Managing helminths of ruminants in organic farming

The use of anthelmintics is strongly limited in organic farming. This may induce a change in the intensity (no of worms) and diversity (proportions of species) of helminth infection. Helminths remain a major preoccupation in organic sheep farming: high levels of infection have been recorded on several farms and helminth diversity is always higher. The helminth infection in milk cattle of northern Europe is controlled and diversity is higher in organic farms, as recorded in sheep. The role of helminth diversity on intensity is still unclear. Grazing management is one of the means to controlling helminths. The use of safe pastures for calves and sheep after weaning is one of the major components of control. The use of alternate or mixed grazing is common for cattle in northern countries but is uncommon for sheep in France. Grazing management is not sufficient to controlling infection in sheep and conventional anthelmintic treatments are performed. Additionally, alternative treatments are used. The alternative therapies based on phytotherapy or homeopathy are largely recommended in organic farming but do not have any demonstrated efficacy. More research is needed to evaluate such therapies.     

Extended summaries physicochemical and biophysical panel symposium neuropeptides

The following are summaries of papers presented at a meeting of the Physicochemical and Biophysical Panel of the Pesticides Group held on 8 December 1987 at the Society of Chemical Industry, 14 Belgrave Square, London SW1X 8PS. The papers published here are entirely the responsibility of the authors and do not reflect the views of the Editorial Board of Pesticide Science.     

Ultrastructural and Cytochemical Investigations of the Antagonistic Effect of Verticillium lecanii on Cucumber Powdery Mildew

ABSTRACT Chronological events of the intercellular interaction between Verticillium lecanii and cucumber powdery mildew, caused by Sphaerotheca fuliginea, were investigated at different times after inoculation by transmission electron microscopy. V. lecanii hyphae colonized host structures by tight binding, apparently mediated by a thin mucilaginous matrix. As early as 24 h after application of the antagonist, increased vacuolation and disorganization of the cytoplasm of the pathogen hyphae were easily detected. By 36 h after treatment, plasmalemma retraction and local cytoplasm aggregation were typical features of damage. Labeling chitin with the wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that intracellular invasion of S. fuliginea by V. lecanii did not cause extensive host cell wall alterations, except in the area of hyphal penetration. By 48 h after inoculation, further cytoplasm disorganization was observed, as evidenced by the loss of cell turgor and contortion of the cell wall. Such deformation suggests that penetration of the antagonist results from mechanical pressure or localized enzymatic hydrolysis through the action of chitinases, as confirmed by the pattern of labeling obtained with the WGA/ovomucoid-gold complex. By 72 h after contact between the fungi, S. fuliginea cells were markedly collapsed, depleted of their protoplasm due to extensive multiplication of the antagonist, and totally encircled by the antagonist. Based on the current observations, the antagonism of S. fuliginea by V. lecanii appears to involve the following events: (i) attachment of the antagonist to the powdery mildew fungus; (ii) mechanical pressure and production of cell-wall degrading enzymes such as chitinases; (iii) penetration and active growth of the antagonist inside the pathogen hyphae; and (iv) digestion of host tissues and release of the antagonist from dead cells of S. fuliginea. The interaction between V. lecanii and S. fuliginea also affected the morphological and structural features of the haustorial bodies, as shown by increased vacuolation, distortion, and necrotization of the haustorial lobes. These observations provide the first experimental evidence that V. lecanii, primarily known as an entomopathogenic fungus, also has the potential to colonize mycelial structures of S. fuliginea. V. lecanii, therefore, may become a valuable alternative to current management of cucumber powdery mildew in greenhouses.     

Metabolism of [3H]triforine in barley grown in the field: The unbound radioactive residue

Barley was sown and grown normally in an experimental field. At the growth stage J,

1 Growth stage J: during the stem extension stage; second node of stem formed and next-to-last leaf just visible.

the aerial part of the plants was sprayed with an aqueous emulsion of a mixture of triforine and [³H]triforine (uniformly labelled in the piperazine ring) using the recommended dose rate of about 240g triforine ha^?1. The barley was harvested when ripe and the straw and grain were analysed separately. The total radioactivity concentration was 20 times higher in straw than in grain. In straw and grain, 12 and 25% respectively of the total incorporated radioactivity in each of these tissues was methanol soluble. The composition of the methanol-soluble radioactive residue was investigated and was shown to contain triforine and its metabolites which were free and unbound in barley straw and grain. No radioactive piperazine was observed, in spite of the high detection sensitivity for radioactivity. The concentrations of triforine and its identified metabolites in straw and grain respectively (mg kg^?1, relative to the fresh weight of tissue) were: triforine, 0.034 and 0.0018; N-[(2,2,2-trichloro-1-(piperazin-1-yl)ethyl]formamide), 0.009 and 0.0006; iminodiacetic acid, 0.021 and 0.001; glycine, 0.043 and 0.0033. Other radioactive water-soluble and very polar, unidentified compounds were observed, corresponding to advanced metabolic products of triforine.     

Brucella suis identification and biovar typing by real-time PCR

Fast and accurate identification of Brucella suis at the biovar level is an important issue for public health laboratories because some of the biovars that infect suidae (boars and pigs) are pathogenic for humans while others are not. Since classical biovar typing methods are often time-consuming, hard to standardize and require high-level biosafety containment, methodological improvements are desirable. This article describes new single nucleotide polymorphism (SNP) signatures for the rapid identification and biovar characterization of B. suis. These SNPs were included together with previously described ones in real-time PCR assays applicable to low-biosafety conditions. Allelic profiles unique for each B. suis biovar were defined and the most relevant signatures were determined on a collection of 137 field strains of worldwide origin characterized previously. Biovars assigned with both present and classical methods were globally consistent except for some biovar 3 field strains which matched the allelic profile of biovar 1.     

Microbial Utilization and Transformation of Humic Acids Extracted from Different Soils

Humic acids (HA) extracted from Chernozem (Haplic Phaeozem), Brown Earth (Cambic Umbrisol) and Podzol (Humic Podzol) were added as a supplemental source of nutrients, or as the sole sources of carbon and nitrogen to aerobic cultures of complex microbial communities indigenous to the same individual soils. Depending on nutrient conditions in the individual cultures and origin of HA, between 14 and 86 % of the added HA was utilized. The formation of microbial biomass was enhanced up to six fold in the full-strength nutrient media supplemented with humic acids but was strongly inhibited if HA served as the sole C source. HA preparations re-isolated from the microbial cultures exhibited elemental and structural changes characteristic for early diagenetic transformations of humic substances. These included an increase in carbon content, C:N ratio, infra-red absorption typical for aromatics, and a decrease in infra-red absorption associated with aliphatic acids, nitrogenous and carbohydrate-like substances.     

Effect of Mixing Conditions on the Behavior of Lipoxygenase,Peroxidase, and Catalase in Wheat Flour Doughs

The effect of mixing has been tested on the extractable activities of lipoxygenase, peroxidase, and catalase from dough after 2, 5, and 20 min of mixing, and 30 min of rest period after 20 min of mixing. Different mixing conditions have been studied including temperature, atmosphere, speed, amount of water added to the dough, buffer solutions between pH 3.6 and 7.5 added to the dough, and different additives (linoleic acid, guaiacol, hydrogen peroxide, ascorbic acid, cysteine, yeast, and sodium chloride). In all the mixing conditions tested, the dough peroxidase activity remains equivalent to the initial flour activity, whereas losses in lipoxygenase and catalase activities largely varied according to mixing conditions. The results show that a self-destruction mechanism as well as physicochemical denaturation are responsible for these losses. Lipoxygenase losses seem mainly associated with the former mechanism, whereas catalase losses are highly increased in acidic conditions (physicochemical denaturation). Therefore, the relative impact of the three oxidoreducing enzymes may be largely modulated by mixing conditions.     

Allium spp thiosulfinates as substitute fumigants for methyl bromide

Methyl bromide, the most widely used fumigant, is considered to be one of the major factors causing depletion of the ozone layer, and this is likely to lead to it being banned in the near future. Allium sulfur volatiles (thiosulfinates, R-S-SO-R′; R, R′=Me, Pr, y Allul), known to be nematicides, have been evaluated as insecticides against insect pests in stored products, in comparison with their degradation compounds (disulfides) which have already been tested. Methyl and allyl thiosulfinates, with 24-h LD₅₀ values of 0.02–0.25 mg litre⁻¹, were more active than disulfides against six test insects and were superior to methyl bromide; it is suggested that they could be used as alternatives to methyl bromide in stored product control. ©1999 Society of Chemical Industry     

Herring Milt and Herring Milt Protein Hydrolysate Are Equally Effective in Improving Insulin Sensitivity and Pancreatic Beta-Cell Function in Diet-Induced Obese- and Insulin-Resistant Mice

Although genetic predisposition influences the onset and progression of insulin resistance and diabetes, dietary nutrients are critical. In general, protein is beneficial relative to carbohydrate and fat but dependent on protein source. Our recent study demonstrated that 70% replacement of dietary casein protein with the equivalent quantity of protein derived from herring milt protein hydrolysate (HMPH; herring milt with proteins being enzymatically hydrolyzed) significantly improved insulin resistance and glucose homeostasis in high-fat diet-induced obese mice. As production of protein hydrolysate increases the cost of the product, it is important to determine whether a simply dried and ground herring milt product possesses similar benefits. Therefore, the current study was conducted to investigate the effect of herring milt dry powder (HMDP) on glucose control and the associated metabolic phenotypes and further to compare its efficacy with HMPH. Male C57BL/6J mice on a high-fat diet for 7 weeks were randomized based on body weight and blood glucose into three groups. One group continued on the high-fat diet and was used as the insulin-resistant/diabetic control and the other two groups were given the high-fat diet modified to have 70% of casein protein being replaced with the same amount of protein from HMDP or HMPH. A group of mice on a low-fat diet all the time was used as the normal control. The results demonstrated that mice on the high-fat diet increased weight gain and showed higher blood concentrations of glucose, insulin, and leptin, as well as impaired glucose tolerance and pancreatic β-cell function relative to those on the normal control diet. In comparison with the high-fat diet, the replacement of 70% dietary casein protein with the same amount of HMDP or HMPH protein decreased weight gain and significantly improved the aforementioned biomarkers, insulin sensitivity or resistance, and β-cell function. The HMDP and HMPH showed similar effects on every parameter except blood lipids where HMDP decreased total cholesterol and non-HDL-cholesterol levels while the effect of HMPH was not significant. The results demonstrate that substituting 70% of dietary casein protein with the equivalent amount of HMDP or HMPH protein protects against obesity and diabetes, and HMDP is also beneficial to cholesterol homeostasis.     

How intensive agricultural practices and flow regulation are threatening fish spawning habitats and their connectivity in the St. Lawrence River floodplain,Canada

Landscape Ecology - Hydrological and land use changes for human purposes, have resulted in the increased fragmentation of river landscapes and the loss of aquatic habitats, leading to profound...