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E J Fjerdingstad

Publications and source records attributed to E J Fjerdingstad.

13 recordsLinked to original sources
PubMed2003

The relationship between multiple mating by queens, within-colony genetic variability and fitness in the ant Lasius niger.

Multiple mating has been suggested to benefit social insect queens because high genetic variation within colonies might decrease the load imposed by sterile diploid males, enhance resistance to parasites and pathogens, and lead to a more effective division of labour and/or a wider range of tolerable environmental conditions. We tested these hypotheses in the ant Lasius niger with three population samples from Switzerland and Sweden. We found no diploid males in young or mature colonies suggesting a lack of diploid male load. Colonies with multiply-mated queens were not larger nor did they produce more sexuals than colonies with singly-mated queens. We did find a significantly lower frequency of multiple mating among newly mated queens than among the queens heading mature colonies in one population sample (Switzerland 1997). However, this result was not repeated in the other study population, or in the following year in the Swiss population.

Animals↗
PubMed1978

Heavy metals in the spinal cord of normal rats and of animals treated with chelating agents: a quantitative (zinc, copper, and lead) and histochemical study.

The amounts of zinc, copper, and lead in the rat spinal cord were determined by means of flameless atomic absorption spectrophotometry. Zinc was present in a concentration about 100 p.p.m. (dry weight), copper in a concentration about 5 p.p.m., and lead in slightly more than 1 p.p.m. Analysis of various levels along the cranio-caudal axis of the rat spinal cord revealed differences in the heavy metal content. The Timm sulfide silver staining method has demonstrated that metals in the spinal cord have a distinct regional distribution. To obtain a differentiation between the stainable metals, the effects of six chelating agents (DEDTC, dithizone, oxine, EDTA, dipyridyl, and phenantroline) on the Timm pattern were tested. EDTA left the pattern unchanged, while the other compounds showed individual differences in their influence on the Timm pattern, suggesting that the heavy metal pattern of the spinal cord consists of multiple compartments. The effect of intravital multiple low dose treatment with three of the chelating agents on the histochemical pattern and the metal content of the spinal cord was also investigated. It was found that a decrease in the metal content was not followed by reduction of stainability and vice versa.

Animals↗
PubMed1976

Euflavine: effect on brain heavy metal content and staining pattern, and on shuttle box behavior in goldfish.

Goldfish were exposed to euflavine in doses of 7-100 mg/l for 1h-14 days. The treatment resulted in a reduced stainability of the brain with the Timm histochemical procedure for "heavy metals". In contrast, analysis by flameless atomic absorption spectrophotometry showed no significant changes in the concentrations of zinc and of copper after euflavine treatment. In the shuttle box a significant increase in general activity was found. These results, compared to earlier work with other chelating agents, indicate that such drugs do not have a uniform effect on behavior, and that they do not cause a true depletion of heavy metals in the brain.

Acridines↗