An Assessment of Desolvation on Rates of Acetyl Transfer: Insights into Enzyme Catalysis

Enzymes greatly enhance the rate of reactions by a variety of physical organic mechanisms. One of the more contentious of these has been desolvation. To get a quantitative assessment of this contribution, we examined acetyl transfer to oxydianions. This is a model reaction for enzymes in which a high-energy acyl phosphate is formed. The aqueous reaction of phosphate or phosphonates with p-nitrophenyl acetate (pNPA) shows a substantial negative deviation from the Brønsted correlation obtained with monoanionic nucleophiles and from the reactivity of other, larger, oxydianions (molybdate, arsenate and vanadate). This, and other data, suggests a significant contribution of desolvation to the activation energy. To further investigate this we studied the effect of various DMSO (dimethyl sulfoxide)/H_2O mixtures on the reaction of chloromethylphosphonate, and of molybdate, on the reaction with pNPA. Increasing the DMSO concentration from 1% to 90% (v/v) increases the second-order rate constant for each of these reactions by over a factor of 5000. This is over a 1000 times greater than the enhancing effect on the reaction of phenoxides and over 105 times the (inhibiting) effect on the reaction with neutral nucleophiles (imidazole). Extrapolation to pure DMSO yields a rate enhancement of ∼10^5, relative to the reaction in water, for the oxydianions. This enhancement is over 3 orders of magnitude greater than that seen with monoanionic phenoxide nucleophiles. This suggests a significant role for desolvation in the reactions in the enzyme-catalyzed nucleophilic reactions of inorganic phosphate but a modest role in reactions with less highly charged nucleophiles

Growing and Marketing Elderberries in Missouri (2012)

The American elderberry (Sambucus canadensis, also known as Sambucus nigra subsp. canadensis) is native to much of eastern and midwestern North America. The plant is a medium to large multiple-stemmed shrub, bush or small tree. Elderberry is commonly found growing in a range of habitats throughout Missouri, but it prefers moist, well-drained, sunny sites and is often found along roadside ditches and streams.By Patrick L. Byers, Andrew L. Thomas, Mihaela M. Cernusca, Larry D. Godsey and Michael A. Gold (University of Missouri)Includes bibliographical reference

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin

Species-specific responses of Late Quaternary megafauna to climate and humans

Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary remain contentious. We use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, underscoring the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.This paper is in the memory of our friend and colleague Dr. Andrei Sher, who was a major contributor of this study. Dr Sher died unexpectedly, but his major contributions to the field of Quaternary science will be remembered and appreciated for many years to come. We are grateful to Dr. Adrian Lister and Dr. Tony Stuart for guides and discussions. Thanks to Tina B. Brandt, Dr. Bryan Hockett and Alice Telka for laboratory help and samples and to L. Malik R. Thrane for his work on the megafauna locality database. Data taken from the Stage 3 project was partly funded by Grant #F/757/A from the Leverhulme Trust, together with a grant from the McDonald Grants and Awards Fund. We acknowledge the Danish National Research Foundation, the Lundbeck Foundation, the Danish Council for Independent Research and the US National Science Foundation for financial suppor

On Bayesian analysis of mixtures with an unknown number of components - Discussion

New methodology for fully Bayesian mixture analysis is developed, making use of reversible jump Markov chain Monte Carlo methods that are capable of jumping between the parameter subspaces corresponding to different numbers of components in the mixture. A sample from the full joint distribution of all unknown variables is thereby generated, and this can be used as a basis for a thorough presentation of many aspects of the posterior distribution. The methodology is applied here to the analysis of univariate normal mixtures, using a hierarchical prior model that offers an approach to dealing with weak prior information while avoiding the mathematical pitfalls of using improper priors in the mixture context

Mid-Atlantic Orchard Monitoring Guide (NRAES 75)

This 361 page publication (NRAES-75) was originally published by the Northeast Regional Agricultural Engineering Service (NRAES, later known as the Natural Resource, Agriculture, and Engineering Service), a multi-university program in the Northeast US disbanded in 2011. Plant and Life Sciences Publishing (PALS) was subsequently formed to manage the NRAES catalog. Ceasing operations in 2018, PALS was a program of the Department of Horticulture in the College of Agriculture and Life Sciences (CALS) at Cornell University. PALS assisted university faculty in publishing, marketing and distributing books for small farmers, gardeners, land owners, workshops, college courses, and consumers.The tree fruit industry represents a complex agroecosystem that requires numerous management decisions in diverse areas in order to maintain profitability in an increasingly competitive global market. Wise decisions begin with a thorough knowledge of the various production components and an awareness of their status in the orchard. Monitoring is the tool for acquiring periodic information about the orchard situation so that timely decisions can be made and action can be taken. It seemed appropriate to assemble the collective expertise of numerous individuals into a regional guide for orchard monitoring because there are more similarities than differences in the production of tree fruits in the mid-Atlantic region. Our goal was to develop a user-friendly, multi-disciplinary guide for use by fruit growers, consultants, chemical field representatives, and research and extension personnel. This Mid-Atlantic Orchard Monitoring Guide is authored by 37 fruit researchers and extension specialists from land grant universities in Maryland, New Jersey, Pennsylvania, Virginia, and West Virginia, as well as researchers from the Pennsylvania Department of Agriculture and the United States Department of Agriculture (USDA). Authors for the various sections of the guide were selected by discipline chairs in entomology, plant pathology/ nematology and horticulture. Discipline chairs were responsible for collecting and assembling written material and photos from the authors for submission to the editor