Fig. 3a–f.
Human lymphocytes were left untreated or exposed to hydrogen peroxide, brevetoxin, or brevenal for 1 h. a A human lymphocyte that has not been exposed to any genotoxic damaging chemical. There is no DNA damage. b Human lymphocytes treated with hydrogen peroxide (positive control). A large amount of DNA damage is present. c Human lymphocytes treated with 10−8 M brevetoxin. Both sources of brevetoxin used in this experiment at a concentration of 10−8 M resulted in a similar degree of DNA damage. d,e Human lymphocytes first treated with brevenal for 1 h prior to treatment with 10−8 M brevetoxin for 2 h (d) or first treated with 10−8 M brevetoxin for 1 h prior to treatment with brevenal for 2 h (e). Upon brevenal pretreatment (1.0 μg/ml) the lymphocytes are protected from the damaging effects caused by brevetoxin. f Human lymphocytes after treatment with the DNA polymerase inhibitor aphidicolin. Lymphocytes were treated first with 10−9 M aphidicolin and 1.0 μg/ml brevenal for 1 h, followed by 10−8 M PbTx for 2 h