Chemical modification employed as a means of probing the cell-wall micropore of pine sapwood

The cell-wall micropore network of oven-dried Corsican and Scots pine sapwood has been investigated by reaction with acetic and propionic anhydride in a non-swelling solvent (xylene). No significant reaction occurred, except in the case of reaction between Corsican pine and acetic anhydride. However, when the wood samples were in a swollen state, reaction occurred between the wood and both anhydrides. It is concluded that the cell-wall micropores of Corsican pine are sufficiently large to allow access of acetic anhydride, but not propionic into the unswollen cell wall; however, with Scots pine, both reagents are too large to gain access. A further series of experiments was performed whereby the volumetric changes of pine sapwood samples due to modification with a range of linear chain anhydrides were determined. With Corsican pine, larger volume changes than theoretically predicted were observed, whereas, with the Scots pine samples, the volume changes were close to those predicted. When account is taken of the volume that the reagent occupies within the cell wall, it was found that larger void volumes occurred in the Corsican pine samples. This result indicates that the cell-wall polymeric environment surrounding a reagent molecule is more compliant in the case of Corsican pine.     

Improved plant heterokaryon formation by surfactant-supplementation of polyethylene glycol fusogen solution

Summary PEG fusion solution for leaf protoplasts of Petunia parodii and cell suspension protoplasts of albino P. hybrida cv. Comanche was supplemented with 0.01–1.0% (w/v) Pluronic F-68. This stimulated protoplast fusion overall, including parental homokaryon formation, with increased means of 23% and 83% respectively, over appropriate controls using 1.0% (w/v) surfactant added to the standard PEG solution. Interestingly, the percentage heterokaryon formation increased near 2-fold (P<0.001) for fusogen solutions supplemented with 0.01% (w/v) Pluronic. Protoplasts regenerated to colonies in KM8P/KM8 liquid medium, indicating no adverse effects of Pluronic F-68 on viability, both in the short and longer terms.Abbreviations BA 6-benzyladenine - MS Murashige & Skoog (1962) - NAA -naphthaleneacetic acid - PEG polyethylene glycol     

Breeding for resistance to lentil Ascochyta blight

Ascochyta blight, caused by Ascochyta lentis, is one of the most globally important diseases of lentil. Breeding for host resistance has been suggested as an efficient means to control this disease. This paper summarizes existing studies of the characteristics and control of Ascochyta blight in lentil, genetics of resistance to Ascochyta blight and genetic variations among pathogen populations (isolates). Breeding methods for control of the disease are discussed. Six pathotypes of A. lentis have been reported. Many resistant cultivars/lines have been identified in both cultivated and wild lentil. Resistance to Ascochyta blight in lentil is mainly under the control of major genes, but minor genes also play a role. Current breeding programmes are based on crossing resistant and high‐yielding cultivars and multilocation testing. Gene pyramiding, exploring slow blighting and partial resistance, and using genes present in wild relatives will be the methods used in the future. Identification of more sources of resistance genes, good characterization of the host‐pathogen system, and identification of molecular markers tightly linked to resistance genes are suggested as the key areas for future study.     

Analysis of competitive ability among genotypes of perennial ryegrass. I. Effect upon survival

Summary An analysis of the effects of competition upon the survival of three morphologically distinct genotypes of perennial ryegrass (Lolium perenne) in monocultures and the corresponding binary mixtures (duocultures), indicated that significant differences occurred between them in respect both of the pressures which they exerted and in their capacity to respond to these pressures. Response depended in this experiment upon cutting regime. This dependency is used to explain the rapid elimination of one of the genotypes from most of its duocultures under an infrequent but not under a frequent cutting regime. The implications of these results for survival in mixed pastures and for the ingress of weeds into such pastures are discussed briefly.     

Evaluation of emamectin benzoate for the control of experimentally induced infestations of Argulus sp. in goldfish and koi carp

The effect of 0.2% emamectin benzoate (SLICE; Intervet/ Schering-Plough Animal Health, Roseland, New Jersey) administered in top-dressed, pelleted commercial fish feed was evaluated for control of freshwater Argulus sp. in goldfish Carassius auratus and koi carp, a variant of common carp Cyprinus carpio, in freshwater aquaria at 24-25 degrees C. Sixteen individually housed goldfish were each exposed to 37 Argulus. The number of fish lice attached to each fish at the start of the experiment was not determined; however, the total number of motile fish lice in each aquarium (on fish and in the water) was determined at the start and end of each experiment. Eight goldfish were fed the control diet (0 microg x kg fish biomass(-1) x d(-1)) and eight were fed the medicated diet (50 microg x kg fish biomass(-1) x d(-1)) for seven consecutive days. After treatment, fish louse infestation in controls was 20.5 +/- 1.5 (mean +/- SE) lice per fish. No Argulus were found on fish in the treated group. In a separate experiment, 10 individually housed koi were each exposed to 128 Argulus. Five koi were fed the control diet and five were fed a low-dose medicated diet (5 microg x kg fish biomass(-1) x d(-1)) for 7 d. After treatment, fish louse infestation among the controls was 14.6 +/- 3.8 lice per koi. No Argulus were found on koi in the treated group. Hence, a 7-d regimen of oral emamectin benzoate controlled experimental infestation of Argulus when administered to goldfish at 50 microg x kg fish biomass(-1) x d(-1) and to koi at 5 microg x kg fish biomass(-1) x d(-1).     

What makes a Salmonella strain epidemic? An expert opinion workshop

An expert opinion workshop was held on the subject of the cause, identification and control of new and emerging Salmonella strains. Experts were invited to complete questionnaires, contribute to structured discussions and take part in cluster group tasks. Outputs of the workshop included that, with current surveillance methods, it might take up to 2.5 years from the first introduction of a new strain into the UK livestock population to its identification as a human epidemic strain. In order to reduce the time to detection and provide more effective control options, several recommendations were made, including better back-tracing of human cases to their source, which would require more effective communication between those responsible for human and veterinary surveillance.     

Toxoplasma gondii in feral American minks at the Maullín river, Chile

American mink (Neovison vison) is a widely distributed invasive species in southern Chile. Thirty four feral minks were trapped at two distinct sites (rural and peri-urban), diet analyzed and Toxoplasma gondii exposure compared using PCR and specific antibodies. Serum samples were evaluated using a commercial latex agglutination test where a titer ≥ 1:32 was considered positive. Of 30 mink analyzed, 21 (70%) were positive to T. gondii antibodies, with titers ranging from 1:32 to 1:2048. As expected, adult mink showed higher seroprevalence of exposure to T. gondii (18/21) than young mink (3/9) (P=0.008). There was not statistically significant difference between sex groups (P=0.687). Differences in seroprevalence were observed between the two sample sites with a higher proportion of positive individuals in the peri-urban area, and therefore, closer to human settlements (35.7% vs. 100%, P=0.0001). Individuals positive to T. gondii using PCR and/or serology showed similar differences by site with higher infected individuals in peri-urban areas (58.8% vs. 100%, P=0.007). Diet of American mink based in fecal composition analyses was mainly based on crustaceans (frequency of occurrence: crustaceans=100%, birds and rodents<7%), suggesting that the high observed prevalence of T. gondii infection might be more associated with its aquatic behavior (e.g. ingestion of oocysts in contaminated fresh water) than with their trophic behavior (e.g. preying over species that can have T. gondii cysts in their tissues). As an invasive species potentially subject to routine culling to maintain population sizes under control, minks could be used as a sentinel species to monitor pathogens of public and wildlife health importance, such as T. gondii, in aquatic environments.     

Feeding distillers dried grains with solubles and organic trace mineral sources to swine and the resulting effect on gaseous emissions

The objective of the study was to evaluate the dietary effects of distillers dried grains with solubles (DDGS) with either inorganic or organic trace mineral sources on air emissions. Three diets were compared: a corn- and soybean meal-based control diet (Con), a diet containing 20% DDGS with inorganic trace mineral sources (20In), and a diet containing 20% DDGS with organic trace mineral sources (20Org). Groups of 6 pigs were allocated randomly to 1 of 12 environmentally controlled rooms for a 98-d experiment. A total of 72 pigs were blocked into 3 light and 3 heavy BW groups to minimize BW variation. Average initial BW for the light and heavy blocks were 22.6 kg and 27.0 kg, respectively. Concentrations and airflow of NH?, H?S, N?O, CH(4), CO?, and nonmethane total hydrocarbons (NMTHC) were measured in the exhaust air from each room. Body weight gain (94 kg per pig; P = 0.36) and G:F (0.39; P = 0.79) were not different as a result of diet, although a reduced feed intake was observed in pigs offered 20Org (P < 0.05). Total daily H?S emission mass was greater (P = 0.03) in rooms where the 20In diet was offered (462.26 mg) compared with rooms where the Con (354.62 mg) and 20Org (323.10 mg) diets were offered. No dietary effect (P = 0.47) was observed when H?S emissions were adjusted for S consumption (14.38 mg of H?S emitted daily per gram of S consumed). Compared with NH? emitted on the Con diet, the daily mass of NH? emitted decreased by 7.6% when pigs were fed 20In and increased by 11.0% in rooms where the 20Org was fed (P < 0.05). On a N consumption basis, feeding swine 20In significantly reduced NH? emissions compared with 20Org and Con, whereas NH? emissions from pigs fed 20Org were significantly greater than emissions from pigs fed the Con diet (P < 0.01). The NH? emission mass from rooms offered the Con, 20In, and 20Org diets was 120.1, 109.8, and 142.8 mg/g of N consumed/d, respectively (P < 0.01). Feeding DDGS with either inorganic or organic trace mineral sources increased the daily emission masses of CH? and NMTHC (P < 0.01), but not N?O emissions. Plasma urea N (P = 0.64), albumin (P = 0.39), globulin (P = 0.75), and total bilirubin concentrations (P = 0.82) were not different between diet groups. Results demonstrated that DDGS will increase H?S, CH?, NH?, and NMTHC emissions from pigs, but organic sources of trace minerals are a promising mitigation strategy to alleviate the adverse effect of DDGS on H?S emissions.