会议号：腾讯会议 962 487 520
Healthy Microalgae Culture Contributes to the Green and Sustainable Development of Aquaculture
Microalgae are closely related to the aquaculture. Microalgae with rich nutrients are important live prey. They can optimize water quality by absorbing excess ammonia nitrogen in water environment. In addition, microalgae containing various functional active substances can also improve the immunity and quality of aquatic animals. A large amount of microalgal biomass is the basis for promoting the application of microalgae in aquaculture. However, like aquatic animal diseases, microalgae cultures are also susceptible to the contamination by various micro-organisms, which is one of the main factors limiting the biomass production and application of microalgae. This project focused on the mixotrophic flagellate Poterioochromonas malhamensis, which was the main harmful organism in the Chlorella cultures. Firstly, the damage characteristics of the flagellate in Chlorella culture were analyzed from different angles, and the early monitoring technology based on qPCR method was established. On this basis, a series of effective prevention and control methods were developed. Meanwhile, Chlorella with anti-predation characteristics was screened, and the anti-predation mechanism was analyzed. On the other hand, we also established the high-density heterotrophic fermentation technology of flagellate. The flagellate biomass was also used to control the Microcystis bloom and produce the aquatic immunostimulant β-1, 3-glucan.
Physiological and molecular responses of Atlantic and Mediterranean sea bass lineages to hypersalinity : A comparative study
摘要：欧洲鲈鱼(Dicentrarchus labrax)会迁移到盐度超过50‰的栖息地，尤其是在地中海泻湖。 我们比较了大西洋和西地中海欧洲鲈鱼对高盐度的生理反应。重点研究了肾脏和肠道在溶质驱动的水重吸收中的作用。 同时分析肠内精氨酸血管后叶催产素和催产素受体(AVTR和ITR)的表达。将鱼从海水(SW, 36‰)转移到SW或高盐水(HW, 55‰)两周后采样。 与SW相比，HW组的肾小球变小，这表明盐度增加时，鲈鱼通过减少肾小球的过滤减少了水分损失。 暴露于高盐度环境的鱼类肾脏相对蛋白含量和NKA酶活性显著升高，两种欧洲鲈鱼离子转运增加。 肾水通道蛋白AQP1a免疫标记主要在不表达NKA和AQP1a的近端小管中检测到，aqp1a在HW中表达下调，提示55‰ aqp1a在溶质耦合吸水过程中作用有限。后肠中，HW中nka α1a、nkcc2、aqp8ab和aqp8aa mRNA表达量高于SW, AQP8ab蛋白相对表达量高于SW。 AQP8ab和NKCC2在肠上皮细胞的亚根尖定位可能表明Na+, Cl-和水吸收之间的功能联系。 在AVTR组中，v1a2组的mRNA水平最高，在鱼转移到HW后，v1a2组在肠道中表达较高。种内比较显示大西洋鲈鱼的血液渗透压在盐度转移后没有变化，但地中海鲈鱼在HW的渗透压高于SW。 在海水组的后肠中观察到地中海鲈鱼NKA活性和溶质耦合吸水有关的几个基因表达相对大西洋鲈鱼较高，这很可能反映了在欧洲鲈鱼谱系中与离子驱动吸水有关的机制的适应性差异。
The European sea bass (Dicentrarchus labrax) migrates towards habitats where salinity can reach levels over 50 ‰, notably in Mediterranean lagoons. We compared physiological responses of Atlantic and West Mediterranean sea bass to hypersalinity. We focused on the role of the kidney and intestine in solute-driven water reabsorption. Intestinal arginine vasotocin and isotocin receptor (AVTR and ITR) expression were also analyzed. Fish were sampled following a two-week transfer from seawater (SW, 36 ‰) to either SW or hypersaline water (HW, 55 ‰). A decreased renal glomerulus size was measured in HW compared to SW indicating that sea bass minimize water loss through urine upon salinity increase. Renal relative protein amounts and activity of Na+/K+-ATPase (NKA) were significantly higher in fish exposed to hypersalinity regardless of their origin indicating increased ion transport. Renal aquaporin 1a (AQP1a) immunolabeling was mainly detected in proximal tubules that do not express NKA and aqp1a, aqp1b were downregulated in HW suggesting a limited role of AQP1 in solute-coupled water uptake at 55 ‰. In the posterior intestine, nka α1a, nkcc2, aqp8ab and aqp8aa mRNA expressions were higher in HW compared to SW as well as relative protein expression of AQP8ab. The sub-apical localization of AQP8ab and apical localization of Na+/K+, 2Cl- cotransporter (NKCC2) in enterocytes could indicate a functional link between Na+, Cl- and water uptake. Among AVTR paralogs, highest mRNA levels were recorded for v1a2 paralog which showed a higher expression in D. labrax intestine after transfer of fish to HW. Intraspecific comparisons showed that blood osmolality was unchanged in Atlantic sea bass following salinity transfer but was higher in Mediterranean sea bass in HW compared to SW. Differences between D. labrax lineages were observed in posterior intestines of fish maintained in SW regarding NKA activities and the expression of several genes involved in solute-coupled water uptake with significantly higher levels in Mediterranean sea bass, most likely reflecting adaptive differences in mechanism linked to ion-driven water reuptake within D. labrax lineages.