Chromosome-breaking activity of extracts of the mushroom Paxillus involutus Fries ex Batsch.

Dry and presoaked seeds of Nigella damascena were treated with aqueous extracts of the mushroom Paxillus involutus. At the first mitosis after the onset of germination, metaphase chromosomes showed damage independent of the origin of the mushrooms. The damaging substance(s) is (are) thermostable. Except a few achromatic gaps, all the lesions observed are of the chromosome type, i.e. are induced at the pre-synthetic G1 stage.

In vivo mutagenicity evaluation of domperidone in Drosophila germ cells and rat bone marrow cells.

Possible induction of chromosome aberrations and gene mutations by domperidone was studied in vivo respectively by a micronucleus test on female rats and a sex-linked recessive lethal test on Drosophila. In accordance with previous results all these studies revealed negative findings for domperidone so that it can be concluded that domperidone has no potential to induce chromosome aberrations and/or gene mutations.

Mutagenicity of some organophosphorus compounds at the ade6 locus of Schizosaccharomyces pombe.

12 organophosphorus insecticides were tested for toxicity and mutagenicity in the forward mutation test system ade6 of the yeast Schizosaccharomyces pombe. EMS and MMS were selected as positive controls. 3 compounds, dichlorvos, trichlorfon and paraoxon, showed a linear dose-response relationship. Among the other compounds investigated, methyl derivatives, though in general more toxic than ethyl derivatives, did not significantly increase the mutation frequency. Trichlorfon, tested in combination with malathion, methylparathion or methylazinphos (guthion), produced clearly synergistic effects for both toxicity and mutagenicity. The addition of S9 microsomal liver fraction decreased the efficiency of both single and combined treatments only where a dose-response relationship or a synergistic effect was obtained.

Genetic effects in the mouse of formaldehyde in combination with adenosine and hydrogen peroxide.

Male mice of the Q strain were injected (i.p.) with a synthetic methylene dinucleotide (Ado-CH2-Ado) and with a mixture of formaldehyde and hydrogen peroxide. Neither injection induced any chromosome lesions in spermatogonia. In the dominant lethal mutation test, the mixture of formaldehyde and hydrogen peroxide had an effect throughout spermatogenesis, but only the rate of pre-implantation losses was increased. Injection of Ado-CH2-Ado increased both pre-and post-implantation deaths at the 1st week but only the frequency of pre-implantation losses at the 6th week.

Metrifonate and dichlorvos: cytogenetic investigations.

Contradictory results are found in the literature about the cytogenetical effects of dichlorvos and metrifonate in mammals whereas their chromosome breaking ability was demonstrated in plant and Drosophila cells. They were tested on both in vitro and in vivo cells for chromosome breakage. Dominant lethal mutations were also investigated in mouse as well as epidemiological studies in man. In our experiments on mouse bone marrow and testis, one acute dose was injected respectively: 10 mg/kg for dichlorvos and 100 mg/kg for metrifonate. These experiments failed to reveal any clastogenic effect in these test systems as well as in chronic treatments respectively 2 p.p.m./5 days a week for 7 weeks for dichlorvos and 0.5 p.p.m. 5 days a week for 7 weeks for metrifonate. In an investigation of dominant lethal mutations, dichlorvos did not enhance the frequency of dead embryos but the frequency of pre-implantation losses was significantly increased in two specific periods of the seven investigated. In the same test, metrifonate did not produce any effect. These data are compared with those obtained with trimethylphosphate and MMS taken as positive controls. These results will serve to reevaluate the cytogenetical risks of dichlorvos and metrifonate.