Use of centromeric and telomeric DNA probes in in situ hybridization for differentiation of micronuclei induced by lomefloxacin

Abstract

Classification of micronuclei induced by lomefloxacin, a difluorinated quinolone bactericidal agent, in mouse bone marrow was performed by fluorescence in situ hybridization using DNA probes for the centromere repeated minor satellite DNA and the telomeric hexamer repeat (5'-TTAGGG-3'). Colchicine and mitomycin C were used as a positive control aneugen and clastogen, respectively, and these compounds produced the expected responses. Single doses of 40, 80, 160, or 320 mg/kg lomefloxacin were given via oral intubations and bone marrow was sampled at 24 and 48 hr after treatment. The micronuclei showed significant increases in both sampling times after doses of 320 mg/kg. A statistically significant increase of micronuclei frequency was also detected for 160 mg/kg lomefloxacin at 48 hr after treatment. The responses were directly correlated with bone-marrow cytotoxicity. Following treatment with 160 and 320 mg/kg lomefloxacin, 48.2 and 50.0% of the induced micronuclei, respectively, showed double labeling with centromeric signals and several telomeric signals, indicating that the induced micronuclei were composed of whole chromosomes. Similarly, 51.8 and 50.0% of the induced micronuclei, respectively, were centromere-negative, demonstrating that lomefloxacin not only induces chromosome loss but also chromosome breakage. The results also showed that chromosomes can be enclosed in a micronucleus before and after centromere separation. Overall, this study provides the first evidence of the potential of lomefloxacin to induce aneugenic effect in mice. However, given the high doses used in this study, the clinical significance of this finding is uncertain.

FISH in micronucleus test demonstrates aneugenic action of rotenone in a common freshwater fish species, Nile tilapia (Oreochromis niloticus)

“…As our study used in vivo exposure, it is probable that in this case the cyclophosphamide also presented this differentiated action due to a metabolisation process. In the treatment with colchicine the number of C + MN markers was much higher than the number of C − MN markers in the exposed individuals, confirming the aneugenic action of the substance, which has already been described by other authors (21,27,28). These data confirm the sensitivity of this experimental protocol in detecting clastogenic and aneugenic agents.…”

“…Cyclophosphamide is a clastogenic agent indicated as a positive control (OECD, 1997). In the FISH technique it is also necessary to use an aneugenic agent; in this work, colchicine was used, as recommended by several authors (21,22). After removing blood, blood smears were prepared and fixed in 100% ethanol for 10 min.…”

Aneugenic Effects of Epirubicin in Somatic and Germinal Cells of Male Mice

“…Animal sacrifice was done under light ether anesthesia, and all efforts were made to minimize suffering. Immediately after the animal was sacrificed by cervical dislocation, both femurs were removed and bone marrow cells were sampled as described previously [16] . In human chemotherapy, epirubicin is typically administered at doses up to 135 mg/m 2 as a single agent every three to four weeks.…”

Comet‐FISH studies for evaluation of genetic damage of citalopram in somatic cells of the mouse

“…). Fifty‐five to 90 MN per group of coded slides were examined for the presence or absence of a centromeric DNA probe as described previously (Attia, ).…”