抗除草剂海洋微藻的生长和积累EPA的特性

在群体水平上研究了海产野生型眼点拟微球藻(Nannochloropsis oculata)及其抗除草剂Sandoz9785的细胞培养物在生长和脂肪酸组成方面的特性。结果表明,野生型藻株对Sandoz 9785较为敏感,除草剂用量为50μmol·L~(-1)时其生长的被抑制率为75％。在除草剂抑制作用下,野生型细胞的总脂肪酸含量显著下降,而EPA含量显著提高。在160μmol·L~(-1)和320μmol·L~(-1)Sandoz 9785浓度下,筛选到抗除草剂的细胞培养物R160和R320,其平均比生长速率与野生型没有显著差异,细胞的总脂肪酸、16;0、16:1ω9、18:0和18:1ω9的含量都低于野生型藻株,但20:5ω3(EPA)含量则高于野生型。R160在无除草剂的培养基中EPA含量最高,可占细胞干重的3.51％,比野生型提高了30％,但与野生型差异不显著。并讨论了抗性培养物抗Sandoz 9785和积累 EPA的机理。     

Microalgae: a novel ingredient in nutrition

Microalgae are known for centuries, but their commercial large-scale production started a few decades ago. They can be grown in open-culture systems such as lakes or highly controlled close-culture systems, have higher productivity than the traditional crops and can be grown in climatic conditions and regions where other crops cannot be grown, such as desert and coastal areas. The edible microalgae are the green algae (chlorophyta) and the cyanobacteria. Microalgae contain substances of high biological value, such as polyunsaturated fatty acids, proteins, amino acids, pigments, antioxidants, vitamins and minerals. They are promising sources for novel products and applications and they can be used in the diet of humans and animals as natural foods with health benefits. Moreover, they can find use in the protection of the environment, as well as in pharmaceuticals, biofuel production and cosmetics.     

海洋微藻抗肿瘤及抗氧化活性初筛

目的 对90株海洋微藻的提取物进行了体外抗肿瘤和抗氧化活性筛选,从中寻找活性微藻藻株.方法以细胞凋亡诱导、细胞坏死以及自由基清除为活性指标,采用SRB,TLC自显影技术和DPPH方法进行抗肿瘤以及抗氧化活性筛选,并对活性藻株代谢产物进行了HPLDUV分析.结果与结论发现5株微藻的提取物具有抗肿瘤活性、1株微藻的提取物具有抗氧化活性.HPLC-UV分析表明,其抗氧化活性可能与具有400nm最大紫外吸收的化合物有关.     

藻类脂肪酸分离提纯及检测

报道了藻类脂肪酸用索氏提取器提取脂肪，甲酯化后用气相色谱仪测定的方法，从单细胞藻类中提取脂肪酸必须破细胞壁后再用乙醚浸泡，提取的时间要达12h以上，大型藻类不用破壁，室温下用乙醚浸泡24h，再用索氏法提取5h左右即可，脂溶性色素含量较高的样品，用乙醚提取的脂肪要在检测之前用活性炭和硅藻土进行脱色，两种物质的量要适宜，否则将影响脂肪酸的含量，硅胶G－CMC混合薄层层析（正己烷，乙酸乙酯85：15为展层剂，10％磷钼酸乙醇液为显色剂），是快速检测脂肪酸的方法，计算脂肪酸的含量时，仅能计算加入石油醚和苯的上层体积，因为下层不含有脂肪酸。     

Boar sperm quality after supplementation of diets with omega‐3 polyunsaturated fatty acids extracted from microalgae

This study evaluated effects of diet supplementation with omega‐3 polyunsaturated fatty acids (PUFA) from microalgae on boar sperm quality. Two groups of boars (n = 3 each) were fed during 75 days either a commercial diet (control), or the same diet supplemented with omega‐3 PUFA from the heterotrophic microalgae Schizochytrium sp. (120 g/kg). Sixteen ejaculates were collected per boar. Some sperm kinetics parameters were inferior for supplemented than for control boars (p < .05): distance average path; distance in both curved and straight line; velocity average path, velocity in both curved and straight line; and amplitude of lateral head displacement. Spermatozoa from supplemented boars presented lower mitochondrial functionality, but greater membrane fluidity compared to the control group (p < .01). Membrane and acrosome integrity, production of reactive oxygen species and lipid peroxidation did not differ (p > .05). Serum cholesterol levels were greater (p < .05) for supplemented than for control boars at the 30th and 60th d of supplementation, but levels of triglycerides and IGF‐1 did not differ (p > .05). Compared to the control, spermatozoa of supplemented boars were slower, travelled shorter distances and presented impaired energy metabolism, but their greater membrane fluidity may potentially favour their cryopreservation.     

Hypocholesterolemic effects of nutraceuticals produced from the red microalga Porphyridium sp in rats

Red microalgae contain functional sulfated polysaccharides (containing dietary fibers), polyunsaturated fatty acids, zeaxanthin, vitamins, minerals, and proteins. Studies in rat models support the therapeutic properties of algal biomass and isolated polysaccharides. Algal products incorporated into rat diets were found to significantly improve total serum cholesterol, serum triglycerides, hepatic cholesterol levels, HDL/LDL ratios and increased fecal excretion of neutral sterols and bile acids. Morphological and metabolic changes were induced by consumption of algal products. These results suggest that red microalgae can be used as potent hypocholesterolemic agents, and they support the potential use of red microalgae as novel nutraceuticals.     

4株经济海洋微藻细胞生长的实验室研究

目的研究角毛藻Chaetocerossp．、绿色巴夫藻Pavlovaviridis、叉鞭金藻Dirateriainornate和杜氏盐藻Dunaliella salina4株经济海洋微藻的细胞生长特性,为微藻在医药学相关行业的开发与应用提供参考依据。方法采用室内实验方法,以添加f／2营养液的人工海水为培养介质,在植物培养箱中利用三角瓶进行微藻培养试验,测定微藻细胞密度,并计算细胞生长速率。结果4株经济海洋微藻的细胞生长呈现明显的缓慢期、快速期和平稳期阶段。角毛藻、绿色巴夫藻、叉鞭金藻和杜氏盐藻的最大细胞密度有明显差别,分别为6．71×10^6、4．916×10^7、1．225×10^7和4．64×10^6个／mL。对4株微藻在1—5d、5～9d、9～13d和13～17d几个时间段的生长速率进行比较分析,结果表明角毛藻、绿色巴夫藻、叉鞭金藻的生长速率在1～5d阶段最大,分别为0．57、0．48、0．55／d;而杜氏盐藻的生长速率在5～9d阶段最大,为0．68／d。结论实验选用的4株海洋微藻的细胞生长特征存在一定异同,在选育微藻株系开展微藻开发利用研究时应该考虑微藻细胞生长繁殖的差异性。     

Mechanism of long-term toxicity of CuO NPs to microalgae

Abstract

Little is known regarding the detailed mechanism of CuO NPs’ toxicity to microalgal primary metabolism pathway. Photosynthesis and respiration are the most important primary metabolism and the main sources of production of reactive oxygen species (ROS), but the effect of CuO NPs on both of them has not been systematically studied to date. Our research demonstrated that long-term treatment with CuO NPs significantly inhibited activities of photosynthesis and respiration in microalgae, and the photosynthesis was more sensitive to the toxicity of CuO NPs than respiration. CuO NPs could be absorbed by microalgae and be converted into Cu₂O NPs concentrated in chloroplast. The internalized Cu, regardless of whether the exposure was Cu²⁺ or CuO NPs had the same capacity to damage chloroplast structure. The result also shows that the oxygen-evolving complex (OEC) in the photosynthetic electron transport chain was the most sensitive site to CuO NPs and Cu²⁺-treated microalgae had the same damage site as that of CuO NPs, which may be related to the Mn cluster that is dissociated by Cu ions released from CuO NPs. The damage of OEC inhibited photosynthetic electron transport to increase excess excited energy, which caused the accumulation of ROS in chloroplast. The accumulation of ROS damaged the structure of cell membrane and aggravated the PSII photoinhibition, further decreasing the efficiency of light energy utilization. In conclusion, the Cu ionic toxicity of photosynthetic apparatus by CuO NPs resulted in the carbon starvation and the accumulation of ROS to inhibit the growth of microalgae.     

Effects of microalgal polyunsaturated fatty acid oil on body weight and lipid accumulation in the liver of C57BL/6 mice fed a high fat diet

Dietary polyunsaturated fatty acids (PUFAs), which are abundant in marine fish oils, have recently received global attention for their prominent anti-obesogenic effects. Among PUFAs, eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), which are n-3 long-chain PUFAs widely referred to as omega-3 oils, were reported to prevent the development of obesity in rodents and humans. In the present study, we evaluated the anti-obesity effects of microalgal oil on high-fat induced obese C57BL/6 mice, compared with commercial omega-3 fish oil and vegetable corn oil. Microalgal oil is an inherent mixture of several PUFAs, including EPA, DHA and other fatty acids produced from a marine microalgal strain of Thraustochytriidae sp. derived mutant. It was found to contain more PUFAs (>80%) and more omega-3 oils than commercial omega-3 fish oil (PUFAs >31%) and corn oil (PUFAs 59%). All three types of oils induced weight loss in high-fat-induced obese mice, with the loss induced by microalgal oil being most significant at 9 weeks (10% reduction). However, the oils tested did not improve blood lipid levels, although microalgal oil showed an apparent inhibitory effect on lipid accumulation in the liver. These findings may be attributed to the higher PUFA content, including omega-3 oils of microalgal oil than other oils. Collectively, these findings suggest that microalgal oil, derived from Thraustochytriidae sp. derived mutant, is a prominent candidate for replacement of omega-3 fish oils based on its apparent anti-obesity effect in vivo.