The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Phospholipase D is one of the crucial enzymes involved in lipid mediated signaling, triggered dur... more Phospholipase D is one of the crucial enzymes involved in lipid mediated signaling, triggered during various developmental and physiological processes. Different members of PLD gene family have been known to be induced under different abiotic stresses and during developmental processes in various plant species. In this report, we are presenting a detailed microarray based expression analysis and expression profiles of entire set of PLD genes in rice genome, under three abiotic stresses (salt, cold and drought) and different developmental stages (3-vegetative stages and 11-reproductive stages). Seven and nine PLD genes were identified, which were expressed differentially under abiotic stresses and during reproductive developmental stages, respectively. PLD genes, which were expressed significantly under abiotic stresses exhibited an overlapping expression pattern and were also differentially expressed during developmental stages. Moreover, expression pattern for a set of stress induced genes was validated by real time PCR and it supported the microarray expression data. These findings emphasize the role of PLDs in abiotic stress signaling and development in rice. In addition, expression profiling for duplicated PLD genes revealed a functional divergence between the duplicated genes and signify the role of gene duplication in the evolution of this gene family in rice. This expressional study will provide an important platform in future for the functional characterization of PLDs in crop plants.
Potassium (K+) is a major macronutrient required for plant growth. An adaptive mechanism to low-K... more Potassium (K+) is a major macronutrient required for plant growth. An adaptive mechanism to low-K+ conditions involves activation of the Ca2+ signaling network that consists of calcineurin B-like proteins (CBLs) and CBL-interacting kinases (CIPKs). The CBL-interacting protein kinase 9 (CIPK9) has previously been implicated in low-K+ responses in Arabidopsis thaliana. Here, we report a protein phosphatase 2C (PP2C), AP2C1, that interacts with CIPK9. Fluorescence resonance energy transfer (FRET), bimolecular fluorescence complementation (BiFC), and co-localization analyses revealed that CIPK9 and AP2C1 interact in the cytoplasm. AP2C1 dephosphorylates the auto-phosphorylated form of CIPK9 in vitro, presenting a regulatory mechanism for CIPK9 function. Furthermore, genetic and molecular analyses revealed that ap2c1 null mutants (ap2c1-1 and ap2c1-2) are tolerant to low-K+ conditions, retain higher K+ content, and show higher expression of K+-deficiency related genes contrary to cipk9 m...
Protein phosphorylation-dephosphorylation is a well-known regulatory mechanism in biological syst... more Protein phosphorylation-dephosphorylation is a well-known regulatory mechanism in biological systems and has become one of the significant means of protein function regulation, modulating most of the biological processes. Protein kinases play vital role in numerous cellular processes. Kinases transduce external signal into responses such as growth, immunity and stress tolerance through phosphorylation of their target proteins. In order to understand these cellular processes at the molecular level, one needs to be aware of the different substrates targeted by protein kinases. Advancement in tools and techniques has bestowed practice of multiple approaches that enable target identification of kinases. However, so far none of the methodologies has been proved to be as good as a panacea for the substrate identification. In this review, the recent advances that have been made in the identifications of putative substrates and the implications of these kinases and their substrates in stress management are discussed.
Background: Phospholipase A (PLA) is an important group of enzymes responsible for phospholipid h... more Background: Phospholipase A (PLA) is an important group of enzymes responsible for phospholipid hydrolysis in lipid signaling. PLAs have been implicated in abiotic stress signaling and developmental events in various plants species. Genome-wide analysis of PLA superfamily has been carried out in dicot plant Arabidopsis. A comprehensive genome-wide analysis of PLAs has not been presented yet in crop plant rice. Methodology/Principal Findings: A comprehensive bioinformatics analysis identified a total of 31 PLA encoding genes in the rice genome, which are divided into three classes; phospholipase A 1 (PLA 1), patatin like phospholipases (pPLA) and low molecular weight secretory phospholipase A 2 (sPLA 2) based on their sequences and phylogeny. A subset of 10 rice PLAs exhibited chromosomal duplication, emphasizing the role of duplication in the expansion of this gene family in rice. Microarray expression profiling revealed a number of PLA members expressing differentially and significantly under abiotic stresses and reproductive development. Comparative expression analysis with Arabidopsis PLAs revealed a high degree of functional conservation between the orthologs in two plant species, which also indicated the vital role of PLAs in stress signaling and plant development across different plant species. Moreover, sub-cellular localization of a few candidates suggests their differential localization and functional role in the lipid signaling. Conclusion/Significance: The comprehensive analysis and expression profiling would provide a critical platform for the functional characterization of the candidate PLA genes in crop plants.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Whereas many molecules that promote cell and axonal growth cone migrations have been identified, ... more Whereas many molecules that promote cell and axonal growth cone migrations have been identified, few are known to inhibit these processes. In genetic screens designed to identify molecules that negatively regulate such migrations, we identified CRML-1, the C. elegans homolog of CARMIL. Although mammalian CARMIL acts to promote the migration of glioblastoma cells,we found that CRML-1 acts as a negative regulator of neuronal cell and axon growth cone migrations. Genetic evidence indicates that CRML-1 regulates these migrations by inhibiting the Rac GEF activity of UNC-73, a homolog of the Rac and Rho GEF Trio. The antagonistic effects of CRML-1 and UNC-73 can control the direction of growth cone migration by regulating the levels of the SAX-3(a Robo homolog) guidance receptor. Consistent with the hypothesis that CRML-1 negatively regulates UNC-73 activity, these two proteins form a complex in vivo. Based on these observations, we propose a role for CRML-1 as a novel regulator of cell ...
Phospholipid hydrolysing enzymes, phospholipase D are represented by multiple gene members encodi... more Phospholipid hydrolysing enzymes, phospholipase D are represented by multiple gene members encoding various isoforms in plants. Different PLD isoforms display a varying requirement for the Ca 2+ and the substrate lipid molecules for their function. By hydrolysing the phosphodiester bond of phospholipids and generating phosphatidic acid (PA), and a soluble head group, phospholipase D regulates various cellular processes in plants such as abscisic acid (ABA) signaling, programmed cell death, defense response to wounding and pathogens, root growth, freezing tolerance and other physiological responses. Studies suggest association of phospholipase D members with various biotic and abiotic stresses and their possible role in stress mediated signaling in plants, as their transcript level and protein activity changes upon exposure to stress stimuli. The focus of this review is discussion of the expression pattern and the functional role of different phospholipase D isoforms under various abiotic and biotic stresses, and the modulation of the stress signaling events leading to stress adaptation and tolerance in plants.
The unc-53/NAV2 gene encodes for an adaptor protein required for cell migrations along the antero... more The unc-53/NAV2 gene encodes for an adaptor protein required for cell migrations along the anteroposterior (AP) axes of C. elegans. This study identifies unc-53 as a novel component of signaling pathways regulating distal tip cell (DTC) migrations along the AP and dorsoventral (DV) axes. unc-53 negatively regulates and functions downstream of ced-10/Rac pathway genes; ced-10/Rac and mig-2/RhoG, which are required for proper DTC migration. Moreover, unc-53 exhibits genetic interaction with abl-1 and unc-5, the two known negative regulators of ced-10/Rac signaling. Our genetic analysis supports the model, where abl-1 negatively regulates unc-53 during DTC migrations and requirement of unc-53 function during both AP and DV DTC migrations could be due to unc-53 mediated regulation of unc-5 activity.
The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant k... more The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant kingdom. The members of this superfamily show diversity in structure and function, despite possessing a conserved G-domain for GTP-binding and hydrolysis. ROP (Rho of Plants) has emerged as plant-specific GTPases to orchestrate unique cellular function such as polarity establishment, stress and plant hormonal signaling. The prominent role in their functional capability is evident from their varied expressional regulation in different developmental and stress conditions. The functional activity of small GTPases is tuned by both positive (guanine exchange factor, GEF) and negative regulators (Guanine Dissociation Inhibitor, GDI and GTPase activating protein, GAP), which favors the ON and OFF state of small GTPases, respectively. The expressional variation of regulators as well as their spatial and temporal expression pattern determine the activity and hence turn-on the switch of small GTPases. In this report, we are exploring the expressional and functional analysis of ROP class of small GTPases in plants under stress and developmental signaling pathways.
Our environment constantly undergoes changes either natural or manmade affecting growth and devel... more Our environment constantly undergoes changes either natural or manmade affecting growth and development of all the organisms including plants. Plants are sessile in nature and therefore to counter environmental changes such as light, temperature, nutrient and water availability, pathogen, and many others; plants have evolved intricate signaling mechanisms, composed of multiple components including several plant hormones. Research conducted in the last decade has placed Strigolactones (SLs) in the growing list of plant hormones involved in coping with environmental changes. SLs are carotenoid derivatives functioning as both endogenous and exogenous signaling molecules in response to various environmental cues. Initially, SLs were discovered as compounds that are harmful to plants due to their role as stimulants in seed germination of parasitic plants, a more beneficial role in plant growth and development was uncovered much later. SLs are required for maintaining plant architecture b...
The risk factors for urinary tract infections (UTIs) from developed countries are not applicable ... more The risk factors for urinary tract infections (UTIs) from developed countries are not applicable to women from developing world. To analyze the behavioral practices and psychosocial aspects pertinent to women in our region and assess their association with acute first time or recurrent UTI. Sexually active premenopausal women with their first (145) and recurrent (77) cystitis with Escherichia coli as cases and women with no prior history of UTI as healthy controls (257) were enrolled at a tertiary care hospital in India, between June 2011 and February 2013. Questionnaire-based data was collected from each participant through a structured face-to-face interview. Using univariate and multivariate regression models, independent risk factors for the first episode of cystitis when compared with healthy controls were (presented in odds ratios [ORs] with its 95% confidence interval [CI]): Anal sex (OR = 3.68, 95% CI = 1.59-8.52), time interval between last sexual intercourse and current episode of UTI was <5 days (OR = 2.27, 95% CI = 1.22-4.23), use of cloth during menstrual cycle (OR = 2.36, 95% CI = 1.31-4.26), >250 ml of tea consumption per day (OR = 4.73, 95% CI = 2.67-8.38), presence of vaginal infection (OR = 3.23, 95% CI = 1.85-5.62) and wiping back to front (OR = 2.52, 95% CI = 1.45-4.38). Along with the latter three, history of UTI in a first-degree female relative (OR = 10.88, 95% CI = 2.41-49.07), constipation (OR = 4.85, 95% CI = 1.97-11.92) and stress incontinence (OR = 2.45, 95% CI = 1.18-5.06) were additional independent risk factors for recurrent cystitis in comparison to healthy controls. Most of the risk factors for initial infection are potentially modifiable but sufficient to also pose risk for recurrence. Many of the findings reflect the cultural and ethnic practices in our country.
In plant cell, cations gradient in cellular compartments is maintained by synergistic action of v... more In plant cell, cations gradient in cellular compartments is maintained by synergistic action of various exchangers, pumps and channels. The Arabidopsis exchanger family members (AtCCX3 and AtCCX5) were previously studied and belong to CaCA (calcium cation exchangers) superfamily while none of the rice CCXs has been functionally characterized for their cation transport activities till date. Rice genome encode four CCXs and only OsCCX2 transcript showed differential expression under abiotic stresses and Ca 2+ starvation conditions. The OsCCX2 localized to tonoplast and suppresses the Ca 2+ sensitivity of K667 (low affinity Ca 2+ uptake deficient) yeast mutant under excess CaCl 2 conditions. In contrast to AtCCXs, OsCCX2 expressing K667 yeast cells show tolerance towards excess Na + , Li + , Fe 2+ , Zn 2+ and Co 2+ and suggest its ability to transport both mono as well as divalent cations in yeast. Additionally, in contrast to previously characterized AtCCXs, OsCCX2 is unable to complement yeast trk1trk2 double mutant suggesting inability to transport K + in yeast system. These finding suggest that OsCCX2 having distinct metal transport properties than previously characterized plant CCXs. OsCCX2 can be used as potential candidate for enhancing the abiotic stress tolerance in plants as well as for phytoremediation of heavy metal polluted soil. Plants require various essential cations for numerous cellular metabolic activities, growth and development. Presence of excess essential ions in the cell leads to ion toxicity while concentration below optimal level leads to ion deficiency symptoms. Therefore, plants have employed wide range of mechanism to uptake mineral nutrients from soil by various transporters presents on the plasma membrane of epidermal root cells. Subsequently minerals from the roots are translocated to different plant organs and tissues for plant growth and development 1. Calcium (Ca 2+) is an essential mineral nutrient as well as a pivotal second messenger in plant cells 2,3. Upon perception of various stimuli, transient increase in [Ca 2+ ] cyt leads to activation of various signal transduction pathways in the plant cells, which regulates the various cellular mechanisms such as opening and closing of stomatal aperture 4 , self-incompatibility during fertilization 5 , development of root hairs and pollen tube growth and guidance 6 , light and circadian signaling 7-9 , hyperosmotic and oxidative stresses 10 , different abiotic stress responses as well as interaction with pathogenic and symbiotic microorganisms 11,12. Therefore, study of calcium transport mediated by different family of calcium transporters in the cell is an important aspect in biological processes. In soil, primarily Ca 2+ absorbs in root by synergistic action of Ca 2+-permeable transporters and translocated to shoot either by apoplastic or symplastic transport 10,13. In the resting cells, submicromolar [Ca 2+ ] cyt is required to regulate various signaling pathways 14-16. In contrast to resting stage of cells, when plants are exposed to various external stimuli like biotic, abiotic, nutrient deficiency, or developmental cues, [Ca 2+ ] cyt level is increased to several hundred folds which generates 'calcium signature' 17. This 'calcium signature' leads to activation of various signaling pathways. This [Ca 2+ ] cyt burst is normalized
Background & objectives: Asymptomatic bacteriuria during pregnancy if left untreated, may lead to... more Background & objectives: Asymptomatic bacteriuria during pregnancy if left untreated, may lead to acute pyelonephritis, preterm labour, low birth weight foetus, etc. Adequate and early treatment reduces the incidence of these obstetric complications. The present study was done to determine presence of asymptomatic bacteriuria (ASB) and obstetric outcome following treatment in early versus late pregnancy. Methods: A prospective cohort study was conducted at a tertiary care teaching hospital of north India. Pregnant women till 20 wk (n=371) and between 32 to 34 wk gestation (n=274) having no urinary complaints were included. Their mid stream urine sample was sent for culture and sensitivity. Women having > 105 colony forming units/ml of single organism were diagnosed positive for ASB and treated. They were followed till delivery for obstetric outcome. Relative risk with 95% confidence interval was used to describe association between ASB and outcome of interest. Results: ASB was fo...
The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant k... more The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant kingdom. The members of this superfamily show diversity in structure and function, despite possessing a conserved G-domain for GTP-binding and hydrolysis. ROP (Rho of Plants) has emerged as plant-specific GTPases to orchestrate unique cellular function such as polarity establishment, stress and plant hormonal signaling. The prominent role in their functional capability is evident from their varied expressional regulation in different developmental and stress conditions. The functional activity of small GTPases is tuned by both positive (guanine exchange factor, GEF) and negative regulators (Guanine Dissociation Inhibitor, GDI and GTPase activating protein, GAP), which favors the ON and OFF state of small GTPases, respectively. The expressional variation of regulators as well as their spatial and temporal expression pattern determine the activity and hence turn-on the switch of small GTPases. In this report, we are exploring the expressional and functional analysis of ROP class of small GTPases in plants under stress and developmental signaling pathways.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Phospholipase D is one of the crucial enzymes involved in lipid mediated signaling, triggered dur... more Phospholipase D is one of the crucial enzymes involved in lipid mediated signaling, triggered during various developmental and physiological processes. Different members of PLD gene family have been known to be induced under different abiotic stresses and during developmental processes in various plant species. In this report, we are presenting a detailed microarray based expression analysis and expression profiles of entire set of PLD genes in rice genome, under three abiotic stresses (salt, cold and drought) and different developmental stages (3-vegetative stages and 11-reproductive stages). Seven and nine PLD genes were identified, which were expressed differentially under abiotic stresses and during reproductive developmental stages, respectively. PLD genes, which were expressed significantly under abiotic stresses exhibited an overlapping expression pattern and were also differentially expressed during developmental stages. Moreover, expression pattern for a set of stress induced genes was validated by real time PCR and it supported the microarray expression data. These findings emphasize the role of PLDs in abiotic stress signaling and development in rice. In addition, expression profiling for duplicated PLD genes revealed a functional divergence between the duplicated genes and signify the role of gene duplication in the evolution of this gene family in rice. This expressional study will provide an important platform in future for the functional characterization of PLDs in crop plants.
Potassium (K+) is a major macronutrient required for plant growth. An adaptive mechanism to low-K... more Potassium (K+) is a major macronutrient required for plant growth. An adaptive mechanism to low-K+ conditions involves activation of the Ca2+ signaling network that consists of calcineurin B-like proteins (CBLs) and CBL-interacting kinases (CIPKs). The CBL-interacting protein kinase 9 (CIPK9) has previously been implicated in low-K+ responses in Arabidopsis thaliana. Here, we report a protein phosphatase 2C (PP2C), AP2C1, that interacts with CIPK9. Fluorescence resonance energy transfer (FRET), bimolecular fluorescence complementation (BiFC), and co-localization analyses revealed that CIPK9 and AP2C1 interact in the cytoplasm. AP2C1 dephosphorylates the auto-phosphorylated form of CIPK9 in vitro, presenting a regulatory mechanism for CIPK9 function. Furthermore, genetic and molecular analyses revealed that ap2c1 null mutants (ap2c1-1 and ap2c1-2) are tolerant to low-K+ conditions, retain higher K+ content, and show higher expression of K+-deficiency related genes contrary to cipk9 m...
Protein phosphorylation-dephosphorylation is a well-known regulatory mechanism in biological syst... more Protein phosphorylation-dephosphorylation is a well-known regulatory mechanism in biological systems and has become one of the significant means of protein function regulation, modulating most of the biological processes. Protein kinases play vital role in numerous cellular processes. Kinases transduce external signal into responses such as growth, immunity and stress tolerance through phosphorylation of their target proteins. In order to understand these cellular processes at the molecular level, one needs to be aware of the different substrates targeted by protein kinases. Advancement in tools and techniques has bestowed practice of multiple approaches that enable target identification of kinases. However, so far none of the methodologies has been proved to be as good as a panacea for the substrate identification. In this review, the recent advances that have been made in the identifications of putative substrates and the implications of these kinases and their substrates in stress management are discussed.
Background: Phospholipase A (PLA) is an important group of enzymes responsible for phospholipid h... more Background: Phospholipase A (PLA) is an important group of enzymes responsible for phospholipid hydrolysis in lipid signaling. PLAs have been implicated in abiotic stress signaling and developmental events in various plants species. Genome-wide analysis of PLA superfamily has been carried out in dicot plant Arabidopsis. A comprehensive genome-wide analysis of PLAs has not been presented yet in crop plant rice. Methodology/Principal Findings: A comprehensive bioinformatics analysis identified a total of 31 PLA encoding genes in the rice genome, which are divided into three classes; phospholipase A 1 (PLA 1), patatin like phospholipases (pPLA) and low molecular weight secretory phospholipase A 2 (sPLA 2) based on their sequences and phylogeny. A subset of 10 rice PLAs exhibited chromosomal duplication, emphasizing the role of duplication in the expansion of this gene family in rice. Microarray expression profiling revealed a number of PLA members expressing differentially and significantly under abiotic stresses and reproductive development. Comparative expression analysis with Arabidopsis PLAs revealed a high degree of functional conservation between the orthologs in two plant species, which also indicated the vital role of PLAs in stress signaling and plant development across different plant species. Moreover, sub-cellular localization of a few candidates suggests their differential localization and functional role in the lipid signaling. Conclusion/Significance: The comprehensive analysis and expression profiling would provide a critical platform for the functional characterization of the candidate PLA genes in crop plants.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
Whereas many molecules that promote cell and axonal growth cone migrations have been identified, ... more Whereas many molecules that promote cell and axonal growth cone migrations have been identified, few are known to inhibit these processes. In genetic screens designed to identify molecules that negatively regulate such migrations, we identified CRML-1, the C. elegans homolog of CARMIL. Although mammalian CARMIL acts to promote the migration of glioblastoma cells,we found that CRML-1 acts as a negative regulator of neuronal cell and axon growth cone migrations. Genetic evidence indicates that CRML-1 regulates these migrations by inhibiting the Rac GEF activity of UNC-73, a homolog of the Rac and Rho GEF Trio. The antagonistic effects of CRML-1 and UNC-73 can control the direction of growth cone migration by regulating the levels of the SAX-3(a Robo homolog) guidance receptor. Consistent with the hypothesis that CRML-1 negatively regulates UNC-73 activity, these two proteins form a complex in vivo. Based on these observations, we propose a role for CRML-1 as a novel regulator of cell ...
Phospholipid hydrolysing enzymes, phospholipase D are represented by multiple gene members encodi... more Phospholipid hydrolysing enzymes, phospholipase D are represented by multiple gene members encoding various isoforms in plants. Different PLD isoforms display a varying requirement for the Ca 2+ and the substrate lipid molecules for their function. By hydrolysing the phosphodiester bond of phospholipids and generating phosphatidic acid (PA), and a soluble head group, phospholipase D regulates various cellular processes in plants such as abscisic acid (ABA) signaling, programmed cell death, defense response to wounding and pathogens, root growth, freezing tolerance and other physiological responses. Studies suggest association of phospholipase D members with various biotic and abiotic stresses and their possible role in stress mediated signaling in plants, as their transcript level and protein activity changes upon exposure to stress stimuli. The focus of this review is discussion of the expression pattern and the functional role of different phospholipase D isoforms under various abiotic and biotic stresses, and the modulation of the stress signaling events leading to stress adaptation and tolerance in plants.
The unc-53/NAV2 gene encodes for an adaptor protein required for cell migrations along the antero... more The unc-53/NAV2 gene encodes for an adaptor protein required for cell migrations along the anteroposterior (AP) axes of C. elegans. This study identifies unc-53 as a novel component of signaling pathways regulating distal tip cell (DTC) migrations along the AP and dorsoventral (DV) axes. unc-53 negatively regulates and functions downstream of ced-10/Rac pathway genes; ced-10/Rac and mig-2/RhoG, which are required for proper DTC migration. Moreover, unc-53 exhibits genetic interaction with abl-1 and unc-5, the two known negative regulators of ced-10/Rac signaling. Our genetic analysis supports the model, where abl-1 negatively regulates unc-53 during DTC migrations and requirement of unc-53 function during both AP and DV DTC migrations could be due to unc-53 mediated regulation of unc-5 activity.
The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant k... more The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant kingdom. The members of this superfamily show diversity in structure and function, despite possessing a conserved G-domain for GTP-binding and hydrolysis. ROP (Rho of Plants) has emerged as plant-specific GTPases to orchestrate unique cellular function such as polarity establishment, stress and plant hormonal signaling. The prominent role in their functional capability is evident from their varied expressional regulation in different developmental and stress conditions. The functional activity of small GTPases is tuned by both positive (guanine exchange factor, GEF) and negative regulators (Guanine Dissociation Inhibitor, GDI and GTPase activating protein, GAP), which favors the ON and OFF state of small GTPases, respectively. The expressional variation of regulators as well as their spatial and temporal expression pattern determine the activity and hence turn-on the switch of small GTPases. In this report, we are exploring the expressional and functional analysis of ROP class of small GTPases in plants under stress and developmental signaling pathways.
Our environment constantly undergoes changes either natural or manmade affecting growth and devel... more Our environment constantly undergoes changes either natural or manmade affecting growth and development of all the organisms including plants. Plants are sessile in nature and therefore to counter environmental changes such as light, temperature, nutrient and water availability, pathogen, and many others; plants have evolved intricate signaling mechanisms, composed of multiple components including several plant hormones. Research conducted in the last decade has placed Strigolactones (SLs) in the growing list of plant hormones involved in coping with environmental changes. SLs are carotenoid derivatives functioning as both endogenous and exogenous signaling molecules in response to various environmental cues. Initially, SLs were discovered as compounds that are harmful to plants due to their role as stimulants in seed germination of parasitic plants, a more beneficial role in plant growth and development was uncovered much later. SLs are required for maintaining plant architecture b...
The risk factors for urinary tract infections (UTIs) from developed countries are not applicable ... more The risk factors for urinary tract infections (UTIs) from developed countries are not applicable to women from developing world. To analyze the behavioral practices and psychosocial aspects pertinent to women in our region and assess their association with acute first time or recurrent UTI. Sexually active premenopausal women with their first (145) and recurrent (77) cystitis with Escherichia coli as cases and women with no prior history of UTI as healthy controls (257) were enrolled at a tertiary care hospital in India, between June 2011 and February 2013. Questionnaire-based data was collected from each participant through a structured face-to-face interview. Using univariate and multivariate regression models, independent risk factors for the first episode of cystitis when compared with healthy controls were (presented in odds ratios [ORs] with its 95% confidence interval [CI]): Anal sex (OR = 3.68, 95% CI = 1.59-8.52), time interval between last sexual intercourse and current episode of UTI was <5 days (OR = 2.27, 95% CI = 1.22-4.23), use of cloth during menstrual cycle (OR = 2.36, 95% CI = 1.31-4.26), >250 ml of tea consumption per day (OR = 4.73, 95% CI = 2.67-8.38), presence of vaginal infection (OR = 3.23, 95% CI = 1.85-5.62) and wiping back to front (OR = 2.52, 95% CI = 1.45-4.38). Along with the latter three, history of UTI in a first-degree female relative (OR = 10.88, 95% CI = 2.41-49.07), constipation (OR = 4.85, 95% CI = 1.97-11.92) and stress incontinence (OR = 2.45, 95% CI = 1.18-5.06) were additional independent risk factors for recurrent cystitis in comparison to healthy controls. Most of the risk factors for initial infection are potentially modifiable but sufficient to also pose risk for recurrence. Many of the findings reflect the cultural and ethnic practices in our country.
In plant cell, cations gradient in cellular compartments is maintained by synergistic action of v... more In plant cell, cations gradient in cellular compartments is maintained by synergistic action of various exchangers, pumps and channels. The Arabidopsis exchanger family members (AtCCX3 and AtCCX5) were previously studied and belong to CaCA (calcium cation exchangers) superfamily while none of the rice CCXs has been functionally characterized for their cation transport activities till date. Rice genome encode four CCXs and only OsCCX2 transcript showed differential expression under abiotic stresses and Ca 2+ starvation conditions. The OsCCX2 localized to tonoplast and suppresses the Ca 2+ sensitivity of K667 (low affinity Ca 2+ uptake deficient) yeast mutant under excess CaCl 2 conditions. In contrast to AtCCXs, OsCCX2 expressing K667 yeast cells show tolerance towards excess Na + , Li + , Fe 2+ , Zn 2+ and Co 2+ and suggest its ability to transport both mono as well as divalent cations in yeast. Additionally, in contrast to previously characterized AtCCXs, OsCCX2 is unable to complement yeast trk1trk2 double mutant suggesting inability to transport K + in yeast system. These finding suggest that OsCCX2 having distinct metal transport properties than previously characterized plant CCXs. OsCCX2 can be used as potential candidate for enhancing the abiotic stress tolerance in plants as well as for phytoremediation of heavy metal polluted soil. Plants require various essential cations for numerous cellular metabolic activities, growth and development. Presence of excess essential ions in the cell leads to ion toxicity while concentration below optimal level leads to ion deficiency symptoms. Therefore, plants have employed wide range of mechanism to uptake mineral nutrients from soil by various transporters presents on the plasma membrane of epidermal root cells. Subsequently minerals from the roots are translocated to different plant organs and tissues for plant growth and development 1. Calcium (Ca 2+) is an essential mineral nutrient as well as a pivotal second messenger in plant cells 2,3. Upon perception of various stimuli, transient increase in [Ca 2+ ] cyt leads to activation of various signal transduction pathways in the plant cells, which regulates the various cellular mechanisms such as opening and closing of stomatal aperture 4 , self-incompatibility during fertilization 5 , development of root hairs and pollen tube growth and guidance 6 , light and circadian signaling 7-9 , hyperosmotic and oxidative stresses 10 , different abiotic stress responses as well as interaction with pathogenic and symbiotic microorganisms 11,12. Therefore, study of calcium transport mediated by different family of calcium transporters in the cell is an important aspect in biological processes. In soil, primarily Ca 2+ absorbs in root by synergistic action of Ca 2+-permeable transporters and translocated to shoot either by apoplastic or symplastic transport 10,13. In the resting cells, submicromolar [Ca 2+ ] cyt is required to regulate various signaling pathways 14-16. In contrast to resting stage of cells, when plants are exposed to various external stimuli like biotic, abiotic, nutrient deficiency, or developmental cues, [Ca 2+ ] cyt level is increased to several hundred folds which generates 'calcium signature' 17. This 'calcium signature' leads to activation of various signaling pathways. This [Ca 2+ ] cyt burst is normalized
Background & objectives: Asymptomatic bacteriuria during pregnancy if left untreated, may lead to... more Background & objectives: Asymptomatic bacteriuria during pregnancy if left untreated, may lead to acute pyelonephritis, preterm labour, low birth weight foetus, etc. Adequate and early treatment reduces the incidence of these obstetric complications. The present study was done to determine presence of asymptomatic bacteriuria (ASB) and obstetric outcome following treatment in early versus late pregnancy. Methods: A prospective cohort study was conducted at a tertiary care teaching hospital of north India. Pregnant women till 20 wk (n=371) and between 32 to 34 wk gestation (n=274) having no urinary complaints were included. Their mid stream urine sample was sent for culture and sensitivity. Women having > 105 colony forming units/ml of single organism were diagnosed positive for ASB and treated. They were followed till delivery for obstetric outcome. Relative risk with 95% confidence interval was used to describe association between ASB and outcome of interest. Results: ASB was fo...
The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant k... more The small GTPase superfamily is comprised of four families (ROP, ARF, RAB and RAN) in the plant kingdom. The members of this superfamily show diversity in structure and function, despite possessing a conserved G-domain for GTP-binding and hydrolysis. ROP (Rho of Plants) has emerged as plant-specific GTPases to orchestrate unique cellular function such as polarity establishment, stress and plant hormonal signaling. The prominent role in their functional capability is evident from their varied expressional regulation in different developmental and stress conditions. The functional activity of small GTPases is tuned by both positive (guanine exchange factor, GEF) and negative regulators (Guanine Dissociation Inhibitor, GDI and GTPase activating protein, GAP), which favors the ON and OFF state of small GTPases, respectively. The expressional variation of regulators as well as their spatial and temporal expression pattern determine the activity and hence turn-on the switch of small GTPases. In this report, we are exploring the expressional and functional analysis of ROP class of small GTPases in plants under stress and developmental signaling pathways.
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Papers by Amita Pandey