Low dose exposure of patulin and protective effect of epicatechin on blood cells in vitro

In the present study, we aimed to assess antioxidant status in erythrocytes in vitro after patulin (PAT) and epicatechin exposure by measuring antioxidant enzymes (superoxide-dismutase – SOD, glutathione peroxidase – GPx and catalase – CAT) and parameters associated with oxidative stress (malondialdehyde – MDA and ROS). We also investigated the effect of PAT on viability and count of lymphocytes and lymphocyte subpopulations in rabbit blood in vitro. Whole blood of rabbits was used for analysis of antioxidant changes in rabbit erythrocytes after epicatechin and PAT treatment (separately or in combination, at concentrations of 0.2; 2; 20; 200?µg mL^–1 of epicatechin and 0.5; 5; 10?µg mL^–1 of PAT). Whole blood of rabbits was also used for analysis of count and viability of lymphocytes after PAT treatment at concentrations of 10; 25 and 50?µg mL^–1. Results from our experiment confirmed the ability of epicatechin to protect cells against oxidative stress and lipoperoxidation. Our findings indicate that mycotoxin PAT in low concentrations did not affect the activity of antioxidant enzymes in erythrocytes of rabbits significantly. Only slight non-significant changes in lymphocytes count after treatment with low doses of PAT in rabbit blood were observed.     

负载型TiO2膜太阳光光催化降解活性深蓝K-R的研究

采用抛物线槽型反应装置，研究了玻璃弹簧和微珠负载型TiO₂膜太阳光催化降解活性深蓝K-R，结果表明,由于玻璃弹簧具有良好的光透距离，脱色性能显著优于玻璃微珠，玻璃弹簧为载体，水溶液浓度为15mg/L,pH为3,流速为20mL/s,太阳光强度在1200 μW/cm₂以上，光降解6h时，脱色率达到96%； 该降解反应可用一级反应动力学方程进行描述，反应速率常数（K）与光强I的关系为：K∝I1.92。     

Chemical recognition of queen cells by honey bee workersApis mellifera (Hymenoptera: Apidae)

Summary Honey bee workers are able to nurse or to destroy and thus to recognize the capped queen cells containing a pupa. Fatty acid esters, especially methyl oleate, methyl palmitate and ethyl oleate were found in significant amounts on the queen pupal cuticle. Methyl oleate, the major component, along with smaller amounts of methyl linoleate and methyl linolenate, were involved in the recognition of queen cells by workers. In natural conditions of the colony, queen cells containing a paraffin pupal lure with methyl oleate were accepted 5.9 days by workers, releasing about 1.8 queen pupa equivalents during that period, when control cells (without ester) were kept only 2.1 days. Although these esters are non specific to honey bees, they are of great importance in social regulation of the honey bee colony.     

Protective effects of vitamin C and curcumin against acrylamide toxicity in embryonic fibroblast cells

Abstract

Acrylamide is a highly soluble and widely produced industrial chemical that has been shown to pose numerous health hazards. This study aimed to assess the effects of acrylamide on the cytotoxicity and oxidative damage in embryonic fibroblast cells (BALB/c 3T3) and to measure protective roles of the natural antioxidants vitamin C and curcumin. Embryonic fibroblast cells were exposed to acrylamide at concentrations of 1, 10, 100, and 1000?μmol/L and vitamin C (50?μmol/L) or curcumin (2.5?μmol/L) for 24?h. Cell viability, cytotoxicity, the activities of antioxidant enzymes superoxide dismutase, glutathione-S-transferase, glutathione peroxidase and catalase, and the markers of oxidative lipid peroxidation, hydroxyl radical, hydrogen peroxide and glutathione were measured. Co-treatment of the acrylamide-exposed fibroblast cells with vitamin C or curcumin attenuated the cytotoxicity and formation of reactive oxygen species and decreased the antioxidant enzyme activity. Thus, it was concluded that vitamin C and curcumin may play a protective role against acrylamide toxicity; the treatment with 50?μmol/L vitamin C was found to be more effective than the treatment with 2.5?μmol/L curcumin.     

Role of NADH-dependent chromium reductases,exopolysaccharides and antioxidants by Paenibacillus thiaminolyticus PS 5 against damage induced by reactive oxygen species

ABSTRACT

Cr (VI) being used in various activities of industries and its improper treatment lead to contamination of environment. Among different methods, biological is the most efficient method to control pollution from soils affected with metals. Present study was designed to assess the role of Paenibacillus thiaminolyticus PS5 for adsorption, Cr (VI) reduction and mechanism of reduction. Sorption of chromium (VI) by strain PS5 was obtained by batch equilibrium method. Cr (VI) reduction in both free and immobilised cells were evaluated by 1,5-Diphenyl Carbazide method. The formation of biofilm by Paenibacillus thiaminolyticus PS5 was observed for colour change as well as quantified spectrophotometrically. Analysis kits were used to measure the amount of eDNA, superoxide and malondialdehyde (MDA). Metal resistant strain PS5 was characterised as P. thiaminolyticus using 16S rRNA gene sequence. Maximum biosorption of Cr (VI) by strain PS5 was found at pH 6–8 and 100–400 µgCr/mL within 24 hours of incubation. Complete reduction of Cr (VI) by strain PS5 was achieved at pH 6–8 and100–300 µg/mL Cr (VI). Paenibacillus thiaminolyticus PS5 immmobilisation on sodium alginate and polyvinyl alcohol facilitated complete reduction of Cr (VI) within 18 hours due to the formation of more biofilm under metal stress conditions. Strain PS5 reduced almost all Cr (VI) into Cr (III) in supernatant, most of which was immobilised by cell debris. Experiments confirmed the reduction of Cr (VI) by cytosolic cell-free extracts which is a mechanism of detoxification. The release of exopolysaccharides and antioxidants by strain PS5 played a protective role against cell damage by Cr (VI) as Cr (VI) could not release the significant amount of eDNA, superoxide and MDA. The present study proved strain PS5 to be a super bioinoculant which has great capacity for adsorption, biotransformation and can activate cytosolic reductases, exopolysaccharides and antioxidants against oxidative damage.     

ALGAL BLOOM PROBABILITY IN A LARGE SUBTROPICAL LAKE1

ABSTRACT: Algal blooms, defined as chlorophyll α concentrations greater than 40 μg l^?1, are common in Lake Okeechobee, Florida. Using logistic regression techniques, we have developed equations that relate limnological variables to algal bloom occurrence in four distinct open-water regions of this large shallow lake: central pelagic, northwest, southwest, and a transition region between the western and pelagic regions. Wind velocity and total phosphorus, which are closely related to resuspended material in the central region, are negatively related to algal bloom occurrence there. In the transition region, algal bloom occurrence is positively related to total nitrogen and wind velocity. Algal bloom occurrence is strongly and positively related to total nitrogen and total phosphorus concentrations in the western regions. The logistic regression model predicts an algal bloom probability greater than 95 percent in the northwest region when total phosphorus exceeds 0.10 mg l^?1 and total nitrogen exceeds 2.5 mg l^?1. In the southwest region the model predicts algal bloom probability of 100 percent when total phosphorus exceeds 0.10 mg l^?1 and total nitrogen exceeds 2.8 mg l^?1. Given 1994 mean total phosphorus concentrations of 0.05 and 0.04 mg l^?1 in the northwest and southwest regions, respectively, total nitrogen would have to remain below 1.32 and 1.43 mg l^?1, respectively, to keep the algal bloom probability below 10 percent. Because the lake is heterogenous, such nutrient standards should be considered on an in-lake regional basis for Lake Okeechobee.     

不同生长期加拿大蓬挥发油对蚕豆保卫细胞的毒性效应

为探讨入侵植物加拿大蓬(Erigeron canadensis L.)的化感作用机制,以蚕豆(Vicia faba L.)叶下表皮为材料,研究了营养期和生殖期加拿大蓬挥发油各1μL、2μL、3μL、4μL、5μL分别处理保卫细胞10 min、20 min、30 min后产生的毒性效应。结果表明:挥发油处理后保卫细胞大量死亡,核形态发生较大改变;细胞死亡率和核异常率显著上升(p0.05),与处理剂量和时间呈正相关(p0.01);营养期挥发油处理后细胞的死亡率和核异常率总体高于生殖期;加入泛Caspase抑制剂后,细胞死亡率显著降低(p0.05)。研究表明,加拿大蓬挥发油引起的保卫细胞死亡为Caspase依赖性的细胞凋亡,营养期挥发油的化感胁迫效应比生殖期更强。结合GC-MS分析可见,不同生长期加拿大蓬挥发油毒性的差异可能与其化感物质的组成和含量差异有关。     

染料敏化太阳能电池纳米TiO2制备及多孔电极膜研究进展

本文就目前在染料敏化太阳能电池产业化中急需解决的TiO2纳晶制备、电极薄膜修饰与改进等热点问题的最新研究进展进行了综合评述,分析了存在的问题并提出了对策.     

2003年北京地区年雨量的预测

通过对北京地区1870年以来年雨量与太阳活动和厄尔尼诺年关系的处理分析,给出了一种预测北京地区年雨量的数学模型,在前5年预测的基础上,给出2003年北京地区年雨量的预测值为450±50mm。