Chromosomal aberrations in native small mammals (peromyscus leucopus) at a petrochemical waste disposal site: II. Cryptic and inherited aberrations detected by G-band analysis

Abstract

Wild rodents (Peromyscus leucopus) collected from a hazardous waste site polluted with petrochemicals and known to have significantly increased frequencies of somatic chromosome aberrations in a standard metaphase chromosome aberration (SMCA) assay were examined by G-banding, a differential staining technique. Several classes of aberrations not detectable with SMCA were identified, including Robertsonian fusions, pericentric and paracentric inversions, and interstitial deletions. Four classes of these more cryptic aberrations were significantly higher in animals from the hazardous waste site compared to animals from reference sites. Several animals also carried apparently inherited aberrations in chromosomes 5, 10, and 21, suggesting that aberrations induced in a parent may be transmitted to offspring. When all classes of aberrations were converted to numbers of lesions per cell, animals from the hazardous waste site did not show elevated frequencies of lesions or aberrant cells, compared to animals from reference sites, unless inherited aberrations were removed from the data set. Then animals collected from the hazardous waste site showed a significantly increased number of aberrations per cell. Two chromosomes (5 and 21) sustained more aberrations than the other members of the complement, suggesting that some chromosomes may be more susceptible to induced damage than others. The method of G-banding itself may obscure much of the damage attributable to single chromatid breaks in SMCA but reveals types of damage not detectable in SMCA, indicating that the application of any single genetic assay technique may seriously underestimate actual levels of induced damage in exposed organisms.