The role of glutathione transferases (GSTs) in the selectivity of the herbicides alachlor, atrazine, fluorodifen and metolachlor, which are detoxified by glutathione conjugation in plants, was determined in seedlings of maize (Zeamays L.) and the associated weed species Abutilontheophrasti Medic., Digitariasanguinalis (L.) Scop. Echinochloacrus-galli (L.) Beauv., Panicummiliaceum (L.), Setariafaberi Herrm. and Sorghumbicolor (L.) Moench. The availability of glutathione was also determined in all species and tissue concentrations were found to be in the range 120–160 μm for all species except D. sanguinalis and S. bicolor, which contained half this amount. GST activities toward the herbicides were determined in crude protein extracts from the plants using HPLC to quantify the biosynthesis of the herbicide conjugates. The specific activities of the GSTs toward the substrates were in the order alachlor>fluorodifen> atrazine>metolachlor in all species except A. theophrasti, where fluorodifen was a better substrate than alachlor. In most cases there was a good correlation between GST activities and the selectivity of the herbicides applied pre-emergence. In the case of atrazine, GST activities were also related to the relative rates of herbicide conjugation invivo. In contrast, there was no simple relationship between glutathione availability and the selectivity of the herbicides. However, with alachlor there was evidence that glutathione availability was limiting GST activity and influencing tolerance. 相似文献
A dermatophytosis, called 'club lamb fungus' by owners, has been affecting show lambs during the lamb show season. Thirty-one families of 108 responding to a questionnaire reported at least one case of dermatophytosis, and 15 of those 31 families reported children or owners involved in showing these lambs developing skin lesions consistent with dermatophytosis. In lambs, gross lesions typical of ovine derma-tophytosis were located on all parts of the body, and consisted of circular areas of matted wool, crusts and discoloration. Lesions appeared either at a single site or were distributed randomly, affecting head, body and extremities. Direct microscopic examination of wool revealed ectothrix, endothrix, and combined endothrix and ectothrix infections. Microsporum gypseum was the only dermatophyte cultured from wool samples collected from affected lambs; however, the presence of endothrix spores suggests that other species may be involved. Arthrospores and fungal hyphae typical of dermatophytes were present in histological sections. 相似文献
Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. A previously developed database that included 87 treatment means from 23 respiration calorimetry studies has been updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926; r2 = 0.99, root mean square prediction error [RMSPE] = 0.04, and P < 0.01 for the intercept and slope. The slope did not differ from unity (95% CI = 0.936 to 1.065); therefore, the intercept (95% CI = −0.567 to −0.218) defines the value of ME predicted from DE. For practical use, we recommend ME = DE – 0.39. Based on the relationship between DE and ME, we calculated the citation-adjusted loss of methane, which yielded a value of 0.2433 Mcal/kg of dry matter intake (DMI; SE = 0.0134). This value was also adjusted for the effects of DMI above maintenance, yielding a citation-adjusted relationship: CH4, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance; r2 = 0.536, RMSPE = 0.0245, and P < 0.01 for the intercept and slope. Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. These two approaches were evaluated using a second, independent database comprising 129 data points from 29 published studies. Four equations in the literature that used DMI or intake energy to predict methane production also were evaluated with the second database. The mean bias was substantially greater for the two new equations, but slope bias was substantially less than noted for the other DMI-based equations. Our results suggest that ME for growing and finishing cattle can be predicted from DE across a wide range of diets, cattle types, and intake levels by simply subtracting a constant from DE. Mean bias associated with our two new methane emission equations suggests that further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane. 相似文献
Two experiments were conducted to evaluate the efficacy of an oil-based substrate, The Water Cleanser? (TWC). The first experiment studied the effects two substrates of different oil composition (TWC, TWC?+), and a commercial bacterial additive (Bio-Aid) on concentrations of nitrogen and phosphorous in indoor aquaria. The second experiment studied the effects of TWC, a bacterial additive, and a combination (TWC?+?B) on concentrations of nitrogen and phosphorous, phytoplankton abundance and diversity in outdoor freshwater crayfish (Cherax cainii, Austin and Ryan, Invertebr Syst 16:357–367, 2002) tanks. In the first experiment, the concentration of TAN decreased more rapidly with Bio-Aid, whilst the maximum concentrations of NO2-N and NO3-N were reduced with the substrates. The concentration of orthophosphate was reduced in aquaria with TWC?+?. In the second experiment, concentrations of TAN, NO2-N, NO3-N and total phosphate were not significantly affected by TWC. After addition of TWC?+?B, there was a significant decrease in the concentrations of nitrate and total phosphate, and a higher abundance of phytoplankton was maintained than with other treatments. Additionally, a population Bacillus sp. was found on the substrate surface. TWC had no adverse effects on phytoplankton abundance or diversity, or C. cainii physiology, weight gain or survival. TWC and TWC?+?were effective bioremediators of eutrophic water, whilst a combination of TWC?+?B was effective in short term bioremediation and in promoting phytoplankton abundance in C. cainii tank culture.