RESUMO
Summarizing paper contains short analysis of the publications resulting cell biological, molecular genetic and population genetic investigations devoted to studying of accute radiation exposure and chronic radiation contamination effects on biological systems after disaster on Chornobyl nuclear power station in 1986.
Assuntos
Acidente Nuclear de Chernobyl , Raios gama/efeitos adversos , Neoplasias Induzidas por Radiação/epidemiologia , Plantas/efeitos da radiação , Radioisótopos/análise , Câncer Papilífero da Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/epidemiologia , Monitoramento Ambiental , Água Subterrânea/análise , Humanos , Neoplasias Induzidas por Radiação/patologia , Neoplasias Induzidas por Radiação/cirurgia , Nitratos/efeitos adversos , Nitratos/análise , Plantas/genética , Proteômica , Doses de Radiação , Lesões por Radiação/diagnóstico , Lesões por Radiação/epidemiologia , Lesões por Radiação/patologia , Ablação por Radiofrequência/métodos , Câncer Papilífero da Tireoide/patologia , Câncer Papilífero da Tireoide/cirurgia , Neoplasias da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/cirurgia , Ucrânia/epidemiologiaRESUMO
The essay contains the author's memories of the events related to the accident at the Chernobyl nuclear power plant and the thoughts about the short and long-term consequences of this disaster for society, human and biota. Awareness of the Chernobyl disaster as a multifaceted great incident which is significant for the whole world came slowly through a series of mistakes and errors. Currently it is essential to give a deeper insight into the lessons of Chernobyl for the sake of the future.
Assuntos
Acidente Nuclear de Chernobyl , Exposição Ambiental/história , Neoplasias Induzidas por Radiação/epidemiologia , História do Século XX , Humanos , Neoplasias Induzidas por Radiação/fisiopatologia , Poluentes Radioativos/efeitos da radiaçãoRESUMO
BACKGROUND AND AIMS: The plants that have remained in the contaminated areas around Chernobyl since 1986 encapsulate the effects of radiation. Such plants are chronically exposed to radionuclides that they have accumulated internally as well as to alpha-, beta- and gamma-emitting radionuclides from external sources and from the soil. This radiation leads to genetic damage that can be countered by DNA repair systems. The objective of this study is to follow DNA repair and adaptation in haploid cells (birch pollen) and diploid cells (seed embryos of the evening primrose) from plants that have been growing in situ in different radionuclide fall-out sites in monitored regions surrounding the Chernobyl explosion of 1986. METHODS: Radionuclide levels in soil were detected using gamma-spectroscopy and radiochemistry. DNA repair assays included measurement of unscheduled DNA synthesis, electrophoretic determination of single-strand DNA breaks and image analysis of rDNA repeats after repair intervals. Nucleosome levels were established using an ELISA kit. KEY RESULTS: Birch pollen collected in 1987 failed to perform unscheduled DNA synthesis, but pollen at gamma/beta-emitter sites has now recovered this ability. At a site with high levels of combined alpha- and gamma/beta-emitters, pollen still exhibits hidden damage, as shown by reduced unscheduled DNA synthesis and failure to repair lesions in rDNA repeats properly. Evening primrose seed embryos generated on plants at the same gamma/beta-emitter sites now show an improved DNA repair capacity and ability to germinate under abiotic stresses (salinity and accelerated ageing). Again those from combined alpha- and gamma/beta-contaminated site do not show this improvement. CONCLUSIONS: Chronic irradiation at gamma/beta-emitter sites has provided opportunities for plant cells (both pollen and embryo cells) to adapt to ionizing irradiation and other environmental stresses. This may be explained by facilitation of DNA repair function.
Assuntos
Adaptação Fisiológica/efeitos da radiação , Betula/efeitos da radiação , Acidente Nuclear de Chernobyl , Reparo do DNA/efeitos da radiação , Oenothera biennis/efeitos da radiação , Pólen/efeitos da radiação , Radioisótopos/farmacologia , Sementes/efeitos da radiação , Adaptação Fisiológica/efeitos dos fármacos , Betula/efeitos dos fármacos , Betula/genética , Betula/fisiologia , Quebras de DNA de Cadeia Simples/efeitos dos fármacos , Quebras de DNA de Cadeia Simples/efeitos da radiação , Reparo do DNA/efeitos dos fármacos , Enzimas de Restrição do DNA/metabolismo , DNA de Plantas/biossíntese , Relação Dose-Resposta à Radiação , Germinação/efeitos dos fármacos , Germinação/efeitos da radiação , Nucleossomos/efeitos dos fármacos , Nucleossomos/efeitos da radiação , Oenothera biennis/genética , Oenothera biennis/fisiologia , Pressão Osmótica/efeitos dos fármacos , Pressão Osmótica/efeitos da radiação , Pólen/efeitos dos fármacos , Pólen/genética , Plântula/efeitos dos fármacos , Plântula/efeitos da radiação , Sementes/efeitos dos fármacos , Sementes/genética , Cloreto de Sódio/farmacologia , Fatores de TempoRESUMO
The cell divisions in pea and maize seedling root meristems were synchronized by treatment with 0.03 per cent hydroxyurea for 24 hours. At different times after block cessation (removing seedlings from hydroxyurea), i.e. according to certain phases and subphases of the mitotic cycle, the seedlings were treated with 60Co gamma-radiation at doses from 3 to 32 Gy. Evaluation of seedling radioresistance by the survival of the main root meristem on the tenth day after irradiation led to the following sequence of cell stages in order of increasing resistance. For the pea root meristem: G2, M, late G1, early S, late S, middle S and early G1. For the maize root meristem: late G2, M, G1, early S, early G2, late S and middle S.
Assuntos
Plantas/efeitos da radiação , Divisão Celular/efeitos dos fármacos , Divisão Celular/efeitos da radiação , Radioisótopos de Cobalto , Relação Dose-Resposta à Radiação , Raios gama , Hidroxiureia/farmacologia , Mitose/efeitos da radiação , Tolerância a RadiaçãoRESUMO
In radicle meristem cells of germinating seeds of the pea (Pisum sativum L) before the onset of replicative synthesis of DNA, irradiation with 2-3 krad of gamma-rays induced the incorporation of 3H-thymidine (3H-TdR). Maximum isotope incorporation was noted during the first 2 hours after irradiation. Higher doses of radiation suppressed 3H-TdR incorporation. It was not seen after gamma-irradiation of air-dried seeds, nor after fast-neutron irradiation. The replication inhibitors hydroxyurea and 5-aminouracil had no effect on the gamma-induced incorporation of 3H-TdR, Whereas caffeine and acriflavine inhibited it to some extent. It is suggested that the gamma-radiation-induced incorporation of 3H-TdR in meristem cells during the pre-replicative period may be connected with repair phenomena.