Authors:Á. Szepesszentgyörgyi, S. Bárány, and I. Mécs
Bacillus thuringiensis ssp. israelensis (Bti) is increasingly used as an ecologically friendly anti-mosquito agent. The bacterium cells undergo fermentation in dilute suspensions; before practical use, therefore it is necessary to concentrate the suspensions. Aggregation by polymers is a powerful tool with which to regulate the stability of suspensions. Typically, polymers at low concentrations destabilize and at high concentrations stabilize colloidal systems. Bti suspensions can be flocculated efficiently by either cationic or anionic polyelectrolytes. Cationic polyelectolytes were found to be the most efficient flocculants for bacterial suspensions. It was shown that the degree of toxicity of the flocculated Bti suspensions for biting mosquito larvae was in the same range than in non-flocculated suspension.
Authors:G. Zapantis, G. Zapantis, Ildikó Csóka, E. Csányi, E. Csányi, G. Horváth, G. Horváth, I. Erős, and I. Erős
The aim of this study was to evaluate the systemic absorption of the topically administered ketamine using different vehicles and additives, in order to develop a transdermal therapeutic system (TTS) of this drug. After the application of different ketamine preparations (1% in hydrogel, o/w cream, or organogel) the ketamine appeared in the blood. The lowest level could be observed with o/w cream, while the highest concentration was achieved by means of the hydrogel system, however this difference was not significant. Further studies are going to be performed with higher drug concentrations for the characterization of the differences in the pharmacodynamics of the drug with different vehicles and to evaluate the correlation between the in vitro and in vivo absorption.
Authors:J.S. Khokhar, S. Sareen, B.S. Tyagi, L. Wilson, I.P. King, S.D. Young, and M.R. Broadley
Correlations between juvenile wheat root traits, and grain yield and yield component traits under optimal field conditions have previously been reported in some conditions. The aim of this study was to test the hypothesis that juvenile wheat root traits correlate with yield, yield components and grain mineral composition traits under a range of soil environments in India. A diverse panel of 36 Indian wheat genotypes were grown for ten days in ‘pouch and wick’ high-throughput phenotyping (HTP) system (20 replicates). Correlations between juvenile root architecture traits, including primary and lateral root length, and grain yield, yield components and grain mineral composition traits were determined, using field data from previously published experiments at six sites in India. Only a limited number of juvenile root traits correlated with grain yield (GYD), yield components, and grain mineral composition traits. A narrow root angle, potentially representing a ‘steep’ phenotype, was associated with increased GYD and harvest index (HI) averaged across sites and years. Length related root traits were not correlated with GYD or HI at most sites, however, the total length of lateral roots and lateral root number correlated with GYD at a sodic site of pH 9.5. The total length of lateral roots (TLLR) correlated with grain zinc (Zn) concentration at one site. A wider root angle, representing a shallow root system, correlated with grain iron (Fe) concentration at most sites. The total length of all roots (TLAR) and total length of primary roots (TLPR) correlated with grain S concentration at most sites. Narrow root angle in juvenile plants could be a useful proxy trait for screening germplasm for improved grain yield. Lateral root and shallow root traits could potentially be used to improve grain mineral concentrations. The use of juvenile root traits should be explored further in wheat breeding for diverse environments.
Authors:C. Kaya, N.A. Akram, M. Ashraf, and O. Sonmez
Application of salt stress (100 mM) through root growing medium caused a considerable decrease in plant fresh and dry biomass, maximum quantum yield (Fv/Fm), chlorophyll contents, leaf water potential, and leaf Ca, K, P and N concentrations of two maize cultivars (Apex 836 and DK 5783). However, salt-induced increase was observed in leaf osmolality (LO), proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), Na+ concentration and activities of enzymatic antioxidants, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Of five humic acid (HA) levels used under non-stress and stress conditions in an initial experiment, 100 mg L−1 was chosen for subsequent studies. Exogenous application of humic acid (HA) at the rate of 100 mM as a foliar or pre-sowing seed treatment significantly increased the plant biomass, Fv/Fm, chlorophyll pigments and proline contents, while it considerably reduced the leaf water potential, H2O2 and MDA contents as well as the activities of all the afore-mentioned enzymatic antioxidants. Of both modes of exogenous treatment, foliar spray was better in improving plant biomass, chlorophyll contents, LO, leaf Na+ as well as the accumulation of all nutrients measured, however, in contrast, seed pre-treatment was more effective in altering leaf proline, H2O2 and MDA contents. Of both maize cultivars, cv. DK 5783 excelled in plant biomass, chlorophyll contents and leaf N, Ca and K concentrations as well as in the activities of all three antioxidant enzymes, whereas cv. Apex 836 was superior in leaf Na+ and P concentrations, H2O2 and MDA contents. Cv. DK 5783 was comparatively better in salt tolerance as compared to cv. Apex 836. Overall, exogenous application of HA was effective in improving salinity tolerance of maize plants which can be attributed to HA-induced increase in plant biomass, chlorophyll contents, mineral nutrients and activities of key antioxidant enzymes.
The role of the dopaminergic and serotonergic system was studied during the embryonic development of the pond snail Lymnaea stagnalis, with special attention to the effect of dopamine and serotonin as well as their agonists and antagonists on the rotation of the veliger larvae, and to the effect of precursors and inhibitors of the synthetizing enzymes on the duration of the embryonic life. Serotonin, D-lysergic acid diethylamide and N,N-dimethyltryptamine increased at a concentration of 1 mM the rotation by 50%, 90% and 87% respectively, and among them D-Lysergic acid diethylamide was found to be the most potent agonist. Other serotonergic agonists and antagonists enhanced the frequency of the rotation (from 165% to 355%) at higher threshold concentrations in the following rank order: methysergid?tryptamine? 2,5-dimethoxy-4-iodoamphetamine ? 5-carboxyamidotryptamine ? bromo-lysergic acid diethylamide ? 7-methyltryptamine. Application of 1-(2-methoxyphenyl) piperazine decreased the rotation by 76%. The reuptake inhibitor desipramine completely blocked the rotation and killed the embryos. Dopaminergic agonists accelerated the rotation by 62% to 233%, and their effect was ranged as follows: dopamine ? apomorphine ? m-tyramine ˜ p-tyramine. Chlorpromazine at 100 µM concentration killed the embryos. At a concentration of 100 µg/ml, tyrosine, the precursor of DA, slowed down the embryonic development by increasing the duration of the embryonic life from 8 to 10 days. Decarboxylase inhibitors, a-methyl-3,4-dihydroxyphenyl-alanine (25 µg/ml) and m-hydroxybenzylhydrazin (5 µg/ml), killed 50% of the embryos, meanwhile the rest hatched ten days later, compared to the control animals. The development was partially blocked by the serotonin precusor L-tryptophane (50 µg/ml). Trytophan hydroxylase blocker, p-chlorphenylalanine (50 µg/ml) resulted in a distortion of the body pattern of the embryos, and prevented the hatching of most (95%) of the animals.
Authors:O. Temiz-Arpaci, T. Coban, B. Tekiner-Gulbas, B. Can-Eke, I. Yildiz, E. Aki-Sener, I. Yalcin, and M. Iscan
The in vitro antioxidant properties of some new benzazole derivatives (1-10) such as benzoxazoles, benzimidazoles, and benzothiazoles were determined by their effects on the rat liver microsomal NADPH-dependent lipid peroxidation (LP) level, the scavenging of superoxide anion and the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds 1, 2, 4 and 6, showed potent scavenging effect on superoxide radical at 10-3 M. Compound 8, 5-nitro-2-(phenoxymethyl)benzimidazole, strongly inhibited lipid peroxidation at 10-3 M concentration.
Community composition may be determined by a variety of factors, including habitat dimension, abiotic conditions, and biotic interactions. Habitat dimensions may influence abiotic conditions, thus modifying community structure or biotic interactions. We used six different mesocosm sizes, two depths crossed with three surface areas, to test hypotheses regarding the direct and indirect effects of habitat dimensions (depth and surface area) on dissolved oxygen concentration and insect communities in artificial water-filled treeholes. Containers were monitored for dissolved oxygen concentrations and insect community composition from June 2002 to November 2003. We predicted that deep mesocosms would have lower species richness and insect larval densities than shallow due to less dissolved oxygen at deeper depths, and that large surface area mesocosms would have greater species richness and abundance of insects than small. Larger surface area habitats may attract more insects because they are easier to find and perceived by ovipositing females to be more stable. Dissolved oxygen concentrations ([DO]) at depth were consistently lower in deep than shallow habitats, and mosquito densities and species richness were lower in those deep mesocosms compared to shallow mesocosms. We found higher insect richness at certain times of the year in large and medium than in small surface area mesocosms. By modifying abiotic factors such as [DO], dimensional aspects of the habitat, in this case depth, may affect community structure in ways not predicted simply by habitat size.
Authors:C. Thiel-Egenter, A. Risch, M. Jurgensen, D. Page-Dumroese, B. Krüsi, and M. Schütz
Interactions between grassland ecosystems and vertebrate herbivores are critical for a better understanding of ecosystem processes, but diverge widely in different ecosystems. In this study, we examined plant responses to simulated red deer (
L.) grazing using clip-plot experiments in a subalpine grassland ecosystem of the Central European Alps. We measured aboveground net primary production (ANPP) and phosphorus (P) concentration of leaf tissue from plants of two vegetation types with different grazing history. The experimental plots were placed on a soil-P gradient and subject to two different clipping treatments, which simulated moderate and heavy grazing, respectively. We found distinct differences in the response of both ANPP and P concentration in leaf tissues in the two vegetation types. Compared to moderate, heavy grazing simulation did not affect ANPP in the vegetation type adapted to grazing, but decreased ANPP in the non-grazing adapted vegetation type. High soil-P levels also had different effects on the response of the vegetation to clipping in the two vegetation types with different grazing history. ANPP correlated positively with soil-P in non-grazing adapted tall-grass vegetation, while in grazing adapted short-grass vegetation a positive relationship between soil-P and the P concentration in leaf tissues was found. Our experiments provide data for a better understanding of ecosystem processes in high-elevation grasslands of the Alps with possible implications for both nature conservation purposes in protected areas and the management of agriculturally used grasslands.
Enzymes of sucrose metabolism viz. sucrose synthase (SS), sucrose phosphate synthase (SPS) and invertase were studied in the leaves of sugarcane (Saccharum officinarum L.) var. 'Co 7527' under the influence of spentwash as ferti-irrigation with respect to crop age. The activity of SS increased with increasing concentrations of spentwash while higher concentration (1,500 ppm BOD) lowered the activity by 1.42% and 4.16%, respectively, in 9 and 12 months old crop. SPS exhibited higher activity in 9 months old sugarcane with stimulatory effect at 1,000 and 1,500 ppm BOD treatment while invertase showed higher activity in 9 months old crop and declined at 12 months by exhibiting stimulatory effect at 1,000 ppm BOD. The elevation in SPS/invertase ratio at higher concentration of spentwash treatment can be attributed to the contributory factor for maintenance of high sucrose level. The study indicated that use of spentwash up to 1,500 ppm BOD as ferti-irrigation does not affect sucrose metabolism.
Authors:A. Behpouri, A. Perochon, F.M. Doohan, and C.K.-Y. Ng
Brachypodium distachyon has emerged as the model species for important temperate grass crops such as wheat and barley and the genome of the B. distachyon community inbred line Bd21 has been sequenced. Methods for tissue culture and Agrobacterium-mediated transformation have been developed for this model grass as a resource for reverse genetics and functional genomic analyses. In order to obtain a high quantity and quality of compact embryogenic callus (CEC) in B. distachyon, it is important to examine and optimize the optimal concentration of the auxin 2,4-D (dichlorophenoxyacetic acid) to use in both callus induction and callus proliferation media. Here, we investigated the effects of different concentrations of 2,4-D on callus induction and callus proliferation of B. distachyon Bd21. Our results showed that 2.5 mg l–1 2,4-D is an optimal concentration to use for both callus induction and proliferation, although 5.0 mg l–1 may also be used for callus proliferation. Additionally, the suitability of hygromycin or bialaphos as selectable markers was examined and results indicated that hygromycin is significantly more efficient than bialaphos when using the Agrobacterium-mediated transformation system.