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  • 1995-1999  (5)
  • 1890-1899
  • methyl mercury  (3)
  • Mouse  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Selective breeding for extremes in open-field activity of mice entails a differentiation of hippocampal mossy fibers (1996)
    Springer
    Behavior genetics 26 (1996), S. 167-176 
    Details
    ISSN: 1573-3297
    Keywords: Mouse ; genetic variation ; hippocampus ; infrapyramidal mossy fibers ; open field ; selective breeding ; hemispheric asymmetries ; exploration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The brains of mice selectively bred for differential locomotor activity in an open field (DeFrieset al., Behav. Genet. 8:3–13, 1978) were analyzed for selection-dependent changes in the size of synaptic fields at the midseptotemporal level of the hippocampus. Timm-stained areas of all hippocampal fields from both left and right hippocampi were measured on five horizontal sections from the midseptotemporal level. The sample included 25 mice from two replicate lines, each one consisting of a high (HI); a low (LO), and a control line (CTL). The main selection effect was an enlargement of the intrainfrapyramidal mossy fiber (IIP-MF) projection in both HI lines by about 70% compared to LO and CTL mice (p〈.0001), while other mossy fiber fields did not show differences. These findings confirm that genetic variations of the IIP-MF projection influence hippocampal processes mediating exploratory activities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359894
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Paw preference and intra-/infrapyramidal mossy fibers in the hippocampus of the mouse (1996)
    Springer
    Behavior genetics 26 (1996), S. 379-390 
    Details
    ISSN: 1573-3297
    Keywords: Mouse ; genetic variation ; hippocampus ; infrapyramidal mossy fibers ; selective breeding ; hemispheric asymmetries ; paw preference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The size of the intra-/infrapyramidal mossy fiber projections (IIP-MF) and their left/right asymmetry were assessed in 86 mice of either sex, including 26 animals from two mouse lines bred for strong or weak paw preference, 38 mice of a randomly bred F3 generation derived from an eight-way cross, and 22 mice with variably sized corpora callosa in which only the left hippocampus was measured. Prior to morphometry, all mice were tested for paw preference. In addition, we compared the strain means in paw preference as observed in nine inbred mouse strains with known differences in their IIP-MF distribution. Mice bred for strong paw preference had a 70% larger IIP-MF projection than weakly lateralized and dyscallosal mice; random-bred mice fell in-between the extremes. The individual scores of the strength of paw preference were positively correlated with the extent of the IIP-MF. Among the inbred strains, the extent of the IIP-MF was similarly correlated with the strength of paw preference. The acallosal mice showed a significant negative correlation between extent of the IIP-MF projection and test-retest reliability of paw use. The left-right asymmetry of the IIP-MF was significantly and positively correlated with the direction of paw preference in the entire sample. We conclude that size and asymmetry of the IIP-MF projection are some of the many factors influencing the direction of paw preference and its strength, albeit moderately. We hypothesize that mice with larger IIP-MF projections use a given paw more consistently, being perhaps more resistant to interferences, and that left-right asymmetries of the IIP-MF may bias and/or reinforce an initial choice of a paw. In addition, the data provide another example of correlations between IIP-MF variations and nonspatial behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02359482
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    System controls on the aqueous distribution of mercury in the northern Florida Everglades (1998)
    Springer
    Biogeochemistry 40 (1998), S. 293-311 
    Details
    ISSN: 1573-515X
    Keywords: aqueous mercury species ; bioaccumulation ; methyl mercury ; marshes ; wetland systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The forms and partitioning of aqueous mercury species in the canals and marshes of the Northern Florida Everglades exhibit strong spatial and temporal variability. In canals feeding Water Conservation Area (WCA) 2A, unfiltered total Hg (HgTU) is less than 3 ng L-1 and relatively constant. In contrast, methyl mercury (MeHg) exhibited a strong seasonal pattern, with highest levels entering WCA-2A marshes during July. Stagnation and reduced flows also lead to particle enrichment of MeHg. In the marshes of WCA-2A, 2B and 3A, HgTU is usually 〈5 ng L-1 with no consistent north–south patterns. However, for individual dates, aqueous unfiltered MeHg (MeHgU) levels increase from north to south with generally lowest levels in the eutrophied regions of northern WCA-2A. A strong relationship between filtered Hg species and dissolved organic carbon (DOC), evident for rivers draining wetlands in Wisconsin, was not apparent in the Everglades, suggesting either differences in the binding sites of DOC between the two regions, or non-organic Hg complexation in the Everglades.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005928927272
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Trophic transfer of methyl mercury in the northern Florida Everglades (1998)
    Springer
    Biogeochemistry 40 (1998), S. 347-361 
    Details
    ISSN: 1573-515X
    Keywords: Everglades ; Hg transfer ; methyl mercury ; periphyton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract There are spatial differences in methyl mercury (MeHg) concentrations in biota in Water Conservation Areas 2 and 3 in the Everglades, with higher concentrations generally found in the southern areas. Fish and hemipterans had the most MeHg on a wet weight basis, with levels exceeding 30 ng g-1. The magnitude of MeHg accumulation in biota varies seasonally and does not always appear to be associated with changes in water column concentration. This is exemplified by periphyton, the base of the foodweb in the Everglades, at a high nutrient sampling site. Although limited in scope, MeHg concentrations presented for biota provide insight into beginning to understand the dynamic nature of Hg transfer in the Everglades foodweb on a spatial and temporal basis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005918101773
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Diel variability of mercury phase and species distributions in the Florida Everglades (1998)
    Springer
    Biogeochemistry 40 (1998), S. 311-325 
    Details
    ISSN: 1573-515X
    Keywords: diel variability ; Everglades ; mercury cycling ; methyl mercury ; photochemical processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Preliminary studies of mercury (Hg) cycling in the Everglades revealed that dissolved gaseous mercury (DGM), total mercury (HgT), and reactive mercury (HgR) show reproducible, diel trends. Peak water-column DGM concentrations were observed on or about noon, with a 3 to 7 fold increase over night-time concentrations. Production of DGM appears to cease during dark periods, with nearly constant water column concentrations that were at or near saturation with respect to the overlying air. A simple mass balance shows that the flux of Hg to the atmosphere from diel DGM production and evasion represents about 10% of the annual input from atmospheric deposition. Production of DGM is likely the result of an indirect photolysis reaction that involves the production of reductive species and/or reduction by electron transfer. Diel variability in HgT and HgR appears to be controlled by two factors: inputs from rainfall and photolytic sorption/desorption processes. A possible mechanism involves photolysis of chromophores on the surface of a solid substrate (e.g., the periphyton mat) giving rise to destabilization of sorbed mercury and net desorption during daylight. At night, the sorption reactions predominate and the water-column HgT decreases. Methylmercury (MeHg) also showed diel trends in concentration but were not clearly linked to the solar cycle or rainfall at the study site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005938607225
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    Paper (German National Licenses)
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