抄録
Chromosome patterns were examined in the parental sensitive, 8-azaguanine (AZG) and amethopterin (AMT) resistant lines of the lymphocytic neoplasm, P388, growing in vitro. The karyotype of the sensitive P388/P line was characterized by a modal chromosome number of 49, which included 15 metacentrics. However, the karyotypes of some of the drug resistant lines were quite different from that of the sensitive line from which they were derived. An increase of chromosome number was found in resistant lines (102B AZG, 102H AZG and 146D AMT) developed by treatment with rather low drug concentrations. Secondarily a decrease in chromosome numbers accompanied even greater resistance (102J AZG and 146J AMT) which had been achieved by treatment with increased concentrations of drugs. In the case of the AZG- resistant lines (102H and 102J), a decrease of submedian metacentric chromosomes was noted. in the AMT-resistant line (146J) there was decrease of telocentric chromosomes. The possible relationship between the development of drug resistance and changes in chromosome pattern was discussed.
