Kinetic models of peroxidase activity in potato leaves infected with late blight based on hyperspectral data

Potato late blight,which is caused by Phytophthorainfestans(Mont.)de Bary,is a worldwide devastating disease for potato.It decreased yields of potato and caused unpredictable losses all over the world.Various simple statistical methods and forecasting models have been developed to predict and manage potato late blight.Meanwhile,there is a rising need to develop prediction models reflecting peroxidase(POD)activity,which is an important health index that varies with infection and correlated with stress resistance in plants.Thus,the aim of this research was to develop kinetic models to predict POD activity.Infection-induced changes in potato leaves stored in an artificial climate chest at 25°C were analyzed using hyperspectroscopy.Four prediction models were developed by using linear partial least squares(PLS)and nonlinear support vector machine(SVM)methods based on the full spectrum and effective wavelengths.The effective wavelengths were selected by the successive projection algorithm(SPA).In this study,the prediction model developed by means of SPA-SVM method obtained the best performance,with a Rp(correlation coefficient of prediction)value of 0.923 and a RMSEp(root mean square error of prediction)value of 24.326.Five-order kinetics models according to the prediction model were developed,and late blight disease can be predicted using this model.This study provided a theoretical basis for the prediction of latencies of late blight.

Activation of Carcinogenic Non-aminoazo Compounds in Horseradish Peroxidase/H_2O_2 System

Eriochrome black T and Nitrosulfophenol S were advocated as the chemical models of carcinogenic non-aminoazo compounds. The main products of their oxidative cleavage in horseradish peroxidase/H2O2 system was identified as the benezenediazonium ion, the ultimate carcinogens, which could bind to DNA. The reaction conditions were investigated preliminarily. Some inhibitors and inducers of the reaction were discovered.

Efficiencies of Chemical Techniques for Rice Grain Freshness Analysis

Two chemical methods which are commonly used for rice grain freshness determination were investigated for their efficiencies. Method 1 is made of bromothymol blue indicator, and the principle is based on indicator＇s color which is changed in according to pH of the stored rice grains. Method 2 is based on peroxidase activity which deteriorates during storage of rice grains. Both methods were used for determination of fresh-aged rice index of six Thai-rice cultivars, four from non-waxy rice cultivars （KDML 105, Chai Nat 1, Chai Nat 2 and Phitsanulok 2） and two from waxy rice cultivars （San-pah-tawng and RD6）. Rice samples were kept in the forms of paddy and polished rice. Fresh-aged rice indices were determined using both methods every two weeks over the storage period of 24 weeks （six months）. It was found that both methods were capable of detecting fresh-aged rice indices. The color of chemical solutions changed with regards to the age of rice grains and it could be detected spectrophotometrically. Rice grains which have been kept as paddy provided more consistent results. Method 1 is recommended for industrial application as it is simple, efficient and inexpensive.

Selection of Rice Genotypes for Salinity Tolerance Through Morpho-Biochemical Assessment

The present study reported the morpho-biochemical evaluation of 15 selected rice genotypes for salt tolerance at the seedling stage. Growth parameters including shoot length, root length, plant biomass, plant turgid weight, plant dry weight along with relative water content were measured after exposure to saline solution （with electrical conductivity value of 12 dS/m）. Genotypes, showing significant differential responses towards salinity in the fields, were assessed through 14 salinity-linked morpho-biochemical attributes, measured at 14 d after exposure of seedling in saline nutrient solution. Relative water content, chlorophyll a/b, peroxidase activity and plant biomass were identified as potential indicators of salt tolerance. Principal component analysis and successive Hierarchical clustering using Euclidean distance revealed that Talmugur, Gheus, Ghunsi, Langalmura, Sabitapalui, and Sholerpona were promising genotypes for further breeding programmes in rice. The maximum Euclidean distance was plotted between Thavallakanan and Talmugur （7.49）, followed by Thavallakanan and Langalmura （6.82）, indicating these combinations may be exploited as parental lines in hybridization programmes to develop salinity tolerant variety.

Changes in Some Physiological Characteristics After Full Heading Stage in Flag Leaves of Super High-Yielding Inbred Rice

In a field experiment, rice cultivar Shanyou 63 was used as a check cultivar to investigate the changes in activity of peroxidase and contents of malondialdehyde and soluble protein after full heading stage in flag leaves of two super high-yielding inbred rice, including Shengtai 1 and Yuxiangyouzhan. The results showed that the peroxidase activities and soluble protein contents in the leaves of the three cultivars tended to increase gradually to peak values and thereafter descended during stage after full heading. Moreover, both the peroxidase activities and soluble protein contents of Shengtai 1 and Yuxiangyouzhan peaked at 8 days after full heading, which was compared with that of Shanyou 63 at 4 days later. Meanwhile, the malondialdehyde contents in the leaves of the three cultivars increased gradually after full heading stage. In addition, activities of peroxidase and contents of malondialdehyde and soluble protein in different cultivars were various at the same time. In general, for Shengtai 1 and Yuxiangyouzhan, the peroxidase activities and soluble protein contents were higher than those of Shanyou 63, whereas the malondialdehyde contents were lower compared with that of Shanyou 63. And these features could make the senescence of leaf become later and slower and photosynthetic product was more in Shengtai 1 and Yuxiangyouzhan than that in Shanyou 63.

Biochemical changes associated with flowering in Bambusa arundinacea and Bambusa nutans

Biochemical changes associated with flowering in Bambusa arundinacea Linn and Bambusa nutans Wall.ex Munro were analyzed.Gregarious flowering was initiated in natural areas and plantations of B.arundinacea in late 2014 and reached full bloom in early 2015,whereas sporadic flowering recorded during 2014–2015 in vegetatively propagated plants of B.nutans.Leaf and nodal shoot samples from flowering culms/shoots and nonflowering culms/shoots were collected in February 2015 at the initiation of fruit filling,then analyzed and compared for soluble sugars,phenols and peroxidase activity.In both species sugars were higher in leaves of flowering culms/shoots and lower in nodal shoots of flowering culms/shoots compared to the nonflowering.Phenols were lower in leaves and nodal shoots of flowering B.arundinacea,but higher in leaves and decreases in nodal shoots of B.nutans.Peroxidase activity increases in leaves and nodal shoots of B.arundinacea after flowering but increases in nodal shoots and decreases in leaves of B.nutans.

Biochemical investigations during in vitro adventitious shoot regeneration in leaflet explants from nodal segments of a mature Albizia procera tree

The in vitro adventitious shoot differentiation in leaflet explants of an adult tree differed from that of leaflet explants of seedlings of Albizia procera（Roxb.）Benth. reported previously elsewhere. The leaflet explants from an adult tree passed through an initial callus phase for30 days on MS medium supplemented with 3 % sucrose,2.5 l M 2,4-D followed by a subsequent adventitious shoot differentiation phase for another 30 days on half MS medium supplemented with 0.25 l M each of BA and IBA.The regeneration rate of in vitro adventitious shoots in explants from the adult tree, i.e.1.66 shoots/callus, was lower than that from seedlings, i.e. [10 shoots/callus,which was reported elsewhere. Correspondingly, the activities of nitrate reductase and peroxidase, and endogenous phenol content remained very low during in vitro adventitious shoot differentiation in leaflet explants of an adult tree possibly due to lower availability of competent stem（juvenile） cells for the process.

Effects of Nitrogenous Fertilizer on Pungency of Hot Pepper (Capsicum annuum L.) Fruits

The response of pungency of hot pepper fruits nitrogenous fertilizer on was invesigated. The results indicated that nitrogenous fertilizer had a significant effect on the capsaicin content of hot pepper fruits at 35 and 42 days after flowering;, capsaicin content gradually decreased, while peroxidase activity increased with nitrogenous fertilizer increasing.

Ecological and Functional Properties of Steppe Soils under Moderate Anthropogenic Impact

Steppe soils of a small industrialized city with moderate anthropogenic impact for example Krasny Kut, Saratov region were analysed to ascertain their ecological and functional state. In the course of this work, the concentration of heavy metals (Zn, Cu, Pb, Ni, Cr and Cd) was determined in the soil samples, including the hazard coefficient (Kо) and the total contamination coefficient (Zc). Magnetic susceptibility, magnetic coefficient (Kmag), thermomagnetic effect (dk) of the soil samples were analysed together with the activity of soil enzymes (dehydrogenases, catalases, peroxidases and invertases). Using ecological and geochemical analytical methods, a widespread excess of maximum permissible concentration (MPC) of mobile forms Ni, Pb, Cu and Zn was recorded in the soil samples of Krasny Kut, and a single excess of MPC was observed for Cr and Cd. According to Zc indicator values, 4 samples were classified as soils with moderately dangerous levels of contamination and 2 samples with dangerous levels of contamination. Using petromagnetic analysis, a few samples were observed to contain a moderate amount of introduced technogenic magnetic particles and one sample with a hazardous amount of introduced technogenic magnetic particles. Medium, high and very high levels of dehydrogenase, catalase, peroxidase and invertase activities were recorded in the soil samples, indicating the absence of ecotoxicants inhibiting the enzymes. The observed peculiarities in the ecological and functional state of soils, representative of the steppe zone of the Eastern part of the European territory of Russia will be required for monitoring, reducing and forecasting the anthropogenic burden on soil ecosystems.

Expression and Antigen Activity Determination of Human Thyroid Peroxidase in Silkworm and Yeast

In this study,we report the expression of human thyroid peroxidase（TPO） in silkworm larvae and Pichia pastoris GS115. Recombinant TPO is sequentially purified from the hemolymph of infected silkworm larvae and yeast using a Ni-NTA resin kit. The concentration of yield of recombinant TPO is 4.87 mg per thousand larvae and 40.83 mg per liter yeast culture. However,the recombinant TPO produced in silkworm show similar binding ability with the specific anti-TPO serum to standard human TPO purified from insect cells. The lower antigen activity indicates the TPO expressed in yeast is not suitable to be used as the coating antigen in enzyme linked immunosorbent assay（ELISA）. The cost of TPO expressed in B. mori is about 1/4 that of in insect cells,and the cost of TPO purified from silkworm for ELISA is only 1/8 that of TPO produced from Sf9 cells. It indicates the Bm NPV-silkworm expression system is a cost-effectiv e platform for producing TPO with high antigen activity.

In situ synthesis of red fluorescent gold nanoclusters with enzyme-like activity for oxidative stress amplification in chemodynamic therapy

Chemodynamic therapy (CDT) has attracted tremendous interest in cancer therapy because it is independent of oxygen and photoirradiation. However, the therapeutic efficacy of CDT is restricted by insufficient H_(2)O_(2) levels in tumor cells. Herein, employing endogenous GSH as a template and cationic polymeric chitosan (CS) as crosslinker and stabilizer exhibiting easy cell uptake, red luminescent gold nanoclusters (denoted CS-GSH@AuNCs) were successfully synthesized in HeLa cells. The in situ synthesized CS-GSH@AuNCs exhibited both superoxidase dismutase (SOD) and peroxidase (POD)-like activity, which could promote the production of H_(2)O_(2) from superoxide anion radicals (O_(2)^(·-)) and then ^(·)OH. The combination of GSH elimination and H_(2)O_(2) elevation boosted the generation of ^(·)OH, which could trigger cancer cell apoptosis and death. The enzyme-like activity of CS-GSH@AuNCs could be effectively activated under acidic conditions, and showed a high killing effect on tumor cells but minimal toxicity to normal cells. The developed GSH consumption and ^(·)OH promotion theranostic platform is an innovative route for enhanced CDT by the amplification of oxidative stress.

Effects of different drying methods on drying kinetics and physicochemical properties of Chrysanthemum morifolium Ramat

The effects of infrared-assisted hot-air drying(IR-HAD),temperature,humidity controlled hot-air drying(THC-HAD),and hot-air drying(HAD)on the drying kinetics,physicochemical properties,chlorogenic acid content and microstructure of chrysanthemum were experimentally examined.The results showed that the drying time reduced with increasing air drying temperature,with IR-HAD needing the shortest drying time,followed by THC-HAD and HAD.The effective moisture diffusivities(Deff)of chrysanthemum under IR-HAD,THC-HAD,and HAD at 60℃ were 3.22×10^(-9) m^(2)/s,2.19×10^(-9) m^(2)/s,and 2.89×10^(-9) m^(2)/s,respectively.IR-HAD preserved chrysanthemum surface color better than THC-HAD and HAD,whereas the THC-HAD samples obtained higher water holding capacity(WHC),water binding capacity(WBC),and chlorogenic acid content.Additionally,peroxidase(POD)residual activity of the samples decreased with increasing blanching time.The current work provides a theoretical basis for the drying of chrysanthemum.