Somatic Effects of Temperature on Development in Drosophila melanogaster. II. Temperature-Effective Period of Truncate

Blanc, Richard; Child, George P.

doi:10.1086/physzool.13.1.30151527

Cited by 5 publications

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“…The sensitive periods for certain of the phenocopies are slightly different from those found for X-rays or temperature treatments. It is rather difficult to compare the work of different investigators, who use different stocks raised at different temperatures, but it would appear that the sensitive period for the production of dumpy wings by ultraviolet corresponds with that found by Blanc and Child (1940) for temperature treatments and that the larval sensitive period for bristle reduction by ultraviolet is identical with the temperature sensitive period determined by Child (1935). In addition there is a sensitive period for bristle reduction by ultraviolet in the pupal stage which was also found in X-radiation experiments (Waddington, 1942;Villee, 1946a).…”

Section: Discussionmentioning

confidence: 97%

A Quantitative Study of Phenocopy Production With Monochromatic Ultraviolet Irradiation

Villee¹

1947

The Biological Bulletin

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Villee, 1946a). It was found that the threshold for the production of phenocopies with X-rays was slightly below 1096 r. units. At that level from to 40 per cent of the flies were killed and from to 10 per cent showed phenocopies. This dosage D in roentgens may be converted to the density of absorbed energy, E, by the formula E = 83 D ergs/cm. 3 (Cole, personal communication) to give 90,968 ergs/cm. 3 The absorbed energy of the ultraviolet radiation, computed from the area and volume of the larva and the minimal threshold intensity of 440 ergs/mm. 2 and assuming total absorbtion by the organism, is 440,000 ergs/mm. 3 From this it can be seen that X-radiation is approximately five times as effective per energy unit as ultraviolet radiation of wave-length 2537 A in producing phenocopies. I want to thank Professor Kenneth S. Cole for his assistance in making these calculations. SUMMARY 1. Drosophila larvae, prepupae and pupae of various ages and genotypes were irradiated with ultraviolet of wave-length 2537 A and in dosages varying from 330 to 79,200 ergs/mm. 2 The phenocopies produced varied with the age of the irradiated fly, the stock used, and the total dosages of the irradiation. Irradiation with ultraviolet does not cause a retardation of pupation as X-radiation does.2. Larvae show a gradual increase in sensitivity to ultraviolet radiation with age from 50 to 100 hours after hatching from the egg to a maximum at one hour after pupation, then a sharp decrease in sensitivity with pupal age. There are two periods in the larval stage, one about 50 and one about 100 hours after hatching, of greater phenocopy production for a given amount of radiation. Irradiations during the first 24 hours of pupal life produce fewer phenocopies for a given amount of radiation than during the larval period.3. The sensitive periods for the production of certain phenocopies by ultraviolet are compared with the sensitive periods for X-ray and temperature treatments. Some are identical, a few are different.

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