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  • 1
    Electronic Resource
    Electronic Resource
    Reliability of heavy metal pollution monitoring utilizing aquatic animals versus statistical evaluation methods (1992)
    Springer
    Archives of environmental contamination and toxicology 23 (1992), S. 476-483 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Heavy metal concentrations in two snail and two fish species were used to compare the pollution of four sites on the River Zala and on the Kis-Balaton Reservoir (Hungary). The effectiveness of different statistical methods (t- and Bartlett's test, analysis of variance and analysis of covariance) were compared. The most reliable results were obtained by using analysis of covariance, with body weight as the covariate, taking the seasonality in metal concentrations into consideration. The different species showed the same relations among sampling stations if analysis of covariance was applied. It is essential to use statistical methods that account for the most important effects (covariates); otherwise, the reliability of the information supported by biomonitors is compromised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203813
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cadmium uptake and depuration in different organs ofLymnaea stagnalis L. and the effect of cadmium on the natural zinc level (1993)
    Springer
    Archives of environmental contamination and toxicology 24 (1993), S. 28-34 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The uptake of cadmium (0.1 mg/L) into various organs of the pond snailLymnaea stagnalis L., the depuration of accumulated Cd, and the change in the natural Zn level under the influence of Cd treatment were investigated during a 2 month period. The snails were fed with lettuce (Latuca sativa). The concentrations of Cd were measured in the whole soft body, various organs (liver, viscera, foot), the shell and the lettuce; and zinc concentrations were measured in various organs and the lettuce. As its Cd concentration remained at 10 μg/g, which was much lower than the initial value for the soft body (69.4±5.71 μg/g), the shell, according to our results, is incapable of accumulating Cd. The uptake pattern of the soft body showed a correlation with the initial Cd levels depending on differences in the Cd concentration of the lettuce. At the higher initial value (69.4±5.71 μg/g) the linear Cd uptake began later then it did at the lower initial value; afterwards the snail was saturated with Cd. In the case of the lower, 9.02±1.3 μg/g initial concentration, a rapid linear Cd uptake occurred till the 7th day, then the intensity of the uptake decreased. Saturation occurred at 200 μg/g Cd concentration, regardless of the initial value. At the lower initial tissue level, the foot and the viscera showed a linear uptake pattern, while the liver, which has the greatest accumulation ability, displayed a logarithmic uptake pattern. The initial and the final Cd concentrations in the foot, viscera, and liver of theL. stagnalis were as follows: 10.3±2.15−60.1±7.13, 5.15±1.04−156±27.2, 14.1±3.09−430±23.3 μg/g respectively. The bioconcentration factors (CF) were in the 102 (foot) and 103 (viscera, liver, soft body) orders of magnitude. Forty to 45% of the accumulated Cd was depurated in Cd-free tap water; during the first three days of the uptake period, a negative linear correlation was found between Cd and Zn levels in the snail organs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01061086
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Modulation of synaptic events by heavy metals in the central nervous system of mollusks (1994)
    Springer
    Cellular and molecular neurobiology 14 (1994), S. 735-754 
    Details
    ISSN: 1573-6830
    Keywords: mercury ; lead ; zinc ; Helix pomatia L. ; Lymnaea stagnalis L. ; identified neurons ; synaptic transmission ; heavy metal toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The effects of heavy metals (Pb2+, Hg2+, and Zn2+) on synaptic transmission in the identified neural network ofHelix pomatia L. andLymnaea stagnalis L. (Gastropoda, Mollusca) were studied, with investigation of effects on inputs and outputs as wells as on interneuronal connections. 2. The sensory input running from the cardiorenal system to the central nervous system and the synaptic connections between central neurons were affected by heavy metals. 3. Lead and mercury (10−5−10−3 M) eliminated first the inhibitory, then the excitatory inputs running from the heart to central neurons. At the onset of action lead increased the amplitude of the excitatory postsynaptic potentials, but blockade of sensory information transfer occurred after 10–20 min of treatment. 4. The monosynaptic connections between identified interneurons were inhibited by lead and mercury but not by zinc. Motoneurons were found to be less sensitive to heavy metal treatment than interneurons or sensory pathways. 5. The treatment with Pb2+ and Hg2+ often elicited pacemaker and bursting-type firing in central neurons, accompanied by disconnection of synaptic pathways, manifested by insensitivity to sensory synaptic influences. 6. Zn2+ treatment also sometimes induced pacemaker activity and burst firing but did not cause disconnection of the synaptic transmission between interneurons. 7. A network analysis of heavy metal effects can be a useful tool in understanding the connection between their cellular and their behavioral modulatory influences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02088681
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Inorganic Mercury and Methylmercury on the Ionic Currents of Cultured Rat Hippocampal Neurons (1997)
    Springer
    Cellular and molecular neurobiology 17 (1997), S. 273-288 
    Details
    ISSN: 1573-6830
    Keywords: mercury ; methylmercury ; calcium currents ; N-methyl-D-aspartate currents ; T currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. The effects of inorganic Hg2+ and methylmercuric chloride on the ionic currents of cultured hippocampal neurons were studied and compared. We examined the effects of acute exposure to the two forms of mercury on the properties of voltage-activated Ca2+ and Na+ currents and N-methyl-D-aspartate (NMDA)-induced currents. 2. High-voltage activated Ca2+ currents (L type) were inhibited by both compounds at low micromolar concentrations in an irreversible manner. Mercuric chloride was five times as potent as methylmercury in blocking L-channels. 3. Both compounds caused a transient increase in the low-voltage activated (T-type) currents at low concentrations (1 μM) but blocked at higher concentrations and with longer periods of time. 4. Inorganic mercury blockade was partially use dependent, but that by methylmercury was not. There was no effect of exposure of either form of mercury on the I–V characteristics of Ca2+ currents. 5. Na+- and NMDA-induced currents were essentially unaffected by either mercury compound, showing only a delayed nonspecific effect at a time of overall damage of the membrane. 6. We conclude that both mercury compounds show a relatively selective blockade of Ca2+ currents, but inorganic mercury is more potent than methylmercury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026338217097
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of Inorganic and Organic Tin Compounds on ACh- and Voltage-Activated Na Currents (2000)
    Springer
    Cellular and molecular neurobiology 20 (2000), S. 591-604 
    Details
    ISSN: 1573-6830
    Keywords: tin ; acetylcholine ; Lymnaea stagnalis L. ; membrane currents ; mollusks ; Na channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Inorganic tin and organotin compounds, occurring in aquatic ecosystems, are toxic and can cause behavioral abnormalities in living organisms. To determine the possible neuronal basis of these actions, the effects of both forms of Sn were studied on identified neurones of the mollusk, Lymnaea stagnalis L. 2. SnCl2 caused a dose-dependent decrease in the acetylcholine (Ach)-induced inward current. The effective threshold concentration, measured by a two microelectrode voltage clamp technique, was 0.1 μM, and the maximal effect occurred at 5 μM SnCl2. The depression of the inward current was greater after a 10 min preapplication (20%) than after 3 min treatment (7%). 3. The next series of experiments compared the actions of inorganic or organic tin compounds. In whole cell clamp experiments both (CH3)2SnCl2 and (CH3)3SnCl, like inorganic Sn, decreased the amplitude of Ach-induced current. Increasing the duration of the preapplication time resulted in an increase in the effect, but the action was not reversible. SnCl2 treatment caused a concentration-dependent alteration (initial potentiation followed by depression) of the amplitude of I Na(V) over the whole voltage range and slightly shifted the I–V curves to the left. In contrast, trimethyl tin decreased the amplitude of I Na(V) only at high concentration (100 μM). The activation time course of I Na was increased (τ = 0.43 ms in control and 0.55 ms in Sn), but Sn did not alter the inactivation parameters (τ = 3.43 and 3.41 ms). 4. These results support earlier findings that agonist- and voltage-activated channels are direct targets of toxic metals. We conclude that tin in both inorganic and organic forms acts at neuronal membranes to modulate synaptic transmission through direct actions on agonist-activated ion channels, and suggest that these actions may be the basis of the altered behavior of animals in tin-polluted environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007016012520
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