Analysis of the β-glucoside utilization (bgl) genes of Shigella sonnei: evolutionary implications for their maintenance in a cryptic state

The pattern of expression of the genes involved in the utilization of aryl β-glucosides such as arbutin and salicin is different in the genus Shigella compared to Escherichia coli. The results presented here indicate that the homologue of the cryptic bgl operon of E. coli is conserved in Shigella sonnei and is the primary system involved in β-glucoside utilization in the organism. The organization of the bgl genes in S. sonnei is similar to that of E. coli; however there are three major differences in terms of their pattern of expression. (i) The bglB gene, encoding phospho-β-glucosidase B, is insertionally inactivated in S. sonnei. As a result, mutational activation of the silent bgl promoter confers an Arbutin-positive (Arb+) phenotype to the cells in a single step; however, acquiring a Salicin-positive (Sal+) phenotype requires the reversion or suppression of the bglB mutation in addition. (ii) Unlike in E. coli, a majority of the activating mutations (conferring the Arb+ phenotype) map within the unlinked hns locus, whereas activation of the E. coli bgl operon under the same conditions is predominantly due to insertions within the bglR locus. (iii) Although the bgl promoter is silent in the wild-type strain of S. sonnei (as in the case of E. coli), transcriptional and functional analyses indicated a higher basal level of transcription of the downstream genes. This was correlated with a 1 bp deletion within the putative Rho-independent terminator present in the leader sequence preceding the homologue of the bglG gene. The possible evolutionary implications of these differences for the maintenance of the genes in the cryptic state are discussed

Characterization and Treatment of Urban Runoff

Master'sMASTER OF ENGINEERIN

The evolution of massive black holes and their spins in their galactic hosts

[Abridged] [...] We study the mass and spin evolution of massive black holes within a semianalytical galaxy-formation model that follows the evolution of dark-matter halos along merger trees, as well as that of the baryonic components (hot gas, stellar and gaseous bulges, and stellar and gaseous galactic disks). This allows us to study the mass and spin evolution of massive black holes in a self-consistent way, by taking into account the effect of the gas present in galactic nuclei both during the accretion phases and during mergers. Also, we present predictions, as a function of redshift, for the fraction of gas-rich black-hole mergers -- in which the spins prior to the merger are aligned due to the gravito-magnetic torques exerted by the circumbinary disk -- as opposed to gas-poor mergers, in which the orientation of the spins before the merger is roughly isotropic. These predictions may be tested by LISA or similar spaced-based gravitational-wave detectors such as eLISA/NGO or SGO.Comment: 26 pages, 15 figures. This version includes minor changes to figs 10 and 11 (left-hand panels) described in erratum (MNRAS 440, 1295, 2014, doi: 10.1093/mnras/stu361), see also http://www2.iap.fr/users/barausse/erratum.pd

ERK1/2 signalling protects against apoptosis following endoplasmic reticulum stress but cannot provide long-term protection against BAX/BAK-independent cell death

Disruption of protein folding in the endoplasmic reticulum (ER) causes ER stress. Activation of the unfolded protein response (UPR) acts to restore protein homeostasis or, if ER stress is severe or persistent, drive apoptosis, which is thought to proceed through the cell intrinsic, mitochondrial pathway. Indeed, cells that lack the key executioner proteins BAX and BAK are protected from ER stress-induced apoptosis. Here we show that chronic ER stress causes the progressive inhibition of the extracellular signal-regulated kinase (ERK1/2) signalling pathway. This is causally related to ER stress since reactivation of ERK1/2 can protect cells from ER stress-induced apoptosis whilst ERK1/2 pathway inhibition sensitises cells to ER stress. Furthermore, cancer cell lines harbouring constitutively active BRAFV600E are addicted to ERK1/2 signalling for protection against ER stress-induced cell death. ERK1/2 signalling normally represses the pro-death proteins BIM, BMF and PUMA and it has been proposed that ER stress induces BIM-dependent cell death. We found no evidence that ER stress increased the expression of these proteins; furthermore, BIM was not required for ER stress-induced death. Rather, ER stress caused the PERK-dependent inhibition of cap-dependent mRNA translation and the progressive loss of pro-survival proteins including BCL2, BCLXL and MCL1. Despite these observations, neither ERK1/2 activation nor loss of BAX/BAK could confer long-term clonogenic survival to cells exposed to ER stress. Thus, ER stress induces cell death by at least two biochemically and genetically distinct pathways: a classical BAX/BAK-dependent apoptotic response that can be inhibited by ERK1/2 signalling and an alternative ERK1/2- and BAX/BAK-independent cell death pathway

Efficient Energy Saving Scheme for On-Chip Caches

This paper discusses efficient energy saving techniques for on-chip caches, focusing especially on drowsy cache schemes

Plasmid-mediated suppression of the mutational activation of the bgl operon in Shigella sonnei

SSOR, a clinical isolate of Shigella sonnei which exhibits a Salicin-negative phenotype, is unable to mutate to give rise to Sal+ derivatives although a homolog of the Escherichia coli bgl operon is retained by the strain. This was correlated to the presence of an endogenous plasmid in the strain. A plasmid-cured derivative, AK711, could give rise to Sal+ mutants in two steps. Introduction of the plasmid DNA, extracted from SSOR, into various strains of E.coli and S. sonnei, resulted in ampicillin resistant transformants. Interestingly, the presence of the plasmid suppressed the mutational activation of the bgl operon in the transformants. This was further substantiated by the observation that, transformants that have lost the plasmid regained the ability for mutational activation of the bgl operon. Preliminary characterisation of the plasmid indicated a size of 3.8 kb with an origin of replication resembling that of ColE1 replicons and the bla gene homolog of Tn3. Observations of the mutation frequency at the srl and lac loci in the presence of the plasmid indicate that there is a reduction in the mutation frequency, suggesting an antimutator activity associated with the plasmid

Analysis of the beta-glucoside utilization (bgl) genes of Shigella sonnei: evolutionary implications for their maintenance in a cryptic state

The pattern of expression of the genes involved in the utilization of aryl beta-glucosides such as arbutin and salicin is different in the genus Shigella compared to Escherichia coli. The results presented here indicate that the homologue of the cryptic bgl operon of E. coli is conserved in Shigella sonnei and is the primary system involved in beta-glucoside utilization in the organism. The organization of the bgl genes in 5. sonnei is similar to that of E. coli; however there are three major differences in terms of their pattern of expression. (i) The bglB gene, encoding phospho-beta-glucosidase B, is insertionally inactivated in 5. sonnei. As a result, mutational activation of the silent bgl promoter confers an Arbutin-positive (Arb(+)) phenotype to the cells in a single step; however, acquiring a Salicin-positive (Sal(+)) phenotype requires the reversion or suppression of the bglB mutation in addition. (ii) Unlike in E. coli, a majority of the activating mutations (conferring the Arb(+) phenotype) map within the unlinked hns locus, whereas activation of the E. coli bgl operon under the same conditions is predominantly due to insertions within the bglR locus. (iii) Although the bgl promoter is silent in the wild-type strain of 5. sonnei (as in the case of E. coli), transcriptional and functional analyses indicated a higher basal level of transcription of the downstream genes. This was correlated with a 1 bp deletion within the putative Rho-independent terminator present in the leader sequence preceding the homologue of the bglG gene. The possible evolutionary implications of these differences for the maintenance of the genes in the cryptic state are discussed

[In Press] Supply chain performance measurement through collaborative effectiveness : an Asia-Pacific perspective

Purpose – The main purpose of this research is to investigate the supply chain performance through collaborative effectiveness, from the organisations of Asia–Pacific region perspective, compared with that of global organisations based on collaborative supply chain practices. Design/methodology/approach – The survey research methodology was adopted, involving the collection of survey data from 223 participants across 10 different industries and 6 geographic regions. Data included 103 organisations in the Asia–Pacific region including Australia, India, China, Malaysia, Singapore, Indonesia and Thailand. Findings – From a collaborative effectiveness perspective, the supply chain performance of Asia–Pacific organisations is different when compared with that of global organisations. It was also found that global organisations are driven by sales performance, while Asia–Pacific organisations are focussing mainly on the cost in terms of the number of employees, and therefore productivity. The metal industry stands out to be the best performing industry from a collaborative effectiveness perspective in the Asia–Pacific region and globally. Practical implications – The research findings can be used as a guide by industry practitioners to develop benchmarks for collaborative supply chain practices by industry and region of operations. This research has been limited to a few industries such as manufacturing, logistics, service and retail industries. Originality/value – This research generates new knowledge on the relationship between the collaborative effectiveness and supply chain performance, from the perspectives of both Asia–Pacific and global organisations, based on a collaborative effectiveness framework. The study proposes an innovative approach of assessing supply chain performance through collaborative effectiveness from the perspectives of geographical boundaries and industry types

Role of Abhrakadi Yogam in the Management of Type II Diabetes Mellitus

Diabetes Mellitus is a metabolic disorder predominantly affecting carbohydrate metabolism, characterized by high blood sugar levels (hyperglycemia). It occurs either due to insufficient secretion of insulin by the pancreas or when cells don’t respond to the insulin being produced. Type 2 diabetes is the most prevalent form of diabetes accounting for about 90% of the total diabetic population. Maintaining a healthy diet, engaging in regular physical activity, and prioritizing mental well-being are the key factors to maintaining proper bodily metabolism. Sedentary lifestyles and hereditary factors primarily contribute to the development of type 2 diabetes by causing metabolic imbalances. In Ayurveda, descriptions of Prameha particularly Madhumeha show close similarities with type 2 diabetes mellitus. According to Ayurveda, all diseases stem from improper functioning of Agni, often interpreted as metabolic errors seen in diabetes. Madhumeha is a condition characterized by vitiation of Tridosha and 10 Dushya. Correcting the Agni and restoring the normalcy of Dosha and Dhatu is necessary for managing Diabetes. Here a literary review is done in evaluating the potential mode of action of Abhrakadi Yogam mentioned in Yogaratnakara, Prameha Chikitsa having Deepana, Srotosodhana, Vatanulomana, Rasayana, Pramehaghna properties in the management of Type 2 diabetes mellitus