Transparency and Mottling, a Case of Mendelian Inheritance in the Goldfish CARASSIUS AURATUS
Chen, S.C.
Genetics 13(5): 434-452
1928
ISSN/ISBN: 0016-6731 PMID: 17246559 Document Number: 3199
A simple autosomal character, "transparent," is described. Homozygous transparent has the following effects: the reflecting tissue is nearly lacking so that the red gills are visible through the oper-culum; the black retinal pigment, through the iris; the white testis or yellow eggs, through the body walls. Melanophores are restricted to a few black dots aggregated near the junction between caudal peduncle and caudal fin. Xanthophores are generally absent. The normal allelomorph of transparent, when homozy-gous, causes production of the reflecting tissue and the 2 kinds of chromatophores to cover the whole body. The heterozygous condition causes production of the type of goldfish called "calico" in the U.S.A. and "shubunkin" in Japan. This heterozygous form is a mosaic of the 2 forms of homozygous fish in regard to the reflecting tissue, but the combined action of the 2 kinds of genes affects the chromatophores so that a characteristic mottled pattern is produced. The transparent condition might be said to be dominant because the heterozygous mottled condition is sharply distinct from the normal form but is somewhat overlapping with the homozygous transparent condition, especially when the fish are smaller than 20 mm in size. Some cases of somatic mutation of normal into transparent gene and 1 case of somatic mutation of transparent into normal gene have been observed. Wild goldfishes have been successfully crossed with different fancy gold-fishes with production of fertile offspring.
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