两种生测法检测杀虫剂对家蝇毒力的比较研究

目的用两种生物检测方法--点滴法与喂饲法检测杀虫剂对家蝇的毒力,比较这两种方法检测结果的差异.方法采用点滴法和喂饲法检测3种类型杀虫剂对两种品系家蝇的毒力.结果Lab品系差异较少,为0.48～1.69倍（LD50/LC50）;Cyh-R品系差异较大,为0.71～87.13倍（LD50/LC50）,抗药性品系的雄蝇差异较小.结论对于敏感品系家蝇可用点滴法或喂饲法检测杀虫剂的毒力,其结果差异不大;对于抗药性品系由于复杂的抗药性机制,两种方法不能替代;对于用做毒饵制剂的杀虫剂,建议用喂饲法进行检测毒力和抗药性研究.     

Toxicity of Chlorate and Chlorite to Selected Species of Algae, Bacteria, and Fungi

The present study confirms that chlorate is toxic only to brown algae and not to species of other ecologically relevant taxa. The brown algaEctocarpus variabilisexhibited a LOEC of 0.005 mM (0.4 mg ClO⁻₃/liter) and an LC₅₀of 0.012 mM, when cultured with nitrate as a sole source of nitrogen. The toxicity to species other than brown algae as measured in growth inhibition tests ranged from 0.75 mM (96-h NOEC) forSelenastrum capricornutumto ≥7.48 mM (48-h NOEC) for the fungusTrichoderma hamatum. The nitrogen source, nitrate or ammonium, did not significantly influence the toxicity to the nonsensitive species. The tests on brown algae found that as compared with ammonium, the toxicity to nitrate-grown cultures is higher by a factor of about 10. This confirms the hypothesis that nitrate reductase is involved in the toxic effects of chlorate on brown algae. Chlorite, tested as a potential toxic metabolite of chlorate, demonstrated high toxicity to many of the taxa tested and only low toxicity toE. variabilis. It may be concluded that brown algae are exceptionally sensitive to chlorate. It may also be concluded that various nitrogen sources could not induce toxicity in nonsensitive species. From these experiments no conclusions could be drawn as to the potential role of chlorite in chlorate toxicity. Furthermore it may be concluded thatE. variabilisis a suitable laboratory test species for further investigations into the mechanism of chlorate toxicity to brown algae.     

扩散管法配制十种挥发性有机化合物标准染毒混合气体的研究

以液态苯、甲苯、对－二甲苯、乙基苯、氯代苯、苯乙烯、异丙苯、四氯乙烯、甲基环己烷和壬烷等常见VOCs为原料,在一定的温度下,通过控制载气流速来配制10年标准染毒气体。详细介绍了配制10种VOCs标准染毒气体的方法,探讨了所配标准气体的准确性和稳定性,提出了用动态配气装置配制10种VOCs标准气体的方法。同时,分别用热解吸－气相色谱法和固相微萃取－气相色变法对所配的VOCs 的标准染毒气体的浓度进行了测定。实验证明,所配标准气体的称量结果与二种方法的测定值相比较,差异无显著性。用扩散管法配制低浓度挥发性有机化合物（ VOCs） 标准染毒混合气体,其VOCs的浓度可以较方便调整。其扩散率的相对标准偏差小于2％ 。该动态配气方法适用于环境中低浓度VOCs 在毒理学 染毒上的应用。且扩散管可重复使用。     

溴杀灵对三种家鼠的毒力测定及灭效研究

本文报道辽宁省化工研究院研制的溴杀灵，对福建省常见３种家鼠的毒力和灭鼠效率。溴杀灵对褐家鼠的ＬＤ５０为１．８０１±０．２３３ｍｇ／ｋｇ，对黄胸鼠的ＬＤ５０为３．２９２±０．４２１ｍｇ／ｋｇ，对小家鼠的ＬＤ５０为１１．００３±１．４３１ｍｇ／ｋｇ。０．０１％溴杀灵大米毒饵对黄胸鼠平均摄食系数为１．７５，室内灭效为１００％，现场灭鼠对褐家鼠的杀灭率为８９．９６％。     

Acute Toxicity Tests with the Tropical Cladoceran <Emphasis Type="Italic">Pseudosida ramosa</Emphasis>: The Importance of Using Native Species as Test Organisms

Cladocerans have long been used for toxicological assessments of a diverse range of substances. The use of cladocerans in toxicity tests has many advantages, such as their short life cycle, parthenogenetic reproduction (clones), and high sensitivity to toxicants, as well as the easy laboratory maintenance of cultures. The most commonly used cladoceran in ecotoxicological studies of aquatic environments is undoubtedly Daphnia magna. Standard methods using cladocerans as test organisms have been documented and adopted by major international organizations and regulatory agencies of many countries. However, today there is a growing need for improving test organisms and protocols to better reflect local species sensitivity or site-specific conditions. The present study aimed to assess the tropical species Pseudosida ramosa as a potential test organism for ecotoxicological purposes, by carrying out standard acute tests with six reference compounds. Based on the results obtained in the present study and in comparison with other cladocerans, it was found that P. ramosa was more sensitive than Daphnia magna, had a sensitivity similar to that of Daphnia similis, and was less sensitive compared to Ceriodaphnia dubia and C. silvestrii (Neotropical species), except for the salts, sodium chloride and potassium chloride. Also, when P. ramosa was compared with test organisms of other taxonomic groups, we observed that it was more sensitive than most of the others, from simple coelenterates to complex fish. Considering these results and the wide distribution of the cladoceran P. ramosa in tropical and subtropical regions, we suggest that this species can be adopted as a test organism, being a good substitute for the exotic daphnid D. magna, for monitoring of toxicants in freshwaters.     

Evaluation of Bread Crumbs as a Potential Carbon Source for the Growth of Thraustochytrid Species for Oil and Omega-3 Production

The utilization of food waste by microorganisms to produce omega-3 fatty acids or biofuel is a potentially low cost method with positive environmental benefits. In the present study, the marine microorganisms Thraustochytrium sp. AH-2 and Schizochytrium sp. SR21 were used to evaluate the potential of breadcrumbs as an alternate carbon source for the production of lipids under static fermentation conditions. For the Thraustochytrium sp. AH-2, submerged liquid fermentation with 3% glucose produced 4.3 g/L of biomass and 44.16 mg/g of saturated fatty acids after seven days. Static fermentation with 0.5% and 1% breadcrumbs resulted in 2.5 and 4.7 g/L of biomass, and 42.4 and 33.6 mg/g of saturated fatty acids, respectively. Scanning electron microscopic (SEM) studies confirmed the growth of both strains on breadcrumbs. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy for both strains were consistent with the utilization of breadcrumbs for the production of unsaturated lipids, albeit at relatively low levels. The total lipid yield for static fermentation with bread crumbs was marginally lower than that of fermentation with glucose media, while the yield of unsaturated fatty acids was considerably lower, indicating that static fermentation may be more appropriate for the production of biodiesel than for the production of omega-3 rich oils in these strains.     

Potential of Traditionally Cooked Green Leafy Vegetables as Natural Sources for Supplementation of Eight Micronutrients in Vegetarian Diets

The potential of 24 green leafy vegetables (GLV) in cooked form was assessed for the contents of eight micronutrients; bioavailability of iron, zinc and copper; and for proximate principles. The bioavailable densities of iron, zinc and copper (1.3±1.2, 1.1±0.5, 0.7±0.3 mg/1000 kcal) in individual GLV and GLV-based meals were higher than those in meals based on cereals or legumes. Average bioavailable iron density in particular, was 3.6 times higher (P<0.01) than the average value for composite cereal–legume-based meals indicating GLV as promising fortificants of iron for vegetarians. Contents per 100 g cooked weight of beta-carotene (80–5920 μg), ascorbic acid (2.2–58.2 mg), folic acid (35.6–185 μg), riboflavin (0.03–0.08 mg) and thiamin (0.04–0.46 mg) were found to show large variability among different GLV but the average levels of beta-carotene and ascorbic acid were significantly higher than the other food classes (P<0.05). The contents of the vitamins were compared in cereal–legume meals (12), cereal–fruit vegetable meals (16), and cereal–GLV meals (30) in another experiment. The results indicate a highly significant and 8.7-13.1-fold rise in beta-carotene levels, and a 1.7–2.3-fold rise in the levels of folic acid and riboflavin in GLV meals as compared to other meals indicating the potential for increasing these three vitamin levels using GLV.     

Continuous Monitoring of Folsomia candida (Insecta: Collembola) in a Metal Exposure Test

Current recommended ecotoxicological tests with the parthenogenetic springtail Folsomia candida using standard OECD soil do not allow for continuous monitoring during the exposure period. Effects of chemicals cannot be determined until the end of the experiment (typically after 4 weeks), since the animals stay below the soil surface. In this study, F. candida were maintained on a plaster of Paris/graphite substrate for 7 weeks and were supplied with an aqueous suspension of yeast contaminated with Cd, Cu, Pb, and Zn as nitrate salts. Growth rate, time to first batch of eggs, quantity of food consumed, and the presence of graphite in the gut (a sign of avoidance of yeast) were all affected by metal contaminated diets. The relative toxicities of Cd:Cu:Pb:Zn in the yeast were 1.0:1.07:12.0:4.3, respectively (on a weight basis) with Cd being the most toxic. Internal body concentrations increased, and the concentration factor (metal concentration in F. candida/metal concentration in yeast) decreased with increasing metal exposure. In general, metals are much less toxic when added to the food of F. candida than when incorporated into soil in standard tests. It is suggested that Collembola have a greater tolerance of metals in the diet since they avoid contaminated food, and are able to excrete assimilated metals at moulting via exfoliation of the midgut epithelium where the elements are retained as part of a storage–detoxification system. The methodology described in this article allows effects on growth to be observed as early as 7 days after the beginning of the experiment.     

Preference and sensitivity to salt taste as determinants of salt-intake

Total salt-intake was estimated in 33 normal subjects using urinary sodium excretion over 7 days, and table and cooking salt use were measured over the same period. Sensitivity to salt taste was measured for 31 of these subjects using a seven-category rating scale for intensity of saltiness with five concentrations of salt in water, bread and mashed potato. Preferences were assessed using a nine-category hedonic rating scale with the bread and mashed potato to determine the maximally-preferred concentration. No differences were found in the taste measures between subjects divided into high and low intake in terms of total salt-intake or total intake divided by body weight. However, differences were found in sensitivity and preferences between groups divided into high and low table salt use. This may be because the major proportion of total salt-intake arose from salt present in foods and this would not be so open to voluntary control as table salt use.     

Use of the Ciliated Protozoan Tetrahymena pyriformis for the Assessment of Toxicity and Quantitative Structure–Activity Relationships of Xenobiotics: Comparison with the Microtox Test

Cytotoxicity and quantitative structure-activity relationships of 13 inorganic and 21 organic substances were determined using three bioassays performed on the ciliated protozoan Tetrahymena pyriformis and the luminescent bacterium Vibrio fischeri. The best concordance of toxicity results was observed between the T. pyriformis FDA--esterase activity and population growth inhibition tests for the organic compounds. The sensitivity of these two assays is compared with that of the Microtox test. The T. pyriformis FDA test showed a high sensitivity is most cases. The aim of the current research was to determine whether the relative toxicity of metal ions and organic molecules, with these three bioassays, was predictable using three ion characteristics and hydrophobicity, respectively. For metal ions, the variable that best modeled the toxicity data obtained with the two T. pyriformis tests was the softness index [sigma(p), i.e., (coordinate bond energy of the metal fluoride--coordinate bond energy of the metal iodide)/(coordinate bond energy of the metal fluoride)]. No correlation was found with the Microtox test. For organic compounds, a significant correlation was observed between the hydrophobicity coefficient and the toxicity data. This correlation is closer with the two tests using Tetrahymena.     

Isolation of a novel gene from Photobacterium damselae subsp. piscicida and analysis of the recombinant antigen as promising vaccine candidate

Photobacterium damselae subsp. piscicida (PDP) is the causative agent of fish pasteurellosis, a bacterial disease causing important losses in marine aquaculture. Vaccines against the pathogen can be a way to control the infection and avoid antibiotic treatments. However, a satisfactory protective vaccine against fish pasteurellosis is not commercially available. In this study, a biotechnogical approach based on reverse vaccinology has been used to identify potential vaccine candidates for the development of a recombinant subunit vaccine. Genome sequencing of clones from a genomic cosmid library of PDP and in silico selection of the surface exposed proteins were the initial steps in vaccine candidate identification. From 370 open reading frames (ORF) eight potential antigens were selected, expressed as recombinant proteins and purified. These vaccine candidates were used to generate specific polyclonal antibodies in mice. Each antibody was then screened in vitro by inhibition adherence assay of live PDP on chinook salmon embryo cells (CHSE-214). A lipoprotein, found to be involved in the adherence of the bacterium to epithelial cells and annotated as PDP_0080, was then selected. The recombinant protein was further investigated in fish vaccination and challenge experiments to assess its ability to protect sea bass, Dicentrarchus labrax, against PDP infection. Immunisation with PDP_0080 recombinant protein elicited high specific antibody titres. Furthermore, the survival rate of fish immunized with the 25 μg dose of protein was significantly higher compared to the control group. The results of the study suggest that the PDP_0080 protein could be a promising candidate for the design of a recombinant vaccine against pasteurellosis.