PcrG protects the two long helical oligomerization domains of PcrV, by an interaction mediated by the intramolecular coiled-coil region of PcrG

PcrV is a hydrophilic translocator of type three secretion system (TTSS) and a structural component of the functional translocon. C-terminal helix of PcrV is essential for its oligomerization at the needle tip. Conformational changes within PcrV regulate the effector translocation. PcrG is a cytoplasmic regulator of TTSS and forms a high affinity complex with PcrV. C-terminal residues of PcrG control the effector secretion

Selection of Non-Crop Plant Mixes Informed by Arthropod-Plant Network Analyses for Multiple Ecosystem Services Delivery towards Ecological Intensification of Agriculture

Ecological intensification (EI) of agriculture through the improvement of ecosystem service delivery has recently emerged as the alternative to the conventional intensification of agriculture that is widely considered unsustainable and has negative impacts on the environment. Although tropical agricultural landscapes are still heterogeneous, they are rapidly losing diversity due to agricultural intensification. Restoration of natural or semi-natural habitats, habitat diversity, and provision of multiple benefits have been identified as important targets for the transition to EI. Choosing the right plant mixes for the restoration of habitats that can offer multiple ecosystem service benefits is therefore crucial. The selection of candidate species for plant mixes is generally informed by studies focusing on a specific ecosystem service (e.g., pollination) and not based on the whole arthropod—non-crop plant interactions matrix. In this study, we try to identify non-crop plant mixes that would provide habitat for pollinators, act as refugia for natural pest predators, and also as a trap crop for potential crop pests by studying non-crop plants—arthropod interaction network. We have identified the non-crop plant species mixes by first identifying the connector species based on their centrality in the network and then by studying how their sequential exclusions affect the stability of the network

Polyphosphate kinase is involved in stress-induced mprAB-sigE-rel signalling in Mycobacteria

Polyphosphate kinase 1 (PPK1) helps bacteria to survive under stress. The ppk1 gene of Mycobacterium tuberculosis was overexpressed in Escherichia coli and characterized. Residues R230 and F176, predicted to be present in the head domain of PPK1, were identified as residues critical for polyphosphate (polyP)-synthesizing ability and dimerization of PPK1. A ppk1 knockout mutant of Mycobacterium smegmatis was compromised in its ability to survive under long-term hypoxia. The transcription of the rel gene and the synthesis of the stringent response regulator ppGpp were impaired in the mutant and restored after complementation with ppk1 of M. tuberculosis, providing evidence that PPK1 is required for the stringent response. We present evidence that PPK1 is likely required for mprAB-sigE-rel signalling. σE regulates the transcription of rel, and we hypothesize that under conditions of stress polyP acts as a preferred donor for MprB-mediated phosphorylation of MprA facilitating transcription of the sigE gene thereby leading finally to the enhancement of the transcription of rel in M. smegmatis and M. tuberculosis. Downregulation of ppk1 led to impaired survival of M. tuberculosis in macrophages. PolyP plays a central role in the stress response of mycobacteria

Enterotoxigenic Escherichia coli heat-labile toxin drives enteropathic changes in small intestinal epithelia

Enterotoxigenic E. coli (ETEC) produce heat-labile (LT) and/or heat-stable (ST) enterotoxins, and commonly cause diarrhea in resource-poor regions. ETEC have been linked repeatedly to sequelae in children including enteropathy, malnutrition, and growth impairment. Although cellular actions of ETEC enterotoxins leading to diarrhea are well-established, their contributions to sequelae remain unclear. LT increases cellular cAMP to activate protein kinase A (PKA) that phosphorylates ion channels driving intestinal export of salt and water resulting in diarrhea. As PKA also modulates transcription of many genes, we interrogated transcriptional profiles of LT-treated intestinal epithelia. Here we show that LT significantly alters intestinal epithelial gene expression directing biogenesis of the brush border, the major site for nutrient absorption, suppresses transcription factors HNF4 and SMAD4 critical to enterocyte differentiation, and profoundly disrupts microvillus architecture and essential nutrient transport. In addition, ETEC-challenged neonatal mice exhibit substantial brush border derangement that is prevented by maternal vaccination with LT. Finally, mice repeatedly challenged with toxigenic ETEC exhibit impaired growth recapitulating the multiplicative impact of recurring ETEC infections in children. These findings highlight impacts of ETEC enterotoxins beyond acute diarrheal illness and may inform approaches to prevent major sequelae of these common infections including malnutrition that impact millions of children

Collating and validating indigenous and local knowledge to apply multiple knowledge systems to an environmental challenge: A case-study of pollinators in India

There is an important role for indigenous and local knowledge in a Multiple Evidence Base to make decisions about the use of biodiversity and its management. This is important both to ensure that the knowledge base is complete (comprising both scientific and local knowledge) and to facilitate participation in the decision making process. We present a novel method to gather evidence in which we used a peer-to-peer validation process among farmers that we suggest is analogous to scientific peer review. We used a case-study approach to trial the process focussing on pollinator decline in India. Pollinator decline is a critical challenge for which there is a growing evidence base, however, this is not the case world–wide. In the state of Orissa, India, there are no validated scientific studies that record historical pollinator abundance, therefore local knowledge can contribute substantially and may indeed be the principle component of the available knowledge base. Our aim was to collate and validate local knowledge in preparation for integration with scientific knowledge from other regions, for the purpose of producing a Multiple Evidence Base to develop conservation strategies for pollinators. Farmers reported that vegetable crop yields were declining in many areas of Orissa and that the abundance of important insect crop pollinators has declined sharply across the study area in the last 10–25 years, particularly Apis cerana, Amegilla sp. and Xylocopa sp. Key pollinators for commonly grown crops were identified; both Apris cerana and Xylocopa sp. were ranked highly as pollinators by farmer participants. Crop yield declines were attributed to soil quality, water management, pests, climate change, overuse of chemical inputs and lack of agronomic expertise. Pollinator declines were attributed to the quantity and number of pesticides used. Farmers suggested that fewer pesticides, more natural habitat and the introduction of hives would support pollinator populations. This process of knowledge creation was supported by participants, which led to this paper being co-authored by both scientists and farmers

Single Phase Active Power Factor Correction Converters - Methods for Optimizing EMI, Performance and Costs

In this thesis, front-end solutions with single-phase power factor correction (PFC) capability are studied. The reduction of current harmonics using various PFC techniques is investigated and related to the EN 61000-3-2 standard. Moreover, power electronics issues concerning diode recovery characteristics, boost inductor design and MOSFET switching speed considerations for optimizing the overall EMI and efficiency performance of continuous mode active PFC Converters are studied. In addition, the design and construction of a 1200 W continuous conduction mode (CCM) PFC circuit prototype, used for making various measurements, is presented and discussed.With the main objective of this dissertation being optimizing performance and cost indices of continuous mode PFC converters, the results of this research work are presented in three main parts. Firstly issues related to generation of harmonic currents by AC-DC single-phase rectifier-capacitor filter circuits when connected to the utility network, the legal obligations set forth by the European standard EN 61000-3-2 for limiting generation of low-frequency harmonics and different PFC techniques and strategies useful for meeting this standard, are studied. A novel approach of having a central PFC circuit for domestic and commercial loads leading to lower current harmonic distortion without the need to install (expensive) active rectifiers in each end-user device is proposed.Secondly, based on various measurement results, some new methods to optimize overall EMI and efficiency performance of continuous mode active PFC circuits are presented. These methods resulted in performance improvements by way of higher efficiency, cost reduction and reduction in radiated and conducted EMI by over 10 to 23 dB μV.Lastly, all papers published in various journals and conferences from the above work, are presented

Single Phase Active Power Factor Correction Converters - Methods for Optimizing EMI, Performance and Costs

In this thesis, front-end solutions with single-phase power factor correction (PFC) capability are studied. The reduction of current harmonics using various PFC techniques is investigated and related to the EN 61000-3-2 standard. Moreover, power electronics issues concerning diode recovery characteristics, boost inductor design and MOSFET switching speed considerations for optimizing the overall EMI and efficiency performance of continuous mode active PFC Converters are studied. In addition, the design and construction of a 1200 W continuous conduction mode (CCM) PFC circuit prototype, used for making various measurements, is presented and discussed.With the main objective of this dissertation being optimizing performance and cost indices of continuous mode PFC converters, the results of this research work are presented in three main parts. Firstly issues related to generation of harmonic currents by AC-DC single-phase rectifier-capacitor filter circuits when connected to the utility network, the legal obligations set forth by the European standard EN 61000-3-2 for limiting generation of low-frequency harmonics and different PFC techniques and strategies useful for meeting this standard, are studied. A novel approach of having a central PFC circuit for domestic and commercial loads leading to lower current harmonic distortion without the need to install (expensive) active rectifiers in each end-user device is proposed.Secondly, based on various measurement results, some new methods to optimize overall EMI and efficiency performance of continuous mode active PFC circuits are presented. These methods resulted in performance improvements by way of higher efficiency, cost reduction and reduction in radiated and conducted EMI by over 10 to 23 dB μV.Lastly, all papers published in various journals and conferences from the above work, are presented

Diode recovery characteristics considerations for optimizing performance & cost of continuous mode boost PFC converters

This paper explores ways, including the use of SiC diodes, to increase the efficiency and switching frequency of continuous mode Boost PFC Converters. The dependence of electrical and thermal performances of these PFC circuits on the characteristics of the power switching devices is studied. By making measurements on a practical 1000 W PFC circuit prototype, this paper shows as to how every specific application would need an unique design solution to optimize the cost and performance of a PFC circuit

<span style="font-size:11.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-GB">Inducibility of dehydration responsive element (DRE)-based promoter through <i style="mso-bidi-font-style:normal">gusA</i> expression in transgenic tobacco</span>

172-177The current study focuses on the pattern of stress-inducibility of a synthetically designed promoter, viz., 4X DRE (four tandem repeats of dehydration-responsive element), in response to the various stress-inducers like NaCl-mediated salinity, polyethylene glycol (PEG)-mediated water deficit, cold and abscisic acid (ABA). The construct, containing the 4X DRE promoter linked to the reporter gene gusA (that encodes β-glucuronidase, GUS), was introduced in tobacco plants via Agrobacterium <i style="mso-bidi-font-style: normal">tumefaciens-mediated transformation. The T2 progenies showed the integration of gusA, as verified by polymerase chain reaction (PCR) and DNA Blot hybridization analysis. The gusA induction was noted upon treatment of T2 transgenics with 20% (w/v) PEG for 24 h, while remained undetected even in PEG-treated wild type (WT) plant. The maximum expression was observed in the transgenic plant T2/3, which also showed induction in gusA expression with other stressors, viz., 200 mM NaCl and cold (4°C). However, PEG-mediated water stress seemed to be the most effective signal for promoter activation, followed by salinity stress and with lesser stimulation by cold. The promoter was activated in a time-dependent manner of stress application, i.e., greater gusA expression was detected after 24 h of stress as compared to 6 h. ABA application, even at a concentration of 100 μM for 24 h, failed to activate reporter gene expression, proving that the promoter is stress-inducible but ABA-independent. Our observation showed the potentiality of 4X DRE for use as a stress-inducible promoter in overexpressing transgene(s) for salinity, drought and cold tolerance. </span