Further investigation of equine fescue oedema induced by Mediterranean tall fescue (Lolium arundinaceum) infected with selected fungal endophytes (Epichloë coenophiala)

Abstract

AIMS

To determine if equine fescue oedema (EFO) induced by grazing Mediterranean-type tall fescue (Lolium arundinaceum) infected with selected endophytes (Epichloë coenophiala) could be prevented by treatment with the corticosteroid, methylprednisolone, and anti-histamine, cetirizine, and to determine concentrations of lolines, specifically N-acetyl norloline (NANL), in grasses grazed by horses that did and did not develop EFO.     

Model selection in a global analysis of a microarray experiment

Analysis of data from complementary DNA microarray experiments is an area of intense research. Options include models at the gene level or at the global level, the latter combining information from all of the profiled genes. In general, a joint analysis is expected to be more powerful than gene-specific analyses. Global analysis of microarray data requires fitting a model that jointly performs data normalization and analyses. The objective of this study was to assess the optimality of alternative models for data normalization and analysis in an experiment to identify differentially expressed genes between 2 muscles in Avile?a Negra Ibérica calves. Three major groups of models were explored according to several aspects including spatial arrangement of spots, other technical sources of variation such as dye effects, assumptions related to effects included in the model, and gene-specific effects. In addition, 3 sources of heterogeneity of residual variance were investigated. All models were compared by Bayes factors and cross-validation predictive densities. The model that included array-block, dye, muscle, and array-dye as systematic effects and all gene-related components as random effects was the best model for normalization and analysis of these data under heterogeneity of residual variances. Furthermore, level of intensity seemed to be the major source of heteroscedasticity for all models investigated. Such models rendered the best goodness of fit without compromising the predictive ability. The best model also provided the best performance to detect genes differentially expressed with the lowest false discovery rate. The large differences found for the model comparison criteria across models indicate the importance of defining the factors that more accurately account for experiment-wide variability to ensure correct inference on differential expression of genes. Our results also illustrate the importance of the experimental setup to account for possible sources of bias in the detection of differentially expressed genes.     

The highly antigenic 53/25 kDa Taenia solium protein fraction with cathepsin-L like activity is present in the oncosphere/cysticercus and induces non-protective IgG antibodies in pigs

Cathepsin L-like proteases are secreted by several parasites including Taenia solium. The mechanism used by T. solium oncospheres to degrade and penetrate the intestine and infect the host is incompletely understood. It is assumed that intestinal degradation is driven by the proteolytic activity of enzymes secreted by the oncosphere. Blocking the proteolytic activity by an antibody response would prevent the oncosphere penetration and further infection. Serine and cysteine proteases including chymotrypsin, trypsin, elastase, and cathepsin L, are secreted by T. solium and Taenia saginata oncospheres when cultured in vitro, being potential vaccine candidates. However, the purification of a sufficient quantity of proteases secreted by oncospheres to conduct a vaccine trial is costly and lengthy. A 53/25 kDa cathepsin L-like fraction partially purified from T. solium cyst fluid was described previously as an important antigen for immunodiagnostics. In this study we found that this antigen is present in the T. solium oncosphere and is also secreted by the cysticercus. This protein fraction was tested for its ability to protect pigs against an oral challenge with T. solium oncospheres in a vaccine trial. IgG antibodies against the 53/25 kDa cathepsin L-like protein fraction were elicited in the vaccinated animals but did not confer protection.     

Development of a bioassay system for monitoring susceptibility in Thrips tabaci

A system is described for collecting adult and larva of Thrips tabaci from onion foliage into insecticide-treated vials to evaluate susceptibility to insecticides. The thrips insecticide bioassay system (TIBS) allows one to treat vials and store them for 3 weeks before thrips are collected. Depending on the population density in the field, collection of the insects for the test required from 3-6 h for one person. Assays are read after 24h. This system was used in 1997 and 1998 in commercial onion fields in Honduras and Nicaragua, and TIBS was sensitive enough to detect differences to the insecticides tested, to thrips life stages and to different generations within an onion-growing season. Data collected suggest that there were not serious problems with thrips insecticide resistance, with the possible exception of cypermethrin in Nicaragua which had a resistance ratio (RR) value of 26.9 for adult thrips. The largest RR values were observed at the end of the growing season, and this may be caused by the season-long selection by insecticide sprays. The mortality of adults and larvae followed the same general pattern, but the ratio between larvae and adults differed for each chemical group.     

L-canavanine inhibits L-arginine uptake by broiler chicken intestinal brush border membrane vesicles

1. Intestinal brush border membrane vesicles (BBMV) were prepared from 3-week-old broiler chickens. 2. Electron microscopy of the BBMV fraction showed single membrane vesicles of different sizes with no electron dense material inside. No other organelles were observed. The sucrase and maltase activities were enriched by factors of 16 and 18, respectively, in the BBMV fraction in comparison with the homogenate. On the other hand, the Na+/K+-ATPase sensitivity to ouabain was increased by a factor of 0.8. 3. The BBMV showed a maximum L-[14C]-arginine uptake (944.9 +/- 22.9 pmoles/mg protein) at 45 s and thereafter it declined slowly. In the presence of 0.5 mM L-canavanine, the L-[14C]-arginine uptake by BBMV was reduced by 43.6% at 45 s. 4. It is concluded that L-canavanine inhibits L-arginine Na+-dependent transport across the enterocyte apical membrane in a highly purified intestinal BBMV from broiler chickens.     

Tiller population dynamics in eight cultivars of elephant grass during undisturbed growth

The aim of the study was to assess tiller population dynamics of aerial and basal tillers in eight cultivars of Pennisetum purpureum (Schumach.), syn. Cenchrus purpureus (Schumach.) Morrone, in a warm humid climate in Veracruz, Mexico. This is a pioneer study on tiller population dynamics in elephant grass under conditions of undisturbed growth. The tiller population assays included data from 14 days after cutting until 154 and 182 days after cutting for the dry and wet seasons, respectively. On each sampling date, a distinctive ring was placed on every new tiller, and rings were removed from dead tillers. Tiller density, mortality and appearance were determined. In wet seasons, copious tillering occurred on initial regrowth (by day 42, mostly aerial tillers, with a ratio of 2:1 to 4:1 for aerial to basal tiller appearance), and on day 98 (a higher proportion of basal tillers, with an aerial to basal tiller ratio of 1.5:1). Aerial tillers showed a higher overall mortality rate than basal tillers (29.0 vs 14.4). Younger basal tillers showed higher mortality than older tillers. Higher tiller density occurred during the dry season, where it increased gradually until day 70 and then declined. The cultivars ‘Cameroon‘, ‘CT115‘ and ‘OM22‘ showed remarkably high tillering ability. The findings indicate that harvesting a forage bank is possible from day 70 during a dry season.     

Blood calcium,glucose and haematology profiles of parturient bitches diagnosed with uterine inertia or obstructive dystocia

Bitches with dystocia most often present with clinical signs of uterine inertia (UI). The aetiology of myometrial dysfunction in most of these cases is still not elucidated. We compared blood ionized calcium (iCa) and glucose concentrations in bitches diagnosed with primary UI (PUI, n = 14), secondary UI (SUI, n = 6) or obstructive dystocia (OD, n = 6), and we described their haematology profiles. Bitches diagnosed with UI had a patent birth canal and delivered no puppies yet (PUI) or only part of the whole litter (SUI). The OD group had no UI and showed strong abdominal contractions. Blood iCa did not differ between the PUI, SUI and OD groups and was not influenced by litter size. There was a significant positive relationship (R² = .241, p = .013) between iCa concentrations and the dam's body weight. Glucose concentrations were also not significantly different between dystocia groups or influenced by body weight and litter size. Hypocalcaemia was detected in 11 bitches, and hypoglycaemia in two bitches. Pregnancy‐associated anaemia was seen in about one‐third of the bitches. Eight of 12 dogs had increased platelet counts, and ten had leukocytosis with mature neutrophilia. Although iCa did not differ between dystocia groups, low concentrations may have contributed to the development of UI in some of the small size bitches. Hypoglycaemia was uncommon, and therefore, we consider low glucose concentrations not to have played an important role in the pathogenesis of UI in our study population. Pregnancy‐associated anaemia, thrombocytosis, leukocytosis and mature neutrophilia were common findings in otherwise healthy bitches diagnosed with different forms of dystocia.     

Activity of an anti-inflammatory drug against cryptosporidiosis in neonatal lambs

The efficacy of the anti-inflammatory drug Bobel-24 against experimental infection by Cryptosporidium parvum was evaluated in neonatal lambs. The animals were treated by oral administration of the drug at 50 or 500 mg/kg of body weight. The prophylactic/therapeutic treatment was started 4 h before inoculation of the lambs with oocysts and was continued for eight consecutive days. The therapeutic treatment was initiated at the onset of diarrhoea, after confirmation of infection, and was continued for six consecutive days. Infection was monitored by daily examination of faecal samples from the first day until 30 days post-inoculation. The criteria considered in evaluating development of the infection and the drug activity were: oocyst shedding, presence of diarrhoea and weight gain at 15 and 30 days post-inoculation. Bobel-24 was effective as a prophylactic/therapeutic treatment at the lowest dose (50 mg/kg of body weight); in the group treated with this dose of drug there was a longer prepatent period, a shorter patent period and a lower intensity of oocyst excretion than in the untreated control group, and the differences were all statistically significant (P<0.05). Moreover, one animal did not excrete oocysts, and two lambs had diarrhoea, for only 1 and 2 days. In the group treated with the higher dose of the drug, the diarrhoea lasted for a significantly shorter period (P<0.05) than in the untreated group.