水环境镉对水生动物毒性的研究进展

重金属镉是目前水环境中长期存在的污染物,因其具有致癌、致畸和致突变等特性而被广泛关注。本文综述了镉的来源和污染现状,并分别从生理生化酶水平、分子水平、细胞组织水平阐述了镉在水生动物体内的蓄积过程、代谢规律及毒性作用。本文同时简述了镉暴露引起的水生生物氧化应激反应、脂质过氧化反应和组织病理学损伤等情况。通过分析、总结前人的研究成果,以利于今后对镉的毒性机理进行深入的研究,进而更好的控制重金属镉对水环境的污染,保护水生生物和水生生态环境,为人类提供安全的水产品提供理论依据。      

Evaluation of bioanalytical assays for toxicity assessment and mode of toxic action classification of reactive chemicals

The toxicity of electrqphiles, including reactive organochlorines, epoxides, and compounds with an activated double bond was investigated. A set of different bioanalytical assays based on genetically modified Escherichia coli strains was set up to quantify cytotoxicity and specific reactivity toward the important biological nucleophiles DNA and glutathione (GSH). The significance of GSH for detoxification was assessed by cellular GSH depletion as well as by growth inhibition of a GSH-deficient strain. Tests for DNA damage comprised the measurement of induction of DNA repair systems, DNA fragmentation, and growth inhibition of a strain deficient in major DNA repair mechanisms. The most suitable assays for detection of mechanisms that underlie the observable cytotoxicity of the tested electrophiles were two sets of strains either lacking GSH or DNA repair in combination with their corresponding parent strains. Comparison of toxicity observed in those strains suggests three clearly distinguishable modes of toxic action for electrophilic chemicals: "DNA damage", "GSH depletion-related toxicity", and "unspecific reactivity". The class of chemicals causing DNA damage includes the epoxides 1,2-epoxybutane, (2,3-epoxypropyl)benzene, and styrene oxide. The class of chemicals with GSH depletion-related toxicity includes compounds with an activated double bond, like acrylates and acrolein. All reactive organochlorines and some epoxides were classified as unspecifically reactive because their toxicity is initiated by reactions with both biological nucleophiles. The work presented here is a contribution for an alternative hazard and effect assessment of organic pollutants based on mode of toxic action classification.     

Assessment of the interaction between aquatic colloids and pharmaceuticals facilitated by cross-flow ultrafiltration

Interactions between pharmaceuticals and aquatic colloids are a key process regulating their environmental fate, but poorly understood. A validated cross-flow ultrafiltration (CFUF) system was used to isolate river colloids and to determine the partition of selected pharmaceuticals between colloidal (>1 kDa but <0.7 microm) and dissolved phases (<1 kDa) by liquid chromatography-tandem mass spectrometry (LC-MS-MS). The kinetics of pharmaceutical binding to colloids was rapid, reaching equilibrium within 5 min. The mass balance of chosen pharmaceuticals through CFUF system was satisfactory for propranolol, sulfamethoxazole, meberverine, carbamazepine, indomethacine, diclofenac, and meclofenamic acid. The partition coefficient normalized to colloidal organic carbon content (Kcoc) varied from 5.45 x 10(4) to 7.54 x 10(5) mL/g for the chosen pharmaceuticals, which are greater than those for endocrine disrupting chemicals (EDCs), suggesting substantially stronger colloidal interactions with pharmaceuticals than with EDCs. Linear relationships were demonstrated between log-Kcoc, and pharmaceutical properties such as log Kow (octanol-water partition coefficient), highlighting the importance of compound hydrophobicity in controlling their binding with colloids. Such a finding is in contrast to that for EDCs whose Kcoc values were independent of their Kow values. The CFUF-LCMS technique has the potential to become a widely applicable tool for quantifying the distribution of emerging organic pollutants between nanoparticles and the dissolved phase.     

In vitro assessment of probiotic bacteria: From survival to functionality

Selection by means of in vitro tests of new probiotic bacteria presents a challenge for scientists as well as for dairy companies. Presently, most probiotics are assessed using assays focused on their ability to survive in, and subsequently colonise, the gastrointestinal environment. This approach has led to selection of strains with confirmed in vivo probioticity, but the science underlying these assays still needs to be refined. As a consequence, we see a different approach emerging that uses functional properties and/or genomic evaluation to select appropriate probiotic strains.     

In vitro and in situ antimicrobial action and mechanism of glycinin and its basic subunit

Glycinin, basic subunit and β-conglycinin were isolated from soybean protein isolate and tested for their antimicrobial action against pathogenic and spoilage bacteria as compared to penicillin. The three fractions exhibited antibacterial activities equivalent to or higher than penicillin in the next order; basic subunit>glycinin>β-conglycinin with MIC of 50, 100 and 1000 μg/mL, respectively. The IC(50%) values of the basic subunit, glycinin and β-conglycinin against Listeria\monocytogenes were 15, 16 and 695 μg/mL, against Bacillussubtilis were 17, 20, and 612 μg/mL, and against S. Enteritidis were 18, 21 and 526 μg/mL, respectively. Transmission electron microscopy images of L. monocytogenes and S. Enteritidis exhibited bigger sizes and separation of cell wall from cell membrane when treated with glycinin or basic subunit. Scanning electron microscopy of B. subtilis indicated signs of irregular wrinkled outer surface, fragmentation, adhesion and aggregation of damaged cells or cellular debris when treated with glycinin or the basic subunits but not with penicillin. All tested substances particularly the basic subunit showed increased concentration-dependent cell permeation assessed by crystal violet uptake. The antimicrobial action of glycinin and basic subunit was swifter than that of penicillin. The cell killing efficiency was in the following descending order; basic subunit>glycinin>penicillin>β-conglycinin and the susceptibility of the bacteria to the antimicrobial agents was in the next order: L. monocytogenes>B. Subtilis>S. Enteritidis. Adding glycinin and the basic subunit to pasteurized milk inoculated with the three bacteria; L. monocytogenes, B. Subtilis and S. Enteritidis (ca. 5 log CFU/mL) could inhibit their propagation after 16-20 days storage at 4 °C by 2.42-2.98, 4.25-4.77 and 2.57-3.01 log and by 3.22-3.78, 5.65-6.27 and 3.35-3.72 log CFU/mL, respectively.     

In vitro assessment of water resistance of sun care products: a reproducible and optimized in vitro test method

The aim of the study was to develop a simple reproducible and reliable in vitro water resistance (WR) method to assess the sun care products. This paper is the result of a scientific collaboration between seven different international industrial laboratories and testing institutes. The same group has already achieved an in vitro protocol for the sun protection factor (SPF) determination [1]. The in vitro WR of sunscreens was tested by applying the same principle as in vivo, which determines the percentage of retention of sunscreen products by assessing the SPF before and after water immersion. Special care was taken to study the parameters influencing the WR and the possibility to follow the kinetics of sunscreen retention during water immersion. The influence of different water qualities has been tested, and osmosed water (1-3 microS cm(-1)) was chosen for the main ring study. Measurement was carried out after 5, 20 and 40 min of immersion. Histograms of selected products demonstrate the percentage of WR at all measuring times and centres, and the regression coefficient to the in vivo determination was shown and statistical calculations clearly demonstrate the reproducibility of the results between the different evaluation centres. The presented method is a practical, convenient and relevant tool for WR screening of sun care and skin care products. It even has the potential to be the starting point for the replacement of the in vivo method in future.     

In vitro assessment of the upper gastrointestinal tolerance of potential probiotic dairy propionibacteria

This study aimed to assess the transit tolerance of potential probiotic dairy propionibacteria strains in human upper gastrointestinal tract in vitro, and to evaluate the effect of food addition on viability of these strains in simulated pH 2.0 gastric juices. The transit tolerance of 13 dairy propionibacteria strains was determined at 37 degrees C by exposing washed cell suspensions to simulated gastric juices at pH values at 2.0, 3.0, and 4.0, and simulated small intestinal juices (pH 8.0) with or without 0.3% bile salts. The viability of dairy propionibacteria in pH 2.0 simulated gastric juice with So-Good original soymilk or Up & Go liquid breakfast was also determined. The simulated gastric transit tolerance of dairy propionibacteria was strain-dependent and pH-dependent. All tested strains were tolerant to simulated small intestinal transit. The addition of So-Good original soymilk or Up & Go liquid breakfast greatly enhanced the survival of dairy propionibacteria strains in pH 2.0 simulated gastric juices. Dairy propionibacteria strains demonstrate high tolerance to simulated human upper gastrointestinal tract conditions and offer a relatively overlooked, yet alternative source for novel probiotics besides Lactobacillus and Bifidobacterium.     

Redistribution and toxic action of DDT deposited in the body]

In tests on Wistar male-rats the toxic action and redistribution of the DDT repository in the fatty tissue were investigated. For this purpose a DDT depot was built up by introducing DDT in a dose of 0.2 mg/kg for a period of 6 months, following which the rats were made to fast for 20 days, this securing the egress of DDT from the depot. Furthermore, some of the rats, once the depot had been built up, were for 1 month put on a ration containing 5 per cent of protein and then subjected to fasting for 20 days, this having been done in order to study the toxic effect of DDT against the background of a diet with a low protein content. It was found that the amount of DDT retained in the organs and tissues (omentum, liver, brain) investigated in the test rats did not exceed 10 per cent of the quantity that had been introduced at the time of building up the depot. At the time of fasting there was noted migration of DDT from the fat depot, it being the same both in the test and control animals. But DDT coming from the DDT repository entered the liver and brain only in the test animals, provoking changes in the activity of a number of enzymes in these organs. A low protein diet somewhat intensified these changes.     

In vivo and in vitro testing for selenium and selenium compounds bioavailability assessment in foodstuff

The assessment of selenium and selenium species bioavailability in foodstuff is of special concern on the context of human nutrition. In vivo (human and animal), and in vitro tests are important approaches for estimating the bioavailability of toxic and essential compounds to humans. An overview on in vivo and in vitro bioavailability assays for releasing selenium and selenium species in foodstuffs is summarized. Se and Se species content in a foodstuff critically influence Se bioavailability and bioactivity to humans and animals. Se bioavailability is affected by foodstuff-matrix major composition and minor components. Foodstuffs processing and/or treatments could enhancement or decrease Se bioavailability. Experimental conditions such as the selection of healthy status of examined people (in in vivo humans approaches), the selection of animal model (in vivo animals approaches), or the selection of GI conditions (in in vitro tests) could determines the results. Thus, international standardized protocol for in vivo and in vitro approaches assessment is mandatory.     

In vitro assessment of grapevine resistance to two populations of phylloxera from Australian vineyards

A perlite-based medium is described for in vitro cocultivation of phylloxera with micropropagated vines. Using this system, as well as cocultivations on excised primary roots, six vine types were screened for resistance to one or two populations of phylloxera (SRU-1 or VWL-1) sourced from different Australian vineyards. When inoculated with VWL-1 phylloxera, V. vinifera cv. Shiraz was rated as susceptible, Ramsey as resistant, Schwarzmann, V. riparia and Börner as highly resistant and V. rotundifolia as immune. When inoculated with SRU-1 phylloxera, both V. vinifera and Schwarzmann were rated as susceptible. The potential use of these in vitro methods for rootstock resistance screening and determination of phylloxera biotypes is discussed. Phylloxera behaviour and root responses observed in vitro are also described.     

The toxic action of phosphine Absorption and symptoms of poisoning in insects

Oxygen appears to be essential for the absorption of phosphine by insects; under anoxic conditions phosphine is not toxic because it is not absorbed to any appreciable extent. Insects treated with cyanide to the point where respiration is inhibited or severely depressed, do not absorb much phosphine. Roaches treated in nitrogen or carbon dioxide are not visibly damaged by high concentrations of phosphine. Opening or closing of the spiracles appears to have little or no influence on absorption or on the toxic effect. After termination of exposure to an air-phosphine atmosphere, the muscular system of the roach continues to exhibit spasms which occur at increasing intervals until muscular energy is exhausted. The extent of injury produced in roaches appears directly related to the concentration of phosphine and is irreversible after termination of exposure. The amount of phosphine absorbed varies in different insect species; some become saturated within a 5-hr exposure period and absorb no more while others continue to absorb it at a slow rate for 24 hr or longer. After phosphine is taken up by the insects it is not desorbed.     

抑菌剂与DNA作用方式的研究方法

防腐剂是食品工业中不可缺少的物质, 但是食品防腐剂仍存在种类少、耐药性和安全性等问题, 新型抑菌剂的研发及其作用机理研究已经成为研究者们关注的重点。脱氧核糖核苷酸(DNA)是抑菌剂发挥作用的重要靶点, 抑菌剂与DNA作用可以抑制微生物的生长繁殖。抑菌剂与DNA的作用方式有直接结合和间接影响, 直接结合方式有静电结合、沟槽结合和嵌插结合, 探究两者作用方式的研究方法对明确抑菌机理具有重要意义。本文综述了抑菌剂与DNA结合方式的研究方法,包括光谱法、电化学方法和热力学方法等常规的方法, 分子对接、分子动力学模拟及单分子力谱技术等新兴方法, 为抑菌机理的研究、新型抑菌剂的开发及在食品工业中的应用提供思路。     

水产品货架期模型的研究进展

本文对水产品的货架期模型研究进行了全面的综述,总结了水产品基于数学方程的预测模型和基于计算机人工神经网络模型的研究,包括:化学反应动力学模型、基于温度变化的货架期模型、微生物生长非生长预测模型以及人工神经网络模型在水产品中的应用。通过比较分析各种预测模型的优势,为水产品的品质保鲜与安全保障技术提供支持。      

In vitro and in vivo assessment of the effect of Laurus novocanariensis oil and essential oil in human skin

Laurus novocanariensis is an endemic plant from the Madeira Island forest that derives a fatty oil, with a strong spicy odour, from its berries that has been used for centuries in traditional medicine to treat skin ailments. This work aimed to investigate the effect of the application of both the oil and its essential oil on normal skin, to assess their safety and potential benefits. Diffusion studies with Franz cells using human epidermal membranes were conducted. The steady‐state fluxes of two model molecules through untreated skin were compared with those obtained after a 2‐h pre‐treatment with either the oil or the essential oil. Additionally, eleven volunteers participated in the in vivo study that was conducted on the forearm and involved daily application of the oil for 5 days. Measurements were performed every day in the treated site with bioengineering methods that measure erythema, irritation and loss of barrier function. Slightly higher steady‐state fluxes were observed for both the lipophilic and the hydrophilic molecule when the epidermal membranes were pre‐treated. Nevertheless, such differences had no statistical significance, which seems to confirm that neither the oil nor the essential oil impaired the epidermal barrier. Results collected with the Chromameter, the Laser Doppler Flowmeter and the visual scoring are in agreement with those established in the in vitro study. They indicate that the repeated application of the oil did not cause erythema, because the results observed in the first day of the study were maintained throughout the week. Application of the oil did not affect the skin barrier function, because the transepidermal water loss remained constant throughout the study. The stratum corneum hydration was slightly reduced on days 4 and 5. This work shows that both the oil and the essential oil were well tolerated by the skin and did not cause significant barrier impairment or irritation.     

茂名地区主要水产品汞含量分析与风险评估

目的：了解茂名地区主要水产品中汞污染的现状和水平,为水产品的质量监管和安全食用提供依据。方法：根据调查问卷选取广东省茂名市4个地区居民常食用的10种水产品为评估对象,采用原子荧光光谱法对样本进行总汞含量测定,采用单因子污染指数法、周均单位体重暴露量和目标危险系数法分别对其进行污染程度评估、膳食暴露评估和健康风险评估。结果：调查发现42.95%的居民对水产品中汞污染的危害认识不足;10种水产品总汞含量范围为ND～0.141 8 mg/kg,检出率为35.9%,金丝鱼样品的总汞检出率和含量明显高于其他的海产品;39个样品中有38个样品的总汞污染指数P_i＜0.2;总汞的周均单位体重暴露量为0.090 9 μg/（kg·BW）,占每周耐受摄入量的2.273%;水产品中总汞的目标危险系数均小于1,平均目标危险系数为0.13。结论：总体上茂名地区10种水产品总汞含量均未超过国家规定的限量标准,汞污染程度处于安全水平,潜在的健康风险较低,可以安全食用。