2003 Volume 11 Issue 3+4 Pages 97-103
The nucleus at interphase can be characterized by distinct morphological features and the distribution pattern of certain chromosomal regions such as nuclear chromocenters (CCs). Parameters of CCs within a nucleus are used to determine the type of resting chromosomes, which is a useful cytological characteristic that can serve as an indicator of cross-compatibility among orchid species. However, it is difficult using conventional imaging methods to identify the CCs within the interphase nucleus with the same level of acuity as human visual perception. This is because numerous variations on density and size are observed among CCs. An unsharp mask filter enables us to simulate human visual perception and allows us to identify CCs within the nucleus regardless of their density and size. As a result, CCs of Spiranthes sinensis (Pers.) Ames. were identified to the same standard as human visual recognition. Moreover, not only the quantitative parameters indicating morphological features but also the distribution pattern of CCs were successfully determined using this method. The numerical parameters of CCs can provide useful information not only for phylogenetic studies of Orchidaeceae but also for the future breeding of new hybrids of orchids.
