The escalating threat of Rhizoctonia cerealis, the causal agent of sharp eyespot in wheat

Rhizoctonia cerealis, the causal agent of sharp eyespot on wheat, was not considered to be an important pathogen for many years. Recently, the disease has become endemic in many countries except for South America. The disease has created a new threat to world wheat production because the damage of wheat sharp eyespot has become increasingly severe. In this paper, previous studies on this pathogen, including the disease geographical distribution, pathogen identification, life cycle, symptoms, favourable environmental conditions, effects on wheat yield and control strategy, are reviewed. Such information will be helpful in management of sharp eyespot.     

Sensitivity to iprodione, difenoconazole and fludioxonil of Rhizoctonia cerealis isolates collected from wheat in China

Since the 1980s wheat sharp eyespot (WSE) caused mainly by Rhizoctonia cerealis has become one of serious diseases of wheat in China. In this study, the sensitivity of 89 R. cerealis isolates to different fungicides was evaluated using mycelial growth inhibition assays. The results showed that all R. cerealis isolates tested were sensitive to iprodione, difenoconazole and fludioxonil with mean EC₅₀ (effective concentration that results in 50% of mycelial growth inhibition) values of 0.419, 0.062 and 0.033 μg/ml, respectively. To evaluate the risk of fungicide resistance in R. cerealis, an attempt was made to induce resistant mutants in the laboratory. Although difenoconazole- and fludioxonil-resistant mutants were not obtained, we obtained seven independently iprodione-resistant (IR) mutants from 89 parental isolates. The EC₅₀ values for these IR mutants were greater than 100 μg/ml, whereas those for the original wild-type counterparts were less than 1 μg/ml. After having been subcultured on PDA for 10 generations, the IR mutants did not show any decrease in resistance to iprodione. Additionally, these IR mutants also showed resistance to fludioxonil but remained sensitive to difenoconazole. Osmotic sensitivity tests showed that the IR mutants were hypersensitive to osmotic stress generated by NaCl. Inoculation tests showed that all the IR mutants lost their ability to infect the host plant. Taken together, these results indicate that the current population of R. cerealis is sensitive to these fungicides and a fitness cost is associated with iprodione-resistant mutants of R. cerealis in both osmotic stress and pathogenicity. The information obtained in this study is useful in monitoring and managing fungicide resistance in R. cerealis populations in China.     

Effect of various levels of dietary <Emphasis Type="Italic">Jatropha curcas</Emphasis> seed meal on rabbits infested by the adult ticks of <Emphasis Type="Italic">Hyalomma marginatum marginatum</Emphasis> I. Animal performance,anti-tick feeding and haemogram

The goal of this study was to investigate the use of Jatropha curcas seed meal (JCSM) in different levels as acaricide in diet of rabbits experimentally infested by Hyalomma marginatum marginatum then determining animal performance, anti-tick feeding and its effects on haemogram of rabbits. Thirty healthy mixed-breed rabbits were randomly divided into five equal groups. The first group was kept as a control fed soya bean meal (20%) as a source of protein. Groups from the second to the fifth fed diets contained 2.5%, 5%, 7.5% and 10% of JCSM instead of soya bean meal as a source of protein, respectively. Feeding and watering were given freely throughout the study. Animal performance for treatment groups were recorded from the 1st week up to the 6th week. Then each group divided into two subgroups, and the ticks were introduced to all of one subgroup and the other kept as control, following them until dropped at the end of the 8th week for all groups of the experiment. Feeding and reproductive performance of the adult tick females were determined. Blood samples were collected and analysed for haematological examination at the 0, 6th and 8th weeks post-treatment from all animals. Result revealed that rabbits received diets containing 5%, 7.5% and 10% had significantly (P < 0.05) lower growth performance than control and 2.5% JCSM groups. Feed intake and body weight gain decreased with increasing the level of JCSM in the diet. The result of anti-tick feeding observed that the highest percentage (60–90%) of rejection was recorded in 10% of JCSM group then the other treated groups (20–30%). Egg mass and reproductive index per female were marked increase (P < 0.001) in groups 2.5%, 5% and 7.5% of JCSM. Macrocytic normochromic anaemia was development after 8 weeks of treatment, which changed to microcytic normochromic anaemia after challenge of ticks in groups received 5%, 7.5% and 10% JCSM. Leukopenia, neutopenia and lymphopenia were noticed (P < 0.05) in all treated groups which more drop in the group received 7.5% JCSM. Also, monocytosis was recorded in 7.5% and 10% JCSM groups. In conclusion, JCSM could be use in the treatment of ectoparasites at level less than 10% in diet. Further investigations should be done to detoxification the Jatropha seed meal to decrease the level of its toxicity.     

Cross-resistance relationships between benzimidazole fungicides and diethofencarb in Botrytis cinerea and their genetical basis in Ustilago maydis

After nitrosoguanidine- or UV-mutagenesis, three different benzimidazole-resistant phenotypes were isolated on media containing benomyl or a mixture of carbendazim and diethofencarb from wild-type strains of Botrytis cinerea Pers. ex Fr. and Ustilago maydis (D.C.) Corda. Mutants of B. cinerea with moderate (MBr) or low (LBr) resistance to benzimidazoles and high resistance to diethofencarb (Dr) were isolated from the fungicide-mixture-containing medium in low frequency (7–1 × 10^?8). Only benzimidazole-resistant strains highly sensitive to diethofencarb (HBrDs) were identified on benomyl-containing medium at a frequency of 6.6 × 10^?6. Fitness-determining characteristics such as sporulation, germination and germ-tube elongation, were found to be reduced significantly in the mutants of B. cinerea that were resistant to both benzimidazoles and diethofencarb. However, pathogenicity of a MBrDr mutant strain on cucumber seedlings was equal to that of the wild type and a carbendazim + diethofencarb mixture was found to control grey mould caused by the wild type, but was not effective when the plant cotyledons were infected by the mutant strain. Three benzimidazole-resistant phenotypes (HBrDs, HBrDr, MBrDr) were isolated easily in U. maydis from a benomyl-containing medium. In contrast with B. cinerea, only one-tenth of the benzimidazole-resistant strains were sensitive to diethofencarb. Genetic analysis of benzimidazole resistance in U. maydis showed that the three benzimidazole-resistant phenotypes were due to three allelic mutations in a single gene and one of them was responsible for the negative cross-resistance between benzimidazoles and diethofencarb.     

In vitro evaluation,in vivo quantification,and microbial diversity studies of nutritional strategies for reducing enteric methane production

The main objective of the present work was to study nutritive strategies for lessening the CH₄ formation associated to ruminant tropical diets. In vitro gas production technique was used for evaluating the effect of tannin-rich plants, essential oils, and biodiesel co-products on CH₄ formation in three individual studies and a small chamber system to measure CH₄ released by sheep for in vivo studies was developed. Microbial rumen population diversity from in vitro assays was studied using qPCR. In vitro studies with tanniniferous plants, herbal plant essential oils derived from thyme, fennel, ginger, black seed, and Eucalyptus oil (EuO) added to the basal diet and cakes of oleaginous plants (cotton, palm, castor plant, turnip, and lupine), which were included in the basal diet to replace soybean meal, presented significant differences regarding fermentation gas production and CH₄ formation. In vivo assays were performed according to the results of the in vitro assays. Mimosa caesalpineaefolia, when supplemented to a basal diet (Tifton-85 hay Cynodon sp, corn grain, soybean meal, cotton seed meal, and mineral mixture) fed to adult Santa Ines sheep reduced enteric CH₄ emission but the supplementation of the basal diet with EuO did not affect (P > 0.05) methane released. Regarding the microbial studies of rumen population diversity using qPCR with DNA samples collected from the in vitro trials, the results showed shifts in microbial communities of the tannin-rich plants in relation to control plant. This research demonstrated that tannin-rich M. caesepineapholia, essential oil from eucalyptus, and biodiesel co-products either in vitro or in vivo assays showed potential to mitigate CH₄ emission in ruminants. The microbial community study suggested that the reduction in CH₄ production may be attributed to a decrease in fermentable substrate rather than to a direct effect on methanogenesis.     

Characterization and tissue distribution of conjugated metabolites of pyrene in the rat

Pyrene (PY) is a polycyclic aromatic hydrocarbon (PAH) that is often used as a biomarker for human and wildlife exposure to PAHs. As the metabolites of PAHs, similar to their parent compounds, pose public health risks, it is necessary to study their characteristics and tissue-specific distribution. The present study was performed to experimentally characterize PY metabolites and analyze the tissue-specific distribution of the conjugated metabolites after oral administration of PY to rats. PY metabolites, such as pyrenediol-disulfate (PYdiol-diS), pyrenediol-sulfate (PYdiol-S), pyrene-1-sufate (PYOS), pyrene-1-glucuronide (PYOG) and 1-hydroxypyrene (PYOH), were detected in rat urine. Although glucuronide conjugate was the predominant metabolite, the metabolite composition varied among tissues. Interestingly, the proportion of PYOH was high in the large intestine. Furthermore, PYOH was the only PY metabolite detected in feces.     

Prevalence,virulence attributes,and antibiogram of Bordetella avium isolated from turkeys in Egypt

Tropical Animal Health and Production - Turkey coryza is a major respiratory disease caused by Bordetella avium (B. avium). It occurs in all ages of turkeys and is characterized by high morbidity...     

β-carotene and retinol contents in the meat of herbivorous ungulates with a special reference to their public health importance

The aim of this study was to estimate total carotenoids, β-carotene and retinol concentrations in the liversand muscles of some ungulates (cattle, buffalo, sheep, goats and horses) in comparison with the Wistar rats asa control. Cattle and horses had the highest contents of total carotenoids and β-carotene. Unexpectedly, sheepwas the highest accumulator of retinol with a mean concentration of 203 ± 23.34 µg/g, whilethe least accumulator was buffalo, having a mean value of 58.28 ± 13.77 µg/g. Livers hadhigher contents of the examined phytochemicals than muscles. Consumption of these tissues may provide humanwith some needs from these important phytochemicals, though ingestion of livers, especially that of the sheep,is not advisable for the pregnant women.     

Enantioselective determination of chiral toxaphene congeners in laying hens and eggs using multidimensional high-resolution gas chromatography

A total of 22 chiral toxaphene congeners were analyzed in organ tissues and eggs of laying hens after they had been fed with food spiked with technical toxaphene. For the analysis, multidimensional high-resolution gas chromatography using a chiral column coated with randomly silylated heptakis(O-tert-butyldimethylsilyl)-beta-cyclodextrin, electron capture detection, and valveless "live column switching" technique was applied. The analytical results were additionally confirmed with mass spectral data, recorded in electron-capture negative ionization mode with selected-ion monitoring mass spectrometry. During both the feeding period of the laying hens with toxaphene-contaminated food (38 weeks, accumulation phase) and the following subsiding period without toxaphenes (another 14 weeks, decontamination phase), organs (liver, kidney, skin/fat), blood, meat, and eggs of the hens served as model matrices for toxaphene uptake. The enantiomeric ratios (ERs) of congeners 26, 31, 32, 40, 41, 42(a+b), 44, 50, and 62--known as the most important components of technical toxaphene occurring in the environment--could be analytically determined. Significant differences were observed with respect to their initial racemic ratios. On the basis of their chemical structures, the metabolic pathways of some congeners could be explained. Astonishingly, some of the toxaphenes applied as racemates could merely be found as single enantiomers at the end of the feeding program, for example, congener 32 in blood and meat samples or congener 44, especially in organ tissues, which showed ERs of zero or infinity. The findings of this study impressively emphasize that it is essential to isolate and analyze individual toxaphene enantiomers in food and biota tissues to be capable of evaluating their toxicity and metabolization more specifically.