Radiation-induced inhibition of eclosion in the tobacco hornworm, Manduca sexta
Control of eclosion in Manduca sexta (laboratory reared at 23 to 25/sup 0/C on 18L:6D) was investigated by utilizing the ED/sub 50/ (x-ray exposure required to prevent eclosion in 50 percent of the irradiated animals) throughout pupal-adult development as a measure of radiation sensitivity. An initial period (day 0 to 6) of nearly constant radiosensitivity (ED/sub 50/ range: 13.0 to 14.4 kr) was followed by a brief period of increased radiosensitivity between day 6.5 to 7.75 (ED/sub 50/:8.23 kr). Thereafter, a pronounced decrease in radiosensitivity was noted through the day of eclosion (day 8: ED/sub 50/ = 19 kr; day 22: ED/sub 50/ = 75 kr). The association between hemolymph ecdysone levels and maximum radiosensitivity observed on day 7 was studied. Animals administered ..beta..-ecdysone on days 1, 4, and 12, and irradiated at various times post-injection, exhibited significant increases in radiosensitivity. Thus, radiosensitivity exhibited by Manduca sexta on days 0 to 7 is in part dependent upon the titer of ecdysone in hemolymph. The role of the brain as a radiosensitive region was investigated in day 10 animals by selectively transplanting ED/sub 100/-irradiated and nonirradiated brains into ED/sub 100/-irradiated and nonirradiated animals. The presence of a radiosensitive component in addition to the brain is proposed since the radiation-induced inhibition of eclosion could not be completely explained in terms of brain damage alone. Selective shielding of day 10 animals x-irradiated at an ED/sub 100/ level demonstrated the absence of radiosensitive regions in the abdomen and their presence in both the head and thorax.
- Research Organization:
- Univ. of Tennessee, Knoxville
- OSTI ID:
- 7211816
- Journal Information:
- Biol. Bull.; (United States), Journal Name: Biol. Bull.; (United States) Vol. 152:2; ISSN BIBUA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ABDOMEN
ANIMALS
ARTHROPODS
BIOLOGICAL EFFECTS
BIOMASS
BODY
BODY AREAS
BRAIN
CENTRAL NERVOUS SYSTEM
CHEST
ELECTROMAGNETIC RADIATION
ENERGY SOURCES
GROWTH
HATCHING
HEAD
HORMONES
INHIBITION
INJECTION
INSECTS
INTAKE
INVERTEBRATES
IONIZING RADIATIONS
METAMORPHOSIS
NERVOUS SYSTEM
NICOTIANA
ORGANS
PLANTS
PUPAE
RADIATIONS
RENEWABLE ENERGY SOURCES
SENSITIVITY
SHIELDING
TIME DEPENDENCE
TRANSPLANTS
X RADIATION