New inversion of the pair no. 3 chromosome in a black rat

Summary A Japanese black rat (Rattus rattus tanezumi) with a subtelocentric pair no. 3 chromosome was found in Gotenba, Japan. By comparison of the length in both members of the chromosome pair, and from the G-ban pattern, the subtelocentrics seemed to have developed from the original acrocentrics by the pericentric inversion.The author wishes to express his sincere thanks to Dr. K. Moriwaki for the help of the collection of the material and also for the skilful technical help of Miss Y. Ochiai. Supported by a grant-in-aid from the Ministry of Education, Science and Culture of Japan (Nos 111510 and 111506). Contribution No. 1125 from the National Institute of Genetics, Japan.