Mutagenic efficiency of organophosphorus insecticides used in combined treatments.

Male mice (Q strain) received two consecutive injections of organophosphorus insecticides: a phosphonate (trichlorfon) was combined to a thiophosphate (methylparathion) or a dithiophosphate (malathion or methylazinphos) in order to evaluate the interactions at the genetic and cytogenetic levels. No increase in chromosome damage was observed in bone marrow cells, spermatogonia, and primary spermatocytes. In a dominant lethal mutation assay, the frequency of postimplantation lethality was not significantly increased over the control level. The percentage of preimplantation losses was enhanced, probably due to a toxic effect on male germ cells.

Lack of synergistic effect between arsenic, mercury and ethyl methane sulfonate on the frequency of chromosomal aberrations in mice.

The influence of arsenic and mercury on the frequency of chromosome aberrations induced by ethylmethane sulfonate was studied in mice. No synergistic effects could be demonstrated in somatic and germ cells of mice given a combined treatment of arsenic trioxide solution (As2O3, 12 mg per kg body weight) or of mercuric chloride solution (HgCl2, 6 mg per kg body weight) with ethylmethane sulfonate (EMS, 200 mg per kg body weight).

Cytogenetic and genetic effects of subchronic treatments with organophosphorus insecticides.

Male mice (Q strain) received 5 days a week for 7 weeks drinking water containing dichlorvos (2 ppm), dimethoate (0.6 ppm), malathion (8 ppm), methylparathion (0.15 ppm), or trichlorfon (0.5 ppm). At the end of the treatment, no chromosome damage was observed in bone marrow cells, spermatogonia, and primary spermatocytes. Dominant lethal mutation assays were performed to investigate the pre- and postimplantation foetal lethality. Only negative results were obtained.

Evaluation of the mutagenic potential of four commercial mixtures of insecticides.

Male mice (Q strain) were given a single ip injection at the maximum tolerated dose of one of four commercial mixtures of insecticides: Luxan Tue-Taons (150 g dimethoate and 150 g fenitrothion/litre), Metadipterex (210 g trichlorfon and 270 g methyldemeton/litre), Dynafos (155 g malathion, 60 g dichlorvos and 75 g carbaryl/litre) and Phosan Plus (95 g dimethoate, 100 g malathion and 100 g methoxychlor/litre). At the maximum tolerated doses, Luxan Tue-Taons (60 mg/kg), Metadipterex (15 mg/kg), Dynafos (50 mg/kg) and Phosan Plus (100 mg/kg) did not induce chromosome aberrations in bone-marrow cells, spermatogonia or primary spermatocytes of the mice. No evidence of potential genetic effects was obtained in a dominant lethal mutation assay.

Absence of genetic and cytogenetic effects in mice treated by the organophosphorus insecticide parathion, its methyl analogue, and paraoxon.

Male mice (Q strain) received a single i.p. injection of 3 organophosphorus compounds: ethylparathion (10 mg/kg), its methyl analogue (methylparathion, 10 mg/kg), or its phosphate derivative (ethylparaoxon, 0.3 mg/kg). The number of chromosome aberrations observed in bone marrow cells and spermatogonia, and the frequency of pre- and postimplantation foetal lethality obtained in a dominant lethal mutation assay, did not conclusively prove that the tested compounds produced a mutagenic effect.

Genetic and cytogenetic effects induced in the mouse by an organophosphorus insecticide: malathion.

Male mice (Q strain) received an ip injection of malathion (300 mg/kg). The percentage of chromosome aberrations was not increased in both bone marrow cells and spermatogonia. In a dominant lethal mutation assay, the frequency of pre- and postimplantation fetal lethality was not significantly enhanced over the control level.

Cytogenetic effects induced by organophosphorus pesticides in mouse spermatocytes.

Male mice (Q strain) received a single i.p. injection of 14 organophosphorus compounds, including 11 insecticides, administered on separate occasions. After a recovery period of 10 to 15 days, the cytogenic effects were analyzed in primary spermatocytes at diakinesis-metaphase I corresponding to the treatment of A4-B type spermatogonia. At the highest tolerated dose, trimethylphosphate (1000 mg/kg), triethylphosphate (300 mg/kg), dichlorvos (10 mg/kg), methylparathion (10 mg/kg), ethylparathion (10 mg/kg), ethylparaoxon (0.3 mg/kg), fenitrothion (1000 mg/kg), methylbromophos (1000 mg/kg), ethylbromophos (1000 mg/kg), dimethoate (10 mg/kg), malathion (300 mg/kg), methylazinphos (1 mg/kg), ethylazinphos (1 mg/kg) and trichlorfon (100 mg/kg) did not produce chromosome damage.

Genetic and cytogenetic effects of Fenitrothion.

Male mice (Q strain) were injected intraperitoneally with a high dose (i.e., 1 g/kg) of the organophosphorus insecticide Fenitrothion. No increase in the percentage of chromosome aberrations was observed in bone marrow cells and spermatogonia. A dominant lethal mutation assay did not show any enhancement of fetal mortality before or after implantation.

Genotoxicity of an organophosphorus insecticide, dimethoate, in the mouse.

The effects of dimethoate were investigated in the mouse after acute (10 mg/kg i.p.) or chronic treatment (0.6 ppm, 5 days a week for 7 weeks). Dominant lethal mutations were scored for a 7-week period after the acute dose, and immediately after exposure for the chronic dose. Chromosome damage was also analysed in bone marrow and spermatogonial cells at the same dose levels (from 12 to 48 h after treatment). MMS (60 mg/kg i.p.) was chosen as the positive control. In no experiment did dimethoate show any genotoxicity.

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.

[A cytotaxonomic study of Rumex. IV. The Acetosa Mill. species]. / Contribution à l'étude cytotaxonomique des Rumex. IV. Le genre Acetosa Mill

1. Karyotypes of 18 species of the sections Scutati (2), Vesicarii (2), Hastati (4), Afroacetosae (2) and Acetosa (8) of the genus Acetosa have been investigated in detail. 2. Four evolutive tendancies were distinguished i.e.: decrease of chromosome number and arm ratio, increase of chromosome length and differentiation of sex crhomosomes. These tendancies are fully expressed in the section Acetosa as compared with the others. 3. In this section, relationships between the subsections Acetosa, Insectivalves and Americanae were established especially dealing with the change of sex determination from the type XX/XY to the type XX/XY1Y2. 4. Evolutive pathways within the genus Acetosa as well as in the whole group of Rumex sensu lato are described.