Dealkylation and loss of capacity for reactivation of cholinesterase inhibited by sarin

Inhibition of rat brain acetylcholinesterase by (32)P-sarin in vivo results initially in (32)P-isopropylmethylphosphonylated enzyme. The percentage of inhibited enzyme that could not be reactivated by pyridinium aldoxime methochloride (aged enzyme) approximated the amount of radioactivity identified as (32)P-methylphosphonate. The (32)P-isopropyl methylphosphonate not released fromthe inhibited enzyme by the oxime accounted for 51 +/- 10 percent ( standard deviation) of the radioactivity fixed to brain tissue. It showed no correlation with aging and was probably bound to sites other than acetylcholinesterase.     

Covariant glacial-interglacial dust fluxes in the equatorial Pacific and Antarctica

Dust plays a critical role in Earth's climate system and serves as a natural source of iron and other micronutrients to remote regions of the ocean. We have generated records of dust deposition over the past 500,000 years at three sites spanning the breadth of the equatorial Pacific Ocean. Equatorial Pacific dust fluxes are highly correlated with global ice volume and with dust fluxes to Antarctica, which suggests that dust generation in interhemispheric source regions exhibited a common response to climate change over late-Pleistocene glacial cycles. Our results provide quantitative constraints on the variability of aeolian iron supply to the equatorial Pacific Ocean and, more generally, on the potential contribution of dust to past climate change and to related changes in biogeochemical cycles.     

采用根滤去污工艺的污水净化植物补救系统决策支持软件

为了开发利用植物去除因吸收污染水而产生的重金属的商业化根滤系统和植物去污补救工艺,研究开发了微型计算机软件,以便为该系统的设计与运行提供参考。建立了一个基于Michaelis-Menton方程的工艺模型,可以定量确定在根滤系统中的植物积累和去除毒素物质的能力。采用一系列的算法处理信息并编入一个根滤设施的系统模型内。该系统模型将植物补救系统的物理元件——植物苗圃、根过滤系统、水的前处理与后处理、植物生物质的产后处理等与系统设计的工程方面包括工艺、运行、设施和系统集成结合起来。该软件内含的工程经济分析工具可用于分析主要设计变量对系统效率的影响     

Simulating leaf area of corn plants at contrasting water status

An exponential decay function was fitted with literature data to describe the decrease in corn leaf expansion rate as predawn leaf water potential decreases. The fitted function was then applied to modify an existing leaf area simulation module in a soil–plant–atmosphere continuum corn simulation model (MaizSim) in order to simulate leaf area of corn plants at different water status. Data were collected from field for two years as well as from sunlit growth chambers located at USDA-ARS facilities in Beltsville, MD with different irrigation frequencies. Comparison among simulations and measurements indicated that the modified leaf area module improved leaf area simulation for corn plant under different drought stress. For plants under more severe drought stress, the improvement in leaf area simulation was more significant. These results suggested that the modified leaf area model presented an approach to mechanistically link corn leaf area with corn plant water status, and was suitable for integration with existing corn models that simulate corn leaf area.     

Modulation of arachidonic acid metabolism by bovine alveolar macrophages exposed to interferons and lipopolysaccharide

Stimulation of bovine alveolar macrophages with calcium ionophore A23187 resulted in marked production of leukotriene (LT)B4 and a lesser increase in thromboxane (TX)B2, whereas opsonized zymosan (OPZ) resulted in production of TXB2 and relatively small increases in LTB4 and prostaglandin (PG)F2 alpha. Alveolar macrophages incubated with recombinant bovine interferon-gamma or lipopolysaccharide, and subsequently stimulated with A23187 or OPZ, had altered arachidonic acid metabolism, producing markedly increased amounts of TXB2 and PGF2 alpha, and slightly increased LTB4. Incubation of alveolar macrophages with lipopolysaccharide had a more profound effect on the increased amounts of TXB2 and PGF2 alpha, observed in response to stimulation with A23187 or OPZ, than did incubation with interferon-gamma. Alveolar macrophages incubated with recombinant bovine interferon-alpha 1-1 also produced slightly increased amounts of LTB4 when stimulated with A23187 or OPZ. Altered arachidonic acid metabolism by alveolar macrophages exposed to interferons and lipopolysaccharide may contribute to the development of pulmonary inflammation, such as in the early stages of bacterial pneumonia following viral infections that induce interferon production.     

Effect of Phosphorus Nutrition on Growth and Physiology of Cotton Under Ambient and Elevated Carbon Dioxide

Phosphorous deficiency in soil limits crop growth and productivity in the majority of arable lands worldwide and may moderate the growth enhancement effect of rising atmospheric carbon dioxide (CO₂) concentration. To evaluate the interactive effect of these two factors on cotton (Gossypium hirsutum) growth and physiology, plants were grown in controlled environment growth chambers with three levels of phosphate (Pi) supply (0.20, 0.05 and 0.01 mm ) under ambient and elevated (400 and 800 μmol mol^?1, respectively) CO₂. Phosphate stress caused stunted growth and resulted in early leaf senescence with severely decreased leaf area and photosynthesis. Phosphate stress led to over 77 % reduction in total biomass across CO₂ levels. There was a below‐ground (roots) shift in biomass partitioning under Pi deficiency. While tissue phosphorus (P) decreased, tissue nitrogen (N) content tended to increase under Pi deficiency. The CO₂ × Pi interactions were significant on leaf area, photosynthesis and biomass accumulation. The stimulatory effect of elevated CO₂ on growth and photosynthesis was reduced or highly depressed suggesting an increased sensitivity of cotton to Pi deficiency under elevated CO₂. Although, tissue P and stomatal conductance were lower at elevated CO₂, these did not appear to be the main causes of cotton unresponsiveness to elevated CO₂ under severe Pi‐stress. The alteration in the uptake and utilization of N was suggested due to a consistent reduction (18–21 %) in the cotton plant tissue N content under elevated CO₂.     

Red sea drillings

Recent drilling in the Red Sea has shown that much of the basin is underlain by evaporites of a similar age to that of evaporites found in the Mediterranean Sea. These evaporites and their structural positions indicate that other brine areas are present-and, indeed, several others have been discovered.     

Mapping sub-field maize yields in Nebraska,USA by combining remote sensing imagery,crop simulation models,and machine learning

Precision Agriculture - Crop yield maps are valuable for many applications in precision agriculture, but are often inaccessible to growers and researchers wishing to better understand yield...     

EFFECTS OF CARBON DIOXIDE AND PHOSPHORUS SUPPLY ON POTATO DRY MATTER ALLOCATION AND CANOPY MORPHOLOGY

□ Data on combined effects of elevated carbon dioxide concentration (CO₂) and phosphorus fertilization (P) on potato are scarce. Growth chamber studies (E1 and E2) that used three P and two CO₂ levels were conducted. Leaf, stem, tuber, and stolon dry matter increased with P. Lateral-stem production was sensitive to P with a minimum 2.5-fold increase in mass. Leaf length increased an average 20.2% in E1 and 38.2% in E2 and leaf area increased an average 336% in E1 and 470% in E2 across CO₂ levels. Tuber dry mass increased 22% in E1 and 38.2% in E2 in response to elevated CO₂ and total dry mass by 14.1 and 15.4%. Tissue P contents increased with P but were unaffected by CO₂. Effects of P on canopy branching were associated with plant N status. The studies suggest elevated CO₂ levels are unlikely to alter potato P requirements on a unit mass basis.     

Potato Stem Density Effects on Canopy Development and Production

Controlled environment studies with potato frequently assume responses from single-stem potato plants can be extrapolated to the field where multiple-stemmed plants are common. Controlled environment studies were conducted to characterize differences in canopy growth, development, and dry matter production between single- and multiple-stemmed potted potatoes. Leaf area distribution was influenced by stem density, with main stem and apical lateral branch leaf area being 150% to 200% larger in triple-stemmed (3S) versus single-stemmed (1S) pots (P < 0.01), while basal lateral branch leaf area was 50% less (P < 0.01). Basal lateral branches were more developed in 1S pots with longer branch lengths, more leaf area, and higher orders of branching. In a second experiment, more leaves were initiated in higher-density pots; however, individual leaf areas were approximately 50% smaller than those in 1S pots. Total leaf area and total, vegetative, and tuber dry matter production were unaffected by stem density in either experiment on a per pot basis. Development and growth of lower basal lateral branches in the 1S potato canopy offset any initial advantage in leaf numbers in the multiple-stemmed plants. These results appeared to validate the assumption that, given a late maturing cultivar and adequate nutrition, responses from single-stemmed plants can be extended to multiple-stemmed plants when expressed on a production area basis. These findings have practical considerations for potato researchers who conduct growth chamber experiments and potato modelers.