海洋斯瓦尼氏菌(Shewanella sp.)的二十碳五烯酸合成基因簇在转基因的海洋聚球藻属蓝藻中的表达

多不饱和脂肪酸作为营养成份日益引起人们的关注,尤其是象二十碳五烯酸(EPA)这类的n-3系不饱和脂肪酸,可以防治许多疾病。目前,食用EPA的主要来源是海洋鱼类。然而,当向食物中添加大量EPA时,鱼油来源的EPA在提纯过程中残留的鱼腥味就成为一个很大的难题。海洋微藻类因可以避免鱼腥味被认为可作为食用EPA的新来源。虽然很多海洋真核微藻类可以生产EPA,但它们的生长速度极慢,不适合工业化生产EPA的要求。海洋蓝藻虽不能产生EPA,但它们能进行高密度培养,且生长速度较真核微藻类要快,应用光生物反应器,海洋蓝藻菌体产量可达10g干重/L。采用遗传工程的方法,可以改造蓝藻生产 EPA。

高碘对小鼠的脑损伤及DHA和EPA的拮抗效应

目的观察二十二碳六烯酸(DHA)和二十五碳烯酸(EPA)对高碘所致的脑蛋白质、核酸代谢和bcl-2、bax基因表达损伤的拮抗效应。方法体质量10￣14g的昆明种小鼠随机分为适碘组(IN)、高碘组(IE)和高碘加DHA和EPA组(IEDE)。IN组动物饮含碘量为50μg/L的去离子水,IE组和IEDE组饮含碘量为3000μg/L的去离子水,IN和IE组动物用普通鼠饲料喂养,IEDE组动物用每公斤含DHA200mg和EPA100mg的鼠饲料喂养。90d后雌雄2∶1合笼,仔鼠继续用亲代喂养条件喂养,30d后处死仔鼠,称全脑和海马组织质量,测大脑蛋白质、DNA、RNA含量和bcl-2、bax基因表达量。结果IE组动物脑和海马组织质量、蛋白质、DNA、RNA数量和bcl-2基因表达均显著低于IN组,bax基因表达则高于IN组,IEDE组脑和海马质量、蛋白质、DNA、RNA含量与IN组差异无统计学意义,但bcl-2表达低于IN组,bax表达高于IN组,而与IE组差异无统计学意义。结论高碘能干扰脑蛋白质和核酸代谢及bcl-2、bax基因表达,使脑质量下降,DHA和EPA可拮抗高碘所致的脑蛋白质和核酸代谢的紊乱,对高碘引起的bcl-2、bax基因表达变化未见明显的调整作用。

DHA和EPA对高碘所致脑损伤的拮抗效应

目的观察二十二碳六烯酸(DHA)二十碳五烯酸(EPA)对高碘所致的脑蛋白质、核酸代谢和bcl-2、bax基因表达损伤的拮抗效应。方法体重10～14g的昆明种小鼠随机分为适碘组(IN)、高碘组(IE)和高碘加DHA和EPA组(IEDE)。IN组动物饮含碘量为50μg/L的去离子水,IN和IEDE组饮含碘量为3000μg/L的去离子水,IN和IE组用普通鼠饲料喂养,IEDE组动物用含DHA200mg/kg和EPA100mg/kg的鼠饲料喂养。90d后雌雄2:1合笼,仔鼠继续用亲代喂养条件喂养,30d后处死仔鼠,称全脑和海马组织重量,测大脑蛋白质、DNA、RNA含量和bcl-2、bax基因表达数量。结果IE组动物脑和海马组织重量、蛋白质、DNA、RNA数量和bcl-2基因表达均显著低于IN组,bax基因表达则高于IN组,IEDE组脑、海马重量、蛋白质、DNA、RNA含量与IN组差异无统计学意义,但bcl-2表达低于IN组,bax表达高于IN组,而与IE组比差异无统计学意义。结论高碘能干扰脑蛋白质和核酸代谢及bcl-2、bax基因表达,使脑重量下降,DHA和EPA可拮抗高碘所致的脑蛋白质和核酸代谢的紊乱,但对高碘引起的bcl-2、bax基因表达变化未见明显的调整作用。

鱼类加工下脚料的资源化与利用途径

介绍用鱼类加工下脚料制取水解蛋白、鱼精蛋白、二十二碳六烯酸(DHA)和二十五碳烯酸(EPA)等营养和生物活性物质的技术工艺,为进一步开发利用鱼下脚料资源提供参考。

气相色谱法测定DHA、EPA

气相色谱法测定ＤＨＡ、ＥＰＡ朱晓琳沈小婉李光１任佳１（江苏省卫生防疫站，南京２１０００９）１南京市卫生防疫站二十六碳烯酸（ＤＨＡ）和二十五碳烯酸（ＥＰＡ）是多烯烃类化合物，一般以深海鱼体内含量较高。据报道ＤＨＡ对脑的生长发育有促进作用，特别对青少年开...

Cloning and characterization of a delta-6 desaturase encoding gene from Nannochloropsis oculata

A gene （NANOC-D6D） encoding a desaturase that removes two hydrogen atoms from fatty acids at delta 6 position was isolated from a cDNA library of Nannochloropsis oculata （Droop） D. J. Hibberd （Eustigmatophyceae）. The unicellular marine microalga N. oculata synthesizes rich long chain polyunsaturated fatty acids （LCPUFAs）, including eicosapentaenoic acid （20：5n-3, EPA）. The deduced protein contains 474 amino acids that fold into 4 trans-membrane domains. The neighbor-joining phylogenetic tree indicates that NANOC-D6D is phylogenetically close to the delta-6 fatty acid desaturase of marine microalgae such as Glossomastix chrysoplasta, Thalassiosira pseudonana, and Phaeodactylum tricornutum. The gene was expressed in Saccharomyces cerevisiae INVScl to verify the substrate specificity of NAN OC-D6D. Our results suggest that the recombinant NANOC-D6D simultaneously desaturates linoleic acid （LA） and a-linolenic acid （ALA）.

A comparative analysis of fatty acid composition and fucoxanthin content in six Phaeodactylum tricornutum strains from diff erent origins

Phaeodactylum tricornutum is a potential livestock for the combined production of eicosapentaenoic acid(EPA) and fucoxanthin. In this study, six marine diatom strains identified as P. tricornutum were cultured and their total lipid, fatty acid composition and major photosynthetic pigments determined. It was found that the cell dry weight concentration and mean growth rate ranged between 0.24–0.36 g/L and 0.31–0.33/d, respectively. Among the strains, SCSIO771 presented the highest total lipid content, followed by SCSIO828, and the prominent fatty acids in all strains were C16:0, C16:1, C18:1, and C20:5(EPA). Polyunsaturated fatty acids, including C16:2, C18:2, and EPA, comprised a significant proportion of the total fatty acids. EPA was markedly high in all strains, with the highest in SCSIO828 at 25.65% of total fatty acids. Fucoxanthin was the most abundant pigment in all strains, with the highest in SCSIO828 as well, at 5.50 mg/g. The collective results suggested that strain SCSIO828 could be considered a good candidate for the concurrent production of EPA and fucoxanthin.

Effects of Temperature, Salinity, Light Intensity, and pH on the Eicosapentaenoic Acid Production of Pinguiococcus pyrenoidosus

The effects of temperature, light intensity, salinity, and initial pH on the growth and fatty acid composition of Pinguiococcus pyrenoidosus 2078 were studied for eicosapentaenoic acid (EPA) production potential. The fatty acid composition was assayed by gas chromatography-mass spectrometry, which indicated that the main fatty acids were C14:0, C16:0 and EPA. The highest EPA percentage 20.83% of total fatty acids was obtained at 20℃ with the temperature being set at 20, 24, and 28℃. Under different salinities and light intensities, the highest percentages of total polyunsaturated fatty acids (PUFAs) and EPA were 17.82% and 31.37% of total fatty acids, respectively, which were achieved at salinity 30 and 100μmol photon m-2s-1 illumination. The highest percentages of total PUFAs and EPA were 38.75% and 23.13% of total fatty acids, respectively, which were reached at an initial pH of 6 with the test range being from 5.0 to 9.0.

Construction and characterization of a normalized cDNA library of Nannochloropsis oculata(Eustigmatophyceae)

We constructed and characterized a normalized cDNA library of Nannochloropsis oculata CS-179,and obtained 905 nonredundant sequences(NRSs) ranging from 431-1 756 bp in length.Among them,496 were very similar to nonredundant ones in the GenBank(E ≤1.0e-05),and 349 ESTs had significant hits with the clusters of eukaryotic orthologous groups(KOG).Bases G and/or C at the third position of codons of 14 amino acid residues suggested a strong bias in the conserved domain of 362 NRSs(>60%).We also identified the unigenes encoding phosphorus and nitrogen transporters,suggesting that N.oculata could efficiently transport and metabolize phosphorus and nitrogen,and recognized the unigenes that involved in biosynthesis and storage of both fatty acids and polyunsaturated fatty acids(PUFAs),which will facilitate the demonstration of eicosapentaenoic acid(EPA) biosynthesis pathway of N.oculata.In comparison with the original cDNA library,the normalized library significantly increased the efficiencies of random sequencing and rarely expressed genes discovering,and decreased the frequency of abundant gene sequences.

The effects of season on fatty acid composition and ω3/ω6 ratios of northern pike(Esox lucius L.,1758) muscle lipids

In the present study, the effects of season on fatty acid composition, total lipids, and ω3/ω6 ratios of northern pike muscle lipids in Klzlhrmak River （Klrlkkale, Turkey） were investigated. A total of 35 different fatty acids were determined in gas chromatography. Among these, palmitic, oleic, and palmitoleic acids had the highest proportion. The main polyunsaturated fatty acids （PUFAs） were found to be docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid. There were more PUFAs than monounsaturated fatty acids （MUFA） in all seasons. Similarly, the percentages of ω3 fatty acids were higher than those of total ω6 fatty acids in the fatty acid composition. ω3/ω6 ratios were calculated as 1.53, 1.32, 1.97, and 1.71 in spring, summer, autumn and winter, respectively. Overall, we found that the fatty acid composition and ω3/ω6 fatty acid ratio in the muscle of northern pike were significantly influenced by season.

Co-Production of Lipids, Eicosapentaenoic Acid, Fucoxanthin, and Chrysolaminarin by Phaeodactylum tricornutum Cultured in a Flat-Plate Photobioreactor Under Varying Nitrogen Conditions

The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L^(-1)(high nitrogen, HN) and 2.9 m mol L^(-1)(low nitrogen, LN) of KNO_3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass(4.1 g L^(-1)). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid(TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids(NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L^(-1)d^(-1) was achieved in the HN group(on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase(on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L^(-1)d^(-1), respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.

Effect of pollution on DNA damage and essential fatty acid profile in Cirrhinus mrigala from River Chenab

The objective of this study was to evaluate the effect of anthropogenic pollution on DNA damage and the fatty acid profile of the bottom dweller fish （Cirrhinus mr^gala）, collected from the River Chenab, in order to assess the effect of the toxicants on the quality of the fish meat. The levels ofCd, Hg, Cu, Mn, Zn, Pb, Cr and Sn and of phenols from this river were significantly higher than the permissible limits set by the USEPA. Comet assays showed DNA damage in Cirrhinus mr^gala collected from three different sampling sites in the polluted area of the river. Significant differences were observed for DNA damage through comet assay in fish collected from polluted compared to control sites. No significant differences were observed for DNA damage between farmed and fish collected from upstream. The micronucleus assay showed similar trends. Fish from the highly polluted sites showed less number of fatty acids and more saturated fatty acids in their meat compared to fish from less polluted areas. Several fatty acids were missing in fish with higher levels of DNA in comet tail and micronucleus induction. Long-chain polyunsaturated fatty acids, eicosapentaenoic acid （20：5n-3） was found missing in the fish from polluted environment while it was found in considerable amount in farmed fish 7.8±0.4%. Docosahexaenoic acid （22：6n-3） also showed significant differences as 0.1±0.0 and 7.0±0.1% respectively, in wild polluted and fanned fishes.

Comparison of Lipids in Organs of the Starfish Asterias amurensis Associated with Different Treatments

Lipids were extracted from organs of the starfish Asterias amurens＆ associated with different treatments （raw-control, boiling and heating）, and then analyzed for lipid content, lipid oxidation index, lipid classes and fatty acid composition. Results showed that boiling softened the hard starfish shells, thus facilitating the collection of starfish organs. As compared with raw organs, the boiled organs had lower water content and higher lipid content, possibly due to the loss of water-holding capacity caused by pro- tein denaturation. Both boiling and heating increased the peroxide value （PV）, thiobarbituric acid （TBA） value and carbon value （CV） of lipids. Despite slight increases in the content of complex lipids, associated lipid composition had no substantial variations upon boiling and heating. For simple lipids, the content of 1, 2-diglyceride decreased in boiled and heated organs, with free fatty acids observed on thin layer chromatography （TLC）. However, neither boiling nor heating significantly changed the fatty acid composi- tions of simple or complex lipids in starfish organs, suggesting that these two treatments had no significant effects on complex lipids in starfish organs. Together, our results indicated that boiling of starfish soon after capture facilitated the handling and extraction of useful complex lipids consisting of abundant glucosylceramide and eicosapentaenoic acid （EPA）-bounded phospholipids.

Docosahexaenoic Acid and Eicosapentaenoic Acid Modulate Calcium Signaling in Murine CD36-Positive Taste Buds Cells, via Phospholipase Pathways

DHA （docosahexaenoic acid） and EPA （eicosapentaenoic acid） induced intracellular calcium increase in taste receptor cells purified from mouse circumvallate papillae. We have demonstrated that DHA and EPA induced calcium increase respectively via cPLA2 （cytosolic phospholipase A2） type lVc and calcium independent iPLA2 （phospholipase A2） type VI. Intracellular calcium increases via PLC （phospholipase C） pathway and leads to a calcium effiux and further SOC （stored operated calcium） channels activation. An abundant increase in intracellular calcium will induce exocytosis of neurotransmitters into the extracellular medium. Our results suggest that DHA and EPA induced calcium signaling, and should be implicated in the transmission of lipid gustatory information to afferent nerve fibers, as shown previously with linoleic acid.

“远亲”食品有利养生

人们常说“远亲不如近邻”。但是从饮食养生的角度讲,远亲食物却有胜于近邻。这是近年来营养学的最新研究成果。 食物的这种远近之分是指它们在空间和生物学关系上与人类的相对距离而言的。例如,猪牛羊与人类生活、生产息息相关,在空间和生物学关系上较鱼虾蟹等水产品要离得近;植物类食物在整体上要较动物类食物远;野生食物又远于人工种植的食物;海洋食物则更远于陆上的植物。 为此,营养学家专门推荐了三类远亲食品,以供人们选择: 1 真菌类 如香菇的营养价值就比较高,据研究每百克香菇含蛋白质37克,磷415毫克,钙124毫克,铁25.

Effectiveness of omega-3 polyunsaturated fatty acids against microbial pathogens

Microorganisms provide both beneficial and harmful effects to human beings. Beneficial effects come from the symbiotic relationship that exists between humans and microbiota, but then several human illnesses have turned some friendly microbes into opportunistic pathogens, causing several microbial-related diseases. Various efforts have been made to create and utilize antimicrobial agents in the treatment and prevention of these infections, but such efforts have been hampered by the emergence of antimicrobial resistance. Despite extensive studies on drug dis- covery to alleviate this problem, issues with the toxicity and tolerance of certain compounds and continuous microbial evolution have forced researchers to focus on screening various phytochemical dietary compounds for antimicrobial activity. Linolenic acid and its derivatives （eicosapentaenoic acid and docosahexaenoic acid） are omega-3 fatty acids that have been studied due to their role in human health, being important for the brain, the eye, the cardiovascular system, and general human growth. However, their utilization as antimicrobial agents has not been widely appreciated, perhaps due to a lack of understanding of antimicrobial mechanisms, toxicity, and route of administration. Therefore, this review focuses on the efficacy, mechanism, and toxicity of omega-3 fatty acids as alternative therapeutic agents for treating and preventing diseases associated with pathogenic microorganisms.

Fatty acid profiles of muscle from large yellow croaker (Pseudosciaena crocea R.) of different age

We investigated the fatty acid profiles of muscle from large yellow croaker （Pseudosciaena crocea R.） of different age. One- and two-year-old fish were cultured in floating net cages and sampled randomly for analysis. Moisture, protein, lipid and ash contents were determined by methods of Association of Analytical Chemist （AOAC） International. Fatty acid profile was deter- mined by gas chromatography. Crude protein, fat, moisture and ash contents showed no significant differences between the two age groups. The contents of total polyunsaturated fatty acids and docosahexaenoic acid （DHA） were significantly higher and eicosapentaenoic acid （EPA） content was significantly lower in the two-year-old large yellow croaker than in the one-year-old （/＇〈0.05）. No significant differences were observed in the contents of total saturated fatty acids and monounsaturated fatty acids, or the ratio ofn-3/n-6 fatty acids among the large yellow croakers of the two age groups. We conclude that large yellow croakers are good food sources of EPA and DHA.