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The vein locus (vn) includes lethal alleles (designated also defective dorsal discs) that prevent growth of dorsal discs and in viable genetic combinations reduce the number of cells of the adult wing. Those effects are prominent in genetic mosaics. Cell proliferation is reduced in all regions of the wing blade in a local autonomous way. These effects are(More)
The bis-dioxopiperazine ICRF-193 has long time been considered as a pure topoisomerase II catalytic inhibitor able to exert its inhibitory effect on the enzyme without stabilization of the so-called cleavable complex formed by DNA covalently bound to topoisomerase II. In recent years, however, this concept has been challenged, as a number of reports have(More)
DNA topoisomerases are highly specialized nuclear enzymes that perform topological changes in the DNA molecule in a very precise and unique fashion. Taking into account their fundamental roles in many events during DNA metabolism such as replication, transcription, recombination, condensation or segregation, it is no wonder that the last decade has(More)
The fluorescence plus Giemsa (FPG) and fluorescence in situ hybridization (FISH) techniques have been used to determine, respectively, the frequencies of sister chromatid exchanges (SCEs) and stable chromosome aberrations (translocations) induced by different concentrations of BrdU in the Chinese hamster ovary cell mutant EM9 and its parental line AA8. The(More)
The effect of thymidine (dT) and 5-fluorodeoxyuridine (FdU) on the frequency of sister-chromatid exchanges (SCEs) was examined in root-tip cells of Allium cepa. dT was unable to induce SCEs at all the concentrations tested. In contrast, FdU was efficient in the induction of SCEs. A nearly 3-fold increase in the frequency of SCEs was obtained with 5 X 10(-7)(More)
Luteolin and quercetin are widely distributed plant flavonoids that possess a variety of chemical and biological activities, including free-radical scavenging and antioxidant activity. Recently, both flavonoids have been reported to inhibit DNA topoisomerases I and II (topo I and topo II), a property that, together with their ability to induce DNA and(More)
The striking phenomenon of endoreduplication has long attracted attention from cytogeneticists and researchers into cell cycle enzymology and dynamics alike. Because of the variety of agents able to induce endoreduplication and the various cell types where it has been described, until now no clear or unique mechanism of induction of this phenomenon, rare in(More)
There are controversial theoretical models about a possible involvement of DNA topoisomerase II (topo II) in the molecular mechanism of sister chromatid exchanges (SCEs). In order to clarify the role of this enzyme, if any, in such recombinational event, CHO parental AA8 and mutant EM9 cells, which shows and extremely high baseline frequency of SCE, have(More)
In April 1998, an ecological disaster resulting from a massive toxic spill of mining acid waste rich in heavy metals posed a serious threat to the Doñana National Park in southwestern Spain. This especially important protected area is the nesting and breeding site for many endangered bird species; white storks (Ciconia ciconia) and black kites (Milvus(More)
We have carried out experiments to study the possible induction of an adaptive response in cultured bovine and rabbit lymphocytes conditioned with subtoxic doses of hydrogen peroxide after stimulation and subsequently challenged with 1 Gy of X-rays. Peroxide treatment was given at different doses 48 h after the addition of PHA to stimulate the cells. A(More)