Toxic Effects, Oxidative Stress and Ultrastructural Changes in Moss Taxithelium Nepalense (Schwaegr.) Broth. Under Chromium and Lead Phytotoxicity

The effect of short-term Pb and Cr (0, 100 and 1000μM) stress in moss Taxithelium nepalense (Schwaegr.) Broth., the possible generation of oxidative stress, antioxidant metabolism and changes in the chloroplast and cell membrane ultrastructure were investigated. In moss cells, treatment of Pb and Cr for 12 and 24 h decreased the dry mass and total chlorophyll content with marked inhibition under Pb. Both Pb and Cr accumulated after 24 h of their treatment where highest accumulation of Pb was visible than that of Cr. The ultrastructural studies at 1000 μM of Pb and Cr showed distortion of the thylakoid, distortion of chloroplast membrane and changes in the chloroplast structure. Chloroplast distortion was highly visible under Pb than that of Cr. The distortion in the cell membrane was evident at high concentration of Pb, while under Cr, minor changes were visible as compared to controls. Both Pb and Cr significantly increased the production of ROS like H₂O₂ and O₂ ^? radical with marked production after 24 h under Pb than that of Cr. The alteration in metabolism of activated oxygen in moss cells was evidenced by the increase in the lipid peroxidation in moss cells, with pronounced effect after 24 h than that of 12 h after Pb and Cr treatment. The SOD activity showed an increasing trend followed by decrease in CAT, POX and GR activity after 12 and 24 h. Both ascorbate and glutathione showed higher accumulation under Pb followed by Cr. The results showed that at high concentration of metals, oxidative stress could be induced in moss cells characterized by the generation of ROS and initiation lipid peroxidation that inhibited the major antioxidant metabolism. Both physiological and ultrastructural studies suggested the possible induction of oxidative stress in Taxithelium nepalense (Schwaegr.) Broth. under Pb and Cr toxicity.     

Development of a radioimmunoassay procedure for aflatoxin B1 measurement

A radioimmunoassaay (RIA) procedure to measure aflatoxin B(1) (AfB(1)) in agricultural commodities was developed. AfB(1) oxime derivative was synthesized, characterized, and used for preparation of (125)I-labeled AfB(1). Antiaflatoxin B(1) serum was raised in-house using AfB(1)-bovine serum albumin conjugate as immunogen. The assay system was optimized in the range of 0.2-5 ng/mL, using a liquid phase (PEG) as well as a solid phase (coated polystyrene beads) separation system. Inter-assay and intra-assay variations, recovery, and parallelism studies validated the assay. AfB(1) analysis was carried out in nearly 130 samples of different agricultural commodities. The correlation coefficient was determined using commercial ELISA and in-house-developed RIA methods.     

Assessment of Suitable Extractants for Predicting Plant-available Potassium in Indian Coastal Soils

The suitability of seven chemical extractants was evaluated on 24 Indian coastal soils for prediction of plant-available potassium (K) to rice (Oryza sativa L. var. NC 492) grown in modified Neubauer technique. Average amounts of soil K extracted were in descending order: 0.5 M NaHCO₃ > neutral 1 N NH₄OAc > 0.02 M CaCl₂ > Bray and Kurtz No.1 > 1 N HNO₃ > 0.1 N HNO₃ > distilled water. The highest simple correlation with plant K uptake was obtained with 0.1 N HNO₃-K (r = 0.848) and lowest with CaCl₂-K (r = 0.805). Predictive models were developed using plant K uptake as the dependent variable and extractable soil K, sand, silt, soil pH, and electrical conductivity as the independent variables. Based on the final R² and ease of measurement, distilled water, 1 N NH₄OAc, and 0.1 N HNO₃ models were the best predictors of plant-available K in coastal soils when used along with sand or soil pH.     

Arsenic Stress in Plants

Being a toxic metalloid and group I carcinogen, Arsenic (As) poses a threat to plants, especially to crops which are consumed by human beings, and sooner or later results in hyper/hypopigmentation and skin cancer. It is a well‐known fact that South‐East Asia is suffering from groundwater As contamination, and according to a recent report, the contamination has been found also in Hungary, Mexico, Argentina, Australia, United States, etc. Thus, As contamination has become a global problem. As is toxic even at low concentration because it has no known function as nutrients. Arsenite (III) and arsenate (V) are the main phytoavailable forms of inorganic arsenic. Being analogous to phosphate, As(V) is transported by a phosphate‐cotransport system in plants, whereas As(III) is transported through ‘OsNIP2.1’ (member of aquaporin superfamily) in rice. Besides, ‘AsSe1’ (As‐accumulation gene), ‘AsTol’ (As‐tolerance gene) and ‘OsACR2.1’ (an arsenate reductase gene) have also been identified. The production of phytochelatins (PCs), a metal‐binding thiol peptide, in response to As stress may hold a way of proper As tolerance in plants but still needs a thorough study. However, with the proper knowledge of arsenic speciation, transportation, accumulation, overexpression in crop plants may result in ways to develop arsenic tolerant transgenics.     

Effect of nutrient density on production performance, egg quality and humoral immune response of brown laying (Dahlem Red) hens in the tropics

A study was conducted to evaluate the effect of various concentrations of metabolizable energy (ME) with graded incremental levels of crude protein (CP) and essential amino acids (lysine and methionine) on production performance, egg quality and humoral immune response of Dahlem Red laying hens. Four experimental diets based on maize–soybean meal-deoiled rice bran were prepared. Diet 1 was fed as a control diet containing 2,600 kcal ME/kg, 15% CP, 0.75% Lys and 0.36% Met, and in the other three diets (D2, D3 and D4), concentrations of the above nutrients were increased by 2.5%, 5.0% and 7.5%, respectively. The levels of Ca (3.5%) and available P (0.32) were constant in all the diets. Each diet was offered ad libitum from 28 to 40 weeks of age to eight replicates containing six birds in each replicate. The egg production, egg weight and egg mass (in grams of egg per hen per day) were not affected by increasing the nutrient density up to 7.5% (2,795 kcal ME/kg diet) compared to the control group (2,600 ME/kg diet). However, feed consumption and feed efficiency (in grams of egg per gram of feed) were influenced by the variation in the nutrient density of diets. As the nutrient density increased by 5% (2,730 ME/kg diet), birds consumed significantly (P < 0.001) less feed. The birds in the 7.5% higher density group produced significantly (P < 0.05) higher egg mass per unit feed consumption compared to the control diet. Increasing nutrient density up to 7.5% had no effect on relative weight of albumen, yolk or shell. The Haugh unit, yolk colour and shell thickness were also not affected due to variation in the nutrient density. The humoral immune response measured at 34 and 40 weeks was progressively improved by increasing the nutrient density up to 5%. Increasing the nutrient density beyond 5% in the diet had no further influence on the humoral immune response. Based on the results of the present study, it can be concluded that Dahlem Red laying hens required 2,795 kcal/kg ME, 16% CP, 0.8% lysine and 0.4% methionine for eliciting optimum performance and immune response during 28 to 40 weeks of age.     

Effect of Nutrient Application on Growth,Metabolic and Enzymatic Activities of Rice Seedlings During Flooding Stress and Subsequent Re‐Aeration

The impact of submergence on the allometry, changes in metabolic activities and antioxidant enzymes during oxidative stress in four Indica rice varieties namely IR‐20, IR‐64 Sub1, Swarna Sub1 and Savitri Sub1 was studied. The differential response of flooding under clear and turbid water with different nutrient application schedules was also examined during and after 12 days of complete submergence. Submergence substantially reduced allometric parameters and the activities of antioxidant enzymes but increased the % change in chlorophyll, soluble sugars and malondialdehyde (MDA) across cultivars with drastic effects on IR‐20. Turbid water resulted in higher leaf senescence, lodging, higher depletion of chlorophyll and soluble sugars because of poor light transmission. Pre‐submergence N application resulted in higher lodging, leaf senescence and higher MDA level but depletion of chlorophyll and NSC leading to higher % change over prior to submergence. Basal P application reduced the senescence and lodging, whereas increased the antioxidant enzyme activities. Foliar spray of post‐submergence N with basal P improved the retention and regain of chlorophyll, soluble sugar and increased the dry matter, leaf area and root shoot ratio. Crop establishment could therefore be enhanced in areas where untimely flooding is anticipated by applying basal P and foliar spray of urea after desubmergence.     

Hepatoprotective effect of Ginkgoselect Phytosome in rifampicin induced liver injury in rats: evidence of antioxidant activity

The protective effects of Ginkgoselect Phytosome((R)) (GBP) on Rifampicin (RMP) induced hepatotoxicity and the probable mechanism(s) involved in this protection were investigated in rats. Liver damage was induced in Wistar rats by administering rifampicin (500 mg/kg, p.o.) daily for 30 days. Simultaneously, GBP at 25 mg/kg and 50 mg/kg, and the reference drug silymarin (100 mg/kg) were administered orally for 30 days/daily to RMP treated rats. Levels of marker enzymes (SGOT, SGPT and SALP), albaumin (Alb) and total proteins (TP) were assessed in serum. The effects of GBP on lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) were assayed in liver homogenates to evaluate antioxidant activity. GBP (25 and 50 mg/kg) and silymarin elicited a significant hepatoprotective activity by lowering the levels of serum marker enzymes and lipid peroxidation and elevated the levels of GSH, SOD, CAT, GPX, GR, Alb and TP in a dose dependant manner. The present findings suggest that the hepatoprotective effect of GBP in RMP induced oxidative damage may be related to its antioxidant and free radical scavenging activity.     

Hydraulics and salinity profile of pitcher irrigation in saline water condition

The hydraulics of pitcher irrigation in saline water condition was studied in laboratory conditions in terms of flow behaviour of pitcher, soil moisture distribution, wetting front advance and distribution of salt concentration in the soil using different pitcher making materials. The Pitcher Type 1 (PT1) made up of local soil and sand yielded the lowest mean hourly depletion ranging from 0.42 to 0.62% depending on salinity of the water used. It was followed by PT2 made up of local soil, sand and resinous material with a mean hourly depletion of 0.51-0.69% and PT3 with local soil, saw dust and sand with a mean hourly depletion of 0.91-1.02%. In all cases, with the increase in salinity level of the water used (ranging from 5 to 20 dS/m), the depletion rate and moisture content in the soil profile were found to decrease.Similarly, it was found that PT1 yielded the lowest wetting front advance and salt movement followed by PT2 and PT3. It was observed that the wetting front advance in the soil decreased with increasing salinity level of the water. The salt concentration in the soil was minimum near the pitcher and maximum at the soil surface and periphery of the wetted zone. In case of PT1, the maximum salt concentration in the soil profile ranged between 1.09 and 3.88 dS/m using water with a salinity ranging from 5 to 20 dS/m, respectively. Similarly, for PT2 the maximum salt concentration in the soil profile also ranged from 1.09 to 3.88 dS/m and for PT3 from 2.30 to 6.07 dS/m. A paired t-test revealed that the moisture as well as the salt distribution of PT3 differed significantly from PT1 and PT2 at α = 0.05. Even, if the salt concentration remained the same and the moisture content remained within field capacity for PT1 and PT2, PT1 is preferred in comparison to PT2 and PT3 as the pitcher material of PT1 is locally economically available.