DNA damage induced by copper deficiency in cattle assessed by the Comet assay

Cattle hypocuprosis is a well-known endemic disease in several parts of the world. In a previous paper, the clastogenic effect of copper deficiency in cattle has been described although the occurrence of DNA damage was not di rectly tested. For this reason, the relation between DNA damage assessed by the Comet assay and Cu plasma concentration was studied in Aberdeen Angus cattle. Blood samples were obtained in heparinized Vacutainer((R)) tubes from 28 fe male Aberdeen Angus cows during pregnancy or immediately after to give birt h. Each sample was divided into two aliquots for Comet assay and Cu plasma determination, respectively. From the 28 cattle sampled, 17 were normocupre mic and 11 were hypocupremic, Results obtained showed that whereas the average plasma Cu level in normocu premic cattle was 67.6 mug/dl, in hypocupremic cattle it was 32.1 mug/dl. T he increase of DNA damage was mostly evidenced by the decrease of comet deg ree 1 cells and an increase of comet degree 2 cells. Correlation analysis c omparing plasma Cu levels and degree 1 cells showed a correlation coefficie nt 0.72 (P < 0.01). The comparison between plasma Cu levels and comet degre e 2 cells was -0.65 (P < 0.01). The comparison between plasma Cu levels and the comet length-head diameter medians determined in 23 out of 28 animals showed a correlation coefficient of -0.54 (P < 0.01). The induction of DNA damage was clearly supported by the fact that the decr ease of plasma Cu levels was correlated with the increase of comet length-h ead diameter. These findings could be considered as a contribution to the h ypothesis that DNA and chromosome damage are a consequence of the higher ox idative stress suffered by hypocupremic animals. (C) 2001 Elsevier Science B.V. All rights reserved.