Identification and Molecular Mapping of a Gene Conferring Resistance to Pyrenophora tritici-repentis Race 3 in Tetraploid Wheat

ABSTRACT Race 3 of the fungus Pyrenophora tritici-repentis, causal agent of tan spot, induces differential symptoms in tetraploid and hexaploid wheat, causing necrosis and chlorosis, respectively. This study was conducted to examine the genetic control of resistance to necrosis induced by P. tritici-repentis race 3 and to map resistance genes identified in tetraploid wheat (Triticum turgidum). A mapping population of recombinant inbred lines (RILs) was developed from a cross between the resistant genotype T. tur-gidum no. 283 (PI 352519) and the susceptible durum cv. Coulter. Based on the reactions of the Langdon-T. dicoccoides (LDN[DIC]) disomic substitution lines, chromosomal location of the resistance genes was determined and further molecular mapping of the resistance genes for race 3 was conducted in 80 RILs of the cross T. turgidum no. 283/Coulter. Plants were inoculated at the two-leaf stage and disease reaction was assessed 8 days after inoculation based on lesion type. Disease reaction of the LDN(DIC) lines and molecular mapping on the T. turgidum no. 283/Coulter population indicated that the gene, designated tsn2, conditioning resistance to race 3 is located on the long arm of chromosome 3B. Genetic analysis of the F(2) generation and of the F(4:5) and F(6:7) families indicated that a single recessive gene controlled resistance to necrosis induced by race 3 in the cross studied.

Ketamine for treatment of catheter related bladder discomfort: a prospective, randomized, placebo controlled and double blind study

BACKGROUND

Intraoperative urinary catheterization might cause postoperative catheter related bladder discomfort (CRBD). We evaluated the efficacy of ketamine as a treatment modality for CRBD.

METHODS

Fifty-four, ASA physical status I and II, male and female adult patients, having CRBD after elective percutaneous nephrolithotomy were randomized into two equal groups of 27 each. In the postoperative period, patients who complained of CRBD received medication depending upon group allocation. Group 1 (Control) received placebo, Group II (Ketamine) received i.v. ketamine 250 microg kg(-1). After induction of anaesthesia patients were catheterized with a 16 Fr Foley's catheter and the balloon was inflated with 10 ml distilled water. Grading of CRBD was done as none, mild, moderate and severe by a blinded observer at 0, 1, 2 and 6 h after operation.

RESULTS

Ketamine reduced the incidence of CRBD (P<0.001) at 2 and 6 h along with reduction in severity (P<0.05) at 1 h compared with control. Higher incidence of mild sedation was observed in the ketamine group (P<0.05) which was not associated with any untoward effects. Operative time and intraoperative fentanyl requirement were similar in both the groups.

CONCLUSION

I.V. ketamine (250 microg kg(-1)) is an effective treatment for reducing the incidence and severity of postoperative CRBD.

Prophylactic gabapentin for prevention of postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy: a randomized, double-blind, placebo-controlled study

BACKGROUND

Gabapentin is an antiepileptic drug. Its antiemetic effect is demonstrated in chemotherapy-induced acute and delayed onset of nausea and vomiting in breast cancer patients.

AIM

To evaluate the antiemetic effect of gabapentin on incidence and severity of postoperative nausea and vomiting in laparoscopic cholecystectomy.

SETTINGS AND DESIGN

Double-blind, randomized, placebo-controlled study.

MATERIALS AND METHODS

Two hundred and fifty patients of ASA physical status I and II, scheduled for laparoscopic cholecystectomy were randomly assigned into two equal groups to receive 600 mg gabapentin or matching placebo two hours before surgery. Standard anaesthesia technique was used. Fentanyl was used as rescue postoperative analgesic. Ondansetron 4 mg was used intravenously as rescue medication for emesis. The total number of patients who had nausea or vomiting, and its severity and total fentanyl consumption in the first 24 hours were recorded.

STATISTICAL ANALYSIS

"Z test" was used to test the significance of severity of post-operative nausea and vomiting between groups. Fentanyl consumed in each group (Mean+/-SD) within 24 hrs was compared using student t test. P value < 0.05 was considered significant.

RESULTS

There were no demographic difference between the two groups. Incidence of post-operative nausea and vomiting within 24 hrs after laparoscopic cholecystectomy was significantly lower in gabapentin group (46/125) than in the placebo group (75/125) (37.8% vs 60%; P =0.04). There was a significantly decreased fentanyl consumption in gabapentin group (221.2+/-92.4 microg) as compared to placebo group (505.9+/-82.0 microg; P =0.01).

CONCLUSION

Gabapentin effectively suppresses nausea and vomiting in laparoscopic cholecystectomy and post-operative rescue analgesic requirement.

Evaluation of capsaicin ointment at the Korean hand acupressure point K-D2 for prevention of postoperative nausea and vomiting

The K-D2 point is the Korean hand acupressure point in Koryo Hand Therapy for prevention of postoperative nausea and vomiting. We evaluated the efficacy of capsaicin ointment at the K-D2 point in 186 patients undergoing laparoscopic cholecystectomy in a randomised, prospective, double-blind and placebo-controlled study. Patients were randomised to have either placebo ointment or capsaicin ointment applied to the K-D2 point of both hands 1 h before surgery under standardised anaesthesia. The ointment was removed 8 h later. Postoperative nausea and vomiting was evaluated 6 and 24 h following surgery. The incidence of postoperative nausea and vomiting was lower in the capsaicin group, with an absolute risk reduction (ARR) of 21%, a relative risk reduction (RRR) of 50% and a number-needed-to-treat (NNT) of 5 at 0-6 h (p = 0.001), and an ARR of 11%, a RRR of 85% and a NNT of 9 at 6-24 h (p = 0.003). The need for rescue anti-emetic treatment was also lower at 0-6 h (3 (3%) vs 11 (12%); p = 0.04) and at 6-24 h (5 (5%) vs 0; p = 0.02).

Short-term effect of complementary feeding frequency on total ad libitum consumption in 6- to 10-month-old breast fed Indian infants

OBJECTIVE

To evaluate the short-term effect of frequency of complementary feeding on total ad libitum consumption in breast fed infants.

METHODS

Twenty infants between 6 to 10 months of age were studied in a tertiary hospital in New Delhi for 48 hours. A traditional gruel made of rice and pulses (mean (SD) caloric density 54.22 (7.08) kcal/100 g) was offered in a randomized manner three (n = 10) or four (n = 10) times per day to the subjects over the first 24 hours with the subjects crossing over in the next 24 hours. They were allowed ad libitum breast feeding with no other food or fluid during the study period. Total caloric intake from breast milk and semisolids was computed for each day.

RESULTS

There was no difference in the total caloric consumption with a semisolid feeding frequency of three or four times per day. The frequency of breast feeding and the breast feeding duration were also comparable (P > 0.05). However, breast milk intake was lower with a semisolid feeding frequency of 4 times/day (mean difference -61.2 g/d [95% confidence interval (CI) -122.2-0.32]; P = 0.051). The time required for feeding was higher (mean difference 14.75 min; P < 0.001), whereas the per meal intake of semisolids was lower with four semisolid feeds per day (mean difference -5.5 kcal/meal; [95% CI -10.19 to -0.81]; P = 0.024).

CONCLUSION

In the short term, a change in semisolid feeding frequency from three to four times per day does not result in enhanced energy consumption because of lower breast milk intake.

Morphological, physiochemical and molecular characterization of Anabaena strains

A set of 30 Anabaena strains, isolated from diverse geographical regions of India, were characterized using morphological and physiochemical attributes as well as molecular marker profiles. Significant differences were observed among the Anabaena strains with regard to the shape and size of trichomes and individual cells within a filament, besides qualitative and quantitative aspects of phycobiliprotein accumulation and activities of enzymes involved in nitrogen metabolism. Analyses of molecular polymorphisms in a selected set of 13 Anabaena strains, using primers based on repetitive sequences in the genome, led to unambiguous differentiation of the strains as well as understanding of their genetic relationships. Informative morphological, physio-chemical and molecular characters have been identified that could aid in differentiation and utilization of Anabaena strains as bioinoculants or as sources of pigments.

Clinical evaluation of the ‘T-Dagger™’: a new bedside percutaneous dilational tracheostomy device

A number of percutaneous dilational tracheostomy devices are now available for clinical use. Recently, a new percutaneous dilational tracheostomy device, the "T-Dagger" (Criticure Invasives, India), has been introduced for rapid bedside percutaneous tracheostomy. In a prospective preliminary study, we have performed percutaneous dilational tracheostomy (PDT) using the T-Dagger in 20 adult ventilated patients in order to evaluate the safety and efficacy of the new device. The T-Dagger facilitated bedside PDT in about 3 min with no untoward incidents. There was no significant bleeding, pneumothorax, pneumomediastinum, tracheal wall injuries or difficulty in ventilation in any of the patients. We conclude that the T-Dagger shows early promise in bedside percutaneous dilational tracheostomy. However, controlled studies are required in a larger patient population before it can be recommended for routine use.

Short-term effect of oil supplementation of complementary food on total ad libitum consumption in 6- to 10-month-old breastfed Indian infants

OBJECTIVES

To evaluate the short term effect of oil supplementation of complementary food on total ad libitum consumption in breastfed infants.

METHODS

Twenty infants between 6 to 10 months of age were studied in a tertiary hospital in New Delhi for 48 hours. They were given three semi-solid complementary feeds per day and ad libitum breastfeeding. No other food or fluid was allowed during the study period. A traditional gruel made of rice and pulses with high energy density (oil added; caloric density = 35 kcal/100 g) or low energy density (without oil; caloric density = 20 kcal/100 g) was offered in a randomized manner on consecutive days to all infants. Total caloric intake from breast milk and semi-solids was computed for each day.

RESULTS

Infants consumed an equivalent amount of semi-solid (mean difference, 10.75 g/day; 95% confidence interval, 10.56 to 32.06; P = 0.304) and a lower amount of breast milk (mean difference, 121.1 g/day; 95% confidence interval, 35.13 to 207.16; P = 0.008) when high energy density feeds were offered. Although the caloric intake from semi-solids increased significantly (18.9 kcal/day; 95% confidence interval, 12.9 to 24.8; P < 0.001) with the high density diet, the total caloric intake (breast milk and study feeds) decreased (mean difference = 59.6 kcal/day; 95% confidence interval, 5.95 to 113.34; P = 0.031). An inverse relationship was found between caloric density of semi-solids and breast milk intake (r = 0.34, r = 0.12, P = 0.032).

CONCLUSION

In the short term, oil supplementation of complementary food in breastfed infants does not translate into enhanced total caloric intake, primarily as a result of breast milk displacement.

Exchangeable sodium induced changes in yield, water relation and cation composition of fennel (Foeniculum vulgare Mill)

A pot experiment was conducted with the objectives to assess the adaptation potential of fennel crop grown at 10, 20, 25, 35 and 40 ESP (exchangeable sodium percentage) levels. Results showed that the rate of seed germination, plant growth including branching pattern, umbels per plant and 1000 test seed weight were adversely affected by sodic soils. Assuming that fifty percent reduction in seed yield and Na+/K+ ratio in leaf tissue as an index of alkali tolerance revealed that fennel was tolerant up to 25 ESP. The cell sap pH and EC reflected optimum osmoticum maintenance to withstand sodicity stress at this level and beyond this leaf water potential decreased (negatively) more to impede water uptake.

Fungicidal elements accumulated in Cryptothecia punctulata (Ascomycetes lichen) of an arecanut orchard in South India

Different nutrient elements were analyzed in the lichen Cryptothecia punctulata collected from the arecanut trees which were exposed to several sprays of a fungicide Bordeaux mixture. The study revealed the accumulation of fungicidal elements such as Cu, Ca and S in higher concentration of 575.4, 10,000 and 21,000 microg g(-1), respectively.

Genetic Control of Resistance to Tan Necrosis Induced by Pyrenophora tritici-repentis, Races 1 and 2, in Spring and Winter Wheat Genotypes

ABSTRACT The symptoms of tan spot of wheat, caused by Pyrenophora triticirepentis, include a tan necrosis component and an extensive chlorosis component. Since tan spot has become the major component of the leafspotting disease complex of wheat in western Canada, the need for resistant cultivars has increased. This study was conducted to determine whether the resistance to tan spot found in a diverse set of spring and winter wheat genotypes was due to resistance genes not previously reported. The genetic control of resistance to necrosis induced by P. triticirepentis race 1 and race 2 was determined, under controlled environmental conditions, for spring wheat genotypes Erik and 86ISMN 2137 and winter wheat genotypes Hadden, Red Chief, and 6B-365. Plants were inoculated at the two-leaf stage and disease reaction was assessed based on lesion type. Tests of the F(1) and F(2) generations, and of F(2:3) and F(2:8) families, indicated that one recessive gene controlled resistance to the necrosis component of tan spot caused by both race 1 and race 2 in each cross studied. Lack of segregation in crosses between the resistant cultivars indicated that the resistance gene was the same in all of the cultivars.

Effect of spironolactone on acid and alkaline phosphatase in the testes of albino rat

The biological activity of the mineralocorticoid antagonist, spironolactone depend upon its metabolism. In this study the effect of diuretic drug compound spironolactone on the acid and alkaline phosphatase in the testes of albino rat. The drug spironolactone was administered orally daily for 7(th), 14(th) and 21(st) days at the dose of 100 mg/kg body weight. Among them, the side effects of drug are that the degradation of alkaline phosphatase in the testes; while acid phosphatase increased significantly may be due to 7a-thiospironolactone is a tissue metabolite of spironolactone and may contribute to the testicular enzymes, therapeutic actions and some other side effects. It is suggested that the decrease and increase of alkaline and acid phosphatase in the testes of albino rat are the due to the side effects of spironolactone drug compound.

Increased epithelial uptake of protein antigens in the ileum of Crohn's disease mediated by tumour necrosis factor alpha

BACKGROUND AND AIMS

The exact nature of the epithelial barrier defect in Crohn's disease remains to be elucidated. Previously we showed increased permeability to proteins in ileal Crohn's disease. Our aims were to study if this barrier defect (a) involves endocytotic uptake of antigens and (b) is related to low grade inflammation not detectable by histology.

METHODS

Macroscopically normal segments of distal ileum of Crohn's disease patients (n = 10) were subgrouped into non-inflamed (histologically unaffected) and slightly inflamed tissues and studied in Ussing chambers, with normal ileal specimens from colon cancer patients (n = 9) as controls. Endocytotic uptake into enterocytes of the protein antigen horseradish peroxidase was assessed by measuring the area of horseradish peroxidase containing endosomes in electron photomicrographs. Mucosal tumour necrosis factor alpha (TNF-alpha) mRNA was quantified using real time polymerase chain reaction. For comparison, the effects of low doses of TNF-alpha on endosomal uptake of horseradish peroxidase were studied in cultured T84 cells grown on filter supports.

RESULTS

The area of horseradish peroxidase containing endosomes was increased (p<0.001) in enterocytes of non-inflamed ileum of Crohn's disease (2.8 (0.7) mum(2)/300 mum(2)) compared with control ileum (0.6 (0.06)). In non-inflamed mucosa, a significant association between endosomal uptake and mucosal expression of TNF-alpha mRNA (p = 0.03) was found. Low concentrations of TNF-alpha (0.25-1.0 ng/ml) enhanced the endosomal uptake of horseradish peroxidase in polarised T84 cells, without affecting transepithelial electrical resistance.

CONCLUSIONS

Our findings suggest increased endosomal uptake of antigens in ileal Crohn's disease that may be mediated by TNF-alpha. These data highlight the transcellular route of antigen uptake in barrier dysfunction and implicate the interaction between epithelial cells and the innate immune system in the development of mucosal inflammation.

Development of a hybrid delta-endotoxin and its expression in tobacco and cotton for control of a polyphagous pest Spodoptera litura

A hybrid delta-endotoxin protein was designed against a polyphagous lepidopteran insect pest Spodoptera litura, which is tolerant to most of the known delta-endotoxins. The hybrid delta-endotoxin was created by replacing amino acid residues 530-587 in a poorly active natural Cry1Ea protein, with a highly homologous 70 amino acid region of Cry1Ca in domain III. The truncated delta-endotoxins Cry1Ea, Cry1Ca and the hybrid protein Cry1EC accumulated in Escherichia coli to form inclusion bodies. The solubilised Cry1EC made from E. coli was 4- fold more toxic to the larvae of S. litura than Cry1Ca, the best known delta-endotoxin against Spodoptera sp. None of the two truncated toxins, solubilised from E. coli caused larval mortality. However, trypsinised Cry1Ca protoxin obtained from E. coli and solubilised from inclusion bodies caused mortality of S. litura with LC50 513 ng/ml semi synthetic diet. A synthetic gene coding for the hybrid delta-endotoxin Cry1EC was designed for high level expression in plants, taking into consideration several features found in the highly expressed plant genes. Transgenic, single copy plants of tobacco as well as cotton were developed. The selected lines expressed Cry1EC at 0.1-0.7% of soluble leaf protein. Such plants were completely resistant to S. litura and caused 100% mortality in all stages of larval development. Hence, unlike in E. coli, the hybrid delta-endotoxin folded into a functionally active conformation in both tobacco and cotton leaves. The truncated Cry1EC expressed in tobacco leaves was about 8-fold more toxic (LC50 58 ng/ml diet) compared to expression in E. coli.

Effect of glucose and light-dark environment on pigmentation profiles in the cyanobacterium Calothrix elenkenii

Calothrix elenkenii was evaluated for accumulation of chlorophyll, beta-carotene and phycobiliproteins when grown under light-dark cycles and darkness, in the presence of glucose. Highest values of beta-carotene, chlorophyll, proteins and acetylene-reducing activity were recorded when the organism was grown in the presence of glucose under light-dark cycles after 15 d of incubation. The presence of glucose in the medium stimulated pigment production, especially of beta-carotene and chlorophyll, which may be due to increased energy-linked assimilation and ATP production. The photoheterotrophic potential of C. elenkenii can be exploited in value addition for increased and economic production of pigments.

Assessment of right ventricular diastolic function: does it predict post-operative course in tetralogy of Fallot

BACKGROUND

In some cases of tetralogy of Fallot the post-operative course is characterized by episodes of low cardiac output, elevated central filling pressures and prolonged ventilation and inotropic support. This may be due to impaired diastolic function of the right ventricle despite preservation of biventricular systolic function.

METHODS AND RESULTS

Sixty-four consecutive patients (mean age 7.06+/-4.9 years) undergoing repair of tetralogy of Fallot were prospectively studied to assess right ventricular diastolic function. 'Restrictive physiology' was defined as presence of laminar antegrade diastolic pulmonary artery flow (A wave) throughout the respiratory cycle, which was coincident with atrial systole. Right ventricle restriction was present in 45/64 (70%, Group 1) patients and absent in 19/64 (30%, Group 2) patients. There was a marked inspiratory augmentation of the pulmonary artery A wave velocity, flow integral and duration. Transtricuspid flow revealed significantly lower peak E velocity, lower E/A ratio, shorter E deceleration time and higher A velocity time integral in those with right ventricular restriction. Biventricular systolic function and transmitral flow were normal in all patients. Those with restrictive physiology had significantly longer mean inotrope support duration, longer ventilation and chest drainage times. Correspondingly, the mean intensive care unit stay (56.7+/-9.3 v. 34.7+/-5.38 hours, p<0.01) and mean hospital discharge time (9.3+/-2.3 v. 6.2+/-0.5 days, p <0.001) was also significantly longer in group 1.

CONCLUSIONS

Right ventricular restriction (as seen by laminar antegrade diastolic pulmonary artery flow throughout the respiratory cycle) exists in a significant subset of patients with tetralogy of Fallot following operative repair. Following surgery, such patients have higher inotropic requirement, longer ventilation times and longer hospital stay.

Genetic resistance of Barbari and Jamunapari kids to natural infection with gastrointestinal nematodes

An investigation was made in 252 Barbari and Jamunapari kids to assess their resistance to natural infection with gastrointestinal (GI) nematodes and to establish indicator traits for such resistance in Indian goats. The indicator traits, faecal egg counts (FEC) and packed cell volume (PCV) were affected by various genetic and non-genetic factors. There were no breed differences in the FEC or PCV at 3, 6 or 9 months of age. Jamunapari male kids had a higher FEC than the female kids at 6 months of age. However, Barbari female kids had a higher FEC than the respective male kids at 9 months of age. At 6 months of age in both breeds, the kids born in the spring (March-April) had a higher FEC than those born in the autumn (October-November). The FEC of kids at 9 months of age was higher than at 3 or 6 months of age. Sire had a significant effect on PCV at 6 and 9 months of age. The kids born in the autumn had a higher PCV than those born in the spring. The PCV of male Barbari kids differed significantly from that of female kids at all the ages. The correlation coefficient of FEC on both body weight and body weight gain was negative, and there was a loss of body weight in the individuals with a high FEC.

Isolation and characterization of an indigenous isolate of Dunaliella sp. for beta-carotene and glycerol production from a hypersaline lake in India

Dunaliella, a green alga grows in a wide range of marine and freshwater habitats such as oceans, brine lakes, salt marshes and salt-water ditches near the sea, predominantly in water bodies containing more than 10% salt. Sambhar salt lake, Rajasthan (India) was found as one of the natural habitat of Dunaliella sp. The species was isolated and screened for accumulation of beta-carotene and glycerol. It was studied for the growth attributes like total protein, optical density, total chlorophyll, total carotenoid, beta-carotene and glycerol. Under unstressed physico-chemical conditions the maximum beta-carotene and glycerol observed was 1.15 pg/cell and 94.26 pg/cell respectively. The stress (salt stress (NaCl), high light intensities and continuous light) allowed the alga to accumulate high beta-carotene (approximately 4.21 pg/cell under 118.18 micromole m(-2) s(-1) of light intensity) without massive reduction in biomass content. This opens up new avenues for exploring this strain for future research and its commercial exploitation.

Isolation and characterisation of phycobiliprotein rich mutant of cyanobacterium Synechocystis sp

Chemical (N' methyl-N'-nitro-N-nitrosoguanidine) mutagenesis and penicillin selection were utilised to isolate a phenotypically altered mutant of cyanobacterium Synechocystis sp. This mutant (ntm60A) exhibited enhanced protein content and nitrogen fixing potential but lower amount of chlorophyll and nitrate reductase activity. A remarkable and significant increase was observed in the total phycobiliprotein content of the mutant, especially in relation to the amount of phycoerythrin. This strain can be exploited as a rich source of natural coloring agent such as phycobilins in the bioindustry.

Effect of nutrient depletion on beta-carotene and glycerol accumulation in two strains of Dunaliella sp

The response of two strains of Dunaliella, a beta-carotene accumulating halotolerant alga, was evaluated under sulphate, nitrate and phosphate limitation. All these factors decreased the growth rate and chlorophyll content but, increased the beta-carotene content of the two isolates of Dunaliella, D1, obtained from GTCC and D2 an indigenous strain isolated from Sambhar salt lake, India. Both the strains exhibited accumulation of beta-carotene and glycerol under the different nutrient limiting conditions. A maximum accumulation of 3.99 pg/cell of beta-carotene was observed under phosphate depletion. However, nutrient depletion did not significantly affect the glycerol accumulation in these cells. D2, the indigenous isolate, was found to be a better accumulator of beta-carotene than D1.

Evaluation of Tolypothrix germplasm for phycobiliprotein content

Twenty Tolypothrix strains, including 15 strains of T. tenuis, three strains of T. ceylonica and one strain each of T. nodosa and T. bouteillei, were evaluated for their phycobiliprotein content and composition. Significant differences among the Tolypothrix strains were found at both inter- and intra-specific levels in the production of phycobiliprotein constituents--phycocyanin (PC), allophycocyanin (APC) and phycoerythrin (PE). Four specific parameters, viz. PC or PE content, total phycobiliprotein and total protein content, and percentage of phycobiliproteins, in a mixture of total proteins were used to select four T. tenuis and one T. ceylonica strain as useful for phycobiliproteins production.

Effect of thiazide drug compound on the testicular protein and cholesterol contents of albino rat

In this study the effect of thiazide diuretic compound on the protein and cholesterol contents in the testes of albino rats as the experimental model. The drug thiazide was administered orally daily for 10,20 and 30 days at the dose of 100mg/kg body weight. Total protein decrease in the testes of rats were evidenced may be due to the side effects of thiazide drug compound which is linked with the hyponatremia and protein metabolism. An elevated level of cholesterol contents observed in thiazide treated rats also revealed that the side effect of drug compound thiazide and also may be due to the stimulation of catecholamine which is stimulated therefore, the biochemical estimation such as protein and cholesterol in the testes after the thiazide treatment determined the effectiveness of diuretic drug compound would provide clinical evidences of their side effects.

Cadmium toxicity induced changes in plant water relations and oxidative metabolism of Brassica juncea L. plants

Excess of cadmium (Cd) induced changes in oxidative scenario and water status of plants viz.., total water content, specific water content, water saturation deficit (WSD) and transpiration of Brassica juncea plants grown in soil pot culture. Although lower and marginal levels of excess cadmium (100 and 250 ppm) improved growth but higher levels (500 ppm) caused significant suppression. Significant accumulation of proline, an indicator of water stress, occurred at higher level of Cd. Gradual increases in activities of certain antioxidant enzymes such as catalase and peroxidase along with increased lipid peroxidation are suggestive of disturbed oxidative metabolism. Taking together, the deleterious effects of Cd and its effects on oxidative metabolism clearly indicate enhanced generation of reactive oxygen species (ROS) to be instrumental in producing toxic effects of Cd. The excess levels of Cd also decreased the concentrations of soluble protein and chlorophylls and increased the ratio of chlorophyll a/b.

Methane production in rice soil is inhibited by cyanobacteria

The present study was aimed at understanding the role of cyanobacteria and Azolla in methane production and oxidation in laboratory simulation experiments using soil samples from rice fields. All the seven cyanobacterial strains tested effected a significant decrease in the headspace concentration of methane in flooded soil, incubated under light. Synechocystis sp. was the most effective in retarding methane concentration by 10-20 fold over that in controls without cyanobacteria. The decrease in the headspace concentration of methane was negligible in nonsterile soil samples, inoculated with Synechocystis sp. and then incubated under dark. Moist soil cores (0-5 cm depth), collected from rice fields that had been treated with urea in combination with a cyanobacterial mixture, Azolla microphylla, or cyanobacterial mixture plus A. microphylla, effected distinctly more rapid decrease in the headspace concentration of methane added at 200 microl(-1) than did the soil cores from plots treated with urea alone (30, 60, 90 and 120 kg N ha(-1)), irrespective of the rate of chemical nitrogen applied to rice fields. Besides, soil cores from plots treated with urea alone at 60, 90 and 120 kg N ha(-1) oxidised methane more rapidly than did the core samples from plots treated with urea alone at 30kg N ha(-1). Cyanobacteria and A. microphylla, applied to flood water, appear to play a major role in mitigation of methane emission from rice fields-through enhanced methane oxidation.