The ultrastructure, neuroanatomy and central projection patterns, including the intercellular connections of the statocyst hair cells of the pond snail, Lymnaea stagnalis, were studied, applying different intra- and extracellular cellular staining techniques combined with correlative light- and electron microscopy. Based on the ultrastructure different hair cells could be distinguished according to their vesicle and granule content, meanwhile the general organization of the sensory neurons was rather uniform, showing clearly separated perinuclear and “vesicular” cytoplasmic regions. Following intra- and extracellular labeling with fluorescence dyes or HRP a typical, local arborization of the hair cells was demonstrated in the cerebral ganglion neuropil, indicating a limited input-output system connected to the process of gravireception. Correlative light- and electron microscopy of HRP-labeled hair cells revealed both axo-somatic and axo-axonic output contacts of hair cell varicosities, and input on sensory axons located far from the terminal arborizations. Our findings suggest (i) a versatile ultrastructural background of hair cells corresponding possibly to processing different gravireceptive information, and (ii) the synaptic (or non-synaptic) influence of gravireception at different anatomical (terminal, axonal and cell body) levels when processed centrally. The results may also serve as a functional morphological background for previously obtained physiological and behavioral observations.
Authors:J. Varga, R. Kiss, T. Mátrai, T. Mátrai, and J. Téren
Ochratoxin A is a mycotoxin produced by Aspergillus and Penicillium species. This mycotoxin is a common contaminant of various food products including cereal products, spices, dried fruits, coffee, beer and wine. Besides cereal products, beer and wine contribute significantly to ochratoxin exposure of humans. We examined the ochratoxin content of Hungarian wines and beers using an immunochemical technique. The detection limit of this technique is 0.01mg l-1. Altogether 65 wine and 25 beer samples were analysed. The presence of ochratoxin A was confirmed by HPLC in positive samples. Ochratoxin A was detected in 97.7% of wines, with ochratoxin concentrations ranging from 0 to 0.533mg l-1. The mean ochratoxin A concentration in wines was 0.110mg l-1. Only one of the Hungarian wines examined contained more than 0.5mg l-1ochratoxin A, the previously suggested EU limit for wine. Our data indicate that red wines are more frequently contaminated, and have higher mean ochratoxin contamination (0.117mg ml-1) than white wines (0.0967mg ml-1), in accordance with previous observations. A North-South gradient in wine ochratoxin concentrations is not evident from our data. For beers, all but one of the samples was found to be contaminated with small amounts of ochratoxin A with a mean concentration of 0.127mg l-1(range: 0.030-0.250mg l-1). Only one of the beers contained ochratoxin A above 0.2mg l-1, the anticipated European Community maximum allowable limit in beer. We could not detect correlation between the type and origin of beer and ochratoxin contamination.
Authors:E. Kuzmann, M. Varsányi, L. Korecz, A. Vértes, T. Masumoto, F. Deák, Á. Kiss, and L. Kiss
Neutron, and Mössbauer spectroscopy were used to study the possibility of cold nuclear fusion in Fe90Zr10 amorphous ribbon having high hydrogen absorbing ability. No significant changes in the neutron and in the spectra were found at deuterization performed electrochemically at different cathodic potentials. The observed differences between the Mössbauer spectra of samples deuterized in air and in nitrogen atmosphere can be explained by decrease of deuterium uptake as well as by a small heat effect due to reaction of hydrogen with oxygen dissolved in water in the case of electrolysis carried out in air.
Authors:K. Balla, I. Karsai, S. Bencze, T. Kiss, and O. Veisz
Stress tolerance is associated with the activation of antioxidant compounds and enzyme systems that are capable of neutralising the reactive oxygen species (ROS) continually produced in response to stress. The present experiment was designed to compare the heat tolerance of four winter wheat varieties in the shooting and grain-filling stages by investigating changes detected in antioxidant enzyme activity and yield components in response to heat stress.Heat treatment was found to cause a significant rise in the activity of the glutathione-S-transferase and catalase enzymes, while there was usually a less intense decline in the activity of guaiacol peroxidase.An analysis of yield data revealed that heat stress had a more pronounced effect during grain filling in this experiment than at the beginning of shooting, as shown by the greater reduction in thousand-kernel weight and yield.
Authors:Nóra Krajcs, L. Márk, K. Elekes, and T. Kiss
Bending, twitching and quivering are different types of tentacle movements observed during olfactory orientation of the snail. Three recently discovered special muscles, spanning along the length of superior tentacles from the tip to the base, seem to be responsible for the execution of these movements. In this study we have investigated the ultrastructure, contractile properties and protein composition of these muscles. Our ultrastructural studies show that smooth muscle fibers are loosely embedded in a collagen matrix and they are coupled with long sarcolemma protrusions. The muscle fibers apparently lack organized SR and transverse tubular system. Instead subsarcolemmal vesicles and mitochondria have been shown to be possible Ca2+ pools for contraction. It was shown that external Ca2+ is required for contraction elicited by high (40 mM) K+ or 10−4 M ACh. Caffeine (5 mM) induced contraction in Ca2+-free solution suggesting the presence of a substantial intracellular Ca2+ pool. High-resolution electrophoretic analysis of columellar and tentacular muscles did not reveal differences in major contractile proteins, such as actin, myosin and paramyosin. Differences were observed however in several bands representing presumably regulatory enzymes. It is concluded that, the ultrastructural, biochemical and contractile properties of the string muscles support their special physiological function.
Authors:T. Kiss, K. Balla, O. Veisz, and I. Karsai
The transitions between various developmental phases are critical in determining the ecological adaptation and yield of cereals. In order to elaborate a methodology for establishing the timing of the consecutive plant developmental phases from germination to the fully developed plant, regular measurements of changes in developmental components were carried out on one winter (Kompolti Korai) and one spring (Morex) barley cultivar in a model experiment. Under the controlled environmental conditions linear regression was characteristic of the associations between the chronological time and all or most of the time course data of plant height, tiller and leaf numbers. The initial growth of the spring barley was twice as intensive as that of the winter barley. The length of the stem elongation phases was similar for the two varieties, but the winter barley cultivar showed significantly more intensive stem growth compared to the spring barley. The spring barley reached all the plant developmental phases significantly earlier than the winter barley. For both cultivars, tillering continued till after first node appearance and there was a definite delay between first node appearance and the beginning of the stem elongation phase. The determination of the full series of phenophases, together with the evaluation of various yield components on the same plant, provide an excellent way of establishing plant developmental patterns and may make a significant contribution to achieving a better understanding of the associations between plant developmental patterns and the adaptation and yielding ability of cereals.
Authors:Éva Lehoczky, T. Németh, Zs. Kiss, and et al.
The pot experiment - carried out in 2000 under greenhouse conditions -
was set up with seven soils differing in Cd and Pb contents and three test
L. cv. Georgikon), lettuce (
L. cv. Balatonzöld) and white mustard (
L. cv. Sirola) with
four replicates. From the seven experimental soils five samples (S1-S5) were
collected from agricultural areas (arable sites) and two (S6-S7) from
spoil-earth, with extremely high Cd and Pb contents. The pots, each containing 1 kg air-dry soil,
were kept at constant soil moisture (60% of maximum water capacity of the
experimental soils) by daily watering, while pots were watered to weight once
weekly. Before sowing the test plants: 50-50-50 mg N, P
O was applied to the experimental soils to maintain the same
nutrient supply. The above-soil plant parts were cut after four weeks. Fresh
and dry weights of plants were determined after harvest.
The aim of the
experiment was to obtain results of Cd and Pb uptake by different plant species
in relation to the heavy metal content and different characteristics of soils. The following conclusions were drawn:
correlation was found between the biomass production of the three test plants
and the heavy metal content of the soils at early growth stage. The heavy metal
concentration range in the soils and plants differed. In the case of Pb the
soil concentration interval was broader than that of the plants'. The opposite
was observed for Cd, where the plants had a wider concentration interval.
Comparing the Pb and Cd concentrations of above-ground plant parts, Pb
concentrations varied in a narrower interval. The maximum values of Pb content
exceeded the Cd content levels, although the mobility of Pb in the soil-plant
system is significantly lower. The comparison of Cd and Pb concentrations of
plants and soils proved these differences. The Cd concentration of plants was
8-231% of the total Cd content of soils. The Pb concentration of plants was the
0.8-28% of the total Pb content of the soils, respectively. Comparing the three
plants in respect of Cd concentrations the order found was as follows: ryegrass
< white mustard < lettuce. In case of Pb, the order depended on the Pb
content level (lower or higher) of the experimental soil. Symptoms of
phytotoxicity were observed only on lettuce plants grown on the contaminated
soils (S6, S7).