- To simulate the effects of deep space travel on humans Shimada et al. (2005) Proc. Natl. Acad. Sci. USA 102:6063–6067 studied the effects of cosmic ray exposure in Medaka fish (Oryzias latipes).Wild type males were exposed to high doses of cosmic rays. They were then mated to females with recessive alleles at five different scale colour loci to determine the mutation frequency.
a) What broad types of mutation will be induced in the male Medaka by exposure to cosmic rays? Can they be measured equally well by this assay?
b) What is the general name for this type of assay.
c) Why did Shimada et al use female fish with multiple recessive alleles in this experiment?
d) Briefly describe another experimental system which the researchers could have used to measure mutation frequency in a higher organism?
e) Exposure to two different types of cosmic rays with energies of 13 keV/mm and 147 keV/mm had virtually identical relative biological effectiveness for cell killing, mutations, and cancer induction. Why do you think this was the case?
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