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Two different rare events occurring simultaneously in the house mouse

1957; Springer Nature; Volume: 11; Issue: 2 Linguagem: Inglês

10.1038/hdy.1957.22

1365-2540

Maureen Macneil,

Hematological disorders and diagnostics

IN an inbred line in which Caracul (Ca, linkage group VI) had been segregating as a backcross for eight generations, there appeared two males which, from their breeding behaviour, were apparently homozygous for this factor.They were members of the same litter, the first produced by their parents.The latter bred seven Caraculs and four normals in three litters, in good agreement with the expected i ratio.The anomalous males (Io/13o.37ocand Io/13o.37od)were given several unrelated does besides their first mates from the inbred line, and bred consistently by all of them as homozygous Caraculs, producing no normals out of over two hundred progeny.A summary of these arid other relevant data is given in the table.There is no possibility of mistaken identity.The inbred line segregates in six factors (ca, belted, bt, misty, m, brown, b, silver, si, and Fused, Fu), which are not found in this combination elsewhere in this laboratory.The anomalous males' phenotypes and breeding performance were such that they could only have come from this line, and their parents bred as expected for all six factors.Neither does it seem likely that Ca was segregating in an unusual fashion in this line or that any other waving factor was present.The eight previous generations produced severally and in the aggregate ratios of Caracul to normal none of which differed significantly from the expected x : i, and three sibs of the anomalous males, mated to normals, also produced good i i ratios.An explanation which at first appears plausible is that the "non-Caracul" parent of the males in question was in fact Caracul.If so, the mating producing them would have been an intercross for Caracul, and the production of two homozygous males out of eleven offspring would not have been surprising.Certainly the ratio seven Caraculs to four normals is not significantly different from 3 : I.