Kinetics study on a novel natural inhibitor of alpha-chymotrypsin

The mechanism of inhibition of alpha-chymotrypsin by benzoylsalireposide (1), a phenolic glycoside isolated from Symplocos racemosa, was investigated. Lineweaver-Burk and Dixon plots and their secondary replots showed that 1 was a non-competitive inhibitor of this enzyme with the Ki value of 29.60 microM.     

Forest Road Detection Using LiDAR Data

We developed a three-step classification approach for forest road extraction utilizing LiDAR data. The first step employed the IDW method to interpolate LiDAR point data （first and last pulses） to achieve DSM, DTM and DNTM layers （at 1 m resolution）. For this interpolation RMSE was 0.19 m. In the second step, the Support Vector Machine （SVM） was employed to classify the LiDAR data into two classes, road and non-road. For this classification, SVM indicated the merged distance layer with intensity data and yielded better identification of the road position. Assessments of the obtained results showed 63% correctness, 75% completeness and 52% quality of classification. In the next step, road edges were defined in the LiDAR-extracted layers, enabling accu- rate digitizing of the centerline location. More than 95% of the Li- DAR-derived road was digitized within 1.3 m to the field surveyed nor- rnal. The proposed approach can provide thorough and accurate road inventory data to support forest management.     

Molecular identification of <Emphasis Type="Italic">Chilli leaf curl India virus</Emphasis> along with betasatellite molecule causing leaf curl disease of menthol mint (<Emphasis Type="Italic">Mentha arvensis</Emphasis> var. Kosi) in India

Whitefly-transmitted begomovirus induces leaf curling and stunting of Mentha arvensis (Kosi) and is responsible for heavy economic losses in and around Lucknow, India. The complete genome was amplified, sequenced and assembled as 2759 bp long, with 1376 bp betasatellite molecule. Because no DNA-B amplicon was detected, the virus was classified as “Old World begomovirus” with the characteristic seven ORFs; two ORFs (AV1, AV2) in the V-sense and five ORFs (AC1–AC5) in the C-sense. BLASTn and phylogenetic analysis showed highest similarity (98%) with chilli leaf curl India virus (ChiLCINV). This is the first report of ChiLCINV infection in M. arvensis (Kosi) from India.     

Disease Progress Based on Effects of Verticillium dahliae and Pratylenchus penetrans on Gas Exchange in Russet Burbank Potato

ABSTRACT The interactive effects of concomitant infection by the nematode Pratylenchus penetrans and the fungus Verticillium dahliae on symptom expression in Russet Burbank potato was studied in growth chamber experiments. Treatments were P. penetrans at three initial densities, V. dahliae at one inoculum density, the combination of the nematode at these three densities and the fungus, and a noninfested control. Gas exchange was measured nondestructively in leaf cohorts of different ages, one to three times weekly, with a LI-COR portable photosynthesis system. The single-pathogen treatments had no effect on assimilation or transpiration rates, but joint infection had a significant impact. In concomitant infection, photosynthesis was impaired more than transpiration, so estimates of leaf health were based on carbon assimilation rates only. Reductions in assimilation rate were apparent before the onset of visual symptoms. Assimilation rates decreased as much as 44% in the top, and newest, leaves of concomitantly infected plants, compared to rates in control plants. Even so, the health of newly produced leaves did not become progressively worse through time. With light use efficiency less than 0.20 mol of CO(2) fixed per mol of photosynthetically active radiation used as the criterion for disease incidence, disease progressed acropetally from the oldest to the youngest leaves. In plants infected with P. penetrans (0.8 nematodes per cm(3) of soil) in combination with V. dahliae, all leaves in cohorts 1 and 2 were symptomatic by 45 days after planting, and leaves in cohorts 3 to 6 became symptomatic at weekly intervals thereafter. For the control and single-pathogen treatments, the first time that light use efficiency fell below 0.20 in all leaves in cohort 1 was 71 days after planting. Concomitant infection reduced leaf life span by about 3 weeks. Both visual and physiological symptom expression were invariant to differences in initial nematode inoculum densities ranging from 0.8 to 2.5 nematodes per cm(3) of soil in one experiment and from 1.3 to 4.1 nematodes per cm(3) of soil in a second experiment.     

Genetic variability of Iranian strains of Pseudomonas syringae pv. syringae causing bacterial canker disease of stone fruits

Strains of Pseudomonas syringae pv. syringae (Pss) were isolated from healthy and diseased stone fruits tissues sampled from 38 stone fruits orchard sites in Iran in 2010 and 2011. These strains were tested for pathogenicity and the presence of the syrB gene and were genetically characterized by using ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and IS50 (insertion sequences) primers and PCR. All 78 strains of Pss tested were moderately to highly pathogenic on Loring peach seedlings. A total of 78 isolates of the Pss amplified a 752-bp fragment with the syrB primers. To assess genetic diversity among the strains, genomic DNA was extracted from strains and used in rep-PCR and IS50-PCR analysis. Cluster analysis was performed using UPGMA. The strains of Pss were separated into nine distinguishable genotypic groups by the combination data set of both rep-PCR and IS50-PCR at 73 % similarity level. There was no significant correlation between genetic diversity and geographical origin of the isolates. These results indicate that a combination of rep-PCR and IS50-PCR fingerprinting can be used as a high resolution genomic fingerprinting method for elucidating intrapathovar diversity among strains of Pss. The results of this study demonstrated the existence of a considerable genetic diversity among Pss strains causing canker of stone fruit trees in Iran. In this study, genetic variability in Iranian strains of Pss were established, which will be of immense use in the development of resistant genotypes against this bacterial pathogen.     

<Emphasis Type="Italic">Marsilea quadrifolia:</Emphasis> a New Bioagent for Treating Wastewater

We report for the first time the capability of four-leaf clover (Marsilea quadrifolia), a wetland plant which grows rooted in soil, in efficiently treating sewage. The use of M. quadrifolia was made possible because of the special attributes of the SHEFROL^® (SHEet Flow ROot Level) bioreactor in which it was employed. This bioreactor enables the use of free-floating aquatic plants as well as terrestrial and rooted-in-soil wetland plants by hydroponics. The plants are staked in narrow channels to enable them to support each other while sewage is made to flow rapidly as a sheet of wastewater at a level that covers only the plant roots (hence the name). It was seen that M. quadrifolia was able to treat sewage of strength varying in the chemical oxygen demand (COD) range of 600–1800 mg/L to the extent of >?80% at a hydraulic retention time (HRT) of just 4.5 h. There was a near total removal of biological oxygen demand and suspended solids while total Kjeldahl nitrogen, soluble phosphorous, and heavy metal zinc were also substantially removed. The macrophyte was equally effective when used indoors under artificial lighting, as well as when used outdoors.     

A comparative study to evaluate efficiency of EDTA and calcium in alleviating arsenic toxicity to germinating and young <Emphasis Type="Italic">Vicia faba</Emphasis> L. seedlings

Purpose

This study delineated the effect of calcium (Ca) and ethylenediaminetetraacetic acid (EDTA) addition on arsenic (As) accumulation and physiological attributes of Vicia faba L.

Materials and methods

Two separate experiments were performed. In the first experiment, V. faba seedlings, grown under hydroponic conditions, were exposed to three levels of As (25, 125 and 250 μM) in the presence and absence of three levels of EDTA (25, 125, 250 μM) and calcium (CaCl₂: 1, 5 and 10 mM). The effect of EDTA and Ca on As accumulation and physiological attributes of V. faba was assessed by determining As contents in roots and shoot, chlorophyll contents, H₂O₂ contents, and lipid peroxidation in young and old leaves. In the second experiment, V. faba seeds were grown in As-contaminated sand culture using the same treatment plan.

Results and discussion

The accumulation and toxicity of As to V. faba plants increased with increasing As levels in nutrient solution. Arsenic exposure enhanced the production of reactive oxygen species (ROS) in both roots and leaves, which resulted in lipid peroxidation and decreased chlorophyll contents. The presence of both EDTA and Ca, in general, significantly decreased As accumulation by V. faba seedlings, Ca being more effective than EDTA. Both the amendments decreased As-induced reactive oxygen species (ROS) production and lipid peroxidation. In the case of chlorophyll contents, EDTA significantly decreased chlorophyll contents, while Ca significantly increased chlorophyll contents compared to As. The effect of all the treatments was more pronounced in roots than leaves and in young leaves compared to old leaves.

Conclusions

It is proposed that EDTA and Ca greatly affect As accumulation and toxicity to V. faba, and the effect varies greatly with their applied levels as well as type and age of plant organs. The germinating seedlings of V. faba may be preferred for risk assessment studies, while transplanting 1-week-old V. faba seedlings to As-contaminated soils can decrease its toxicity.

     

Effects of cow manure and sewage sludge on the activity and kinetics of <Emphasis Type="SmallCaps">l</Emphasis>-glutaminase in soil

A study was conducted to investigate the effects of cow manure and sewage sludge application on the activity and kinetics of soil l-glutaminase. Soil samples were collected from a farm experiment in which 0, 25, and 100 Mg ha⁻¹ of either cow manure or sewage sludge had been applied annually for 4 consecutive years to a clay loam soil (Typic Haplargid). A chemical fertilizer treatment had also been applied. Results indicated that the effects of chemical fertilizer and the solid waste application on pH in the 18 surface soil (0–15 cm) samples were not significant. The organic C content, however, was affected significantly by the different treatments, being the greatest in soils treated with 100 Mg ha⁻¹ cow manure, and the least in the control treatment. l-Glutaminase activity was generally greater in solid-waste applied soils and was significantly correlated (r = 0.939, P < 0.001) with organic C content of soils. The values of l-glutaminase maximum velocity (Vmax) ranged from 331 to 1,389 mg NH₄ ⁺–N kg⁻¹ 2 h⁻¹. Values of the Michaelis constant (K _m) ranged from 35.1 to 71.7 mM. Organic C content of the soils were significantly correlated with V _max (r = 0.919, P < 0.001) and K _m (r = 0.763, P < 0.001) values. These results demonstrate the considerable influence that solid waste application has on this enzymatic reaction involved in N mineralization in soil.     

Dynamics of maize straw–derived nitrogen in soil aggregates as affected by fertilization

Journal of Soils and Sediments - The addition of maize residue nitrogen (N) to the soil strongly influences soil N accumulations, but the specific contributions of maize residue N to soil...