Banding of human chromosomes with basic fuchsin

Summary In this paper a technique is described for the banding of human metaphase chromosomes with basic fuchsin. The main characteristics of the G-banding pattern obtained with this cationic triphenylmethane dye are:the secondary constriction regions of chromosomes Nos. 1 and 16 are strongly stained, especially in the latter one;the heterochromatic area of chromosome No. 9, usually negative with most other G-banding techniques, is clearly visible as an intensely stained band adjacent to the centromere;the chromosomal outline is often very distinct, facilitating the study of the telomeres; a number of chromosomal regions with bright Q fluorescence such as the polymorphic regions of the chromosomes Nos. 3, 4, and Y also stain strongly with basic fuchsin.The basic fuchsin technique combines therefore properties of G-, C-, and Q-banding methods and seems very suitable for use in e.g., family and linkage studies.Several triphenylmethanes closely related to basic fuchsin produce similar banding patterns. The band-producing ability is, however, diminished in those dyes which contain methylated amino groups. If the methyl groups are attached to the carbon atoms at the 3-positions in the phenyl rings, band formation seems unaffected.The way in which basic fuchsin and chromatin may interact as well as the possible mechanism(s) of band formation with this dye are discussed.