Radiation-induced DNA damage in canine hemopoietic cells and stromal cells as measured by the comet assay

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.

Blood-forming system in rats after whole-body microwave exposure; reference to the lymphocytes

The influence of 2.45 GHz microwave (RF/MW) irradiation on blood-forming cells after whole-body irradiation of rats was investigated. The exposures were conducted with a field power density of 5-10 mW/cm2, and whole-body average specific absorption rate (SAR) of 1-2 W/kg. Four experimental subgroups were created and irradiated 2, 8, 15 or 30 days, for 2 h a day, 7 days a week. Concurrent sham-exposed rats were also included in the study. The cell response was assessed by number and type of the bone marrow nuclear cells and peripheral blood white cells using standard laboratory methods. Significant decrease in lymphoblast count was obtained at 15 and 30th experimental day (P < 0.05), whereas other examined parameters did not significantly differed in comparison to the sham-exposed controls. The findings point out at stress response in blood-forming system in rats after selected microwave exposure, which could be considered rather as sign of adaptation than malfunction.

Single cell gel electrophoresis assay: methodology and applications

The single cell gel electrophoresis or Comet assay is a sensitive, reliable, and rapid method for DNA double- and single-strand breaks, alkali-labile sites and delayed repair site detection, in eukaryotic individual cells. Given its overall characteristics, this method has been widely used over the past few years in several different areas. In this paper we review the studies published to date about the principles, the basic methodology with currently used variations. We also explore the applications of this assay in: genotoxicology, clinical area, DNA repair studies, environmental biomonitoring and human monitoring.

Changes in the repair capacity of blood cells as a biomarker for chronic low-dose exposure to ionizing radiation

The purpose of this study was to examine whether changes in the repair capacity of blood cells could be used as a valuable biomarker for radiation exposure. To characterize the repair kinetics in nonirradiated and irradiated cells we first performed in vitro split dose experiments. DNA damage and DNA repair capacity were analysed using the comet assay. Our results showed that the first in vitro irradiation affects the repair system of the cells, resulting in a decreased repair capacity after the second irradiation. Furthermore, the second irradiation results in a large amount of DNA damage in the blood cells. To test whether the analysis of the DNA repair capacity after in vitro irradiation is also a valuable method for in vivo studies of donors exposed to radiation, we analysed the repair capacity of blood cells of two exposed groups: patients subjected to a radioiodine therapy and chronically irradiated volunteers from the Chernobyl region. Both groups also showed a significantly impaired repair capacity indicating a stress on the hematopoietic system. In addition, in the group of the Ukrainians DNA damage after in vitro irradiation was significantly higher than in a control group. These results lead to the presumption that the repair capacity and the DNA damage after in vitro irradiation might be a very useful biological marker for radiation exposure in population monitoring.