Environmental factors function as constraints on soil nitrous oxide fluxes in bioenergy feedstock cropping systems

Nitrous oxide (N₂O) is a potent greenhouse gas and major component of the net global warming potential of bioenergy feedstock cropping systems. Numerous environmental factors influence soil N₂O production, making direct correlation difficult to any one factor of N₂O fluxes under field conditions. We instead employed quantile regression to evaluate whether soil temperature, water‐filled pore space (WFPS), and concentrations of soil nitrate () and ammonium () determined upper bounds for soil N₂O flux magnitudes. We collected data over 6 years from a range of bioenergy feedstock cropping systems including no‐till grain crops, perennial warm‐season grasses, hybrid poplar, and polycultures of tallgrass prairie species each with and without nitrogen (N) addition grown at two sites. The upper bounds for soil N₂O fluxes had a significant and positive correlation with all four environmental factors, although relatively large fluxes were still possible at minimal values for nearly all factors. The correlation with was generally weaker, suggesting it is less important than in driving large fluxes. Quantile regression slopes were generally lower for unfertilized perennials than for other systems, but this may have resulted from a perpetual state of nitrogen limitation, which prevented other factors from being clear constraints. This framework suggests efforts to reduce concentrations of in the soil may be effective at reducing high‐intensity periods—”hot moments”—of N₂O production.     

Somatic cell nuclear transfer efficiency: How can it be improved through nuclear remodeling and reprogramming?

Fertile offspring from somatic cell nuclear transfer (SCNT) is the goal of most cloning laboratories. For this process to be successful, a number of events must occur correctly. First the donor nucleus must be in a state that is amenable to remodeling and subsequent genomic reprogramming. The nucleus must be introduced into an oocyte cytoplasm that is capable of facilitating the nuclear remodeling. The oocyte must then be adequately stimulated to initiate development. Finally the resulting embryo must be cultured in an environment that is compatible with the development of that particular embryo. Much has been learned about the incredible changes that occur to a nucleus after it is placed in the cytoplasm of an oocyte. While we think that we are gaining an understanding of the reorganization that occurs to proteins in the donor nucleus, the process of cloning is still very inefficient. Below we will introduce the procedures for SCNT, discuss nuclear remodeling and reprogramming, and review techniques that may improve reprogramming. Finally we will briefly touch on other aspects of SCNT that may improve the development of cloned embryos.     

A robust and cost-effective method for the production of Val, Leu, Ile (δ1) methyl-protonated 15N-, 13C-, 2H-labeled proteins

A selective protonation strategy is described that uses [3-2H] 13C -ketoisovalerate to introduce (1H- methyl)-leucine and (1H- methyl)-valine into 15N-, 13C-, 2H-labeled proteins. A minimum level of 90% incorporation of label into both leucine and valine methyl groups is obtained by inclusion of 100 mg/L -ketoisovalerate in the bacterial growth medium. Addition of [3,3-2H2] -ketobutyrate to the expression media (D2O solvent) results in the production of proteins with (1H-1 methyl)-isoleucine (>90% incorporation). 1H-13C HSQC correlation spectroscopy establishes that CH2D and CHD2 isotopomers are not produced with this method. This approach offers enhanced labeling of Leu methyl groups over previous methods that utilize Val as the labeling agent and is more cost effective.     

Effect of prostaglandin E1 administration on the heart glycogen synthase and phosphorylase systems

The effects of intravenous administration of PGE₁ on the glycogen synthase and phosphorylase system in rat heart were studied.Unlike the consistent effects of PGE₁ on glycogen synthase in liver, the response in heart was variable. A significant decrease in the per cent synthase occurred in fasted intact rats while a significant increase was seen in adrenalectomized hydrocortisone treated fasted rats. No significant effect was seen on the synthase system in either fed intact or fasted adrenalectomized rats.Phosphorylase activity was increased significantly following PGE₁ administration in fed intact rats and slightly increased in adrenalectomized fasted rats. The phosphorylase system was not affected in fasted intact and fasted adrenalectomized rats given glucocorticoid replacement. With our present state of knowledge an adequate explanation for the response of these heart enzymes to PGE₁ under the various conditions of this study does not appear possible.