‘Wavy–Fused’ Mutants in the Medaka, Oryzias latipes

Abstract

AIDA¹ first reported the occurrence of wavy and fused vertebral mutations in the medaka. These characters are simple recessive to normal and are independent of all known genetic characters and sex. The vertebral column of the wavy fish curves dorso-ventrally (Fig. 1 B) and some centra of the fused fish are fused (Fig. 1 C). Fig. 1 AD show the backbones of normal and wavy–fused fish. Recently, Takeuchi² also reported a wavy mutant of the medaka which had appeared in the breeds of Yamamoto in Nagoya University and this mutant was used in the present experiment. Although the wavy mutant is a simple recessive, the way in which it expresses itself suggests the presence of modifiers of the principal gene. The fused mutant used here originally appeared in Aida's breed and has been kept in the laboratory of Yamamoto (Nagoya). A detailed genetic investigation of the fused mutants was performed by Yamamoto et al.³.