Damage to grass shrimp (Palaemonetes pugio) embryo DNA by summer sunlight followed by DNA repair in the dark |
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Authors: | G B Kim R F Lee D L Mitchell |
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Institution: | (1) Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, Georgia 31411, USA Fax: 001 (0)912-598-2310 e-mail: kgb@skio.peachnet.edu, US;(2) MD Anderson Cancer Center, Science Park Research Division, Smithville, Texas 78957, USA, US |
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Abstract: | DNA strand damage, using the single-cell gel electrophoresis (comet) method, was determined in different-stage embryos of
grass shrimp (Palaemonetes pugio) collected from surface waters of a local estuary near Savannah, Georgia, USA. Late-stage embryos collected from the estuarine
river at midday in the summer or placed in a solar simulator showed extensive DNA strand damage. The solar simulator, which
produced the total irradiance found at midday in the summer at 34°N caused DNA strand damage in embryos similar to that found
in sunlight-exposed embryos. A large increase in cyclobutane pyrimidine dimers (18 cyclobutane pyrimidine dimers per 1000
kilobases) were detected in DNA from the late-stage embryos exposed to the solar simulator for 1 h (solar irradiance of 126 μW
cm−2). DNA repair took place within a few hours when late-stage embryos collected at midday from the river were transferred to
the dark. Early grass-shrimp embryo stages showed no DNA strand damage either after placement in the solar simulator or when
collected at midday in the summer. This lack of solar-damaged DNA in early-stage embryos was probably due to the presence
of high concentrations of carotenoids, which can act as anti-oxidants to prevent damage from activated oxygen species produced
by cells exposed to ultraviolet light. These carotenoids are utilized by the developing embryos, and only low concentrations
of carotenoids were present in late embryo stages.
Received: 24 May 1999 / Accepted: 11 May 2000 |
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