湛江等鞭金藻的超微结构研究

用光学（相差）显微镜、扫描电镜和透射电镜观察了湛江等鞭金藻的外部形态和内部结构。湛江等鞭金藻有两条比藻体略长的鞭毛,两鞭毛几乎等长,光滑、无突起和纤毛。藻体表面无鳞片包被。细胞内有一整块怀形色素体,细胞核在怀形色素体中,白糖素１～２个位于细胞中前部。细胞内有线粒体、内质网和高尔基体,还有由两个椭圆形小体组成的眼点都位于细胞的前端。     

氮浓度对球等鞭金藻3011和8701叶绿素荧光特性及生长的影响

在温度(23±1)℃,盐度31,光照度5000 lx的条件下,研究不同氮浓度(0、55、440、880、1760、7040μmol/L)培养基对球等鞭金藻3011和8701光系统Ⅱ(PSⅡ)最大光能转化效率(Fv/Fm)、叶绿素含量以及细胞密度的影响。单因子方差分析表明,氮浓度对2株微藻的光合作用及生长均有显著影响(P<0.05)。3011的Fv/Fm、叶绿素含量及细胞密度均随着起始氮浓度的增加而增加,在7040μmol/L时达到最大值;8701的Fv/Fm、叶绿素含量及细胞密度均随着起始氮浓度的增加而增加,在440μmol/L时达到最大值,其后随氮浓度的增加其上述指标反而下降。3011和8701进行光合作用和生长的最适氮浓度分别为7040μmol/L和440μmol/L。     

Effects of single and combined microalgae on larval growth, development and survival of the commercial sea cucumber Holothuria spinifera Theel

The results of the study on the suitable algal feed for the mass rearing of holothurian larvae through hatchery system are presented. Auricularia larvae, after 48 h of fertilization, obtained from induced spawning of Holothuria spinifera, were fed with different algae Isochrysis galbana, Nanochloropsis salina, Pavlova lutheri, Tetraselmis chuii and Chaetoceros calcitrans as well as I. galbana+C. calcitrans to ascertain the effect of single and combined microalgal diet. The rate of feeding was 2 × 10⁴ cells larvae^–1 day^–1 for a period of 9–12 days. The growth rate of 59 μm day⁻¹ with 90% and 43 μm day⁻¹ with 100% occurrence of late auricularia in the larvae fed with C. calcitrans alone and I. galbana+C. calcitrans, respectively, indicated that C.calcitrans itself or in combination with I. galbana is the effective feed for the larvae of H. spinifera.     

3种饵料金藻的超低温保存研究↑（*）

用两步冷冻法研究绿色巴夫藻（Ｐａｖｌｏｖａｖｉｒｉｄｉｓ）、湛江等鞭金藻（Ｉｓｏｃｈｒｙｓｉｓｚｈａｎｊｉａｎｇｅｎｓｉｓ）、球等鞭金藻（Ｉ．ｇａｌｂａｎａ３０１１）的超低温保存（液氮,－１９６℃）,探讨了影响存活率的内、外因素。结果表明,降温速率０．７℃／ｍｉｎ,预冻温度－４０℃,预冻时间３０ｍｉｎ时可获得较高的存活率。１５％ＤＭＳＯ或１５％ＤＭＳＯ＋１０％蔗糖是良好的抗冻保护剂。某些藻类在生长静止期或在低于最适温度下培养时可显著提高其存活率。通过控制内、外条件,３种金藻的存活率都可达到３０％以上,比以往的报道有显著提高。     

紫外线辐照对3种海洋微藻蛋白质含量的效应

［目的］为通过紫外线诱变育种的方法来提高海产单胞藻饵料蛋白质含量提供参考。［方法］采用波长为253.7 nm的紫外线,分别辐照盐藻、三角褐指藻以及湛江等鞭藻3种海洋微藻0、2、4、6、8、10 min,测定蛋白质含量,分析紫外线辐照对3种海洋微藻蛋白质含量的影响。［结果］紫外线辐照后,盐藻的蛋白质含量与对照相比,呈下降趋势, 由对照的6.70 mg/g,最低下降到2.32 mg/g;三角褐指藻经2～10 min照射,蛋白质含量均呈上升趋势,其中辐照时间2 min的处理上升幅度最大, 蛋白质含量升高到5.28 mg/g;湛江等鞭藻经过2、4、6 min的照射,蛋白质含量分别是对照的653%、737%和153%,明显增加,而经过8～10 min的照射,湛江等鞭藻死亡。［结论］紫外线辐照对不同藻类的蛋白质含量具有不同的效应。     

Analysis of light absorption and photosynthetic activity by Isochrysis galbana under different light qualities

The effect of light qualities, for example white light (WL), blue light (BL), red light (RL) and green light (GL), respectively, provided by the LEDs on the growth, pigment content, light absorption and chlorophyll fluorescence parameters of Isochrysis galbana strain IOAC724S was measured. The growth rate of algae exposed to GL was not significantly different from that of WL, but was significantly higher than that of blue light (BL) or red light (RL). These four light colours were all efficiently absorbed by algal cells, with an absorption rate up to 92%–93%. The light absorbed by pigments contributes only part of the light absorbed by cells, ranging from 8.3% (at RL) to 59.7% (at BL). Among the monochromatic light, the highest light absorption was obtained in cells cultivated at BL, but the photochemical reaction was lowered. No positive effect of monochromatic RL was found. Cells cultivated at BL and RL were, respectively, restricted by down‐regulated photosynthetic efficiency and sufficient light absorption; meanwhile, GL showed a dramatic increase in photosynthetic efficiency, associated with a light absorption close to that for cells exposed to WL (both at 30.6%), suggesting that GL promotes the photosynthesis of I. galbana by balancing the light absorption and utilization.     

对虾育苗中常用海洋微藻抑菌作用的研究

研究了等鞭金藻、三角褐指藻、扁藻对对虾育苗中致病菌鳗弧菌、假单胞菌的抑菌效果。结果表明,等鞭金藻、三角褐指藻、扁藻的水溶性物质及脂溶性物质对鳗弧菌有抑制作用;等鞭金藻、三角褐指藻的水溶性物质及等鞭金藻、三角褐指藻、扁藻的脂溶性物质对假单胞菌有抑制作用。在抑菌试验中,等鞭金藻、三角褐指藻、扁藻密度达10×104/ml时,对对虾育苗池水的抑菌作用较好,特别是对弧菌的抑制效果明显。     

Do strain differences in microalgae alter their relative quality as a food for the rotifer Brachionus plicatilis?

Brachionus plicatilis is used in aquaculture to feed larval fish and crustaceans. It is well established that different prey species alter rotifer productivity. Isochrysis galbana is one microalgal prey that is commonly fed to rotifers, and there are several strains of this flagellate available to aquaculturists. As microalgae strains may differ in their composition and growth attributes, we rigorously examined if growth and biochemical differences in I. galbana strains elicit differences in the growth and biochemical attributes of B. plicatilis. Four I. galbana strains and one strain of the flagellate Nanochloropsis were grown under standard conditions. Growth rate, cell volume, production, and composition (dry weight, carbohydrate, protein, lipid) were measured. Significant differences occurred between strains in all of these attributes (at times 2 to 3 fold), but no clear pattern emerged that one strain was superior. Of note was that for some measurements, strain differences were significantly greater than differences between species. The strains were then fed to rotifers, and a number of parameters were measured: growth rate, reproductive rate, fecundity attributes, a number of developmental rates, and composition (dry weight, carbohydrate, protein, lipid). There were significant effects of prey strain on some of these attributes, but none was dramatic (rarely more than 10% and occasionally up to 30%), suggesting that aquaculturists need not be too concerned regarding which I. galbana strain they use. However, we do indicate subtle differences, induced by different prey strains and suggest that for maximum productivity these differences should be considered.     

Complementary Analytical Platforms of NMR Spectroscopy and LCMS Analysis in the Metabolite Profiling of Isochrysis galbana

This study was designed to profile the metabolites of Isochrysis galbana, an indigenous and less explored microalgae species. ¹H Nuclear Magnetic Resonance (NMR) spectroscopy and Liquid Chromatography-Mass Spectrometry (LCMS) were used to establish the metabolite profiles of five different extracts of this microalga, which are hexane (Hex), ethyl acetate (EtOAc), absolute ethanol (EtOH), EtOH:water 1:1 (AqE), and 100% water (Aq). Partial least square discriminant analysis (PLS–DA) of the generated profiles revealed that EtOAc and Aq extracts contain a diverse range of metabolites as compared to the other extracts with a total of twenty-one metabolites, comprising carotenoids, polyunsaturated fatty acids, and amino acids, that were putatively identified from the NMR spectra. Meanwhile, thirty-two metabolites were successfully annotated from the LCMS/MS data, ten of which (palmitic acid, oleic acid, α-linolenic acid, arachidic acid, cholesterol, DHA, DPA, fucoxanthin, astaxanthin, and pheophytin) were similar to those present in the NMR profile. Another eleven glycerophospholipids were discovered using MS/MS-based molecular network (MN) platform. The results of this study, besides providing a better understanding of I. galbana’s chemical make-up, will be of importance in exploring this species potential as a feed ingredient in the aquaculture industry.     

球等鞭金藻8701的耐低温机理

对耐低温品系球等鞭金藻８７０１在低温下与活性氧清除和伤害有关的几个生理生化指标进行了研究，探讨了其耐低温机理，并与该藻种的低温敏感品系球等鞭金藻３０１１进行了比较，结果表明，（１）球等鞭金藻８７０１在低温下（８℃）培养一周，其超氧化物歧化酶（ＳＯＤ）活性略有下降，但仍保持极高的酶活性，因此能够及时清除低温胁迫产生的过量活性氧，使其细胞内保持较低的膜脂过氧化水平和较低的电解质外渗率,（２）球等鞭金藻３０１１在低温下胁迫一周，其细胞内的膜脂过氧化水平和电解质在率大大高于球等鞭金藻８７０１，这与其ＳＯＤ活性较低，并且在低温下其活性大幅度下降有关，（３）与ＤＯＤ相比，两种不同品系球等鞭金藻的过氧化物酶（ＰＯＤ）对减轻其低温伤害，提高其耐低能力，不起主要作用。