Mitogen-activated protein kinases in the acute diabetic myocardium

Diabetes mellitus (DM) causes myocardial remodeling on the subcellular level and alterations in the function of the cell membranes ion transport systems resulting in contractile dysfunction. The present study was aimed to investigate the expression and activation of mitogen-activated protein kinases (MAPKs) and their possible role in the acute diabetic rat hearts. Rats were injected with single dose of streptozotocin (45 mg/kg, i.v.), and after 1 week the disease was manifested by hyperglycemia and cardiac dysfunction. The Langendorff-perfused hearts were subjected to ischemia (5 or 30 min occlusion of LAD coronary artery). The protein pattern in cytosolic fraction of the heart tissue was determined after electrophoretic separation. The levels and activation of MAPKs were determined by Western blot analysis using specific antibodies. No differences between the diabetics and controls in the level of ERKs were found at baseline. However, in DM samples ERKs phosphorylation was markedly increased, and further changes occurred during ischemia. Also content of phoshorylated c-Raf kinase (an upstream activator of ERKs) was slightly increased at baseline conditions in the diabetic samples. In contrast, no significant changes in the contents and phosphorylation of p38-MAPK were observed at baseline. But some differences in the p38-MAPK phosphorylation were found during ischemia.The results show that differential pattern of protein kinase cascades activation in the diabetic hearts might be account for the modulation of their response to ischemia.     

Should we take measurements at an intermediate design point?

It is well known that, for estimating a linear treatment effect with constant variance, the optimal design divides the units equally between the two extremes of the design space. If the dose-response relation may be nonlinear, however, intermediate measurements may be useful in order to estimate the effects of partial treatments. We consider the decision of whether to gather data at an intermediate design point: do the gains from learning about nonlinearity outweigh the loss in efficiency in estimating the linear effect? Under reasonable assumptions about nonlinearity, we find that, unless sample size is very large, the design with no interior measurements is best, because with moderate total sample sizes, any nonlinearity in the dose-response will be difficult to detect. We discuss in the context of a simplified version of the problem that motivated this work-a study of pest-control treatments intended to reduce asthma symptoms in children.     

Ligand Binding to CNS Muscarinic Receptor Is Transiently Modified by Convulsant 3-Mercaptopropionic Acid Administration

The administration of convulsant drugs has proven a powerful tool to study experimental epilepsy. We have already reported that the administration of convulsant 3-mercaptopropionic acid (mp) at 150 mg/kg enhances binding affinity of muscarinic antagonist [³H]quinuclidinyl benzilate ([³H]QNB) to certain rat CNS membranes during seizure and postseizure without affecting site number. Results obtained with a 100-mg/kg dose of mp have shown reversible increases in [³H]QNB binding to cerebellum and hippocampus, whereas a delayed response has been found in striatum. Neither a subconvulsant dose nor in vitro addition modifies binding. In order to evaluate preseizure, seizure as well as early (30 min) and late (24 h) postseizure stages, we employed a 50 mg/kg dose and tested [³H]QNB binding to CNS membranes. Changes in binding were as follows (in %): in cerebellum, +37, +86, and +40 at preseizure, seizure and early postseizure stages, respectively, but there was a decrease at late postseizure; in hippocampus, +27 at pre- and seizure stages, but a decrease at early and late postseizure. No changes were found in striatum or cerebral cortex membranes at any stage studied. Saturation curves analysed by Scatchard plots indicated that changes in [³H]QNB binding to cerebellar membranes are attributable to an increase in ligand affinity at seizure, followed by a decrease in binding site number at postseizure. A similar profile was observed for hippocampus except that the decrease in binding site number, though lower than at postseizure, was already evident at seizure stage. Results confirm a region-specific response to the convulsant and transient changes provide an example of neuronal plasticity.     

Effect of deleterious mutation-accumulation on the fitness of RNA bacteriophage MS2

Abstract.— RNA viruses show the highest mutation rate in nautre. It has been extensively demonstrated that, in the absence of purifying selection, RNA viruses accumulate deleterious mutations at a high rate. However, the parameters describing this accumulation are, in general, poorly understood. The present study reports evidences for fitness declines by the accumulation of deleterious mutations in the bacteriophage MS2. We estimated the rate of fitness decline to be as high as 16% per bottleneck transfer. In addition, our results agree with an additive model of fitness effects.     

Last judgment: the visionary biology of J.B.S. Haldane

This paper seeks to reinterpret the life and work of J. B. S. Haldane by focusing on an illuminating but largely ignored essay he published in1927, “The Last Judgment” – the sequel to his better known work, Daedalus (1924). This astonishing essay expresses a vision of the human future over the next 40,000,000 years, one that revises and updates Wellsian futurism with the long range implications of the “new biology” for human destiny. That vision served as a kind of lifelong credo, one that infused and informed his diverse scientific work, political activities, and popular writing, and that gave unity and coherence to his remarkable career. This revised version was published online in July 2006 with corrections to the Cover Date.     

A simple method for screening antimicrobial compounds with application to plant disease and fruit quality

Aims:  It is often difficult to extrapolate information from a Petri dish and apply it to commercial applications as with antimicrobial assays. Often large volumes of commodities are used for a virtually untested protocol and result in an unnecessary expenditure of time and materials. An intermediate method, where experimental compounds could be tested directly on a specific commodity without expending large quantities of either sample or compound, would be practical and economical.
Methods and Results:  A method was developed that employs the use of a small experimental chamber in which pieces of natural materials (e.g. fruit) can be tested with antimicrobial compounds. This method uses a type of autoclavable incubation chamber with a filter paper base, hydrating sponge pieces and a sterile glass sample platform. The chamber offers a sterile, controlled environment and can be manipulated to serve a number of studies.
Conclusion:  The chamber results are more analogous to what happens on whole fruit than the Petri dish.
Significance and Impact of the Study:  This method is presently used to screen for antimicrobial compounds and treatments needed to control serious economic pests compromising Florida's agriculture.     

Evolutionary rescue by compensatory mutations is constrained by genomic and environmental backgrounds

Since deleterious mutations may be rescued by secondary mutations during evolution, compensatory evolution could identify genetic solutions leading to therapeutic targets. Here, we tested this hypothesis and examined whether these solutions would be universal or would need to be adapted to one's genetic and environmental makeups. We performed experimental evolutionary rescue in a yeast disease model for the Wiskott–Aldrich syndrome in two genetic backgrounds and carbon sources. We found that multiple aspects of the evolutionary rescue outcome depend on the genotype, the environment, or a combination thereof. Specifically, the compensatory mutation rate and type, the molecular rescue mechanism, the genetic target, and the associated fitness cost varied across contexts. The course of compensatory evolution is therefore highly contingent on the initial conditions in which the deleterious mutation occurs. In addition, these results reveal biologically favored therapeutic targets for the Wiskott–Aldrich syndrome, including the target of an unrelated clinically approved drug. Our results experimentally illustrate the importance of epistasis and environmental evolutionary constraints that shape the adaptive landscape and evolutionary rate of molecular networks.     

Pipeliner: software to evaluate the performance of bioinformatics pipelines for next‐generation resequencing

The choice of technology and bioinformatics approach is critical in obtaining accurate and reliable information from next‐generation sequencing (NGS) experiments. An increasing number of software and methodological guidelines are being published, but deciding upon which approach and experimental design to use can depend on the particularities of the species and on the aims of the study. This leaves researchers unable to produce informed decisions on these central questions. To address these issues, we developed pipeliner – a tool to evaluate, by simulation, the performance of NGS pipelines in resequencing studies. Pipeliner provides a graphical interface allowing the users to write and test their own bioinformatics pipelines with publicly available or custom software. It computes a number of statistics summarizing the performance in SNP calling, including the recovery, sensitivity and false discovery rate for heterozygous and homozygous SNP genotypes. Pipeliner can be used to answer many practical questions, for example, for a limited amount of NGS effort, how many more reliable SNPs can be detected by doubling coverage and halving sample size or what is the false discovery rate provided by different SNP calling algorithms and options. Pipeliner thus allows researchers to carefully plan their study's sampling design and compare the suitability of alternative bioinformatics approaches for their specific study systems. Pipeliner is written in C++ and is freely available from http://github.com/brunonevado/Pipeliner .     

Julius Sachs (1832–1897) and the Unity of Life

In 1865, the German botanist Julius Sachs published a seminal monograph entitled Experimental-Physiologie der Pflanzen (Experimental Physiology of Plants) and hence became the founder of a new scientific discipline that originated 150 y ago. Here, we outline the significance of the achievements of Sachs. In addition, we document, with reference to his Vorlesungen über Pflanzen-Physiologie (Lectures on the Physiology of Plants, 1882), that Sachs was one of the first experimentalists who proposed the functional unity of all organisms alive today (humans, animals, plants and other “vegetable” organisms, such as algae, cyanophyceae, fungi, myxomycetes, and bacteria).     

Place and Response Learning in the Open-field Tower Maze

This protocol describes how the Open-field Tower Maze (OFTM) paradigm is used to study spatial learning in rodents. This maze is especially useful for examining how rats learn to use a place- or response-learning to successfully navigate in an open-field arena. Additionally, this protocol describes how the OFTM differs from other behavioral maze paradigms that are commonly used to study spatial learning in rodents. The OFTM described in this article was adapted from the one previously described by Cole, Clipperton, and Walt (2007). Specifically, the OFTM was created to test spatial learning in rodents without the experimenter having to consider how “stress” might play a role as a confounding variable. Experiments have shown that stress-alone can significantly affect cognitive function¹. The representative results section contains data from an experiment that used the OFTM to examine the effects of estradiol treatment on place- and response-learning in adult female Sprague Dawley rats². Future studies will be designed to examine the role of the hippocampus and striatum in place- and response-learning in the OFTM.