Trait plasticity alters the range of possible coexistence conditions in a competition–colonisation trade‐off

Most of the classical theory on species coexistence has been based on species‐level competitive trade‐offs. However, it is becoming apparent that plant species display high levels of trait plasticity. The implications of this plasticity are almost completely unknown for most coexistence theory. Here, we model a competition–colonisation trade‐off and incorporate trait plasticity to evaluate its effects on coexistence. Our simulations show that the classic competition–colonisation trade‐off is highly sensitive to environmental circumstances, and coexistence only occurs in narrow ranges of conditions. The inclusion of plasticity, which allows shifts in competitive hierarchies across the landscape, leads to coexistence across a much broader range of competitive and environmental conditions including disturbance levels, the magnitude of competitive differences between species, and landscape spatial patterning. Plasticity also increases the number of species that persist in simulations of multispecies assemblages. Plasticity may generally increase the robustness of coexistence mechanisms and be an important component of scaling coexistence theory to higher diversity communities.     

Kinetics of deactivation for thermostable DNA polymerase enzymes

Summary The kinetics of thermal deactivation for thermostable DNA polymerase enzymes were investigated by using the experimental data published elsewhere (Nielson et al. 1996. Strategies. 9, 7–8). The order of deactivation (a) and the deactivation rate constants (k _d) were determined for different Taq DNA polymerase enzymes and were found to be of first order.     

HIV-1 Vpr Modulates Macrophage Metabolic Pathways: A SILAC-Based Quantitative Analysis

Human immunodeficiency virus type 1 encoded viral protein Vpr is essential for infection of macrophages by HIV-1. Furthermore, these macrophages are resistant to cell death and are viral reservoir. However, the impact of Vpr on the macrophage proteome is yet to be comprehended. The goal of the present study was to use a stable-isotope labeling by amino acids in cell culture (SILAC) coupled with mass spectrometry-based proteomics approach to characterize the Vpr response in macrophages. Cultured human monocytic cells, U937, were differentiated into macrophages and transduced with adenovirus construct harboring the Vpr gene. More than 600 proteins were quantified in SILAC coupled with LC-MS/MS approach, among which 136 were significantly altered upon Vpr overexpression in macrophages. Quantified proteins were selected and clustered by biological functions, pathway and network analysis using Ingenuity computational pathway analysis. The proteomic data illustrating increase in abundance of enzymes in the glycolytic pathway (pentose phosphate and pyruvate metabolism) was further validated by western blot analysis. In addition, the proteomic data demonstrate down regulation of some key mitochondrial enzymes such as glutamate dehydrogenase 2 (GLUD2), adenylate kinase 2 (AK2) and transketolase (TKT). Based on these observations we postulate that HIV-1 hijacks the macrophage glucose metabolism pathway via the Vpr-hypoxia inducible factor 1 alpha (HIF-1 alpha) axis to induce expression of hexokinase (HK), glucose-6-phosphate dehyrogenase (G6PD) and pyruvate kinase muscle type 2 (PKM2) that facilitates viral replication and biogenesis, and long-term survival of macrophages. Furthermore, dysregulation of mitochondrial glutamate metabolism in macrophages can contribute to neurodegeneration via neuroexcitotoxic mechanisms in the context of NeuroAIDS.     

Functional assignment to JEV proteins using SVM

Identification of different protein functions facilitates a mechanistic understanding of Japanese encephalitis virus (JEV) infection and opens novel means for drug development. Support vector machines (SVM), useful for predicting the functional class of distantly related proteins, is employed to ascribe a possible functional class to Japanese encephalitis virus protein. Our study from SVMProt and available JE virus sequences suggests that structural and nonstructural proteins of JEV genome possibly belong to diverse protein functions, are expected to occur in the life cycle of JE virus. Protein functions common to both structural and non-structural proteins are iron-binding, metal-binding, lipid-binding, copper-binding, transmembrane, outer membrane, channels/Pores - Pore-forming toxins (proteins and peptides) group of proteins. Non-structural proteins perform functions like actin binding, zinc-binding, calcium-binding, hydrolases, Carbon-Oxygen Lyases, P-type ATPase, proteins belonging to major facilitator family (MFS), secreting main terminal branch (MTB) family, phosphotransfer-driven group translocators and ATP-binding cassette (ABC) family group of proteins. Whereas structural proteins besides belonging to same structural group of proteins (capsid, structural, envelope), they also perform functions like nuclear receptor, antibiotic resistance, RNA-binding, DNA-binding, magnesium-binding, isomerase (intra-molecular), oxidoreductase and participate in type II (general) secretory pathway (IISP).     

Metabolic Syndrome Is Associated with Increased Oxo-Nitrative Stress and Asthma-Like Changes in Lungs

Epidemiological studies have shown an increased obesity-related risk of asthma. In support, obese mice develop airway hyperresponsiveness (AHR). However, it remains unclear whether the increased risk is a consequence of obesity, adipogenic diet, or the metabolic syndrome (MetS). Altered L-arginine and nitric oxide (NO) metabolism is a common feature between asthma and metabolic syndrome that appears independent of body mass. Increased asthma risk resulting from such metabolic changes would have important consequences in global health. Since high-sugar diets can induce MetS, without necessarily causing obesity, studies of their effect on arginine/NO metabolism and airway function could clarify this aspect. We investigated whether normal-weight mice with MetS, due to high-fructose diet, had dysfunctional arginine/NO metabolism and features of asthma. Mice were fed chow-diet, high-fat-diet, or high-fructose-diet for 18 weeks. Only the high-fat-diet group developed obesity or adiposity. Hyperinsulinemia, hyperglycaemia, and hyperlipidaemia were common to both high-fat-diet and high-fructose-diet groups and the high-fructose-diet group additionally developed hypertension. At 18 weeks, airway hyperresponsiveness (AHR) could be seen in obese high-fat-diet mice as well as non-obese high-fructose-diet mice, when compared to standard chow-diet mice. No inflammatory cell infiltrate or goblet cell metaplasia was seen in either high-fat-diet or high-fructose-diet mice. Exhaled NO was reduced in both these groups. This reduction in exhaled NO correlated with reduced arginine bioavailability in lungs. In summary, mice with normal weight but metabolic obesity show reduced arginine bioavailability, reduced NO production, and asthma-like features. Reduced NO related bronchodilation and increased oxo-nitrosative stress may contribute to the pathogenesis.     

Rheological properties of guar gum and hydroxyethyl guar gum in aqueous solution

The rheological properties of aqueous solutions of guar gum (GG) and hydroxyethyl guar gum (HEG) have been investigated. The flow properties of these polysaccharide solutions were studied at the shear rate in the range 1.5–1310s⁻¹ using a Rheotest-2 viscometer. The flow of these polysaccharide solutions was described by equation of state based on Cross model. The basic rheological parameters, like zero shear rate viscosity (η_o), elasticity modulus (G_o) and relaxation time (gl_o) were calculated using simple and established relations. Master viscosity curves indicated that the molecular weight distribution of native guar gum has been changed by hydroxyethylation under specified reaction conditions. The effect of concentration and temperature on η_o and λ_o has been studied, and the relations among these were established by simple equations.     

The effect of oxidants on biomembranes and cellular metabolism

During the reductive process in the tissues, the aerobes generate a number of oxidants. Unless these oxidants are reduced, oxidative damage and cell death would occur. Oxidation of plasma membrane lipids leads to autocatalytic chain reactions which eventually alter the permeability of the cell. The role of oxidative damage in the pathophysiology of diabetic complications and ischemic reperfusion injury of myocardium, especially the changes in the channel activity which may lead to arrhythmia have been studied. Hyperglycemia activates aldose reductase which could efficiently reduce glucose to sorbitol in the presence of NADPH. Since NADPH is also aldose required by glutathione reductase for reducing oxidants, its diversion would lead to membrane lipid oxidation and permeability changes which are probably responsible for diabetic complications such as cataractogenesis, retinopathy, neuropathy etc. Antioxidants such as butylated hydroxy toluene (BHT) and also reductase inhibitors prevent or delay some of these complications. By using patch-clamp technique in isolated frog myocytes, we have shown that hydroxy radicals generated by ferrous sulfate and ascorbate as well as lipid peroxides such as t-butyl hydroperoxide facilitate the entry of Na⁺ by oxidizing Na⁺-channels. Increased intracellular Na⁺ leads to an increase in Na⁺/Ca²⁺ exchange. The increased Na⁺ concentration by itself may produce electrical disturbance which would result in arrhythmia. Increased Ca²⁺ may affect proteases and may help in the conversion of xanthine dehydrogenase to xanthine oxidase, consequently increased production of super oxide radicals. Increased membrane lipid peroxidation and other oxygen free-radical associated membrane damage in myocytes has been demonstrated.     

The distribution of the Hb Constant Spring gene in Southeast Asian populations

Summary The distribution of the hemoglobin Constant Spring (Hb CS) gene in eight populations in Southeast Asia (including Assam) was determined using oligonucleotide hybridization. Hb CS was absent in two Assamese populations with a high prevalence of Hb E. The Hb CS gene frequency was 0.033 in northern Thailand and near 0.01 in central Thailand and Cambodia. High frequencies, between 0.05 and 0.06, were observed in northeastern Thailand. The present data and a similar study in Laotians suggest that the Lao-speaking populations of the Mekong River basin in northeastern Thailand and Laos have the highest frequencies of the Hb CS gene in Southeast Asia.     

A study of diabetes in relation to blood groups and cholesterol levels

Summary Four hundred and sixteen patients suffering from diabetes were studied for AB0 Rhesus blood groups, to find out whether there is any association between blood group and diabetes. Though the relative incidence was found to be higher in blood group 0 and B, the difference was not statistically significant. This study confirms the earlier findings of high cholesterol levels in diabetes, particularly in patients with blood groups A and AB, and the overall mean cholesterol level as 253 mg/100 ml. This study also shows that diabetes with a cholesterol level of more than 300 mg/100 ml is a coronary risk factor.

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Zusammenfassung 416 Patienten mit Diabetes wurden nach AB0 und Rh untersucht, um Assoziationen zwischen Blutgruppe und Diabetes zu finden. Es fand sich ein leichtes, nicht signifikantes Überwiegen von 0 und B. Ein besonders hoher Serum-Cholesteral-Spiegel fand sich beim Diabetes insbesondere bei Patienten der Gruppen A und AB. Die Studie zeigt auch, daß ein Cholesteral-Spiegel von mehr als 300 mg% ein Risikofaktor für Coronarerkrankungen ist.