Gauri Dutta Sharma

Excess copper induced oxidative stress and response of antioxidants in rice.

To investigate the effects of copper (Cu), rice plant (Oryza sativa. L. var. MSE-9) was treated with different Cu concentrations (0, 10, 50 and 100 μM) for 5 days in hydroponic condition. Gradual decrease in shoot and root growth was observed with the increase of Cu concentration and duration of treatment where maximum inhibition was recorded in root growth. Cu was readily absorbed by the plant though the maximum accumulation was found in root than shoot. Hydrogen peroxide (H(2)O(2)) production and lipid peroxidation were found increased with the elevated Cu concentration indicating excess Cu induced oxidative stress. Antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) and glutathione reductase (GR) were effectively generated at the elevated concentrations of Cu though catalase (CAT) did not show significant variation with respect to control. Ascorbate (ASH), glutathione (GSH) and proline contents were also increased in all the Cu treated plants compared with the control. SOD isoenzyme was greatly affected by higher concentration of Cu and it was consistent with the changes of the activity assayed in solution. The present study confirmed that excess Cu inhibits growth, induced oxidative stress by inducing ROS formation while the stimulated antioxidative system appears adaptive response of rice plant against Cu induced oxidative stress. Moreover proline accumulation in Cu stress plant seems to provide additional defense against the oxidative stress.

Hepatoprotective and immunomodulatory properties of aqueous extract of Curcuma longa in carbon tetra chloride intoxicated Swiss albino mice.

OBJECTIVE To evaluate the hepatoprotective and immunotherapeutic effects of aqueous extract of turmeric rhizome in CCl4 intoxicated Swiss albino mice. METHODS First group of mice (n=5) received CCl4 treatment at a dose of 0.5 mL/kg bw (i.p.) for 7 days. Second group was fed orally the aqueous extract of turmeric at a dose of 50 mg/kg bw for 15 days. The third group was given both the turmeric extract (for 15 days, orally) and CCl4 (for last 7 days, i.p.). The fourth group was kept as a control. To study the liver function, the transaminase enzymes (SGOT and SGPT) and bilirubin level were measured in the serum of respective groups. For assaying the immunotherapeutic action of Curcuma longa (C. longa), non specific host response parameters like morphological alteration, phagocytosis, nitric oxide release, myeloperoxidase release and intracellular killing capacity of peritoneal macrophages were studied from the respective groups. RESULTS The result of present study suggested that CCl4 administration increased the level of SGOT and SGPT and bilirubin level in serum. However, the aqueous extract of turmeric reduced the level of SGOT, SGPT and bilirubin in CCl4 intoxicated mice. Apart from damaging the liver system, CCl4 also reduced non specific host response parameters like morphological alteration, phagocytosis, nitric oxide release, myeloperoxidase release and intracellular killing capacity of peritoneal macrophages. Administration of aqueous extract of C. longa offered significant protection from these damaging actions of CCl4 on the non specific host response in the peritoneal macrophages of CCl4 intoxicated mice. CONCLUSIONS In conclusion, the present study suggests that C. longa has immunotherapeutic properties along with its ability to ameliorate hepatotoxicity.

In silico analyses of superoxide dismutases (SODs) of rice (Oryza sativa L.)

Superoxide dismutases (SODs), members of the metalloenzymes family are most effective intracellular enzymatic antioxidant in aerobic organisms. These enzymes provide the first line of defense in plants against the toxic effects of elevated levels of reactive oxygen species (ROS) generated during various environmental stresses. The availability of high-throughput computational tools has provided better opportunities to characterize the protein features and determine their function. In the present study an attempt was made to gain an insight into the structure and evolution of subunits of SODs (Cu-Zn, Mn and Fe SODs) of rice. The 3-Dimensional structures of SODs were modeled based on available X-ray crystal structures and further validated. The primary sequence, secondary and tertiary structure analysis revealed Mn and Fe SOD to be structurally homologous while Cu-Zn SOD is un-related to either of them. Comparative structural study also revealed former two were dominated by α-helices followed by β-strands in contrast; Cu-Zn SOD dominated by β-strands. Molecular phylogeny indicated a common evolutionary origin of Mn and Fe SOD while Cu-Zn SOD may have evolved separately.

Human sperm and other seminal constituents in male infertile patients from arsenic and cadmium rich areas of Southern Assam

In the present study the occurrence of two heavy metals, arsenic and cadmium, have been reported in the drinking water and seminal plasma of infertile male patients as compared to a control group. The study originated from a survey of geogenic groundwater contamination with the heavy metals arsenic and cadmium in Southern Assam, India as an increase in the incidence of male infertility was being reported from these areas. According to WHO protocol, patients with sperm concentration < 20x106/ml were selected as cases (oligozoospermic and azoospermic), and those with > 20x106/ml, without any extreme pathological disorders and having fathered a child within 1-2 years of marriage were the control (normozoospermic) group. The study reports an inverse relationship between total sperm count and heavy metal content in drinking water as well as seminal plasma of the subjects. Moreover, a high correlation between altered semenological parameters and lower expression of accessory sex gland markers like fructose, acid phosphatase, and neutral α-glucosidase in the seminal plasma of patients is reported. The study also highlights significant differences of the sperm function parameters like hypo-osmotic swelling, acrosome reaction, and nuclear chromatin decondensation in the patient group as compared to controls. These findings are significant as they address a likely association between heavy metal stress and altered sperm function as well as seminal enzyme inhibition.

Molecular Phylogeny, Homology Modeling, and Molecular Dynamics Simulation of Race-Specific Bacterial Blight Disease Resistance Protein (xa5) of Rice: A Comparative Agriproteomics Approach

Rice (Oryza sativa L.), a model plant belonging to the family Poaceae, is a staple food for a majority of the people worldwide. Grown in the tropical and subtropical regions of the world, this important cereal crop is under constant and serious threat from both biotic and abiotic stresses. Among the biotic threats, Xanthomonas oryzae pv. oryzae, causing the damaging bacterial blight disease in rice, is a prominent pathogen. The xa5 gene in the host plant rice confers race-specific resistance to this pathogen. This recessive gene belongs to the Xa gene family of rice and encodes a gamma subunit of transcription factor IIA (TFIIAγ). In view of the importance of this gene in conferring resistance to the devastating disease, we reconstructed the phylogenetic relationship of this gene, developed a three-dimensional protein model, followed by long-term molecular dynamics simulation studies to gain a better understanding of the evolution, structure, and function of xa5. The modeled structure was found to fit well with the small subunit of TFIIA from human, suggesting that it may also act as a small subunit of TFIIA in rice. The model had a stable conformation in response to the atomic flexibility and interaction, when subjected to MD simulation at 20 nano second in aqueous solution. Further structural analysis of xa5 indicated that the protein retained its basic transcription factor function, suggesting that it might govern a novel pathway responsible for bacterial blight resistance. Future molecular docking studies of xa5 underway with its corresponding avirulence gene is expected to shed more direct light into plant-pathogen interactions at the molecular level and thus pave the way for richer agriproteomic insights.

Morphological and molecular diversity of endophytic Colletotrichum gloeosporioides from tea plant, Camellia sinensis (L.) O. Kuntze of Assam, India

Thirty isolates of endophytic fungi were isolated from healthy asymptomatic leaves of tea plant (Camellia sinensis) and identified morphologically based on colony morphology, spore shape and size, growth and sporulation rate. Internal transcribed spacer r-DNA sequence analysis supported for molecular identification of all the isolates. Based on morphological and molecular characteristics the isolates were identified as Colletotrichum gloeosporioides. Variations on colony morphology which included the production of conidial masses, led to divide the isolates into different groups. Variations on spore size, growth rate and sporulation rate were exhibited by all the isolates. With RAPD molecular markers, genetic variations among the thirty isolates were observed. Genetic variations and relatedness among the thirty isolates were analyzed with UPGMA phylogram using NTSYS program. Two major groups were obtained among the thirty isolates. Group I comprised of 16 isolates which included three sub groups (Ia, Ib and Ic) and Group II constituted fourteen isolates and it also had three sub groups (IIa, IIb and IIc). A partial co-relationship among the isolates was established on the basis of morphological and molecular based clustering.