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Repetitive acoustic stimuli elicit steady-state response (SSR) in the gamma-band both in humans and in mammals. Our aim was to investigate changes of the spontaneous gamma activity and the SSR in the auditory cortex of cats in the background of an instrumental conditioning situation. Epidural electrodes were chronically implanted above the auditory neocortex. The presentation rate of the clicks varied between 20 and 65/s. Spontaneous EEG and SSR were collected in three behavioral states: in an indifferent environment, in the instrumental cage while the cat was waiting for the light CS, and when she stepped on the pedal and was waiting for the meat reward. Using different repetition rate clicks we determined which stimulus rate elicited the largest SSR in these three situations. In quiet animal the highest SSR appeared at 28-30/s. Before and during the CS the optimal stimulus rate shifted to 32-38/s. The frequency of the spontaneous gamma activity changed in parallel way depending on the situation. We conclude that both the SSR and the spontaneous gamma activity reflect resonant activity of the same neuronal circuit of the auditory cortex, and it is modulated by the motivational state of the animal.

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Mycotoxin fumonisin B1 (FB1) a natural inhibitor of ceramide synthase contaminating mainly the cornbased food and feed may cause dysfunctions in the nervous system. In the present study peripheral neural dysfunctions were biomonitored after dietary FB1 exposure in rats. Daily oral doses of 6.2 mg/kg body weight/day FB1 were applied in rats for 2 weeks. Before and after FB1 treatment nerve conduction velocities of tibial and sciatic nerves and spinal reflexes were analyzed in vivo. Electrophysiological recordings of biphasic plantar EMG (M and H components) and evaluation of sensory and motor nerve conduction velocities were carried out. Nerve conduction velocities revealed decreasing tendencies after FB1 exposure. The flexor reflex and the H-components of the extensor reflex were significantly reduced. The proposed in vivo biomonitoring can reveal functional impairment of the peripheral nervous system caused by mycotoxin exposure. Reduction of conduction velocity and altered reflexes after FB1 exposure are suspected to be associated with modified signal transmission due to toxic systemic effects and possible changes in sphingolipid metabolism.

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Community Ecology
Authors: F. Attorre, M. Alfó, D. Bottini, and et al.

A detailed analysis of the relationship between woody types and environmental variables (pedological and topographical) was carried out inside the city of Rome. Twenty-three sample sites 100 m2 each were selected according to the principle that they were inside woody vegetation patches greater than 2.3 ha. Presence-absence data were analysed through hierarchical classification and principal coordinates analysis in order to detect woody vegetation types. The six groups identified were then analysed according to thirty-four variables: a spatial discriminant analysis was performed using soil physical and chemical variables measured in the A1 and A2 horizons, topographical variables (altitude, slope and aspect), and annual potential irradiation. This procedure was able to quantify the contribution of the spatial distribution of the samples with respect to that of the environmental variables, thus improving the discriminant model. The combination of three variables: aspect, organic matter A2 and exchangeable cations A2 is the most effective in discriminating the woody types allowing a hypothesis for the planning and management of these communities.

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Significant amounts of aluminium (Al) are commonly present in rivers and lakes, largely in particulate form in neutral waters. Freshwater bivalves, as filter feeders are therefore exposed to both particulate and dissolved metal and are potentially vulnerable to Al. The effect of Al on filtering behaviour of the freshwater mussel Anodonta cygnea L. was investigated during short (1 hour) and long-term (15 days) exposure to environmentally relevant concentrations (250 and 500 mg l-1) at neutral pH. Water flow through the outflow siphon was monitored as an indicator of pumping capacity. Short-term (1 hour) exposure to 500 mg l-1 added Al produced an irreversible decrease in the duration of filtering periods, presumably as an avoidance response to the toxicant. One-hour exposure 250 mg l-1 Al had no detectable effect. When mussels were exposed to 250 or 500 mg l-1 added Al for 15 days, siphon activity measured in days 11-15 of exposure was inhibited by 50% and 65%, respectively, compared to pre-exposure levels. Recovery occurred following transfer of mussels to uncontaminated water. Interaction between Al and freshwater bivalves at neutral pH may affect both the performance of the mussels and the chemical speciation of the metal in the natural environment.

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Community Ecology
Authors: F. Attorre, M. Alfó, D. Bottini, and et al.

A detailed analysis of the relationship between woody types and environmental variables (pedological and topographical) was carried out inside the city of Rome. Twenty-three sample sites 100 m2 each were selected according to the principle that they were inside woody vegetation patches greater than 2.3 ha. Presence-absence data were analysed through hierarchical classification and principal coordinates analysis in order to detect woody vegetation types. The six groups identified were then analysed according to thirty-four variables: a spatial discriminant analysis was performed using soil physical and chemical variables measured in the A1 and A2 horizons, topographical variables (altitude, slope and aspect), and annual potential irradiation. This procedure was able to quantify the contribution of the spatial distribution of the samples with respect to that of the environmental variables, thus improving the discriminant model. The combination of three variables: aspect, organic matter A2 and exchangeable cations A2 is the most effective in discriminating the woody types allowing a hypothesis for the planning and management of these communities.

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Genetic/genomic polymorphism, i.e. variations in DNA sequences are ideally assayed by direct nucleotide sequencing of a gene region or other homologous segment of the genome. An easier and cheaper approach, however, if the variants are analyzed by hybridization technology using restriction fragment length polymorphisms (RFLPs) or by detection of the number of tandem repeats (VNTR) of small DNA segments, the “minisatellites”. In this study we describe results of the DNA analysis of repetitive sequences of human 6th chromosome by the application of a chemiluminescent labeled probes. The allele frequency distribution of polymorphic DNA sequences has been determined in unrelated individuals. The isolated genomic DNA was cut with Pst I restriction enzyme, size fractionated on agarose gel and hybridized with a chemiluminescent labeled D6 S132 probe. At this locus the Pst I cleaved DNA fragments are ranging from 1841 to 6098 base pairs (bp). Specific genetic pattern was characterized by more frequent fragments (3313 and 3884 bp), and the rarely occurring ones (clustered between 1841-2595 and 5227-6098 bp). Our study provides a further possibility for characterization of individual genomic patterns.

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The characteristics discussed are measurable on the process “trajectory”, the path traced out by vegetation transitions in time. It is argued that since the trajectory is symptomatic of factor influences and governing principles, it has to be an object of central interest in dynamic studies. Theoretical points, scaling scenarios, and analytical tools are the main topics. Numerical examples illustrate the applications.

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Most of the factors initiating food or fluid intake have already been studied, but much less is known about those terminating ingestion. We have hypothetised that discomfort originating from the gastrointestinal system may be one of those factors. Gut distension cause pain if the intestinal volume changes but merely discomfort if only the tension of the gut wall increases. It seems that mild unpleasantness (i.e. discomfort) arising from the gut as a result of moderate (quasi-isometric) distension, among and in concordance with other factors, may significantly reduce intake and hence contribute to physiological satiety. The arising discomfort can be detected by measuring the amount and rate of the ingestion, by recording and analysing ingestive behavior by taste-aversivity and taste-reactivity tests, etc. Conclusions of all experiments point to the same direction: tension increase in the gut wall causes discomfort and results in decrease of intake, i.e. satiety.

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Indexing and mapping of co-occurrence for multiple species is central to many analyses of conservation needs, ecosystem health, and community composition. Species richness is often used because of its simplicity and interpretability, but a variety of ecologically based weighting schemes for species have been developed for special purposes such as determining biotic integrity. This work is concerned with indexing a balance between common and uncommon species for preliminary assessments of conservation needs. A Regional Habitat Importance Index is constructed in a manner that provides joint ordering of species and landscapes. The index lends emphasis to species having a scarcity of habitat over a region, low representation in conservation areas, and shortage of opportunity for expanding protection. Application of the index is illustrated for mammals and birds in the context of GAP Analysis for the state of Pennsylvania, USA.

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A neighbourding -quadrate transect study was conducted in order to examine the possibile relationship between small scale topography and coenotaxa occurrence and cover in subassociations of Festucetum vaginataeRapaics ex Soó 1929 sandy grassland plant community near Fülöpháza. These investigations served as a starting point in later soil seed bank studies. Cover of species was recorded in three transects of different exposition starting on the top of different dunes and ending in the depressions. Subassociations and facies forming species of the community occurred in all investigated transects. Parts of the transects could not have been classified unambiguously into any of the coenotaxa mentioned in the literature. In these zones the charactersitic species of the different subbasociations and facies were occurding together. These patches are propbably also the ones where changes in dominance relations and simultaneous spread of a species can relatively easily happen, as it is the case with Cleistogenes serotina. Annual vegetation of the open sandy grassland, ond the other hand, has occured only in the transition zones, between the subassociations or facies. In these transects moss-lichen synusia were peresent usually in the subassociation Festucetum vaginatae pennatae Kerner 1863.

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