Changes in performance,blood parameters,humoral and cellular immune responses in weanling piglets exposed to low doses of aflatoxin

A feeding trial was conducted to evaluate the effect of aflatoxin (AF)-contaminated diets on growth and hematological and immunological parameters. Low doses of aflatoxins (140 and 280 ppb) were included in a corn-soybean diet provided for ad libitum consumption to 36 weanling piglets for a period of 4 wk. A "dose-related" decrease in weight gain was observed in treated animals. This effect was significant (P < 0.05) in the 280 ppb-treated group compared to the control group. Ingestion of AF-contaminated feed at either level had no effect on total red blood cell numbers or on their relative number of lymphocytes, monocytes, neutrophils, basophils, and eosinophils in blood. Likewise, AF did not alter globulin, albumins, or total protein concentrations in serum, nor did AF alter the expression of regulatory cytokines produced by either Th1 (IL-2) or Th2 (IL-4) lymphocyte subsets in phytohemagglutinin-stimulated blood samples. By contrast, AF had a biphasic effect on total white blood cell number; the low dose of AF (140 ppb) decreased the total number of white blood cells, whereas the high dose (280 ppb) had the opposite effect. Consumption of AF also increased the concentration of gamma-globulin in the serum. A reduced immune response induced by Mycoplasma agalactiae in the 280-ppb-treated group was also observed. Cytokine mRNA expression in phytohemagglutinin-stimulated blood cells indicated that AF decreased proinflammatory (IL-1beta, TNF-alpha) and increased anti-inflammatory (IL-10) cytokine mRNA expression. These results demonstrate that low doses of AF depress growth and alter many aspects of humoral and cellular immunity in pigs.     

Acetylcholine receptor synthesis in retina and transport to optic tectum in goldfish

Previous studies have suggested that the retinotectal system of the goldfish contains a nicotinic acetylcholine receptor (nAChR) that is sensitive to alpha-bungarotoxin. Extracellularly recorded field potentials elicited in response to visual stimulation can be blocked by alpha-bungarotoxin, and alpha-bungarotoxin can interfere with the maintenance of retinotectal synaptic connections. Whether the transmission between the retinal ganglion cells and the tectal cells is mediated by acetylcholine and whether nAChR's exist on the dendrites of tectal cells are questions that remain. The experiments described in this report were designed to determine the site of synthesis of the nAChR's associated with the goldfish retinotectal projection. Radioactive (35S-labeled) methionine was injected into either the eye or the tectal ventricle, and the incorporation of radioactivity into the nAChR was measured by immunoprecipitation. The use of this technique provides evidence that an nAChR associated with the goldfish retinotectal projection is synthesized in the retina and transported to the optic tectum, which suggests a presynaptic site of acetylcholine action on retinal terminals.     

Reorganisation of wood production for improved performance: a swiss forest district case study

An extremely fragmented timber supply, high harvesting costs, low profitability, high subsidies and insufficient competitiveness characterise forest enterprises in Switzerland. In a case study using a forest district in the state of Solothurn as an example, it was sought to identify strengths and weaknesses of wood production and to formulate possible improvement opportunities. The results indicate that there is considerable potential for industry rationalisation. The greatest handicaps are the small sized forest holdings, excessive numbers of staff, insufficient use of modern harvesting technology and costly business administration. The most eminent of the proposed improvement measures are those which aim to increase concentration of timber supplies and reduce production costs. These include greater centralising of timber sales as well as planning and steering of production, making full use of modern harvesting systems, reducing transaction costs, supporting administration, planning and steering of wood production with modern information technology and reducing input on stand tending. In principle, amelioration can be best achieved by close cooperation with neighbours or even merger of enterprises. Consequently, there is a need for related business tasks to be combined in functions. The paramount prerequisite for success is the willingness and readiness of all affected stakeholders to make changes. The situation described is typical for Swiss forestry and the proposed solutions could well be used as models for a wide range of Swiss forest districts.     

Diagnosis of feline leukaemia virus infection by semi-quantitative real-time polymerase chain reaction

In this paper the design and use of a semi-quantitative real-time polymerase chain reaction assay (RT-PCR) for feline leukaemia virus (FeLV) provirus is described. Its performance is evaluated against established methods of FeLV diagnosis, including virus isolation and enzyme-linked immunoassay (ELISA) in a population of naturally infected cats. The RT-PCR assay is found to have both a high sensitivity (0.92) and specificity (0.99) when examined by expectation maximisation methods and is also able to detect a large number of cats with low FeLV proviral loads that were negative by other conventional test methods.     

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission

Enterohaemorrhagic Escherichia coli (EHEC) constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin (Stx)-producing E. coli (STEC) firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Stx production is essential but not sufficient for EHEC virulence. Most strains are capable of colonising the intestinal mucosa of the host with the "attaching and effacing" mechanism, genetically governed by a large pathogenicity island (PAI) defined as the Locus of Enterocyte Effacement. Other virulence factors carried by mobile genetic elements like PAI and plasmids have been recently described, and their role in the pathogenic process has not been fully elucidated. EHEC are zoonotic pathogens. They rarely cause disease in animals, and ruminants are recognised as their main natural reservoir. Cattle are considered to be the most important source of human infections with EHEC O157, and the ecology of the organism in cattle farming has been extensively studied. The organism has also been reported in sheep, goats, water buffalos, and deer. Pigs and poultry are not considered to be a source of EHEC and the sporadic reports may derive from accidental exposure to ruminant dejections. The epidemiology of EHEC infections has remarkably changed during the past ten years and an increasing number of unusual food vehicles have been associated with human infections. New routes of transmission have emerged, like contact with animals during farm visits and a wide variety of environment-related exposures. As for other zoonotic agents, having animals and raw products that are free from EHEC is not possible in practice. However, their occurrence can be minimised by applying high standards of hygiene in all the steps of the food production chain.     

脲酶抑制剂/硝化抑制剂对土壤中尿素氮转化及形态分布的影响

运用^15N尿素示踪技术,以壤质草甸棕壤和春小分别作供试土壤和作物进行盆栽试验,结果表明,与单^15N尿素或^15N尿素＋氢素＋氢醌（HQ）相比,配施双氰胺（DCD）尤其与HQ组合可使土壤保持较高的^15N回收率,其中有^15N占相当大的比例,在小麦孕穗期前,上述两处理可有效地保持尿素解后土壤中NH^ 4 -^15N含量,并显著降低（NO^ 3 NO^-2)-^15N的富集;促进肥料^15N固持－矿化的周转,HQ与DCD配合施用对尿素施用后土壤中残留^15N量及有机^15N的再矿化和NH^ 4-^15N含量具有一定的协同作用。     

Interplay Between Oxytetracycline and the Homozygote kdr (L1014F) Resistance Genotype on Fecundity in Anopheles gambiae (Diptera: Culicidae) Mosquitoes

The insecticide resistance in Anopheles gambiae mosquitoes has remained the major threat for vector control programs but the fitness effects conferred by these mechanisms are poorly understood. To fill this knowledge gap, the present study aimed at testing the hypothesis that antibiotic oxytetracycline could have an interaction with insecticide resistance genotypes and consequently inhibit the fecundity in An. gambiae. Four strains of An. gambiae: Kisumu (susceptible), KisKdr (kdr (L1014F) resistant), AcerKis (ace-1 (G119S) resistant) and AcerKdrKis (both kdr (L1014F) and ace-1 (G119S) resistant) were used in this study. The different strains were allowed to bloodfeed on a rabbit previously treated with antibiotic oxytetracycline at a concentration of 39·10^–5 M. Three days later, ovarian follicles were dissected from individual mosquito ovaries into physiological saline solution (0.9% NaCl) under a stereomicroscope and the eggs were counted. Fecundity was substantially lower in oxytetracycline-exposed KisKdr females when compared to that of the untreated individuals and oxytetracycline-exposed Kisumu females. The exposed AcerKis females displayed an increased fecundity compared to their nontreated counterparts whereas they had reduced fecundity compared to that of oxytetracycline-exposed Kisumu females. There was no substantial difference between the fecundity in the treated and untreated AcerKdrKis females. The oxytetracycline-exposed AcerKdrKis mosquitoes had an increased fecundity compared to that of the exposed Kisumu females. Our data indicate an indirect effect of oxytetracycline in reducing fecundity of An. gambiae mosquitoes carrying kdr^R (L1014F) genotype. These findings could be useful for designing new integrated approaches for malaria vector control in endemic countries.