Carthage College

About: Carthage College is a education organization based out in Kenosha, Wisconsin, United States. It is known for research contribution in the topics: Orthogonal frequency-division multiplexing & MIMO. The organization has 1155 authors who have published 1416 publications receiving 16572 citations. The organization is also known as: Carthage.

Stoichiometry of soil enzyme activity at global scale

Abstract: Extracellular enzymes are the proximate agents of organic matter decomposition and measures of these activities can be used as indicators of microbial nutrient demand. We conducted a global-scale meta-analysis of the seven-most widely measured soil enzyme activities, using data from 40 ecosystems. The activities of b-1,4-glucosidase, cellobiohydrolase, b-1,4-N-acetylglucosaminidase and phosphatase g )1 soil increased with organic matter concentration; leucine aminopeptidase, phenol oxidase and peroxidase activities showed no relationship. All activities were significantly related to soil pH. Specific activities, i.e. activity g )1 soil organic matter, also varied in relation to soil pH for all enzymes. Relationships with mean annual temperature (MAT) and precipitation (MAP) were generally weak. For hydrolases, ratios of specific C, N and P acquisition activities converged on 1 : 1 : 1 but across ecosystems, the ratio of C : P acquisition was inversely related to MAP and MAT while the ratio of C : N acquisition increased with MAP. Oxidative activities were more variable than hydrolytic activities and increased with soil pH. Our analyses indicate that the enzymatic potential for hydrolyzing the labile components of soil organic matter is tied to substrate availability, soil pH and the stoichiometry of microbial nutrient demand. The enzymatic potential for oxidizing the recalcitrant fractions of soil organic material, which is a proximate control on soil organic matter accumulation, is most strongly related to soil pH. These trends provide insight into the biogeochemical processes that create global patterns in ecological stoichiometry and organic matter storage.

Apoptosis: A Target for Anticancer Therapy

Abstract: Apoptosis, the cell’s natural mechanism for death, is a promising target for anticancer therapy. Both the intrinsic and extrinsic pathways use caspases to carry out apoptosis through the cleavage of hundreds of proteins. In cancer, the apoptotic pathway is typically inhibited through a wide variety of means including overexpression of antiapoptotic proteins and under-expression of proapoptotic proteins. Many of these changes cause intrinsic resistance to the most common anticancer therapy, chemotherapy. Promising new anticancer therapies are plant-derived compounds that exhibit anticancer activity through activating the apoptotic pathway.

Evolutionary-Economic Principles as Regulators of Soil Enzyme Production and Ecosystem Function

Abstract: Extracellular enzymes allow microbes and plant roots to acquire resources from complex molecules, and thereby catalyze the rate-limiting step in soil carbon and nutrient cycling. We examine the hypothesis that extracellular enzyme producers are under evolutionary pressure to minimize the cost:benefit ratio of enzyme production. Consistent with this prediction, enzyme producers generally allocate more resources to enzymes that target limiting nutrients. Additionally, regulatory systems have evolved to increase enzyme production when substrates are abundant and available resources are scarce. Finally, theoretical models predict that producers should control enzyme diffusion rates and adopt strategies to reduce competition for enzymatic reaction products. Because extracellular enzymes regulate ecosystem processes, enzyme allocation could affect ecosystem responses to environmental change. In particular, shifts in enzyme allocation may result in negative feedbacks to changes in resource availability. Enzyme allocation patterns therefore link ecological and evolutionary constraints at the organismal level with ecosystem-level processes.

Studies of the diffuse interstellar bands. iii. hd 183143

Abstract: Echelle spectra of HD 183143 [B7Iae, E(B − V) = 1.27] were obtained on three nights, at a resolving power R = 38,000 and with a signal-to-noise ratio ≈ 1000 at 6400 A in the final, combined spectrum. A catalog is presented of 414 diffuse interstellar bands (DIBs) measured between 3900 and 8100 A in this spectrum. The central wavelengths, the widths (FWHM), and the equivalent widths of nearly all of the bands are tabulated, along with the minimum uncertainties in the latter. Among the 414 bands, 135 (or 33%) were not reported in four previous, modern surveys of the DIBs in the spectra of various stars, including HD 183143. The principal result of this study is that the great majority of the bands in the catalog are very weak and fairly narrow. Typical equivalent widths amount to a few mA, and the bandwidths (FWHM) are most often near 0.7 A. No preferred wavenumber spacings among the 414 bands are identified which could provide clues to the identities of the large molecules thought to cause the DIBs. At generally comparable detection limits in both spectra, the population of DIBs observed toward HD 183143 is systematically redder, broader, and stronger than that seen toward HD 204827 (Paper II). In addition, interstellar lines of C2 molecules have not been detected toward HD 183143, while a very high value of N(C2)/E(B − V )i s observed toward HD 204827. Therefore, either the abundances of the large molecules presumed to give rise to the DIBs, or the physical conditions in the absorbing clouds, or both, must differ significantly between the two cases.