Radiation-induced mutations at mouse hemoglobin loci.

Abstract

In experiments designed to detect new mutations affecting Hb, the male or female parent in reciprocal crosses of 2 mouse strains that differ in alleles at the Hb (Hba, Hbb) loci as well as at 5 other specific loci were irradiated. Offspring were analyzed for Hb properties (electrophoretic pattern, solubility, crystal pattern), serum albumin differences, erythrocyte lysis, reticulocyte count and external appearance. Five Hb variants were found among the mutants. In 3, the genetic contribution from the irradiated father was not expressed with regard to the .alpha.-chain; one carried a tandem duplication (the 1st known case in the mouse) involving Hbb; and one probably resulted from double nondisjunction of chromosome 7. Major chromosome aberrations may mimic Hb mutations; this indicates the need, in similar experiments, to follow F1 screening with thorough cytogenetic analysis. The variants in which there is nonexpression of the .alpha. chain may be the result of small deficiencies or of faults in transcription or translation. Mutation rates based on these 3 variants were not out of line with earlier specific-locus results, although confidence limits were still wide.