Das motorische Intentionspotential

Autocorrelation of the EEG was used to registrate a potential from the intact human scalp during intended, but not executed movements (dorsalflexion of the right hallux, imaginated in equal time intervals). This "Motor Intention Potential" (MIP) is a possible electrophysiological sign of the otherwise purely introspectively experienced intention of a voluntary movement and the cortex of the frontal lobes is suspected to be its origin. The average maximum amplitude height is 6 microV, and the potential shows a continuous decrease from the frontal to occipital region. The duration of MIP is in the range of seconds. Methodological questions are discussed, and the MIP is differentiated from other event-, movement- and imagination-related potentials. An attempt is made to place the motor intention potential in the context of existing movement theories.     

Ökotoxikologische Untersuchung von Sedimenten und Schwebstoffen

The potential risk of ground-water contamination through the infiltration of contaminants originating from suspended matter and sediments deposited within flood retention areas in the Upper Rhine valley, as well as subsequent problems for drinking water production, were analyzed by means of the bacterial dehydrogenase activity (DHA; sediment contact test) assay with Arthrobacter globiformis and in a prolonged embryo toxicity assay using zebrafish (Danio rerio). Since the direct uptake of contaminants from particle-bound sources has usually been assumed to play only a minor role in bioaccumulation, the availability of organic extracts to biota has generally been regarded as being overestimated. In order to confirm or discard this hypothesis, organic (acetone) extracts of recently suspended, freeze-dried matter, as well as freeze-dried sediments collected from Rhine flood plains (i.e. soil samples) were compared to corresponding native samples in order to screen for the relative availability of particle-bound contaminants. Whereas a significantly higher ecotoxicological burden was observed for some native soil samples, organic extracts of suspended matter proved to be more toxic than corresponding native samples when compared to organic extracts using each test system. With respect to organic extracts, the suspended matter samples were more toxic than soil samples taken from a rarely flooded site. In contrast to the native samples, the rarely flooded soils revealed a higher toxicity than suspended matter. Therefore, organic extracts did not necessarily overestimate the toxicity of soil and suspended matter samples. Moreover, considerable toxicity of particle-bound contaminants to both bacteria and fish embryos, even in native samples, corroborate the hypothesis that particle-bound contaminants may be more readily available than is generally assumed.     

Detecting and quantifying male sea urchin spawning with time-integrated fertilization assays

There has been much modeling and experimentation on factors affecting fertilization success in free-spawning marine invertebrates, but for many species spawning has rarely been observed in nature, if at all, and then mostly qualitatively. Understanding the dynamics of spawning and fertilization is especially important for species, such as the green sea urchin, Strongylocentrotus droebachiensis (O.F. Müller), that have been widely depleted by harvesting. Time-integrated fertilization assays provide measures of sperm-availability adjacent to spawning populations for extended periods and with unprecedented temporal resolution. In such assays unfertilized eggs are held in baskets permeable to sperm and suspended in the water column as long as the eggs remain viable. In a consecutive series of 24- to 72-h assays the time course and spatial extent of sperm availability were measured near an aggregation of 250 sea urchins suspended in a cage at a field site in West Boothbay Harbor, Maine, USA. The assays were conducted in March and April, 2000, the spawning season of the green sea urchin. The distribution of embryonic stages within the assays revealed fine-scale temporal information on the timing of fertilization. The time series of multiple assays indicated that over a substantial portion of the spawning season there was an almost continuous low level of male spawning, a pattern consistent with a slow decline in gonad index observed in both male and female urchins. Fertilization rates averaged only 17% for the eggs in the basket nearest the spawning urchins (20 cm away), and the rates declined sharply over a distance of <1 m. Thus, despite the potential benefits of long egg life in integrating sperm supply over several days, the spatial effects on fertilization success were marked. Owing to the urchins' captivity and the lack of site replication, the generality of the observed spawning pattern must be confirmed. Nonetheless, the method lends itself to wider application among natural populations.     

Apparent segregation of null alleles ascribed to deletions of the ornithine transcarbamylase gene in congenital hyperammonaemia

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder of the urea cycle mapped to chromosome Xp21.1. Here, we show that apparent segregation of null alleles at the OTC locus and flanking polymorphic loci mimicked false maternity or false paternity in three affected families. Based on these observations, we suggest giving consideration to gene deletion when dealing with segregation of null alleles in OTC deficiency.     

Sex-biased investment in yolk androgens depends on female quality and laying order in zebra finches (Taeniopygia guttata)

The Trivers–Willard hypothesis predicts sex biases in parental investment according to parental condition. In addition, parents may need to sex bias their investment if there is an asymmetry between the sexes in offspring fitness under different conditions. For studying maternal differential investment, egg resources are ideal subjects because they are self contained and allocated unequivocally by the female. Recent studies show that yolk androgens can be beneficial to offspring, so here we test for sex-biased investment with maternal investment of yolk testosterone (T) in zebra finch (Taeniopygia guttata) eggs. From the Trivers–Willard hypothesis, we predicted females to invest more in male eggs in optimum circumstances (e.g. good-condition mother, early-laid egg), and more in female eggs under suboptimal conditions (e.g. poor-condition mother, late-laid egg). This latter prediction is also because in this species there is a female nestling disadvantage in poor conditions and we expected mothers to help compensate for this in female eggs. Indeed, we found more yolk T in female than male eggs. Moreover, in accordance with our predictions, yolk T in male eggs increased with maternal quality relative to female eggs, and decreased with laying order relative to female eggs. This supports our predictions for the different needs and value of male and female offspring in zebra finches. Our results support the idea that females may use yolk androgens as a tool to adaptively manipulate the inequalities between different nestlings.     

Correlations between mutagenic activity of organic extracts of airborne particulate matter, NOx and sulphur dioxide in southern Germany: results of a two-year study

Goals, Scope and Background Among other substances, sulphur dioxide (SO2), nitric oxide (NO) and nitrogen dioxide (NO2) are parameters which are routinely measured to describe basic air quality. Organic extracts of airborne particulate matter contain mutagenic chemical compounds of different origins. The aim of the study was to find correlations between routine monitoring data and mutagenic activity of organic extracts of simultaneously drawn samples.Methods Specimens were collected over a period of two years at 8 sampling sites in south-west Germany. Simultaneously, concentrations of NO, NO2, and SO2 were measured on-line within the framework of the official air monitoring network of Baden-Württemberg, Germany. Dust samples were collected for biotesting using high volume air samplers equipped with glass fibre filters. After sampling was completed, filters were extracted and samples were prepared for biological testing. Mutagenic activity was tested by means of the plate incorporation assay (Ames test) using S. typhimurium TA98 and TA100 tester strains. During the first year of the study, all tests have been performed with and without metabolic activation. Additionally, a series of tests has been performed in parallel with TA98 and TA98NR.Results and Discussion Comparison of Ames test data obtained with and without metabolic activation indicates no statistically significant difference between both methods. Therefore, during the second year of the study, all tests have been performed without metabolic activation. Average yearly activities at the sampling sites were between 1 und 27 Revertants per m³ (Rev/m³). High activities were preferably found at congested sites (Karlsruhe, up to 95 Rev/m³). However, peak values of over 100 Rev/m³ were found in other places where pollution by traffic is significantly lower. The reason for these high level values is not evident. Tests performed using TA98NR tester strain indicate a significant share (average 31%) of compounds requiring activation by nitroreductase for mutagenic activity. Average mutagenic activity can be correlated to routine monitoring parameters. Comparison of averaged data for particular sampling sites indicates significant correlation between nitric oxide and mutagenic activity in TA98 (r²=0.90), while correlation between nitrogen dioxide (0.84) or sulphur dioxide (0.52) and mutagenic activity is weaker. For TA100, correlations are generally weaker than for TA98. Comparison of data for mutagenic activity and routine monitoring data of distant sites being sampled simultaneously shows parallel behaviour.Conclusions Results from this study show that mutagenic activity can be compared to seasonal and local variations of gaseous indicator air pollutants. Tester strain TA98 generally shows the best correlations. Although pollution by particle-bound mutagenic substances is significantly higher during the cold season than during summer on average, mutagenic activity of airborne dust is not a continuous effect. During winter, peak levels as well as low pollution periods can occur. Even during winter time mutagenic activity can reach very low levels typical for summertime. Comparison of results for distant sampling sites where samples have been collected simultaneously indicate that “classical” indicators of air pollution and bacterial mutagenicity of organic extracts from airborne particulate matter are influenced by connected effects. Seasonal trend of mutagenic activity, in particular, is similar to the concentrations of nitrogen oxide. NO is a strong indicator for vehicle exhaust gases. It is concluded that the average mutagenic activity at particular sites can be estimated using NO concentrations as an indicator.     

The effect of entrapped nonaqueous phase liquids on tracer transport in heterogeneous porous media: laboratory experiments at the intermediate scale

This work considers the applicability of conservative tracers for detecting high-saturation nonaqueous-phase liquid (NAPL) entrapment in heterogeneous systems. For this purpose, a series of experiments and simulations was performed using a two-dimensional heterogeneous system (10x1.2 m), which represents an intermediate scale between laboratory and field scales. Tracer tests performed prior to injecting the NAPL provide the baseline response of the heterogeneous porous medium. Two NAPL spill experiments were performed and the entrapped-NAPL saturation distribution measured in detail using a gamma-ray attenuation system. Tracer tests following each of the NAPL spills produced breakthrough curves (BTCs) reflecting the impact of entrapped NAPL on conservative transport. To evaluate significance, the impact of NAPL entrapment on the conservative-tracer breakthrough curves was compared to simulated breakthrough curve variability for different realizations of the heterogeneous distribution. Analysis of the results reveals that the NAPL entrapment has a significant impact on the temporal moments of conservative-tracer breakthrough curves.     

LIMPACT: Ein Expertensystem zur Absch?tzung der Pflanzenschutzmittel-Belastung kleiner Flie?gew?sser mittels der Makroinvertebraten-Fauna

Zusammenfassung  Die Entwicklung, der Aufbau und die Evaluierung eines biologischen Indikatorsystems für die Pflanzenschutzmittel-Belastung in kleinen Flie?gew?ssern wird vorgestellt. In Flie?gew?ssern mit landwirtschaftlichem Einzugsgebiet stuft das Expertensystem LIMPACT die Belastung in vier Klassen ‘unbelastet/nicht nachgewiesen’, ‘gering’, ‘mittel’ und ‘hoch’ belastet ein. Eingangsdaten sind dabei die Abundanzdaten der benthischen Makroinvertebraten-Fauna zu vier Terminen im Jahresverlauf (M?rz/April; Mai/Juni; Juli/August; September/Oktober) und neun physikalisch-chemische bzw. morphologische Flie?gew?sserparameter. Die Wissenbasis wurde mit dem Shellbaukasten D3 aufgebaut und enth?lt 921 Regeln zum etablieren oder de-etablieren einer Bewertungsklasse. Es wurden 39 Arten und Taxa analysiert und dabei 13 positive und 24 negative Indikatorspezies definiert. Positive Indikatorarten zeigen eine hohe Belastung durch hohe Abundanzen an, w?hrend negative Indikatorarten durch eine hohe Abundanz eine Belastung ausschlie?en und unbelastete B?che anzeigen. Die Datenbasis enthielt 157 j?hrliche Untersuchungen und wurde auch zur Evaluierung eingesetzt. Die korrekte Klassifikationsrate liegt bei 66,7–85,5% der F?lle. Die meisten verbleibenden F?llen werden nicht falsch eingestuft, sondern infolge der konservativen Bewertung bei geringer Datengrundlage nicht klassifiziert. Online First: 31.05.2002     

Dynamic studies on the mobility of trace elements in soil and sediment samples influenced by dumping of residues of the flood in the Mulde River region in 2002

In the analysis of soil samples, batch sequential extraction procedures are traditionally used for the fractionation of trace elements to access their mobility and potential risk for the contamination of groundwater. In the present work a continuous-flow technique has been used that enables not only the fast and efficient leaching of trace elements but as well as time-resolved studies on the mobilization of arsenic and selected heavy metals in different forms to be made. Rotating coiled columns (RCC) earlier used mainly in countercurrent chromatography have been successfully applied to the dynamic leaching of heavy metals from soils contaminated by flooding sludge's. The sample was retained in a PTFE rotating column as the stationary phase whereas aqueous solutions were continuously pumped through. The contents of elements were determined by on-line coupling of RCC and inductively coupled plasma atomic emission spectrometry (ICP-AES). This enables real-time data on the leaching process to be obtained. Dynamic and traditional batch procedures were compared. It has been shown that the aqueous elution under centrifugal forced conditions is much more effective for the mobilization of heavy metals. Hence, the dynamic leaching is characterized by a substantially more intensive interaction between solid and water and is besides substantially more time-saving than the conventional batch procedure. The RCC procedure was also employed for preliminary leaching studies with a simulated "acid rain". In comparison with the water leaching, the mobilization of heavy metals and arsenic from soil samples with employment of simulated acid rain as eluent was less effective.