A CRITICAL-ASSESSMENT OF KARYOTYPE ANALYSIS BY IMAGING METHODS

A critical evaluation of the digital data of 250 barley metaphase spre ads obtained by image analysis revealed the instability of the chromos omal morphology during the mitotic metaphase stage. Both the relative length (RL) and arm ratio (AR) of the chromosomes, which are the two m ajor numerical parameters in karyotype analysis, varied in the differe nt chromosomal spreads. The ranking of the chromosomes for the respect ive parameters within a complement changed accordingly. The data indic ated that karyotype analysis based merely on the numerical parameters RL and AR may lead to the misidentification of chromosomes, causing a misinterpretation of the data from different chromosomes when averagin g several data. Thus, most of data of the RL and AR which have so far been reported may need reexamination except for the cases where chromo somes were identified based on other critical parameters, e.g., bandin g pattern, condensation pattern, in situ hybridization, etc. Different ial condensation between the chromosome arms may be the cause of the i nstability of the karyotype.