COMUTAGENIC EFFECT OF TANNIC-ACID ON RING-X CHROMOSOME LOSS INDUCED BY MITOMYCIN-C IN SPERM CELLS OF DROSOPHILA-MELANOGASTER

To investigate the effects of tannic acid (TA) on ring-X chromosome lo ss, Drosophila melanogaster females exposed to different TA concentrat ions were crossed with untreated, methyl methanesulfonate (MMS)- or mi tomycin C (MMC)-treated males which carried a ring-X chromosome. Proge ny were analyzed for loss of the ring-X. The results of this in vivo s tudy showed that TA had no suppressing effect on chromosome loss occur ring spontaneously or after induction by MMS in mature spermatozoa. In contrast, TA caused a significant increase in the frequency of MMC-in duced ring-X loss. The increase caused by this co-mutagenic effect rea ched values of 34, 33 and 40% at TA concentrations of 10, 25 and 50 mM , respectively. These increments may reflect the action of TA on a uvr ABC-type enzyme which, by increasing the double-strand breaks (DSBs), somehow interferes with the post-replicational repair responsible for the final DSB correction.