title: Techniques for imaging human metaphase chromosomes in liquid conditions by atomic force microscopy.
abstract: The purpose of this study was to obtain three-dimensional images of wet chromosomes by atomic force microscopy (AFM) in liquid conditions. Human metaphase chromosomes-obtained either by chromosome spreads or by an isolation technique-were observed in a dynamic mode by AFM in a buffer solution. Under suitable operating conditions with a soft triangular cantilever (with the spring constant of 0.08-0.4 N m(-1)), clear images of fixed chromosomes in the chromosome spread were obtained by AFM. For imaging isolated chromosomes with the height of more than 400 nm, a cantilever with a high aspect ratio probing tip was required. The combination of a Q-control system and the sampling intelligent scan (SIS) system in dynamic force mode AFM was useful for obtaining high-quality images of the isolated chromosomes, in which globular or cord-like structures about 50 nm thick were clearly observed on the surface of each chromatid.
authors.affiliation: Division of Microscopic Anatomy and Bio-imaging, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Ushiki
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Shigeno
authors.forename: Osamu
authors.initials: O
authors.lastname: Hoshi