Use of Malathion Against Ectoparasites on Lactating Cows

The clinical effect, residues in milk and toxicological properties of a non-commercial formulation of malathion used as an ectoparasitic agent on cattle were investigated. The results show that the malathion preparation has a desired clinical effect. The maximum concentration of malathion in milk after topical application of 5 g malathion was 0.054 μg/ml 4–6 h post-treatment, and declined to 0.005 and 0.002 μg/ml 24 and 48 h post-treatment, respectively. Totally 0.006–0.03 % of the applied dose was excreted in the milk. No toxic effect, measured as inhibition of the cholinesterases in erythrocytes and plasma, could be detected after therapeutic use of malathion. The pharmacokinetic evaluation after 2.5 g intravenous administration of malathion, indicated that the kinetics could probably be described by a multicompartment model.     

Slugs: Potential Novel Vectors of Escherichia coli O157

Field and laboratory studies were performed to determine whether slugs could act as novel vectors for pathogen (e.g., Escherichia coli O157) transfer from animal feces to salad vegetables. Escherichia coli O157 was isolated from 0.21% of field slugs from an Aberdeenshire sheep farm. These isolates carried the verocytotoxin genes (vt1 and vt2) and the attaching and effacing gene (eae), suggesting that they are potentially pathogenic to humans. Strain typing using multilocus variable number tandem repeats analysis showed that slug and sheep isolates were indistinguishable. Laboratory experiments using an E. coli mutant resistant to nalidixic acid showed that the ubiquitous slug species Deroceras reticulatum could carry viable E. coli on its external surface for up to 14 days. Slugs that had been fed E. coli shed viable bacteria in their feces with numbers showing a short but statistically significant linear log decline. Further, it was found that E. coli persisted for up to 3 weeks in excreted slug feces, and hence, we conclude that slugs have the potential to act as novel vectors of E. coli O157.     

Slugs: potential novel vectors of Escherichia coli O157

Field and laboratory studies were performed to determine whether slugs could act as novel vectors for pathogen (e.g., Escherichia coli O157) transfer from animal feces to salad vegetables. Escherichia coli O157 was isolated from 0.21% of field slugs from an Aberdeenshire sheep farm. These isolates carried the verocytotoxin genes (vt1 and vt2) and the attaching and effacing gene (eae), suggesting that they are potentially pathogenic to humans. Strain typing using multilocus variable number tandem repeats analysis showed that slug and sheep isolates were indistinguishable. Laboratory experiments using an E. coli mutant resistant to nalidixic acid showed that the ubiquitous slug species Deroceras reticulatum could carry viable E. coli on its external surface for up to 14 days. Slugs that had been fed E. coli shed viable bacteria in their feces with numbers showing a short but statistically significant linear log decline. Further, it was found that E. coli persisted for up to 3 weeks in excreted slug feces, and hence, we conclude that slugs have the potential to act as novel vectors of E. coli O157.     

An Optical Model for Phototactic Orientation in Dictyostelium discoideum Slugs

The optical properties of an enlarged optical model of the tipof a slug (a glass tube filled with sucrose solution) of Dictyosteliumdiscoideum were studied to validate the hypothesis that theorganism orients itself with respect to lateral light usinga lens effect: Light is focussed by refraction onto the distalside of the slug where the higher "signal" compared to the frontside causes a turn toward the light. Light was effectively focusedeven when the model deviated only as little as 10° fromthe light direction. Slugs of D. discoideum strains HO596 and HO813 show bidirectionalphototaxis: They orient themselves at some angle on either sideof the incident light beam. This angle is {small tilde}80°in HO596 and {small tilde}70° in HO813. We suggest thatthis phenomenon can be explained by the optical properties ofthe slug such as absorption and scattering, shape of the tipor location and extension of the light-sensitive zone. The angleof orientation with respect to light is regulated by a balancebetween a turn toward and a turn away from the light direction. (Received October 15, 1985; Accepted February 10, 1986)     

The Role of Small Cardioactive Peptide, SCPB, in the Regulatory Responses of Terrestrial Slugs

The feeding motor program in Limax maximus is the neural correlateof feeding and consists of a discrete pattern of cyclical efferentactivity generated by the buccal ganglia in response to stimulationof chemosensory pathways. The small cardioactive peptide, SCP_B(10^–6 to 10^–9 M), increases the responsiveness ofthe FMP and the endogenous activity of specific feeding motoneuronssuch as the fast salivary burster. Stimulation of buccal neuron,B1, which contains SCP_B-like immunoreactive substance, similarlyincreases the activity of feeding motoneurons. Furthermore,both exogenous SCP_B and stimulation of Bl increase the contractileforce of the heart. Thus it appears that the peptidergic neuronBl is a multifunctional interneuron that is involved in thecontrol of both peripheral and central targets.     

Biocontrol of Slugs in Protected Lettuce Using the Rhabditid Nematode Phasmarhabditis hermaphrodita

In two experiments, the rhabditid nematode Phasmarhabditis hermaphrodita, a parasite of slugs, was cultured in vitro and applied as a drench to soil at four dose rates (3 108, 1 109, 3 109 and 1 1010 ha-1) 1 or 4 days before planting lettuce seedlings in a polythene tunnel. The effects of the four nematode doses on slug damage during the first 3 weeks after planting and on the numbers of slugs found within and below lettuce plants at harvest were measured. Results were then compared with untreated plots and with plots where methiocarb pellets were applied at the recommended field rate. In the first experiment, methiocarb pellets significantly reduced the percentage of plants damaged by slugs, but the nematode did not. In the second experiment, methiocarb pellets and the second highest dose of nematodes significantly reduced the percentage of plants damaged by slugs. The different effect of the nematode in the two experiments may have resulted from differences in the timing of nematode application and/or differences in the pattern of slug damage between experiments. At the end of the first experiment, the highest two doses of nematodes and methiocarb pellets had significantly reduced the number of slugs found within lettuce plants at harvest and on the soil surface below the plants. At the end of the second experiment, analysis of variance showed no significant effects of any treatment on slug numbers or biomass, but regression analysis showed significant negative relationships between nematode dose and total slug numbers, numbers of Arion ater agg. and biomass of Deroceras reticulatum. In both experiments, increasing nematode dose significantly reduced the numbers of slugs found contaminating the harvested lettuce. At the end of the second experiment, the mean weight of individuals of A. ater agg. increased with rising nematode dose.     

Cell Movements and Mechanical Force Distribution During the Migration of Dictyostelium Slugs

Migration of Dictyostelium discoideum slugs results from coordinated movement of their constituent cells. It is generally assumed that each cell contributes to the total motive force of the slug. However, the basic mechanisms by which mechanical forces (traction and resistive forces) are transmitted to the substrate, their magnitude and their location, are largely unknown. In this work, we performed detailed observations of cell movements by fluorescence microscopy using two-dimensional (2D) slugs. We show that 2D slugs share most of the properties of 3D ones. In particular, waves of movement propagate in long 2D slugs, and slug speed correlates with slug length as found in 3D slugs. We also present the first measurements of the distribution of forces exerted by 2D and 3D slugs using the elastic substrate method. Traction forces are mainly exerted in the central region of the slug. The large perpendicular forces around slug boundary and the existence of parallel resistive forces in the tip and/or the tail suggest an important role of the sheath in the transmission of forces to the substrate.     

Production, Characterization, and Use of Monoclonal Antibodies Against Acremonium coenophialum

Monoclonal antibodies were produced using intact mycelium of the fungus Acremonium coenopbialum as the immunogen. During the initial stages of characterization, the antibodies were found to react to A. coenophialum, A. loliae, Epichloe typhina , and also to cross-react with some other fungi normally associated with tall fescue. Careful selection of the ELISA system in which the antibodies were used eliminated reactions to all but the two Acremonium spp. and E. typhina. Asa result it was possible to detect Acremonium spp. (presumably A. coenophialum ) sensitively and unambiguously in leaf tissue of tall fescue.     

Inhibition of Phototaxis and Motility by UV-B Irradiation in Dictyostelium discoideum Slugs

The effect of monochromatic irradiation in and near the UV-Bregion (280–320 nm) on motility (speed of movement) andwhite light-induced phototactic orientation was studied in slugsof the cellular slime mold Dictyostelium discoideum (NC-4).Motility decreased to about 50% in UV-B fluences (about 100Jm^–2 at 280 nm) well below those required to inhibit slugand sorocarp development or to impair viability. At wavelengthsof 270–300 nm, the phototactic orientation was almosttotally eliminated by an exposure to U V (about 0.1 Wm^–2)for as short a time as half an hour when administered at thebeginning of the 24 h exposure to white light. (Received July 22, 1983; Accepted September 27, 1983)     

Field Test Using the Nematode Phasmarhabditis hermaphrodita for Biocontrol of Slugs in Spain

An experiment was carried out between May and July 1999 in Galicia (North-West Spain) to test the capacity of the nematode Phasmarhabditis hermaphrodita to protect field grown lettuces from slug damage in our field conditions. The experiment compared a single dose of nematodes (3 ×109 ha -1) with mini-pellets containing 5% metaldehyde, applied at the recommended field rate (3 g pellets m -2), and untreated plots. Slug damage for each lettuce head was estimated on six dates during the first 4 weeks after planting. At harvest, each lettuce head was weighed, scored as marketable or not by weight and external aspect, and inspected for slugs. Metaldehyde significantly reduced slug damage to lettuce plants from the first day after planting to the third week. Nematodes significantly reduced slug damage from the second to the third week. At harvest, 6 weeks after planting, the mean weight of the lettuce heads and the number of marketable heads in the nematode plots were as good as in the metaldehyde plots, and both treatments were significantly better than the untreated plots. The number of slugs within the harvested plants was significantly reduced only with the metaldehyde treatment.     

Marine Snails and Slugs: a Great Place To Look for Antiviral Drugs

Molluscs, comprising one of the most successful phyla, lack clear evidence of adaptive immunity and yet thrive in the oceans, which are rich in viruses. There are thought to be nearly 120,000 species of Mollusca, most living in marine habitats. Despite the extraordinary abundance of viruses in oceans, molluscs often have very long life spans (10 to 100 years). Thus, their innate immunity must be highly effective at countering viral infections. Antiviral compounds are a crucial component of molluscan defenses against viruses and have diverse mechanisms of action against a wide variety of viruses, including many that are human pathogens. Antiviral compounds found in abalone, oyster, mussels, and other cultured molluscs are available in large supply, providing good opportunities for future research and development. However, most members of the phylum Mollusca have not been examined for the presence of antiviral compounds. The enormous diversity and adaptations of molluscs imply a potential source of novel antiviral compounds for future drug discovery.