Review: The strobilurin fungicides

The original article to which this Correction refers was published in Pest Management Science 58 (7): 649–662 (2002).Copyright © 2004 Society of Chemical Industry     

Effects of forage type and gibberellic acid on nitrate leaching losses

Nitrogen (N) leaching from soil into water is a significant concern for intensively grazed forage‐based systems because it can cause a decline in water quality and is a risk to human health. Urine patches from grazing animals are the main source of this N. The objective of this study was to quantify the effect that forage type and gibberellic acid (GA) application had on N leaching and herbage N uptake from urine patches on perennial ryegrass–white clover (RGWC), Italian ryegrass and lucerne. A lysimeter study was conducted over 17 months to measure herbage growth, N uptake and N loss to water beneath each of the three forage types with the following treatments: control, urine (700 kg N/ha) and urine with GA (8 g GA active ingredient/ha). Compared with RGWC (205 kg N/ha), N leaching losses were 35.3% lower from Italian ryegrass (133 kg N/ha) and 98.5% higher from lucerne (407 kg N/ha). These differences in leaching loss are likely to be due to winter plant growth and N uptake. During the winter months, Italian ryegrass had higher N uptake, whereas lucerne had lower N uptake, compared with RGWC. The application of GA had no effect on N leaching losses, DM yield or N uptake of forage treated with 700 kg N/ha urine.     

Bayesian methods for estimating pathogen prevalence within groups of animals from faecal-pat sampling

Pathogens such as Escherichia coli O157:H7 and Campylobacter spp. have been implicated in outbreaks of food poisoning in the UK and elsewhere. Domestic animals and wildlife are important reservoirs for both of these agents, and cross-contamination from faeces is believed to be responsible for many human outbreaks. Appropriate parameterisation of quantitative microbial-risk models requires representative data at all levels of the food chain. Our focus in this paper is on the early stages of the food chain-specifically, sampling issues which arise at the farm level. We estimated animal–pathogen prevalence from faecal-pat samples using a Bayesian method which reflected the uncertainties inherent in the animal-level prevalence estimates. (Note that prevalence here refers to the percentage of animals shedding the bacteria of interest). The method offers more flexibility than traditional, classical approaches: it allows the incorporation of prior belief, and permits the computation of a variety of distributional and numerical summaries, analogues of which often are not available through a classical framework. The Bayesian technique is illustrated with a number of examples reflecting the effects of a diversity of assumptions about the underlying processes. The technique appears to be both robust and flexible, and is useful when defecation rates in infected and uninfected groups are unequal, where population size is uncertain, and also where the microbiological-test sensitivity is imperfect. We also investigated the determination of the sample size necessary for determining animal-level prevalence from pat samples to within a pre-specified degree of accuracy.     

Current status of two endangered Caribbean rodents

Living rodents of the genus Geocapromys of the hutia family have been known during this century on three Caribbean islands (Walker, 1968). Visits were made in 1974 to Jamaica and Little Swan Island to check the current status of two of these endangered populations. It appears from these field investigations that the Swan Island hutia, Geocapromys brownii thoracatus, has been exterminated from Little Swan Island. The main cause may have been predation by cats introduced in the late 1950s and after. The Jamaican hutia, G. b. brownii, remains in three remote areas of Jamaica. It exists at low population levels which have been much reduced from those occurring 30 years ago. The Jamaican hutias are shy and secretive in habits compared to the undisturbed Bahamian hutias, G. i. ingrahami, of East Plana Cay, Bahama Islands.     

Implementation of two high through-put techniques in a novel application: detecting point mutations in large EMS mutated plant populations

Background  

The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal.     

Effect of Leptin on In Vivo Goat Embryo Production

The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E₂) and progesterone (P₄) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E₂ concentrations on day of oestrus (r = 0.562; p < 0.01) and P₄ concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats.     

Diffusion of N-labelled N2O into soil columns: a promising method to examine the fate of N2O in subsoils

Nitrous oxide research has generally focused directly on measuring fluxes of N₂O from the soil surface. The fate of N₂O in the subsoil has often been placed in the ‘too hard’ basket. However, determining the production, fate and movement of N₂O in the subsoil is vital in fully understanding the sources of surface fluxes and in compiling accurate inventories for N₂O emissions. The aim of this study was to generate and introduce into soil columns ¹⁵N labelled N₂O, and to try and determine the consumption of the ¹⁵N₂O and production of ambient N₂O. Columns, 100 cm long by 15 cm diameter, were repacked with sieved soil (sampled from 0 to 5 cm depth) and instrumented with silicone rubber gas sampling ports. Nitrous oxide enriched with ¹⁵N was generated using a thermal decomposition process at 300 °C and then transferred to 2 l flasks. After equilibrating with SF₆ tracer gas the ¹⁵N₂O was introduced into the soil columns via passive diffusion. Gas samples from the soil profile and headspace flux were taken over a 12-day period. A watering event was simulated to perturb the ¹⁵N₂O gas composition in the soil profile. Using the measured ¹⁵N enriched fluxes and the rate of decline in ¹⁵N in the N₂O reservoir, from which the N₂O diffused into the soil, we calculated an N₂O sink (consumption plus absorption by water) equal to 0.48 ng N₂O g⁻¹ soil h⁻¹. The decrease in the ¹⁵N enrichment between successive soil depths indicated N₂O production in the soil profile and we calculated a net N₂O production rate of 0.88 ng N₂O g⁻¹ soil h⁻¹. This pilot study demonstrated the potential for simultaneously measuring both N₂O consumption and production rates, using the ¹⁵N enrichment of the N₂O measured. Further potential refinements of the methodology are discussed.     

Isolation and characterization of lymphocytes from bovine intestinal epithelium and lamina propria

The lymphocyte populations of the bovine gut lamina proprial (LP) and epithelial tissues were isolated and characterized with respect to cells bearing surface and cytoplasmic immunoglobulin (Ig). Functional characteristics of cells from the two tissues, including responsiveness to Concanavalin A (Con A), anti-bovine immunoglobulin (anti-Ig), Con A supernatants of bovine peripheral blood lymphocytes (bConA sup) and recombinant human IL-2 (rhIL-2), were also assessed. Less than 1% of the mononuclear cells in the epithelial tissue (IEL) stained for cytoplasmic Ig, and 9% stained positively for surface Ig. IEL did not proliferate in response to anti-Ig, although cells of this population did respond to Con A, bConA sup, and rhIL-2. Twenty-seven percent of bovine gut LP lymphocytes stained for surface Ig, while 39% of these cells were positive for cytoplasmic Ig. LP lymphocytes proliferated in response to all four stimulants used, Con A, anti-Ig, bConA sup and rhIL-2.