Introduction

1. 14.7 13.5 10.9 0.23 0 0.21 0.000003 small 0.0 normal 0 100 2500 5000 0.18 Micro moles of Cadmium. 0.16 No. of cellsX 100 million. Normal Small 0.04 0.002 0.0003 0 0 0.003 0.002 0.002 0.001 0 100 5000 . Micro moles of Cadmium Micromoles of Cadmium. In the zero to 300 micro mole range of CdCl2, toxicity Was absent. Among numerous normal size colonies, a few small colonies were also observed. • Cadmium toxicity and mutagenicity in excision repair deficient and proficient strains of Salmonella typhimurium • Kip Green, Gyula Ficsor, and Leonard Ginsberg, Biological Sciences Department Western Michigan University, Kalamazoo, MI Results Introduction Toxicity of Cadmium Chloride inexcision repair proficientstrain. Toxicity of Cadmium Chloride in theexcision repair deficientstrain. Normal and Small colonies. ● Cadmium is a naturally occurring metallic element, and is ubiquitous in the environment. ● It is taken up by plants, e.g. tobacco. ● It has no beneficial biologic role. ● Ouch-ouch disease in Japan. ● Devastating to male fertility in mice. Normal and Small colonies:excision repair deficient, control X108 cells Normal Small 0 3.3 33 330 Hypothesis At 2500 to 5000 micro moles of Cadmium, normal colonies are more frequent than small colonies. At high doses Cadmium replaces Zinc in an S.O.S. repair protein. Cadmium toxicity inexcision repair deficientstrain: Normal and Small colonies. Discussion Methods & Materials Normal and Small colonies:excision repair deficient, Cd-treated 10.5 9.7 CdCl2 was not toxic over a range of 3.3 and 330 micro moles. Cell killing is more than 99.9% at doses of 2500 micro moles to 5000 micro moles. At high doses, many slow growing (small) mutant colonies were seen in theexcision repair deficientstrain. In the absence of excision repair, cell survival depends on the SOS repair. We suggest that at high doses, Cd replaces zinc in a SOS protein and causes a higher level of mutations (small) then would be the case if Zinc was present. This hypothesis is supported by the fact that whenexcisionrepair is present,and the SOS repair is absent, fewer mutations are induced. X108 cells: 8.6 ● S. typhimurium is treated with Cadmium Chloride. ● After 24hrs, the cells were washed and plated. ● After incubation @ 37.5 Celsius for 24 hrs. colonies were counted and were observed for colony size. Normal 0.0 Small 0.0013 Small 0.0003 Normal 0 10 100 5000 Micromoles of Cadmium. 10 & 100 micro moles of CdCl2 were not toxic, and there were more normal colonies than small colonies. At 5000 micro moles CdCl2 was toxic, and there were more small colonies than normal colonies. Excision repair deficient and proficient strains used. Normal and Small colonies:excision repair proficient, Cd-treated Cadmium toxicity inexcision repair deficientstrain. (repeat experiment.) Acknowledgements X108 cells: ● We thank financial support from the NIH Bridges Program. Normal ● The excision repair deficient strainscan notrepair DNA damage during DNA replication (first line of defense) ● The excision repair proficient strain canrepair DNA replication DNA damage. Small 10 & 100 micro moles CdCl2 were not toxic. 5000 micro moles of CdCl2 was toxic. At the more toxic dosage, At 5000 micro moles CdCl2 was toxic, and there were more small colonies than normal colonies.