Scale Interactions and Regional Climate: Examples from the Susquehanna River Basin

One of the most difficult problems faced by climatologists is how to translate global climate model (GCM) output into regional- and local-scale information that health and environmental effects researchers can use. It will be decades before GCMs will be able to resolve scales small enough for most effects research, so climatologists have developed climate downscaling methods to bridge the gap between the global and local scales. There are two main streams of climate downscaling research. First, high-resolution, limited-area climate models can be embedded in the coarse-scale GCMs, producing much finer resolution climate data. Second, empirical downscaling techniques develop transfer functions linking the large-scale atmospheric circulation generated by the GCMs to surface data. Examples of both types of downscaling, aimed at improving projections of future climate in the Susquehanna River Basin (the Mid-Atlantic Region of the United States), are presented. A third case is also described in which an even higher-resolution nested atmospheric model is being developed and linked to a hydrologic model system, with the ultimate goal of simulating the environmental response to climate forcing at all time and space scales.     

Friends of mine: An invasive freshwater mussel facilitates growth of invasive macrophytes and mediates their competitive interactions

1. Increasing rates of invasions in ecosystems worldwide necessitate experiments to determine the role of biotic interactions in the success and impact of multiple alien species. Here, we examined competitive and facilitative interactions among various combinations of three widespread and often co-occurring invaders: the zebra mussel Dreissena polymorpha, and the macrophytes Elodea canadensis and Elodea nuttallii.
2. Using a mesocosm-based, factorial experimental design, we assessed the effect of interspecific competition on macrophyte growth rates in the absence and presence at varying biomass of D. polymorpha.
3. Growth rates (wet g/day) of E. canadensis and E. nuttallii were similar when grown in isolation. When grown together, in the absence of D. polymorpha, E. canadensis growth was not significantly reduced in the presence of E. nuttallii and vice versa. In the presence of D. polymorpha (26.0 ± 1 mm), monocultural growth of E. canadensis was largely unaffected, while E. nuttallii growth was strongly enhanced. Low (2.64 g) and medium (3.96 g) mussel biomass led to negative interspecific effects between E. canadensis and E. nuttallii; at high (5.28 g) mussel biomass, the effect of interspecific competition was negated.
4. Overall, D. polymorpha alleviated competitive interactions between the two invasive macrophytes when all three species co-occurred, and substantially enhanced growth of E. nuttallii with increasing mussel biomass, thereby suggesting a possible influence on the relative dominance of these macrophytes in the field.
5. Our study demonstrates how facilitations can cause shifts in dominance among closely related invaders. The consequences of such facilitations for the structure and function of communities remain to be explored generally.

     

A transmembranous NADH-dehydrogenase in human erythrocyte membranes

Evidence is presented for a transmembranous NADH-dehydrogenase in human erythrocyte plasma membrane. We suggest that this enzyme is responsible for the ferricyanide reduction by intact cells. This NADH-dehydrogenase is distinctly different from the NADH-cytochromeb ₅ reductase on the cytoplasmic side of the membrane. Pretreatment of erythrocytes with the nonpenetrating inhibitor diazobenzene sulfonate (DABS) results in a 35% loss of NADH-ferricyanide reductase activity in the isolated plasma membrane. Since NADH and ferricyanide are both impermeable, the transmembrane enzyme can only be assayed in open membrane sheets with both surfaces exposed, and not in closed vesicles. The transmembrane dehydrogenase has affinity constants of 90 µM for NADH and 125 µM for ferricyanide. It is inhibited byp-chloromercuribenzoate, bathophenanthroline sulfonate, and chlorpromazine.     

Deficiency of Pten accelerates mammary oncogenesis in MMTV-Wnt-1 transgenic mice

Background  

Germline mutations in the tumor suppressor PTEN predispose human beings to breast cancer, and genetic and epigenetic alterations of PTEN are also detected in sporadic human breast cancer. Germline Pten mutations in mice lead to the development of a variety of tumors, but mammary carcinomas are infrequently found, especially in mice under the age of six months.     

Papaver bracteatum,potential commercial source of codeine

Papaver bracteatum, native to Iran and southern Russia, has been grown successfully in many countries. Research in the northwest United States has confirmed the potential for its commercial production as a source of the alkaloid thebaine. Potential for the chemical conversion of thebaine into codeine, one of man’s most widely used alkaloidal medicinal agents, is reviewed. Economic and social advantages of growing this species over opium poppy (Papaver somniferum) are discussed. The value of the seed oil for cooking and industrial use is considered.     

Affinity chromatography purification of penicillinase of Bacillus licheniformis 749-C and its use to measure tuurnover of the cell bound enzyme

Affinity chromatography purification of small amounts of penicillinase using cephalosporin C covalently linked to Sepharose 4B has been used in examining the turnover of cell-bound penicillinase by B. licheniformis 749/C. Under conditions in which most of the nascent penicillinase is retained by the cells, turnover could be demonstrated (15% of the cell-bound enzyme in 2.5 hours), although most of the secreted enzyme is derived from newly-formed molecules.