The objective of this study was to investigate the processability of hot-melt extrusion (HME) to ... more The objective of this study was to investigate the processability of hot-melt extrusion (HME) to formulate ocular inserts of valacyclovir hydrochloride and evaluate the in vivo bioavailability of the formulation. To optimize the formulation of this drug, different physical mixtures of the polymers and plasticizer were prepared. The physical mixture was extruded through a co-rotating twin-screw extruder and the obtained ocular inserts were cut with dimensions of 4 mm × 2 mm × 1 mm to enhance the formulation instillation in the eye. Ocular inserts were evaluated for drug content, weight variation, uniformity of thickness, in vitro drug release, and in vivo drug bioavailability. The ocular inserts were thermally characterized using differential scanning calorimetry (DSC). The attributes observed for the ocular inserts were within the target specifications. The ocular inserts of valacyclovir hydrochloride were successfully prepared using the HME. They provided sustained drug release along with enhanced drug permeation when compared to the eyedrop solution and dissolve completely in 8 h. Additionally, the obtained results demonstrated that the formulation of ocular inserts of valacyclovir hydrochloride using HME was reproducible, robust and effective method.
The aim of the study was to determine the effect of rhododendron flower juice on the bioavailabil... more The aim of the study was to determine the effect of rhododendron flower juice on the bioavailability of Amlodipine in rats. This study was carried out in rats as a parallel design study. After the analysis of blood samples, it has been concluded that a component (s) of rhododendron flower juice inhibits the CYP3A4 mediated metabolism of Amlodipine. AUC was determined with the help of Trapezoidal rule. C max and T max were determined from the area under the plasma concentration-time curve. Statistical analysis was performed on the data obtained from both the group of rats. One way Analysis of Variance (ANOVA) from which Tukey-Kramer Multiple Comparisons Test was applied to the data obtained. This test compared all the parameters such as AUC, C max and T max without flower juice and after giving flower juice and the standard deviation of AUC of amlodipine with and without juice was found to be 14.25 and 10.44 respectively. AUC of the amlodipine after giving rhododendron flower juice...
Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the... more Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the steroid hormone ecdysone, in response to neural signals, at precise stages during development. In this study we have analyzed, using genetic and molecular methods, the roles played by two major signaling pathways in the regulation of larval molting in Drosophila. Previous studies have shown that mutants for the inositol 1,4,5-trisphosphate receptor gene (itpr) are larval lethals. In addition they exhibit delays in molting that can be rescued by exogenous feeding of 20-hydroxyecdysone. Here we show that mutants for adenylate cyclase (rut) synergize, during larval molting, with itpr mutant alleles, indicating that both cAMP and InsP3 signaling pathways function in this process. The two pathways act in parallel to affect molting, as judged by phenotypes obtained through expression of dominant negative and dominant active forms of protein kinase A (PKA) in tissues that normally express the ...
The use of sequence-specific transcription activator-like effector nucleases (TALENs) and the clu... more The use of sequence-specific transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeats-associated system (CRISPR/Cas9) have provided powerful reverse genetic approaches to the targeted modification of genomes in numerous organisms. Both systems have been employed to generate loss-of-function alleles in bread wheat, by targeting multiple and single copies of genes. Here we present protocols for modifying the wheat genome using the two systems. The protocols include the design of TALEN and CRISPR/Cas9 target sites and their construction, evaluation of their activities in protoplasts, transformation of plants, and mutation screening.
Inequalities in survival from colorectal cancer (CRC) across socioeconomic groups and by area of ... more Inequalities in survival from colorectal cancer (CRC) across socioeconomic groups and by area of residence have been described in various health care settings. Few population-wide datasets which include clinical and treatment information are available in Australia to investigate disparities. This study examines socio-demographic differences in survival for CRC patients in South Australia (SA), using a population-wide database derived via linkage of administrative and surveillance datasets. The study population comprised all cases of CRC diagnosed in 2003-2008 among SA residents aged 50-79 yrs in the SA Central Cancer Registry. Measures of socioeconomic status (area level), geographical remoteness, clinical characteristics, comorbid conditions, treatments and outcomes were derived through record linkage of central cancer registry, hospital-based clinical registries, hospital separations, and radiotherapy services data sources. Socio-demographic disparities in CRC survival were examin...
Key message Our results indicate that OsPGK2a-P gene is differentially regulated in contrasting r... more Key message Our results indicate that OsPGK2a-P gene is differentially regulated in contrasting rice cultivars under stress and its overexpression confers salt stress tolerance in transgenic tobacco. Abstract Phosphoglycerate kinase (PGK; EC = 2.7.2.3) plays a major role for ATP production during glycolysis and 1, 3-bisphosphoglycerate production to participate in the Calvin cycle for carbon fixation in plants. Whole genome analysis of rice reveals the presence of four PGK genes (OsPgks) on different chromosomes. Comparative expression analysis of OsPgks in rice revealed highest level of transcripts for OsPgk2 at most of its developmental stages. Detailed characterization of OsPgk2 transcript and protein showed that it is strongly induced by salinity stress in two contrasting genotypes of rice, i.e., cv IR64 (salt sensitive) and landrace Pokkali (salt tolerant). Ectopic expression of OsPgk2a-P (isolated from Pokkali) in transgenic tobacco improved its salinity stress tolerance by higher chlorophyll retention and enhanced proline accumulation, besides maintaining better ion homeostasis. Ectopically expressing OsPgk2a-P transgenic tobacco plants showed tall phenotype with more number of pods than wild-type plants. Therefore, OsPgk2a-P appears to be a potential candidate for increasing salinity stress tolerance and enhanced yield in crop plants.
Salt and drought stresses negatively affect rice yield. The magnitude of yield reduction depends ... more Salt and drought stresses negatively affect rice yield. The magnitude of yield reduction depends on the genotype and developmental stage of the plant, and the severity of the stress. While natural variations for stress tolerance exist in the primary and secondary gene pool of rice, conventional breeding to develop salt and drought tolerant varieties has been slow and less successful due to the complexity and low heritability of stress tolerance traits. Extremophiles, such as halophytes, adapt to abiotic stresses by physiological and biochemical adjustments through coordinate regulation and expression of a cascade of genes. Halophytes are of interest to translate their stress adaptation machinery into crop plants. Based on the concept that monocot halophytes are ideal for translational studies for cereals, we profiled the root and leaf transcriptome of Spartina alterniflora (smooth cordgrass), a Louisiana native monocot halophyte, which can withstand salinity up to double the strengt...
Cyclophilins are a set of ubiquitous proteins present in all subcellular compartments, involved i... more Cyclophilins are a set of ubiquitous proteins present in all subcellular compartments, involved in a wide variety of cellular processes. Comparative bioinformatics analysis of the rice and Arabidopsis genomes led us to identify novel putative cyclophilin gene family members in both the genomes not reported previously. We grouped cyclophilin members with similar molecular weight and subtypes together in the phylogenetic tree which indicated their co-evolution in rice and Arabidopsis. We also characterized a rice cyclophilin gene, OsCyp2-P (Os02g0121300), isolated from a salinity-tolerant landrace, Pokkali. Publicly available massively parallel signature sequencing (MPSS) and microarray data, besides our quantitative real time PCR (qRT-PCR) data suggest that transcript abundance of OsCyp2-P is regulated under different stress conditions in a developmental and organ specific manner. Ectopic expression of OsCyp2-P imparted multiple abiotic stress tolerance to transgenic tobacco plants a...
Thank you for your interest in our study (1) and the constructive comments. The purpose of our st... more Thank you for your interest in our study (1) and the constructive comments. The purpose of our study was to assess the agreement/concordance in the interpretation of CT pulmonary angiogram studies by our oncall residents and staff radiologists to identify and discuss variations in their respective interpretations. A descriptive comparison was therefore used in addition to k values similar to the other papers quoted in our study (2-5). We do recognize that a complete statistical analysis was not performed and appreciate the suggestion.
Meeting the food demands and ensuring nutritional security of the ever increasing global populati... more Meeting the food demands and ensuring nutritional security of the ever increasing global population in the face of degrading natural resource base and impending climate change is the biggest challenge of the twenty first century. The consequences of mineral/micronutrient deficiencies or the hidden hunger in the developing world are indeed alarming and need urgent attention. In addressing the problems associated with mineral/micronutrient deficiency, grain legumes as an integral component of the farming systems in the developing world have to play a crucial role. For resource-poor populations, a strategy based on selecting and/or developing grain legume cultivars with grains denser in micronutrients, by biofortification, seems the most appropriate and attractive approach to address the problem. This is evident from the on-going global research efforts on biofortification to provide nutrient-dense grains for use by the poorest of the poor in the developing countries. Towards this end,...
Hox proteins are well known for executing highly specific functions in vivo, but our understandin... more Hox proteins are well known for executing highly specific functions in vivo, but our understanding of the molecular mechanisms underlying gene regulation by these fascinating proteins has lagged behind. The premise of this review is that an understanding of gene regulation-by any transcription factor-requires the dissection of the cis-regulatory elements that they act upon. With this goal in mind, we review the concepts and ideas regarding gene regulation by Hox proteins and apply them to a curated list of directly regulated Hox cis-regulatory elements that have been validated in the literature. Our analysis of the Hox-binding sites within these elements suggests several emerging generalizations. We distinguish between Hox cofactors, proteins that bind DNA cooperatively with Hox proteins and thereby help with DNA-binding site selection, and Hox collaborators, proteins that bind in parallel to Hox-targeted cis-regulatory elements and dictate the sign and strength of gene regulation. Finally, we summarize insights that come from examining five X-ray crystal structures of Hox-cofactor-DNA complexes. Together, these analyses reveal an enormous amount of flexibility into how Hox proteins function to regulate gene expression, perhaps providing an explanation for why these factors have been central players in the evolution of morphological diversity in the animal kingdom.
Physiology and molecular biology of plants : an international journal of functional plant biology, 2010
The stress of low oxygen concentrations in a waterlogged environment is minimized in some plants ... more The stress of low oxygen concentrations in a waterlogged environment is minimized in some plants that produce aerenchyma, a tissue characterized by prominent intercellular spaces. It is produced by the predictable collapse of root cortex cells, indicating a programmed cell death (PCD) and facilitates gas diffusion between root and the aerial environment. The objective of this study was to characterize the cellular changes take place during aerenchyma formation in root of rice that accompany PCD. Scanning electron microscopy and transmission electron microscopy were used for cellular analysis of roots. Aerenchyma development was observed in both aerobic and flooded conditions. Structural changes in membranes and organelles were examined during development of root cortex cells to compare with previous examples of PCD. There was an initial collapse which started at a specific position in the mid cortex, indicating loss of turgor, and the cytoplasm became more electron dense. These cell...
Physiology and molecular biology of plants : an international journal of functional plant biology, 2012
In waterlogged soil, deficiency of oxygen triggers development of aerenchyma in roots which facil... more In waterlogged soil, deficiency of oxygen triggers development of aerenchyma in roots which facilitates gas diffusion between roots and the aerial environment. However, in contrast to other monocots, roots of rice (Oryza sativa L.) constitutively form aerenchyma even in aerobic conditions. The formation of cortical aerenchyma in roots is thought to occur by either lysigeny or schizogeny. Schizogenous aerenchyma is developed without cortical cell death. However, lysigenous gas-spaces are formed as a consequence of senescence of specific cells in primary cortex followed by their death due to autolysis. In the last stage of aerenchyma formation, a 'spoked wheel' arrangement is observed in the cortical region of root. Ultrastructural studies show that cell death is constitutive and no characteristic cell structural differentiation takes place in the dying cells with respect to surrounding cells. Cell collapse initiation occurs in the center of the cortical tissues which are char...
Development of highly efficient and reproducible plant regeneration system has tremendous potenti... more Development of highly efficient and reproducible plant regeneration system has tremendous potential to provide improved technology to assist in genetic transformation of indica rice cultivars for their further exploitation in selection. For the development of a highly reproducible regeneration system through somatic embryogenesis, mature embryos of highly popular rice cultivars i.e., Govind (for rainfed areas), Pusa Basmati-1 (aromatic basmati) and Jaya (for irrigated areas) were used. Optimum callus formation (%) to MS medium supplemented with 2, 4-D was obtained at 12.0 microM in Govind, 14.0 microM in Jaya and 15.0 microM in Pusa Basmati-1. All the cultivars showed good proliferation on MS medium without hormone. In Govind, highest embryogenic response was observed in MS medium supplemented with 2, 4-D (0.4 microM) + kinetin (0.4 microM), while in Pusa Basmati-1 with 2, 4-D (0.4 microM) + kinetin (2.0 microM) and in Jaya on hormone-free MS medium. Excellent embryo regeneration in...
Salinity is one of the most important environmental constraints limiting agricultural productivit... more Salinity is one of the most important environmental constraints limiting agricultural productivity. Considering the importance of the accumulation of osmolytes, myo-inositol in particular, in halophytic plant's adaptive response to salinity, an effort was made to overexpress the SaINO1 gene from the grass halophyte Spartina alterniflora encoding myo-inositol 1-phosphate synthase (MIPS) in Arabidopsis thaliana. We demonstrated that SaINO1 is a stress-responsive gene and its constitutive over expression in Arabidopsis provides significantly improved tolerance to salt stress during germination and seedling growth and development. The transgenics retained more chlorophyll and carotenoid by protecting the photosystem II. The low level of stress-induced cellular damage in the transgenics was clearly evident by lower accumulation of proline in comparison to WT. Our results indicated that possible overaccumulation of MIPS enzyme in the cytosol protected the transgenic Arabidopsis plants overexpressing SaINO1 from the toxic effect of Na þ under salt stress by reducing cellular damage and chlorophyll loss.
The objective of this study was to investigate the processability of hot-melt extrusion (HME) to ... more The objective of this study was to investigate the processability of hot-melt extrusion (HME) to formulate ocular inserts of valacyclovir hydrochloride and evaluate the in vivo bioavailability of the formulation. To optimize the formulation of this drug, different physical mixtures of the polymers and plasticizer were prepared. The physical mixture was extruded through a co-rotating twin-screw extruder and the obtained ocular inserts were cut with dimensions of 4 mm × 2 mm × 1 mm to enhance the formulation instillation in the eye. Ocular inserts were evaluated for drug content, weight variation, uniformity of thickness, in vitro drug release, and in vivo drug bioavailability. The ocular inserts were thermally characterized using differential scanning calorimetry (DSC). The attributes observed for the ocular inserts were within the target specifications. The ocular inserts of valacyclovir hydrochloride were successfully prepared using the HME. They provided sustained drug release along with enhanced drug permeation when compared to the eyedrop solution and dissolve completely in 8 h. Additionally, the obtained results demonstrated that the formulation of ocular inserts of valacyclovir hydrochloride using HME was reproducible, robust and effective method.
The aim of the study was to determine the effect of rhododendron flower juice on the bioavailabil... more The aim of the study was to determine the effect of rhododendron flower juice on the bioavailability of Amlodipine in rats. This study was carried out in rats as a parallel design study. After the analysis of blood samples, it has been concluded that a component (s) of rhododendron flower juice inhibits the CYP3A4 mediated metabolism of Amlodipine. AUC was determined with the help of Trapezoidal rule. C max and T max were determined from the area under the plasma concentration-time curve. Statistical analysis was performed on the data obtained from both the group of rats. One way Analysis of Variance (ANOVA) from which Tukey-Kramer Multiple Comparisons Test was applied to the data obtained. This test compared all the parameters such as AUC, C max and T max without flower juice and after giving flower juice and the standard deviation of AUC of amlodipine with and without juice was found to be 14.25 and 10.44 respectively. AUC of the amlodipine after giving rhododendron flower juice...
Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the... more Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the steroid hormone ecdysone, in response to neural signals, at precise stages during development. In this study we have analyzed, using genetic and molecular methods, the roles played by two major signaling pathways in the regulation of larval molting in Drosophila. Previous studies have shown that mutants for the inositol 1,4,5-trisphosphate receptor gene (itpr) are larval lethals. In addition they exhibit delays in molting that can be rescued by exogenous feeding of 20-hydroxyecdysone. Here we show that mutants for adenylate cyclase (rut) synergize, during larval molting, with itpr mutant alleles, indicating that both cAMP and InsP3 signaling pathways function in this process. The two pathways act in parallel to affect molting, as judged by phenotypes obtained through expression of dominant negative and dominant active forms of protein kinase A (PKA) in tissues that normally express the ...
The use of sequence-specific transcription activator-like effector nucleases (TALENs) and the clu... more The use of sequence-specific transcription activator-like effector nucleases (TALENs) and the clustered regularly interspaced short palindromic repeats-associated system (CRISPR/Cas9) have provided powerful reverse genetic approaches to the targeted modification of genomes in numerous organisms. Both systems have been employed to generate loss-of-function alleles in bread wheat, by targeting multiple and single copies of genes. Here we present protocols for modifying the wheat genome using the two systems. The protocols include the design of TALEN and CRISPR/Cas9 target sites and their construction, evaluation of their activities in protoplasts, transformation of plants, and mutation screening.
Inequalities in survival from colorectal cancer (CRC) across socioeconomic groups and by area of ... more Inequalities in survival from colorectal cancer (CRC) across socioeconomic groups and by area of residence have been described in various health care settings. Few population-wide datasets which include clinical and treatment information are available in Australia to investigate disparities. This study examines socio-demographic differences in survival for CRC patients in South Australia (SA), using a population-wide database derived via linkage of administrative and surveillance datasets. The study population comprised all cases of CRC diagnosed in 2003-2008 among SA residents aged 50-79 yrs in the SA Central Cancer Registry. Measures of socioeconomic status (area level), geographical remoteness, clinical characteristics, comorbid conditions, treatments and outcomes were derived through record linkage of central cancer registry, hospital-based clinical registries, hospital separations, and radiotherapy services data sources. Socio-demographic disparities in CRC survival were examin...
Key message Our results indicate that OsPGK2a-P gene is differentially regulated in contrasting r... more Key message Our results indicate that OsPGK2a-P gene is differentially regulated in contrasting rice cultivars under stress and its overexpression confers salt stress tolerance in transgenic tobacco. Abstract Phosphoglycerate kinase (PGK; EC = 2.7.2.3) plays a major role for ATP production during glycolysis and 1, 3-bisphosphoglycerate production to participate in the Calvin cycle for carbon fixation in plants. Whole genome analysis of rice reveals the presence of four PGK genes (OsPgks) on different chromosomes. Comparative expression analysis of OsPgks in rice revealed highest level of transcripts for OsPgk2 at most of its developmental stages. Detailed characterization of OsPgk2 transcript and protein showed that it is strongly induced by salinity stress in two contrasting genotypes of rice, i.e., cv IR64 (salt sensitive) and landrace Pokkali (salt tolerant). Ectopic expression of OsPgk2a-P (isolated from Pokkali) in transgenic tobacco improved its salinity stress tolerance by higher chlorophyll retention and enhanced proline accumulation, besides maintaining better ion homeostasis. Ectopically expressing OsPgk2a-P transgenic tobacco plants showed tall phenotype with more number of pods than wild-type plants. Therefore, OsPgk2a-P appears to be a potential candidate for increasing salinity stress tolerance and enhanced yield in crop plants.
Salt and drought stresses negatively affect rice yield. The magnitude of yield reduction depends ... more Salt and drought stresses negatively affect rice yield. The magnitude of yield reduction depends on the genotype and developmental stage of the plant, and the severity of the stress. While natural variations for stress tolerance exist in the primary and secondary gene pool of rice, conventional breeding to develop salt and drought tolerant varieties has been slow and less successful due to the complexity and low heritability of stress tolerance traits. Extremophiles, such as halophytes, adapt to abiotic stresses by physiological and biochemical adjustments through coordinate regulation and expression of a cascade of genes. Halophytes are of interest to translate their stress adaptation machinery into crop plants. Based on the concept that monocot halophytes are ideal for translational studies for cereals, we profiled the root and leaf transcriptome of Spartina alterniflora (smooth cordgrass), a Louisiana native monocot halophyte, which can withstand salinity up to double the strengt...
Cyclophilins are a set of ubiquitous proteins present in all subcellular compartments, involved i... more Cyclophilins are a set of ubiquitous proteins present in all subcellular compartments, involved in a wide variety of cellular processes. Comparative bioinformatics analysis of the rice and Arabidopsis genomes led us to identify novel putative cyclophilin gene family members in both the genomes not reported previously. We grouped cyclophilin members with similar molecular weight and subtypes together in the phylogenetic tree which indicated their co-evolution in rice and Arabidopsis. We also characterized a rice cyclophilin gene, OsCyp2-P (Os02g0121300), isolated from a salinity-tolerant landrace, Pokkali. Publicly available massively parallel signature sequencing (MPSS) and microarray data, besides our quantitative real time PCR (qRT-PCR) data suggest that transcript abundance of OsCyp2-P is regulated under different stress conditions in a developmental and organ specific manner. Ectopic expression of OsCyp2-P imparted multiple abiotic stress tolerance to transgenic tobacco plants a...
Thank you for your interest in our study (1) and the constructive comments. The purpose of our st... more Thank you for your interest in our study (1) and the constructive comments. The purpose of our study was to assess the agreement/concordance in the interpretation of CT pulmonary angiogram studies by our oncall residents and staff radiologists to identify and discuss variations in their respective interpretations. A descriptive comparison was therefore used in addition to k values similar to the other papers quoted in our study (2-5). We do recognize that a complete statistical analysis was not performed and appreciate the suggestion.
Meeting the food demands and ensuring nutritional security of the ever increasing global populati... more Meeting the food demands and ensuring nutritional security of the ever increasing global population in the face of degrading natural resource base and impending climate change is the biggest challenge of the twenty first century. The consequences of mineral/micronutrient deficiencies or the hidden hunger in the developing world are indeed alarming and need urgent attention. In addressing the problems associated with mineral/micronutrient deficiency, grain legumes as an integral component of the farming systems in the developing world have to play a crucial role. For resource-poor populations, a strategy based on selecting and/or developing grain legume cultivars with grains denser in micronutrients, by biofortification, seems the most appropriate and attractive approach to address the problem. This is evident from the on-going global research efforts on biofortification to provide nutrient-dense grains for use by the poorest of the poor in the developing countries. Towards this end,...
Hox proteins are well known for executing highly specific functions in vivo, but our understandin... more Hox proteins are well known for executing highly specific functions in vivo, but our understanding of the molecular mechanisms underlying gene regulation by these fascinating proteins has lagged behind. The premise of this review is that an understanding of gene regulation-by any transcription factor-requires the dissection of the cis-regulatory elements that they act upon. With this goal in mind, we review the concepts and ideas regarding gene regulation by Hox proteins and apply them to a curated list of directly regulated Hox cis-regulatory elements that have been validated in the literature. Our analysis of the Hox-binding sites within these elements suggests several emerging generalizations. We distinguish between Hox cofactors, proteins that bind DNA cooperatively with Hox proteins and thereby help with DNA-binding site selection, and Hox collaborators, proteins that bind in parallel to Hox-targeted cis-regulatory elements and dictate the sign and strength of gene regulation. Finally, we summarize insights that come from examining five X-ray crystal structures of Hox-cofactor-DNA complexes. Together, these analyses reveal an enormous amount of flexibility into how Hox proteins function to regulate gene expression, perhaps providing an explanation for why these factors have been central players in the evolution of morphological diversity in the animal kingdom.
Physiology and molecular biology of plants : an international journal of functional plant biology, 2010
The stress of low oxygen concentrations in a waterlogged environment is minimized in some plants ... more The stress of low oxygen concentrations in a waterlogged environment is minimized in some plants that produce aerenchyma, a tissue characterized by prominent intercellular spaces. It is produced by the predictable collapse of root cortex cells, indicating a programmed cell death (PCD) and facilitates gas diffusion between root and the aerial environment. The objective of this study was to characterize the cellular changes take place during aerenchyma formation in root of rice that accompany PCD. Scanning electron microscopy and transmission electron microscopy were used for cellular analysis of roots. Aerenchyma development was observed in both aerobic and flooded conditions. Structural changes in membranes and organelles were examined during development of root cortex cells to compare with previous examples of PCD. There was an initial collapse which started at a specific position in the mid cortex, indicating loss of turgor, and the cytoplasm became more electron dense. These cell...
Physiology and molecular biology of plants : an international journal of functional plant biology, 2012
In waterlogged soil, deficiency of oxygen triggers development of aerenchyma in roots which facil... more In waterlogged soil, deficiency of oxygen triggers development of aerenchyma in roots which facilitates gas diffusion between roots and the aerial environment. However, in contrast to other monocots, roots of rice (Oryza sativa L.) constitutively form aerenchyma even in aerobic conditions. The formation of cortical aerenchyma in roots is thought to occur by either lysigeny or schizogeny. Schizogenous aerenchyma is developed without cortical cell death. However, lysigenous gas-spaces are formed as a consequence of senescence of specific cells in primary cortex followed by their death due to autolysis. In the last stage of aerenchyma formation, a 'spoked wheel' arrangement is observed in the cortical region of root. Ultrastructural studies show that cell death is constitutive and no characteristic cell structural differentiation takes place in the dying cells with respect to surrounding cells. Cell collapse initiation occurs in the center of the cortical tissues which are char...
Development of highly efficient and reproducible plant regeneration system has tremendous potenti... more Development of highly efficient and reproducible plant regeneration system has tremendous potential to provide improved technology to assist in genetic transformation of indica rice cultivars for their further exploitation in selection. For the development of a highly reproducible regeneration system through somatic embryogenesis, mature embryos of highly popular rice cultivars i.e., Govind (for rainfed areas), Pusa Basmati-1 (aromatic basmati) and Jaya (for irrigated areas) were used. Optimum callus formation (%) to MS medium supplemented with 2, 4-D was obtained at 12.0 microM in Govind, 14.0 microM in Jaya and 15.0 microM in Pusa Basmati-1. All the cultivars showed good proliferation on MS medium without hormone. In Govind, highest embryogenic response was observed in MS medium supplemented with 2, 4-D (0.4 microM) + kinetin (0.4 microM), while in Pusa Basmati-1 with 2, 4-D (0.4 microM) + kinetin (2.0 microM) and in Jaya on hormone-free MS medium. Excellent embryo regeneration in...
Salinity is one of the most important environmental constraints limiting agricultural productivit... more Salinity is one of the most important environmental constraints limiting agricultural productivity. Considering the importance of the accumulation of osmolytes, myo-inositol in particular, in halophytic plant's adaptive response to salinity, an effort was made to overexpress the SaINO1 gene from the grass halophyte Spartina alterniflora encoding myo-inositol 1-phosphate synthase (MIPS) in Arabidopsis thaliana. We demonstrated that SaINO1 is a stress-responsive gene and its constitutive over expression in Arabidopsis provides significantly improved tolerance to salt stress during germination and seedling growth and development. The transgenics retained more chlorophyll and carotenoid by protecting the photosystem II. The low level of stress-induced cellular damage in the transgenics was clearly evident by lower accumulation of proline in comparison to WT. Our results indicated that possible overaccumulation of MIPS enzyme in the cytosol protected the transgenic Arabidopsis plants overexpressing SaINO1 from the toxic effect of Na þ under salt stress by reducing cellular damage and chlorophyll loss.
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Papers by Rohit Joshi