Localization of calcium pump activity in smooth muscle

A microsomal fraction isolated from longitudinal smooth muscle of guinea pig ileum actively sequesters calcium ion in the presence of magnesium and adenosine triphosphate in a fashion previously described for microsomes of the rabbit aorta. This activity in guinea pig ileum appears to be associated primarily with the plasma membrane as is found in the red cell. By contrast the uptake of calcium in aortic smooth muscle appears to be associated to an appreciable extent with intracellular membranes, possibly analogous to the sarcoplasmic reticulum of skeletal muscle.     

Effect of T-2 toxin on brain biogenic monoamines in rats and chickens.

Two experiments were conducted to determine the effect of T-2 toxin on brain biogenic monoamines and their metabolites. Male rats (180 g) and cockerels (28 day, 300 g) were orally dosed with T-2 toxin at 2.5 mg kg-1 body weight. In the first experiment, whole brains were collected 2, 6, 12, 24 and 48 h postdosing and analyzed for monoamines by high performance liquid chromatography with electro-chemical detection. T-2 toxin did not influence whole brain concentrations of monoamines in either species. In the second experiment, brains were collected 24 h postdosing, dissected into five brain regions, and analyzed for monoamines. T-2 toxin treatment resulted in increased serotonin and 5-hydroxy-3-indoleacetic acid in all brain regions of the rat. However, this was not seen in poultry where T-2 toxin treatment resulted in an increase in 5-hydroxy-3-indoleacetic acid, no alteration in serotonin concentration and a decrease in regional norepinephrine and dopamine concentrations. These results suggest that T-2 toxin influences brain biogenic amine metabolism and that there is an intraspecies difference in the central effects of this mycotoxin.     

Potato growth in response to relative humidity

Potato plants (Solanum tuberosum L. cvs. Russet Burbank, Norland, and Denali) were grown for 56 days in controlled-environment rooms under continuous light at 20C and 50% or 85% RH. No significant differences in total plant dry weight were measured between the humidity treatments, but plants grown under 85% RH produced higher tuber yields. Leaf areas were greater under 50% RH and leaves tended to be larger and darker green than at 85% RH.     

Factors Affecting the Use of Conservation Tillage in the United States

Conservation tillage was used on nearly 36% of planted hectares in 1996 in the U.S. This level has remained relatively unchanged since 1991. The use of conservation tillage varies by crop and is dependent on site-specific factors including soil sype, topsoil depth, and local climate conditions. A number of economic, demographic, geographic, and policy factors have affected the adsorption of conservation tillage. While it is not possible to quantify exactly the impact of these factors, it is clear that management complexities and profitability are key factors impeding the further adsorption of conservation tillage.     

Al-substituted goethite—An indicator of pedogenic and other weathering environments in South Africa

Over 200 goethite-containing samples from widely diverse environments along the eastern seaboard of South Africa were examined and described, mainly by X-ray powder diffraction (XRD).Aluminium-substituted goethites ranging from 0 to about 32 mole % AlOOH were identified mainly by XRD line-shift and chemical extraction. They occur in every soil zone and major soil type in one or other form from sources such as: (1) non-hydromorphic- highly weathered (strongly acid soils, ferruginous bauxites, saprolites) and moderately weathered (moderately acid soils) environments; (2) hydromorphic environments (mottles, concentrations, pipe stems, crusts, ferricretes, geodes); and (3) crusts in calcareous environments. These goethites, formed in different climatic and weathering environments were grouped according to their amount of Al-substitution and crystallinity (as determined by XRD line broadening). Al-substitution in goethite formed in hydromorphic, moderately acid soils and calcareous environments was generally low (0–15 mole %). Goethite formed in non-hydromorphic highly weathered environments was generally high in Al-substitution (15–32 mole %) and increased in the following order: saprolites and strongly acid, freely drained soils < ferruginous bauxites < strongly acid soils overlying plinthite.This study showed that the degree of Al-substitution and crystallinity of goethites may reflect the environment in which they have formed and serve as an indicator of soilforming processes.