ABSTRACT
0. 05) while UDS was induced by Polygala tenyi folia willd with various doses comparing with normal control. Nevertheless, Polygala tenyi folia willd in doses ranged from 1. 0 to 4. 0 g ? kg-1 inhibited strikingly UDS induced by Pb (CH3COO)2 (P
ABSTRACT
To reveal functional organization of chromosome at late stages of antogenesis we observed heterochromatinization (genetically inactive regions of condensed hetero - or euchromatin) of chromosomes (electron micrographs of lymphoblasts chromatin: heat absorption of condensed chromatin: Ag-positive NORs and associations of acrocentric chromosomes: RNA transcriptional activity): mutation level (aberrations and aneuploidy) and DNA repair capacity (intensity of unscheduled DNA synthesis and sister chromatid exchanges - SCEs.) during aging (from 70 to 114 year). The results obtained permit us to infer that enhanced heterochromatinization in old age blocks reparative enzymes resulting in increased numbers of cells with chromosome mutations. We may conclude that the lowering of DNA repair and the increase of mutation frequency at aging are secondary to the progress of heterochromatinization in chromosomes (gene repression). This indicates a key role of heterochromatinization in aging process.
ABSTRACT
Objective To study the antagonistic effect of organic extracts of Fruit of Chinese Wolfberry (FCW) on chromium (Ⅵ) _induced mutation. Methods Using unscheduled DNA synthesis (UDS) assay, the effects of 0.02 g/ml, 0.01 g/ml and 0.005 g/ml organic extracts of FCW on UDS induced by potassium bichromate [0.31 ?g/ml Chromuim (Ⅵ)] in human peripheral blood lymphocytes were determined. The effects of the order of adding organic extract of FCW and potassium bichromate into cultured lymphocyte suspension on UDS were observed at the same time. Results The value of CPM revealed a significantly higher level in positive control group exposed to 0.31 ?g/ml chromium (Ⅵ) compared with that in negative control group exposed to disstilled water (P
ABSTRACT
Antimutagenic effect of p-aminobenzoic acid (PABA) and sodium bisulfite (NaHSO_3)on the mutagenicity of N-methyl-N-nitro-N-nitrosoguanidine (MNNG) was detected by the mehod of human lymphocytes unscheduled DNA Sythesis (LIDS). The results showed that when the concentration of PABA and NaHSO_3 was varied in presence of a constant concentration of MNNG, 5 ?10~(-5) mol/L concentration of PABA, 3 ? 10~(-4) mol/L concentration of NaHSO_3 were the most effective, while the concentration of MNNG varied in the presence of a constant concentration of PABA and NaHSO_3, antimutagenicity was the most effective at high concentration of MNNG. The results indicated that the PABA and NaHSO_3 exhibited antimutagenic activity towards MNNG-induced mutagenicity in LIDS and the extents of antimutagenicity were related with the concentration of MNNG.