Pleiotropic Effects of a Mutant at the P Locus from X-Irradiated Mice.

means of the well-known method of irradiation followed by testing with BTfecessive-marker stocks, many visible mutants at specific loci have been obtained in mice by several investigators. In some instances the mutants so obtained are presumably identical with the markers employed in the tester stock, but very often distinctive new alleles are involved. These latter may be of intrinsic interest in regard to knowledge of the locus, and they may also be useful additions to the available supply of markers. Numerous mutations at the p locus (“pink-eyed-dilute”) in linkage group I of the mouse are on record ( GRUNEBERC 1952; CARTER 195 7; RUSSELL and RUSSELL 1959). Most of these resulted from irradiation of spermatogonial cells. RUSSELL and RUSSELL (1959) state that 14 of 22 such induced mutants in their studies were carried to homozygous condition, but no detailed characterization of any has been reported. In the present study such a characterization has been completed. The unusual degree of pleiotropy revealed makes the mutant significant and probably valuable for further studies, particularly of spermiogenesis and odontogenesis.