Quinone accumulation in S-ethyl dipropylthiocarbamate-treated wheat

Wheat (Triticum aestivum L. cv Holley) was grown for 15 days in sand into which S-ethyl dipropylthiocarbamate (EPTC) (0, 15.6, 31.25, 62.5, or 125.0 μg/kg) had been incorporated. Growth was decreased more by EPTC under high light intensity (270 μein/m²/sec) than under low light (20 μein/m²/sec) intensity. Wheat grown in the dark did not respond to EPTC at these concentrations. In high light intensity, plastoquinone-9, plastohydroquinone-9, α-tocopheroquinone, and α-tocopherol contents (nanomoles per gram fresh weight) increased as EPTC concentration increased. Similar but less marked results occurred at the low light intensity. Plastohydroquinone-9/plastoquinone and α-tocopherol/α-tocopheroquinone ratios increased at both light intensities as EPTC concentration increased. This indicated an EPTC-induced inhibition of plastohydroquinone and α-tocopherol epoxidation. Chlorophyll a and b and total carotenoid contents increased as EPTC concentration increased in plants grown at high light intensities. Changes in the membrane electron carriers contents per unit of chlorophyll or carotenoid (micrograms per milligram of pigment) occurred. As a tentative hypothesis, it is suggested that transmembrane electron transport systems were inhibited, but growth in size (fresh weight per pot) was inhibited more than was synthesis of the various pigments and quinones. Thus, a separation of growth and metabolic response to EPTC was demonstrated.     

Comparative enzyme activities and cytochrome P-450 levels of some rat tissues with respect to their metabolism of several pesticides

Cytochrome P-450, A- and B-esterase, amidase, and glutathione S-aryl transferase were assayed in the postmitochondrial centrifugal fraction, microsomes, and supernatant of rat liver, lungs, kidneys, and testes. Liver microsomes contained the highest P-450 levels and A-esterase activity. B-esterase activity was more generally distributed and higher in the microsomal tissue fractions. Microsomal amidase activity was highest in rat lung and lowest in the liver (per mg protein). Glutathione S-aryl transferase activity was highest in the liver. The in vitro metabolism of carbaryl, phosphamidon, and chlorotoluron by the various centrifugal fractions revealed many differences. Carbaryl metabolism was greater in the liver microsomal fractions than in any other preparation. 1-Naphthol was the major metabolite in all tissue fractions. Although very little metabolism of phosphamidon occurred in the rat, metabolism in the rat liver postmitochondrial fraction was slightly higher with respect to the production of metabolites than in the supernatant and microsomes combined. Chlorotoluron was not metabolized by any of the tissue fractions of the rat. At least a low level of activity toward some compounds was observed in all tissues, but this study confirmed that the liver was the most active metabolizing tissue as well as having the highest levels of enzymatic activity usually associated with pesticide metabolism.     

Geriatric heart diseases in dogs.

A discussion of the diagnosis and therapy of heart disease in an aged pet does not differ significantly from that in a pet of any age. Mitral regurgitation constitutes by far the most important geriatric heart disease, and the selection of drugs to treat heart disease of aging pets is based on identification of specific pathologic features (eg, atrial fibrillation, left atrial enlargement) for which each aspect of treatment (eg, diuretics, angiotensin-converting enzyme inhibitors, spironolactone) is specific.     

A leakiness index for assessing landscape function using remote sensing

The cover, number, size, shape, spatial arrangement and orientation of vegetation patches are attributes that have been used to indicate how well landscapes function to retain, not ‘leak’, vital system resources such as rainwater and soil. We derived and tested a directional leakiness index (DLI) for this resource retention function. We used simulated landscape maps where resource flows over map surfaces were directional and where landscape patch attributes were known. Although DLI was most strongly related to patch cover, it also logically related to patch number, size, shape, arrangement and orientation. If the direction of resource flow is multi-directional, a variant of DLI, the multi-directional leakiness index (MDLI) can be used. The utility of DLI and MDLI was demonstrated by applying these indices to three Australian savanna landscapes differing in their remotely sensed vegetation patch attributes. These leakiness indices clearly positioned these three landscapes along a function-dysfunction continuum, where dysfunctional landscapes are leaky (poorly retain resources). This revised version was published online in July 2006 with corrections to the Cover Date.