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Biomedical subjects

S Kessler

Publications and source records attributed to S Kessler.

At least 163 records · Page 9Linked to original sources
PubMed1975

Gene substitutions and geotaxis in Drosophila melanogaster.

Tightly linked gene markers at the white locus of Drosophila were placed, by repeated backcrossing, on each of two genetic backgrounds. Ten genotypes representing various combinations of homo- and heterozygosity were studied in a Hirsch-type geotactic maze. In general, the effects of genetic background, dominance, and epistasis were found to exceed the additive effects of gene substitutions. The results domonstrate the feasibility of analyzing the contributions of single genes to behaviors known to be polygenically determined.

Animals↗
PubMed1975

A biometrical analysis of a mating characteristic in Drosophilia.

A model is described for the biometrical analysis of interaction behavioural characteristics. The model is illustrated by analysis of the mating speed of Drosophila pseudoobscura derived from crosses of fast and of slow mating strains generated through artificial selection.

Animals↗
PubMed1975

Scanning electron microscopy of mast cell degranulation.

Scanning and transmission electron microscopy were used to study the morphologic changes occurring in isolated mast cells after stimulation by compound 48/80. Two approaches were used to obtain cells for scanning electron microscopy. Cells incubated in suspension were collected on Millipore filters and air-dried from isopropyl alcohol. Other cells were allowed to attach to cover slips, stimulated, fix in situ, and dried from Freon at its critical point. Resting mast cells prepared by the latter method were covered by a tracery of shelflike ridges, whereas cells prepared by the first method had no ridges but presented a bumpy surface disclosing the underlying granules. Stimulation by compound 48/80 caused marked changes in the surface configuration of the cells, with loss of the regular pattern of ridges, extrusion of granules, and the appearance of openings leading to the interior of the cell. Correlation with transmission electron microscopy indicates that these openings lead to channels containing granules and lined by an intact membrane. These openings give extracellular cations access to granules within the confines of the cell, where the cations may exchange for histamine.

Animals↗
PubMed1975

Genetic determination of aggressive behavior and brain cyclic AMP.

Inbred mouse strains exhibit differences in brain cyclic AMP concentrations. In two mouse strains, we have shown that both the tendency for aggressive attack and high brain cyclic AMP content are inherited as recessive traits and that these traits maintain a close association in segregating generations.

Aggression↗