challenge although the total number of copies reduced with time. Gene expression profiles in the LCDV-challenged group indicated that post-larvae triggered a wide defensive response compared to SWC 24 h after challenge, which was modulated by programming and bioactive compound treatments. Cluster analysis of expressed genes separated the SW and Y groups indicating long-lasting effects of yeast β-glucan treatment in larvae. A noteworthy interaction between Nanno-programming and Y-treatment on the regulation of antiviral genes was observed. Overall, the data demonstrate the capacity of microalgal crude extracts to modify sole larval plasticity with long-term effects on larval growth and the immune responses.

免疫刺激剂是水产养殖中的关键分子，因为它们可增强防御反应并防御病原体。本研究调查了微藻Nannochloropsis gaditana的全细胞粗提物对塞内加尔唯一幼虫的处理（Nanno）以及生长和免疫系统的程序设计。孵化后的幼虫用Nanno提取物处理2小时，然后与未处理的对照组（CN）平行孵化（dph）培养32天。Nanno幼体孵化后21天的干重和长度（dph）高于CN组。这些重量差异随后在32 dph时得到确认。为了评估与Nanno编程治疗相关的免疫反应的变化，为Nanno和CN幼虫提供了两种生物活性化合物酵母β-葡聚糖（Y）和来自硅藻Phaeodactylum tricornutum（MAe）的微藻提取物。通过活体猎物将生物活性治疗剂给予治疗组（卤虫无节肢动物，200卤虫mL ^-1） 在阴性对照（SW）的情况下用MAe或Y（2 mg mL ^-1 SW）或未经处理的猎物富集30分钟。通过监测48小时内的基因表达，酶活性和死亡率来评估治疗效果。与SW组相比，提供有生物活性化合物Y和MAe的幼虫后鞋底在48小时时死亡率增加。此外，Nanno程序设计的死亡率高于幼虫后CN。在试验开始后的6和24小时，幼虫后提供的Nanno和MAe的溶菌酶和总抗蛋白酶的酶活性明显高于其相应的对照（分别为CN和SW）。免疫基因转录本显示il1b，cxc10和mx mRNA在6和24小时，Nanno和CN幼虫之间的差异显着。此外，il1b，tnfa，cxc10，irf3，irf7和mx的表达通过生物活性疗法进行了修饰，但存在时间差异。生物活性治疗后48小时，幼虫后Y和SW受到淋巴囊病病毒（LCDV）的攻击。在LCDV攻击后3、6和24小时，程序或生物活性治疗组之间的病毒拷贝数没有差异，尽管拷贝总数随时间减少。LCDV攻击组的基因表达谱表明，与攻击后24小时的SWC相比，幼虫后引发了广泛的防御反应，这是通过程序设计和生物活性化合物处理来调节的。表达基因的聚类分析将SW和Y组分开，表明酵母β-葡聚糖处理对幼虫具有持久作用。观察到Nanno编程和Y处理之间抗病毒基因调控之间的值得注意的相互作用。总体，