Inhibitory effects and mechanisms of high molecular-weight phlorotannins from Sargassum thunbergii on ADP-induced platelet aggregation

We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii (STP) on ADP-induced platelet aggregation and arachidonic acid (AA) metabolism in New Zealand white rabbits and Wistar rats. The inhibition of STP on platelet aggregation was investigated using a turbidimetric method, and the levels of the terminal products of AA metabolism were measured using the corresponding kits for maleic dialdehyde (MDA), thromboxane B-2 (TXB2) and 6-keto-prostaglandin F-1 alpha (6-keto-PGF(1 alpha)) by colorimetry and radioimmunoassay, as appropriate. We found that STP could inhibit ADP-induced platelet aggregation, and the inhibitory ratio was 91.50% at the STP concentration of 4.0 mg/mL. Furthermore, STP markedly affected AA metabolism by decreasing the synthesis of MDA (P < 0.01) and increasing the synthesis of 6-keto-PGF(1 alpha), thus changing the plasma TXB2/6-keto-PGF(1 alpha) balance when the platelets were activated (P < 0.01). Therefore, STP altered AA metabolism and these findings

Molecular cloning and stress-dependent expression of a gene encoding Delta(12)-fatty acid desaturase in the Antarctic microalga Chlorella vulgaris NJ-7

The psychrotrophic Antarctic alga, Chlorella vulgaris NJ-7, grows under an extreme environment of low temperature and high salinity. In an effort to better understand the correlation between fatty acid metabolism and acclimation to Antarctic environment, we analyzed its fatty acid compositions. An extremely high amount of Delta(12) unsaturated fatty acids was identified which prompted us to speculate about the involvement of Delta(12) fatty acid desaturase in the process of acclimation. A full-length cDNA sequence, designated CvFAD2, was isolated from C. vulgaris NJ-7 via reverse transcription polymerase chain reaction (RT-PCR) and RACE methods. Sequence alignment and phylogenetic analysis showed that the gene was homologous to known microsomal Delta(12)-FADs with the conserved histidine motifs. Heterologous expression in yeast was used to confirm the regioselectivity and the function of CvFAD2. Linoleic acid (18:2), normally not present in wild-type yeast cells, was detected in transformants of CvFAD2. The induction of CvFAD2 at an mRNA level under cold stress and high salinity is detected by real-time PCR. The results showed that both temperature and salinity motivated the upregulation of CvFAD2 expression. The accumulation of CvFAD2 increased 2.2-fold at 15A degrees C and 3.9-fold at 4A degrees C compared to the alga at 25A degrees C. Meanwhile a 1.7- and 8.5-fold increase at 3 and 6% NaCl was detected. These data suggest that CvFAD2 is the enzyme responsible for the Delta(12) fatty acids desaturation involved in the adaption to cold and high salinity for Antarctic C. vugaris NJ-7.

Necessity of dietary lecithin and eicosapentaenoic acid for growth, survival, stress resistance and lipoprotein formation in gilthead sea bream Sparus aurata

The substitution of dietary docosahexaenoic acid (DHA) with eicosapentaenoic acid (EPA) reduces larval growth in gilthead sea bream. However, the value of EPA when dietary DHA is able to meet the requirements of the larvae has not been sufficiently studied. Dietary phosphoacylgliceride levels also affect fish growth and it has been suggested that they enhance lipid transport in developing larvae. The present experiment was carried out to further study the effect of dietary lecithin and eicosapentaenoic acid on growth, survival, stress resistance,. larval fatty acid composition and lipid transport, when DHA is present in the microdiets of gilthead:sea bream. Eighteen thousand gilt-head sea bream larvae of 4.99+/-0.53 mm total length were fed three microdiets tested by triplicate: a control diet [2% soybean lecithin (SBL) and 2.89% EPA], a low EPA diet,(2% SBL and 1.63% EPA) and a no SBL diet (0% SBL and 2.71% EPA). Handling, temperature and salinity tests determined larval resistance to stress. The results show that when dietary DHA levels are high, but dietary arachidonic acid (ARA) levels are about 0.2%, EPA is necessary to improve larval growth, and survival. Larval EPA content, but not DHA or ARA, was affected by dietary EPA levels. Increased dietary EPA improved larval stress resistance to handling and temperature tests, which could be related to its possible role as a regulator of cortisol production whereas it did not affect stress resistance after salinity shock. Larvae fed the no SBL diet showed a lower lipid content characterized by a low proportion of saturated and monounsaturated fatty acids, together with a significant reduction in the appearance of lipoprotein particles in the lamina propria and in the size of such particles, denoting a critical reduction in dietary lipid transport and utilization, and lower larval growth and survival rates.

Association of pro staglandin-endoperoxide synthase 2 (PTGS2) polymorphisms and Alzheimer's disease in Chinese

Cyclooxygenase-2 (COX-2, encoded by the gene prostaglandin-endoperoxide synthase 2, PTGS2) is a key enzyme in the conversion of arachidonic acid to prostaglandins. The prostaglandins produced by COX-2 are involved in inflammation and pain response in diff

Combined effects of polyfluorinated and perfluorinated compounds on primary cultured hepatocytes from rare minnow (Gobiocypris rarus) using toxicogenomic analysis

Polyfluorinated and perfluorinated compounds (PFCs) are used in numerous commercial products and have been ubiquitously detected in the environment as well as in the blood of humans and wildlife. To assess the combined effects caused by PFCs in mixtures, gene expression profiles were generated using a custom cDNA microarray to detect changes in primary cultured hepatocytes of rare minnows exposed to six individual PFCs (perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorododecanoic acid, perfluorooctane sulfonate, and 8:2 fluorotelomer alcohol) and four formulations of the PFCs mixtures. Mixtures as well as individual compounds consistently regulated a particular gene set, which suggests that these conserved genes may play a central role in the toxicity mediated by PFCs. Specifically, a number of genes regulated by the mixtures were identified in this study, which were not affected by exposure to any single component. These genes are implicated in multiple biological functions and processes, including fatty acid metabolism and transport, xenobiotic metabolism, immune responses, and oxidative stress. More than 80% of the altered genes in the PFOA- and PFOS-dominant mixture groups were of the same gene set, while the gene expression profiles from single PFOA and PFOS exposures were not as similar. This work contributes to the development of toxicogenomic approaches in combined toxicity assessment and allows for comprehensive insights into the combined action of PFCs mixtures in multiple environmental matrices. (C) 2009 Elsevier B.V. All rights reserved.

青杨(Populus cathayana Rehd)雌雄植株对锈病和干旱胁迫的生理响应及差异蛋白质组比较

雌雄异株植物对环境的不同响应一直是一个有趣而新颖的研究领域，由于雌雄个体不同的繁殖成本及不同的生存策略，使得雌雄植株在生长、存活、生殖格局、空间分布、资源配置等方面已经表现出明显的不同，在生理和分子水平上也表现出明显的性别间差异。干旱是制约农林业发展的环境因子之一，叶锈病是对杨树危害最严重的病害之一，由于长期进化的结果，不同性别的植物必然对生物和非生物胁迫有着不同的响应。本文以雌雄异株的青杨为模式植物，研究雌雄间在生理、生化、亚细胞结构和蛋白质水平上对生物和非生物胁迫的差异响应。主要研究结果如下： （1） 青杨雌雄植株对锈病胁迫的生理生化差异响应 在正常的对照组中，雄株叶片比雌株叶片有着较高的活性氧自由基产生速率、较高的SOD、POD、PPO 和较低的CAT 活性；在锈病感染的早期阶段， SOD、POD、CAT 活性、活性氧自由基产生速率、H2O2 含量、膜脂过氧化程度和细胞膜的电渗率在雌雄株中都增加，而PPO 仅在雄株中增加明显，APX 仅在雌株中增加明显，并且雌株比雄株有着更严重的锈病感染程度、细胞膜的伤害程度和光合系统II 的破坏程度，雌株有更多的净光合速率、气孔导度和叶绿素a 含量的降低，在同工酶变化上，雌雄间对锈病也显示出不同的表达模式。结果显示，雄株比雌株对锈病有着更好的抗性和更有效的ROS 清除系统。 （2） 青杨雌雄植株对干旱胁迫的生理生化及亚细胞结构的差异响应 与较好水分条件相比，干旱下雄株比雌株有着更高的A-Ci 响应参数，如Rubisco 最大羧化速率、光呼吸速率、暗呼吸速率和最大电子传递速率等。干旱显著地增加了膜脂过氧化程度和游离脯氨酸含量，并且雄株比雌株表现出较低的膜脂过氧化程度，较高的总蛋白和游离脯氨酸含量。无论是中度干旱还是极度干旱，除了CAT 外，雄株比雌株表现为较强的抗氧化酶活性，在同工酶谱带上，雌雄间表现出不同的变化模式，并且有些条带是干旱影响应的，而有些条带是性别特异性的，这些性别特异性条带能够作为鉴定性别快速而准确的标记。干旱显著地影响了线粒体、叶绿体和细胞壁的结构，尤其在中度干旱胁迫下，雄株线粒体和叶绿体比雌株呈现出较好的完整性，并且雄株细胞壁要比雌株更厚。因此， 雄株比雌株表现出更强的干旱忍耐性和更高效的抗氧化酶系统。 （3） 青杨雌雄植株对干旱胁迫的蛋白质组差异响应 用双相电泳检测到雌雄间近1000 个蛋白点，通过对比发现对照组雌雄间有54 个差异蛋白点，干旱下雌雄间有108 个差异点，其中102 个被质谱成功鉴定。对照组雌雄间的差异蛋白主要集中在与光合作用相关蛋白、抗氧化酶、胁迫防御蛋白和一些调节基因表达的蛋白；干旱胁迫下雌雄间差异蛋白明显增多，主要有参与信号转导、调节基因表达、蛋白质加工、转录产物的转录翻译后修饰的调节性蛋白蛋白和参与氧化还原平衡、抗胁迫、细胞壁合成、光合作用、能量代谢、氨基酸代谢和脂肪酸代谢等的功能性蛋白。干旱下这些蛋白的表达量在雌雄中有的表现出相同的表达模式，如干旱下雌雄株中Rubisco 激活酶、小热激蛋白等表达都增加，而有的表现出相反的表达模式，如Rubisco 大亚基的降解片段、羰酸酯酶等在雄株中表达量上调而在雌株中却是下调。因此，雌雄间在蛋白质水平上对干旱胁迫响应的差异是显著的，也是复杂的。 It is an interesting and novel topic that dioecious plants possess different responses to environmental stress. As for the different productive cost and different survive strategy, different sexual plants have shown obviously morphological, physiological and molecular differences. Drought is one of the most worldwidely important environmental stress factors that limit plant growth and ecosystem productivity. Rust disease is one of the economically important diseases in many trees. As a result of the long evolutionary process, male and female plants should show different responses to abiotic and biotic stress. In this paper, using a dioeious tree of Populus cathayana Rehd as a model, we study the sexual differences to drought and rust disease stress in physiological, biochemical, sub-cellular and proteomics levels. The main results are follows: (1) The sexual differences in physiology and biochemistry of poplar to rust disease In controls, males showed higher production of superoxide radicals, higher activities of SOD, POD, PPO and lower CAT activity. Under rust disease, the activities of antioxidant, the content of ROS and the degree of cellular member destroyed were increased in both sexes, except for PPO in diseased males and APX in diseased females. However, females showed more seriously disease severity and cellular member and PS II destroyed degrees. Net photosynthesis rate, transpiration rate and chlorophyll a content were decreased more in diseased females than in males. There were also some different changes inantioxidant isozymes under rust disease. The results suggested that male poplar possessed a more effectively antioxidant system and were more resistant to rut disease than females. (2) The sexual differences in physiology and biochemistry of poplar to drought stress Under drought stress, there were higher rates of RuBP-saturated CO2 assimilation, dark respiration, photorespiratory release of oxygen, the max electron transportrate in CO2-saturated and carboxylation efficiency in males than in females. And males showed lower TBARS and higher proline content. Except for CAT, the activities of other antioxidants were higher in males than in females. Meanwhile, there were obviously differences in isozyme changes between teo sexes. Drought stress obviously destroyed the integralities of chloroplasts and mitochondria and the sexual differences in sub-cellular level were obviously under the moderate water stress. Male cell walls were more sensitive to drought stress than did female. The results suggested males were more resistant to drought stress. (3) The sexual differences in proteomics of poplar to drought stress By 2-D and MS analysis, we identified 102 different protein spots between males and females. Under control conditions, the different proteins were mainly in photosynthesis related proteins, antioxidants, stress response proteins and some gene expression related proteins. Under drought stress, the different proteins were focused on (i) regulated proteins such as signaling conduction, kinase, HSP, gene expressional regulation and protein modification, (ii) functional proteins such as photosynthesis, energy metabolism, antioxidant, redox, stress response, lipid metabolism and amino acid metabolism. Some protein showed the same expressional pattern, while some showed contrary expressional pattern. Thus, the results suggested that sexual differences in proteomics were significant and complex.

No C_4 Plants Found at the Haibei Alpine Meadow Ecosystem Research Station in Qinghai, China: Evidence from Stable Carbon Isotope Studies

Using the measurement of stable carbon isotopes in leaves as a tool to investigate photosyn-thetic pathway of 102 plant species grown at an alpine meadow ecosystem, at the foot of the Qilian Mountain, Qinghai, China. The results indicate that the δ~(3)C values of plants have a narrow range from -28.24‰ to -24.84‰, which means that none of the species examined belongs to C_4 and crassulaceous acid metabolism (CAM) photosynthetic pathway and all of these species perform photosynthesis through the C_3 pathway. This is likely due to a long-term adaptation to environments at the alpine meadow ecosystem.

Efficient synthesis and utilization of phenyl-substituted heteroaromatic carboxylic acids as aryl diketo acid isosteres in the design of novel HIV-1 integrase inhibitors

Three new types of aryl diketo acid (ADK) isosteres were designed by conversion of the biologically labile 1,3-diketo unit into heteroaromatic motif such as isoxazole, isothiazole, or 1H-pyrazole to improve the physicochemical property of ADK-based HIV-1

Effect of dietary linolenic acid/linoleic acid ratio on growth performance, hepatic fatty acid profiles and intermediary metabolism of juvenile yellow catfish Pelteobagrus fulvidraco

The present study aimed to evaluate the effect of dietary linolenic acid (LNA)linoleic acid (LA) ratio on growth performance, hepatic fatty acid profile and intermediary metabolism of juvenile yellow catfish Pelteobagrus fulvidraco. Six isonitrogenous and isolipidic diets were formulated to contain incremental levels of LNA from 0 to 5% at the expense of corn oil (rich in LA), resulting in six dietary treatments with LNA to LA ratios ranging from 0.35 to 14.64. The experiment continued for 7 weeks. Best growth and feed intake were obtained in the fish fed the diets containing the LNA/LA ratios of 1.17 and 2.12 (P<0.05). In contrast, feed conversion ratio was the lowest for fish fed the diets containing the LNA/LA ratios of 1.17 and 2.12 (P<0.05). Dietary LNA to LA ratios significantly influenced viscerosomatic index and hepatosomatic index (P<0.05), but not condition factor (P>0.05). Body composition was also significantly influenced by dietary LNA to LA ratios (P<0.05). Generally, liver FA compositions reflected dietary FA profiles. Declining LA and increasing LNA contents in liver were observed with the increasing dietary LNA/LA ratios (P<0.05). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased with the increasing LNA to LA ratios, suggesting that yellow catfish could elongate and desaturate C18 polyunsaturated fatty acids into highly unsaturated fatty acids. As a consequence, the n-6 fatty acids (FA) declined, and total n-3 FA and n-3/n-6 ratios increased with the dietary ratios of LNA/LA (P<0.05). Dietary LNA to LA ratios significantly influenced several enzymatic activities involved in liver intermediary metabolism (P<0.05), such as lipoprotein lipase, hepatic lipase, pyruvate kinase, succinate dehydrogenase, malic dehydrogenase and lactate dehydrogenase, suggesting that dietary LNA/LA ratios had significant effects on nutrient metabolism in the liver. To our knowledge this is the first demonstration of the effects of dietary LNA to LA ratios on the enzymatic activities of liver in fish, which provides information on diet quality and utilization, and can also be used as an indicator of the nutritional status of this fish. (C) 2009 Elsevier B.V. All rights reserved.

The effect of some triazole derivatives as inhibitors for the corrosion of mild steel in 1 M hydrochloric acid

Corrosion inhibition by some new triazole derivatives on mild steel in 1 M hydrochloric acid solutions has been investigated by weight loss test, electrochemical measurement, scanning electronic microscope analysis and quantum chemical calculations. The results indicate that these compounds act as mixed-type inhibitors retarding the anodic and cathodic corrosion reactions and do not change the mechanism of either hydrogen evolution reaction or mild steel dissolution. The studied compounds following the Langmuir adsorption isotherm, and the thermodynamic parameters were determined and discussed. The effect of molecular structure on the inhibition efficiency has been investigated by ab initio quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, energy gap (LUMO-HOMO), dipole moment and molecular orbital densities were calculated. (C) 2009 Published by Elsevier B.V.

Experimental and theoretical investigation of the adsorption behaviour of new triazole derivatives as inhibitors for mild steel corrosion in acid media

Three triazole derivatives (4-chloro-acetophenone-O-1'-(1',3',4'-triazolyl)-metheneoxime (CATM), 4-methoxyl-acetophenone-O-1'-(1',3',4'-triazolyl)-metheneoxime (MATM) and 4-fluoro-acetophenone-O-1'-(1',3',4'-triazolyl)-metheneoxime (FATM)) have been synthesized as new inhibitors for the corrosion of mild steel in acid media. The inhibition efficiencies of these inhibitors were evaluated by means of weight loss and electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and polarization curves. Then the surface morphology was studied by scanning electron microscopy (SEM). The adsorption of triazole derivatives is found to obey Langmuir adsorption isotherm, and the thermodynamic parameters were determined and discussed. The relationship between molecular structure of these compounds and their inhibition efficiency has been investigated by ab initio quantum chemical calculations. The electronic properties such as the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energy levels, energy gap (LUMO-HOMO), dipole moment and molecular orbital densities were computed. (c) 2007 Elsevier Ltd. All rights reserved.

Two serine protease inhibitors from the skin secretions of the toad, Bombina microdeladigitora

Two serine protease inhibitors (named BMSI 1 and BMSI 2, respectively) were identified from the skin secretions of the toad, Bombina microdeladigitora. The cDNAs encoding BMSIs were cloned from a cDNA library prepared from the toad skin. The deduced complete amino acid sequences of BMSIs indicate that mature BMSI1 and BMSI2 are composed of 60 amino acids including 10 half-cystines to form 5 disulfide bridges. A FASTA search in the databanks revealed that BMSIs exhibit sequence similarity with other serine protease inhibitors from amphibians of the genus Bombina. BMSI1 potently inhibited trypsin and thrombin with a K(i) value of 0.02 mu M and 0.15 mu M, respectively. Sequence analysis revealed that all serine protease inhibitors from five amphibians of the genus Bombina share highly conserved primary structures. (c) 2007 Elsevier Inc. All rights reserved.

Identification of triosephosphate isomerase (TIM) genes from Microcystis (Cyanobacteria : Chroococcales) and theoretical analyses of the potential of cyanobacterial TIM as a target for designing specific inhibitors

The genes encoding triosephosphate isomerase (TIM) in three species of Microcystis (M. aeruginosa, M. viridis and M. wesenbergii) were investigated. Reverse transcriptase-polymerase chain reaction indicated that they were transcribed in the cells. Analyses showed that their DNA and deduced amino acid sequences were highly conserved between all the three species, only a single nonsynonymous substitution was seen at position 31, from an Asp in M. aeruginosa and M. viridis to Glu in M. wesenbergii. Sequence alignment of these with 12 other known cyanobacterial TIM sequences showed that all the cyanobacterial TIMs had a very high level of amino acid identity (over 50% between each two). Comparison of the cyanobacterial TIMs with other reported TIMs (from diverse lineages of the three Domains) showed that they possessed common active-site residues and sequence motifs. All cyanobacterial TIMs have two common cysteine residues (Cys127 and Cys176), and the Cys176 is almost cyanobacteria-specific with only one exception in Streptomyces coelicolor. Both secondary structure alignment and comparative modelling of Synechocystis sp. TIM showed that Cys176 was located at the hinge region of the flexible loop-6 and might therefore be critical to the movement of TIM's loop-6, which is important to the function of the enzyme. Thus, the cyanobacterial TIM-specific Cys176 may be a potential site for the discovery of suitable drugs against cyanobacteria, and such drugs may have utility in controlling water blooms due to cyanobacteria.