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Karyotyping is one of cytogenetically important technique, and widely used for medical and biological purposes: the detection of chromosome abnormalities, chromosome classifications, etc. However, the traditional method for the karyotyping involves complicated, time consuming processes such as Giemsa-staining for G-banding, alkaline treatment combined with Giemsa-staining for C-banding and multicolor fluorescence in situ hybridization (FISH). Recently, our group started to develop a novel karyotyping method which is an integrated technique composed of atomic force microscopy (AFM), molecular biology, and image processing methods. One goal of this study is to develop a new, simple chromosome classification system based on AFM without any staining nor FISH treatment, which could be realized through the use of topographic information of chromosome. The previous papers and our preliminary study suggest that the height profile of chromosome could reflect the genomic structure of the chromosome, G-banding and/or chromomere patterns, which could be useful information for the chromosome classification. Therefore, the normalized height profile along the long axis of chromosome was then constructed by means of the image processing technique-based procedure. For the study, we used silkworm chromosome as a main target, because the size of silkworm chromosomes are small and indistinguishable by the traditional staining method. Furthermore, our group have been proceeding with a silkworm genomic sequencing project and genomic information and tools is usable to examine the experimental data. As the result of the analysis, relative position of peaks and valleys in the surface height profile of the chromosomes were reproducibly obtained by AFM throughout the specimen. These results suggest the feasibility of development of AFM-based karyotyping method. Further analysis will contribute to a realization of next-generation karyotyping system. |