Evaluating the Genotoxicity Enhancement of the Antileukemic Drug 6-Mercaptopurin When Combined With Iraqi Nerium oleander and Narcissus tazetta Extracts in vivo

The present study was aimed to evaluate the genotoxicity of the aqueous extracts of Nerium oleander leaves and Narcissus tazetta bulbs each alone and together with the antileukemic drug 6-Mercaptopurin (6MP) in order to investigate the extracts ability to elevate the chemotherapeutic drug genotoxicity which may influence its treatment of cancer. The cytotoxicity test shows that the LD50 of the aqueous extract of Narcissus tazetta was 752.083 mg/kg and for Nerium oleander was 922.023 mg/kg. On the basis of the achieved LD50 values, the doses 92, 46 ,23 mg/kg of Nerium oleander and the doses 75, 37,18 mg/kg of Narcissus tazetta extracts were chosen, depending on chromosome aberrations, Micronuclei and Mitotic index as a powerful cytogenetic assays in bone marrow cells of Swiss albino male mice. The result indicated that Nerium oleander extract alone at the dose 92mg/kg induced significant effect on centromere break and ring chromosome comparing with the negative control (untreated mice) and significantly increased the mean values of chromatid gap and ring chromosome when compared with the positive control ( 6MP ). While only the dose 46 mg/kg and 23 mg/kg of N. oleander aqueous extracts significantly decreased mitotic index and when combined with 6MP it can enhance its antimitotic activity but not significantly. Moreover the extracts alone and when combined with 6MP did not significantly change the total number of red blood micro nucleated cells. For Narcissus tazetta extract, the three experimental doses alone lead to significant increase in chromosomal aberrations like: chromatid break with fragment, chromatid break without fragment, chromatid gap, centromeric break, ring chromosome and dicentric chromosome. While only the dose 75mg/kg had induced significant structural chromosomal abnormalities such as chromatid break with fragment, chromatid break without fragment centromeric break and ring chromosome, when combined with 6MP. The three doses of N. tazetta extract alone, had led to significant reduction in mitotic index compared with untreated control and also its combination with 6-MP significantly decreased the percentage of mitotic index. Moreover, only the doses 75 mg/kg and 37 mg/kg of N. tazetta extracts, when had given alone caused significant increase of the total micronucleated cells. While only the dose 75mg/kg of N. tazetta had induced significant frequency of the total micronucleated cell when combined with 6MP. In the present report, we attempted to establish that N.tazetta and Nerium oleander aquatic extracts enhance the genotoxicity and bioactivity induced by the antileukemic drug 6MP , thus preventing the development of cellular drug resistance which is a major problem that can face cancer patients using this drug .The current study serve the purpose of which is to search for local plants that may contribute to the establishment of novel supportive complementary and alternative medicine (CAM) during the chemotherapy of cancer in Iraq , Further studies are merited to explore this possibility.

Study of chromosomal abnormalities in Channa punctatus exposed to fenvalerate

The chromosomal aberration test in kidney cells of Channa punctatus was conducted to study the genotoxic effect of synthetic pyrethroid fenvalerate, Different chromosomal abnormalities were seen and their frequency was recoded in metaphase spreads obtained from fishes exposed to three sub lethal concentrations (0.0625, 0.0314 and 0.0157 ppm) of this compound. The exposure to fenvalerate caused various structural abnormalities in chromosomes such as chromatid break, fragment, gap, chromatid separation, deletion and ring type chromosomes. Results obtained in present investigations clearly indicate that fenvalerate acts as a genotoxic agent in Channa punctatus.

Cytogenetic Study on Workmen Occupationally Exposed to Pesticides

Cytogenetic Study on Workmen Occupationally Exposed to PesticidesA cytogenetic study was performed on 40 workmen who were exposed to the pesticides malathion and chlorpyrifos and on 30 healthy males who had not been so exposed. The exposed workers had a consistent increase in chromosome abnormalities including chromatid gap, chromatid break, isochromatid break, dicentric and ring chromosomes, as determined by the standard chromosome aberration assay, when compared to the control group. The incidence was significantly higher in exposed smokers than that for exposed non smokers and than that for the unexposed controls as well. These findings provide further evidence for the intrinsic mutagenic activity of the pesticides studied.

RECOMBINATION AT THE BAR LOCUS IN AN INVERTED ATTACHED-X SYSTEM IN DROSOPHILA MELANOGASTER

ABSTRACT Recombination at the Bar locus in Drosophila melanogaster was investigated in an inverted attached-X system which enhanced the frequency of homozygosis for the Bar region. Females among the progeny of homozygous B mothers were searched for changes of B to BB and to B+. Marker genes were followed and exceptional half-tetrads were analyzed in regard to two hypotheses: that of exchange between obliquely synapsed members of the duplication, which is associated with exchange of outside markers, and that of intrachromosomal exchange, which does not involve recombination of markers.—Recombinant exceptions of B+ /BB genotype, carrying the outside marker combinations predicted on the hypothesis of exchange between obliquely synapsed duplication members, were encountered repeatedly. It is established that B+ and BB strands are reciprocal products of the same event.—Twelve nonrecombinant exceptional strands were isolated; ten of these were B+ and two were BB. Only one of the nonrecombinant half-tetrads offered the opportunity to test the prediction of reciprocity of the intrachromosomal event. Analysis showed the exceptional female to be of the constitution BB/B, a type not expected on the hypothesis. While it could have arisen through some kind of copy error in the repair of a chromatid break, a valid test of the hypothesis of intrachromosomal exchange must rest on the isolation and analysis of more cases of the appropriate exceptional genotype.—In several cases Bar changes were found to be associated with aberrations; all but one of these involved spontaneous, cytologically identifiable deletions.