RESUMO
The cytogenetic effect of DDT on human blood cultures, in vitro, was investigated. Two types of experiment were carried out: one, in which the DDT concentrations found in the culture media were similar to those found in the plasma of individuals of the Brazilian population (0.06-0.20 ìg/ml); in the second experiments, doses from 1 to 15 ìg/ml were used. No correlation was found between DDT doses and cells with chromosomal aberrations. The Poisson test of comparison between means showed that at certain DDT concentrations (0.20, 4.05 and 8.72 ìg/ml) the proportion of cells with structural aberrations was significantly greater than in the controls.
Assuntos
Humanos , DDT , Linfócitos , Linfócitos/sangue , Linfócitos/ultraestrutura , Cromossomos , SangueRESUMO
Workers from three insecticide plants in direct contact with 2,2-bis (â-chloro-phenyl)-1,1,1,-trichloroethane (DDT) did not differ significantly in the frequencies of cells with chromosomal aberrations when compared with controls from the same plants but not in direct contact with the drug. The same was true when a group of workers from one plant was compared with a control group from the Institute Butantan, with no history of occupational exposure to DDT. Yet, when the control group from one of the three plants, which showed high DDT plasmic levels, was added to the group in direct contact with the insecticide, the frequency of cells with chromatid aberrations was significantly higher, suggesting that DDT causes chromatid lesions. A positive correlation was found between DDT levels and times of exposure, but being in direct or indirect contact with DDT was not always correlated with the degree of contamination.
Assuntos
Masculino , Humanos , Adulto , DDT , Aberrações Cromossômicas , Cromossomos , Inseticidas/análise , Inseticidas/toxicidade , Doenças Profissionais/induzido quimicamente , Doenças Profissionais/sangue , Exposição AmbientalRESUMO
Chromosome measurements were performed in four species of snakes related at the level of suborder (Boa constrictor amarali, Xenodon merremii, Philodryas patagoniensis, Bothrops jararaca). The data obtained point out that pairs 1-3 were common to the four snakes and probably inherited from the ancestor of the suborder Serpentes. Pairs 5-8-W were characteristic of each snake; hence, it is possible to assume that they followed evolving after the appearing of the suborder Serpentes. Z-chromosomes were metacentric in B. constrictor amarali, X. merremii and B. jararaca and slightly submetacentric in P. patagoniensis. Area of these chromosomes varied from 8.6-10.6% of the haploid set in the four species studied.-The study of chromosome replication at the end of the S period points out that "shared chromosomes" have similar patterns of labeling. Therefore, it is proposed that the distribution of late replicating regions and heterochromatin in the genome is phylogenetically transmitted and probably genetically determined.-The analysis of the ending-sequence of chromosome replication shows that sex chromosomes finish earlier than macroautosomes. It is concluded that snakes probably have no mechanism of sex chromosome heterochromatinization in either sex. The absence of late replicating Z-chromosome in the males, favours the hypothesis that no mechanism of sex dosage compensation is acting in the suborder Serpentes.
Assuntos
Feminino , Animais , Cromossomos/genética , Replicação do DNA/genética , Serpentes/genética , Especificidade da Espécie , Evolução Biológica , Timidina , TrítioRESUMO
Odontophrynus cultripes Reinhardt and Lutken, 1862 has 22 chromosomes in its diploid complement. Spermatocyte I contained 11 ring bivalents and metaphase II exhibited 11 chromosomes. Odontophrynus americanus (Duméril and Bibron) 1882 has 44 chromosomes in somatic as well as germ cells, these can be sorted into 11 groups of homologues. Metaphase I showed varying numbers of quadrivalents and metaphase II exhibited 22 dyads. Ceratophrys dorsataWied., 1824 has 104 chromosomes in somatic and germ cells; these 104 chromosomes comprise 8 each of 13 kinds of homologues. The spermatocyte I contained ring octovalents and other multivalents, and metaphase II 52 chromosomes. The above findings indicate that evolution by polyploidization occurred in South American frogs belonging to the family Ceratophrydidae.
Assuntos
Animais , Anfíbios/genética , Cromossomos/genética , Poliploidia , América do SulRESUMO
Odontophrynus americanus has 2n=44 chromosomes in somatic and gonad cells which can be ordered in 11 groups of homologues. In spermatocytes I they form mostly ring quadrivalents. In metaphase II 22 dyads are present. There is no indication of abnormalities in and gonad development.