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E Bolton

Publications and source records attributed to E Bolton.

31 records · Page 2Linked to original sources
PubMed1983

Bithorax phenocopy and pattern formation. II. A model of prepattern formation.

Phenocopy maps are constructed from the spatial pattern of the phenocopy spots using a distance function defined on the frequencies with which two compartments transform separately and jointly. The temporal changes in distances between different compartments in turn enable us to make inferences concerning the diffusion-like processes involved in prepattern formation of the metathorax. A model is presented which accounts for the data in terms of the propagation of two wavefronts in sequence and in approximately orthogonal directions. Sensitivity to transformation by ether is limited in time to the interval between the passing of the two wavefronts. Changes caused by 13 successive generations of ether treatment can be interpreted in terms of alterations in the timing and rates of wave propagation. A comparison of phenocopy and fate maps suggests that the prepatterning processes affect primarily the blastoderm cytoplasm or surface membrane.

Animals↗
PubMed1983

Bithorax phenocopy and pattern formation. I. Spatiotemporal characteristics of the phenocopy response.

In four different lines of Drosophila melanogaster the highest frequencies of bithorax phenocopies result from ether treatment during the precellular blastoderm stages. The spatial characteristics of the phenocopy spots are dependent on the precise timing of phenocopy induction, and are not in accord with those predicted from the model of sequential determination of whole compartments put forward by Garcia-Bellido et al. in 1976. Ether treatment for 13 successive previous generations gave rise to changes in the spatiotemporal characteristics of the phenocopy response. Our results suggest the involvement of continuous diffusion-like processes in the prepatterning event which is affected by ether.

Age Factors↗
PubMed1979

Protective effect of prophylactic penicillin on splenectomized mice exposed to an aerosolized suspension of type III Streptococcus pneumoniae.

Prophylactic penicillin has been recommended for use in asplenic patients and postsplenectomy patients. A laboratory model using aerosolized pneumococci has been devised to test the effectiveness of prophylactic penicillin in a manner analogous to human experience. There is increased mortality, over time, in asplenic mice exposed to aerosolized type III Streptococcus pneumoniae. One hundred twenty-one male Swiss mice (mean weight 26 g) were divided into four groups: splenectomized, sham-operated, splenectomized + penicillin, and sham-operated + penicillin. After 2 wk the four groups were exposed for 30 min to an aerosolized atmosphere of 2.4 x 10(9) colony-forming units of type III S. pneumoniae using a Tri-R model A-42 airborne infection apparatus. Penicillin was given at a daily intramuscular dosage of 40,000 units procaine penicillin G beginning 2 days prior to exposure and continuing through the third day after exposure. The splenectomized and sham-operated mice given penicillin showed significantly lower mortality (p less than 0.001) than mice not given penicillin.

Aerosols↗