Impact of biotransformation and bioavailability on the toxicity of the insecticides alpha-cypermethrin and chlorfenvinphos in earthworm

Knowledge about the bioavailability and metabolism of pesticides in soil organisms facilitates interpretation of its toxicity in soil. The present study relates uptake kinetics and metabolism of two insecticides, the pyrethroid alpha-cypermethrin (alpha-CYP) and the organophosphate chlorfenvinphos (CFVP), in the earthworm Eisenia fetida to their lethal and sublethal toxicity. Experiments were conducted in two soils with different organic matter contents to provide media with contrasting sorption capacity for the insecticides. The results showed that organophosphate CFVP was, when taken up by earthworms, rapidly and irreversibly bound to biomolecules and the fraction of extractable parent insecticide and metabolites was low. In contrast, alpha-CYP was rapidly metabolized by earthworms but did not form conjugates. It seems that the phase II metabolism of alpha-CYP is inhibited in earthworms, resulting in an increasing accumulation of its metabolites. Instantaneous binding of non-altered CFVP to the target site presumably resulted in a higher toxicity compared to alpha-CYP and explains the small difference between lethal and reproduction toxicity. For alpha-CYP, however, accumulation of alpha-CYP metabolites in earthworms during chronic exposure may explain the large observed difference between lethal and sublethal toxicity. Bioaccumulation and toxicity of either insecticide decreased with increasing organic matter content in soil, emphasizing the role of compound sorption on bioavailability and toxicity for soil organisms.     

Natural and experimental Salmonella Typhimurium infections in foxes (Vulpes vulpes)

The red fox (Vulpes vulpes) can be considered as a relevant indicator species for Salmonella in the local environment and Salmonella faecal carriage was investigated in 215 red foxes in Norway shot during the winters 2002/2003 and 2003/2004. Fourteen (6.5%) of the foxes carried Salmonella. Four isolates were determined as serovars Kottbus (n=2) and Hessarek (n=2) of Salmonella enterica subspecies enterica, and one as S. enterica subspecies IIIb:61:k:1,5,(7). The remaining nine isolates were S. enterica subspecies enterica serovar Typhimurium 4,12:i:1,2 and all displayed the same pulsed-field gel electrophoresis (PFGE) profile designated A2. This serovar regularly causes disease outbreaks amongst small passerine birds during winter and most of these outbreaks are associated with the PFGE profile A2. The results strongly indicated that the Salmonella Typhimurium infections in red foxes were primarily acquired through ingestion of infected small passerines. To investigate the capability of the A2 strain to establish a true intestinal infection in the fox an inoculation experiment with an A2 isolate from small passerines was carried out in farmed silver foxes (V. vulpes). The experiment also included one strain with an uncommonly occurring profile (X201) from small passerines. To highlight possible differences in capability of the two inoculation strains to pass the acid gastric juice in the fox, in vitro studies of their acid tolerance was carried out. Also their catalase activity and biofilm production were studied. All three foxes inoculated with the A2 strain developed sub-clinical intestinal infection of 2 weeks duration, whereas none of the three foxes inoculated with the X201 strain shed this bacterium. The X201 strain displayed a much lower capability, than the A2 strain, to survive at pH 3 in vitro. The low acid tolerance probably made it difficult for the X201 strain to pass the stomach and establish an intestinal infection in the experimental foxes. Reduced catalase activity and biofilm production were found for the X201 strain, indicating that the low acid tolerance was caused by a defect in the stationary-phase stress response system.     

Monitoring of artemisinin, dihydroartemisinin, and artemether in environmental matrices using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS)

The area cultivated with Artemisia annua for the extraction of the antimalarial compound artemisinin is increasing, but the environmental impact of this cultivation has not yet been studied. A sensitive and robust method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of artemisinin in soil. Dihydroartemisinin and artemether were included in the method, and performance on analytical columns of both traditional C(18) phenyl-hexyl and porous shell particles-based Kinetex types was characterized. The versatility of the method was demonstrated on surface water and groundwater samples and plant extracts. The limit of detection was 55, 30 (25 ng/g soil), and 4 ng/mL for dihydroartemisinin, artemisinin, and artemether, respectively. Method performance was demonstrated using naturally contaminated soil samples from A. annua fields in Kenya. The highest observed concentrations were above EC(10) for lettuce growth. Monitoring of artemisinin in soil with A. annua crop production seems necessary to further understand the impact in the environment.     

Proteases of Clostridium Botulinum: II. The Relationship Between Growth Medium and the Production of Proteases by Clostridium Botulinum Types A,B, C,D, E and F

The present investigation was carried out in order to find a suitable medium for the production of proteolytic enzymes from different types of Clostridium botulinum. Proteolytic activity was found in Clostridium botulinum types A, B, C, D and F, while supernatants of Clostridium botulinum type E did not possess any proteolytic activity at all.Skim milk medium possessed the greatest ability for the production of proteolytic enzymes from the different cultures of Clostridium botulinum tested, while Robertson’s meat broth produced lowest amounts. Highest titres were usually found after 4–5 days of incubation and, after this period, the level of proteolytic activity decreased.     

Dimension and design of the farrowing unit

1引言 分娩舍是母猪场中最昂贵的猪舍,同时也是最重要的一个.它应该能够在开展作业时,向母猪、新生仔猪以及工作人员提供一个舒适的环境.分娩舍的设计目标是为了能够培养出尽可能多的仔猪和尽可能高的仔猪断奶体重.当然,技术仅仅是这一等式的一部分;环境温度和管理也发挥了重要的作用.     

Dimension and design of the mating and control unit

1引言 配种和轻胎舍是母猪场中最重要的一个组成部分.因此,它必须能带来高妊娠率、高产仔、均衡的体况、较长的母猪使用寿命和低返情率.也就是说,配种和轻胎舍的设计必须有助于管理者获得较高的生产率.     

Residues of Sulfadimidine/Sulfanilamide and Sulfamethoxypyridazine in Sheep Tissue

Following treatment of sheep with different sulfonamides, residues in kidney, liver, and muscle have been determined by microbiological and chemical methods. By the microbiological method residues could be detected in kidney until the third day after the combined treatment with sulfadimidine/sulfanilamide. Using the chemical method, residues of about 3.80 p.p.m. could be found that day in kidney, while the concentrations in liver and muscle were about 1.90 and 1.20 p.p.m., respectively. On the eighth day after the last treatment traces of the medicine could be found in kidney, liver and muscle by using the chemical method.Residues of sulfamethoxypyridazine could be detected micro-biologically in kidney the second day after the last administration of the drug. The concentration at that time in kidney, liver and muscle determined by chemical analyses was about 4.66, 2.45 and 1.23 p.p.m., respectively. Traces of sulfamethoxypyridazine in kidney, liver and muscle could also be detected on the eighth day after the last medication.Considering altered metabolic rates of sick animals and variations in excretion rates between individuals of the same species, as well as variation in size of the doses applied, a 10 day withdrawal period for sulfonamides is proposed.     

Antioxidant activity of knotwood extractives and phenolic compounds of selected tree species

The antioxidant potency and the radical scavenging capacity of superoxide and peroxyl radicals were assessed for 13 hydrophilic knotwood extracts of commercially important wood species, or fractions thereof, as well as for five pure wood-derived lignans and the flavonoid taxifolin. The chemical composition of the knotwood extracts was determined by gas chromatography combined with mass spectrometry. Most of the investigated wood species were rich in hydrophilic extractives (10-20% of the dry wood) with one or a few compounds dominating in each extract. All extracts had a high antioxidative potency and/or radical scavenging capacity as compared to the well-known antioxidants Trolox and butylated hydroxyanisole. The pure wood-derived lignans and taxifolin also had a high antioxidative potency and/or radical scavenging capacity. However, the antioxidant potency and/or radical scavenging capacity of several of the hydrophilic knotwood extracts were higher than that of the dominating compounds in pure form.     

Cleaning heavy metal contaminated soil with soluble humic substances instead of synthetic polycarboxylic acids

Abstract

Soils contaminated with heavy metals constitute a serious and widespread ecological problem but to clean such soils requires strong chemicals such as polycarboxylates; frequently ethylenediaminetetraacetic acid and nitrilotriacetic acid are used. However, these compounds are synthetic and toxic and their replacement by natural products such as soluble humic substances as washing agents for cleaning heavy metal polluted soils would be environmentally very attractive. In fact, such a replacement seems possible at least on cadmium and copper contaminated soil inasmuch as humic substances, depending on the concentration, were found to extract up to 45% and 54% of total cadmium and copper from a highly contaminated calcareous soil. Even though higher amounts of the two metals were extracted by ethylenediaminetetraacetic acid and nitrilotriacetic acid, the humic substances undoubtedly extracted the most reactive fractions. However, the humic substances extracted only 4% of total lead and 17% of total nickel, whereas the percentages for the synthetic polycarboxylates were about 30% for nickel and lead. Ethylenediaminetetraacetic acid and nitrilotriacetic acid may therefore be replaced by humic substances as washing agents for cadmium, copper and maybe nickel contaminated soils, whereas they seem unsuited for cleaning lead contaminated soils, at least if the soils are as calcareous as the soil tested.