Induction and repair of DNA strand breaks and oxidised bases in somatic and spermatogenic cells from the earthworm Eisenia fetida after exposure to ionising radiation

Methods for analysing oxidised DNA lesions [formamidopyrimidine glycosylase (Fpg)-sensitive sites] in coelomocytes and spermatogenic cells from the earthworm Eisenia fetida using the Fpg-modified comet assay were established. The DNA integrity (SSBs = strand breaks plus alkali labile sites and Fpg-s...

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Bibliographic Details
Published in:Mutagenesis 2011-11, Vol.26 (6), p.783-793
Main Authors: Hertel-Aas, Turid, Oughton, Deborah Helen, Jaworska, Alicja, Brunborg, Gunnar
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Body Weight - radiation effects
Comet Assay
DNA Breaks - radiation effects
DNA Repair - radiation effects
Dose-Response Relationship, Radiation
Eisenia fetida
Fundamental and applied biological sciences. Psychology
Gamma Rays
Male
Molecular and cellular biology
Molecular genetics
Mutagenesis. Repair
Oligochaeta - cytology
Oligochaeta - radiation effects
Oxidation-Reduction - radiation effects
Purines - metabolism
Pyrimidines - metabolism
Radiation, Ionizing
Spermatozoa - cytology
Spermatozoa - metabolism
Spermatozoa - radiation effects
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Summary:Methods for analysing oxidised DNA lesions [formamidopyrimidine glycosylase (Fpg)-sensitive sites] in coelomocytes and spermatogenic cells from the earthworm Eisenia fetida using the Fpg-modified comet assay were established. The DNA integrity (SSBs = strand breaks plus alkali labile sites and Fpg-sensitive sites) in cells from E. fetida continuously exposed to 60Co gamma-radiation (dose rates 0.18-43 mGy/h) during two subsequent generations (F0 and F1) were measured and related to effects on reproduction end points which have already been reported. The data suggest a slight increase of Fpg-sensitive sites in spermatogenic cells from worms exposed at 11 mGy/h in the F0 generation but not in F1, whereas reduced reproduction had been observed at dose rates at or >4 mGy/h in F0 and at 11 mGy/h in F1. Using acute X-rays (41.9 Gy/h), dose-response relationships were established for SSBs in coelomocytes and spermatogenic cells exposed in vitro. In vivo DNA repair was studied by measuring the decrease in damage (SSBs and Fpg-sensitive sites) in coelomocytes and spermatogenic cells isolated from worms at different times (0-6 h) after acute X-ray exposure (4 Gy). SSBs were repaired in coelomocytes following biphasic kinetics, i.e. with a fast and a slow half-life (t 1/2) of 36 min (95%) and 6.7 h (5%), respectively. Fpg-sensitive sites were repaired at considerably lower rates (t 1/2 = 4-5 h). In spermatogenic cells, SSB repair during the first hour was observed but a half-life could not be estimated. Repair of Fpg-sensitive sites could not be determined. In general, a reduced repair of Fpg-sensitive sites suggests a higher potential for accumulation of oxidised lesions, compared to SSBs, in earthworms exposed to radiation and other environmental contaminants. This is the first study comparing DNA damage with reproduction in earthworms exposed to ionising radiation.
ISSN:0267-8357
1464-3804
DOI:10.1093/mutage/ger048