The frequency of the non-disjunction of the composite members of the tetravalent formed in the first spermatocytes of the 11-Y translocation heterozygous male in the NIG-III strain rat is examined in the chromosome distribution of the second spermatocytes. Among 239 spermatocytes so far examined, 219 (91.6%) have 21 univalents as expected, but the other 20 cells (9.4%) have 20 and 22 univalents occurring by the non-disjunction of any one component of the tetravalent. The occurrence of the non-disjunction almost coincides with the expected one in the chromosome constitution of the offspring born after mating between the heterozygous males and the normal females.
Banding growth in liquid media exhibited by mutants in orthophosphate repressible cyclic phosphodiesterase, cpd-1 and cpd-2, was found to be due to the alternate appearance of submerged mycelia and submerged conidia. Thus cpd-1 and cpd-2 exhibited rhythmic conidiation both in liquid and on solid media, which indicated the persistence of circadian rhythm in liquid media. The examination of the levels of cyclic 3', 5'-AMP in wild type, cpd-1, cpd-2 and band (bd) strain revealed rhythmic oscillations in cyclic 3', 5'-AMP levels with period lengths of about 24hr. Conidiation on solid media took place 2-3hr after the appearance of a major peak of cyclic 3', 5'-AMP.