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Biomedical subjects

L Ehrman

Publications and source records attributed to L Ehrman.

At least 55 records · Page 3Linked to original sources
PubMed1970

Antimycoplasmal antibiotics and hybrid sterility in Drosophila paulistorum.

Male hybrids between the Santa Marta and Mesitas strains of Drosophila paulistorum are sterile. The sterility can be partially alleviated by treatment of the Santa Marta mothers with the antimycoplasmal antibiotics tylosin tartrate and tetracycline hydrochloride. The proportions of hybrid males in which there are mature motile spermatozoa are higher in the progenies of drug-treated mothers than in the controls. Electron microscopy reveals mycoplasma-like bodies in the untreated controls, but not in the sons of the treated females. The mycoplasma-like symbionts appear to be implicated in the production of the sterility in the hybrid males.

Animals↗
PubMed1970

Simulation of the mating advantage in mating of rare drosophila males.

In several species of Drosophila, certain males mate more frequently when they are less abundant than they do when they are in the majority. The mating advantage may be artificially induced by the use of a "double chamber" technique, even when there is no difference in the actual frequencies of the competing males.

Animals↗
PubMed1970

The mating advantage of rare males in Drosophila.

The mating advantage of rare Drosophila males in tested using two eye color mutants. In one experiment, the flies remained for three hours in observation chambers containing 25 pairs; in another experiment they stayed for 24 hours in mass cultures of 200 individuals. The outcome of this latter experiment was followed for ten generations, with all competition other than that for mates eliminated. For initial frequencies of 80 per cent for the common and 20 per cent for the rare type, the frequencies converged to approximate equality because the rare males were favored as mates. When the formerly rare type increases in frequency, it loses its mating advantage, and a balanced equilibrium is eventually attained.

Animals↗
PubMed1968

Unusual filamentous structures in the paragonia of male Drosophila.

Drosophila paulistorum is a complex of five incipient species which when crossed produce sterile hybrid males and fertile females. Sterility of the male progeny can sometimes be induced by injecting females of one strain (Mesitas) with a homogenate of males of another strain (Santa Marta) or of hybrids between these strains, and then crossing the recipient females to Mesitas males. Filamentous structures have been found in cytoplasmic vacuoles in paragonial cells in males of these and other similar strains and their hybrids. These structures, which contain RNA, possess a helical substructure and resemble certain viruses. Large filamentous structures found in the lumen of the paragonia are also described.

Animals↗