In Japanese quail ♀ × chicken ♂ hybrids, the preferential transcription and translation of a maternally derived quail allele appeared to occur at the autosomally inherited liver alcohol dehydrogenase (ADH) locus. In these hybrids, the product of a paternally derived chicken allele was not detectable until 3 days after the hatching (Castro-Sierra and Ohno, 1968). The present study was designed to answer the following two questions: (1) Exactly when and where in development does ADH first appear? (2) Does the appearance of the maternal gene product precede that of the paternal ADH in development of intraspecific heterozygotes as well? B and C electrophoretic variants of ADH of the Japanese quail were utilized. Developmental sequence was established. Whole embryo extracts of earlier developmental stages showed no ADH activity. At the 9th day of incubation, ADH activity was detected for the first time in newly organized liver. Until the time of hatching, no other tissue showed ADH activity. A few days after the hatching, ADH activity appeared in the kidney. Thus, the transcriptional activity by the ADH locus of Japanese quail appears highly tissue-specific. Four hundred and seven progeny resulting from 9 breeding pairs of the 5 heterozygote-producing mating types were analyzed at the 9th day (-8 days) of incubation and at the day of hatching (day 0) for their ADH phenotypes. It is concluded that so far as B/C heterozygotes of Japanese quail are concerned, the synchronous appearance of both parental gene products is a rule at this locus. © 1969 Plenum Publishing Corporation.
