The cross-linking agent hexamethylphosphoramide predominantly induces intra-locus and multi-locus deletions in postmeiotic germ cells of Drosophila.
The nature of DNA sequence changes induced by the cross-linking agent hexamethylphosphoramide (HMPA) within and in the vicinity of the vermilion locus of Drosophila melanogaster that produce a vermilion mutant phenotype was analyzed after exposure of postmeiotic male germ cells. Mutagenized males were mated to either females wild-type (exr+) for nucleotide excision repair (NER) or to females having a deficiency (exr-) for NER. Rearrangements, mostly deletions, represented by far the most frequent type of mutational events induced by HMPA that are detected as vermilion mutations. In the exr+ group, all but one (a double substitution) of 21 mutants characterized were large sequence changes: we found 5 intra-locus deletions, 3 intra-locus deletions associated with insertions and 12 multi-locus deletions. When taken together, deletions and deletion/insertion mutations represent 96% of the HMPA-induced DNA modifications obtained under proficient repair conditions. Of the 10 mutants obtained from crosses with exr- females, 6 intra-locus and 2 multi-locus deletions were found, as opposed to just 1 point mutation and 1 double substitution. The "hypomutability effect" observed with exr- genotypes in relation to the wild type seems to be caused by a decrease in the frequency of multi-locus deletions in the former group. The results suggest that the NER system is involved in the generation of multi-locus deletions, whereas intra-locus deletions appear to be formed through a postreplication slipped-misrepair pathway. It is concluded that an eukaryotic in vivo system with no limitations for the recovery of multi-locus deletions, such as vermilion, should be used for the analysis of DNA damage induced by cross-linking agents.
Aguirrezabalaga
I
I
Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, Sylvius Laboratories, The Netherlands.
Nivard
M J
MJ
Comendador
M A
MA
Vogel
E W
EW
D000818:Animals; D001483:Base Sequence; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D003433:Crosses, Genetic; D018736:DNA Adducts; D004249:DNA Damage; D004252:DNA Mutational Analysis; D004260:DNA Repair; D004331:Drosophila melanogaster; D005260:Female; D005804:Genes, Lethal; D005808:Genes, Recessive; D006492:Hempa / Q000494:pharmacology* / Q000633:toxicity; D008297:Male; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000187:drug effects*; D009154:Mutation; D017384:Sequence Deletion; D013094:Spermatozoa / Q000187:drug effects*
D003432:Cross-Linking Reagents; D018736:DNA Adducts; D006492:Hempa