Insights on plant chromosome structure provided by the FPG technique

• Published in: Experimental cell research Vol. 147; no. 1; pp. 221 - 225
• Main Authors: Cortes, Felipe, Escalza, Pablo, Rodriguez-Higueras, Jose Maria
• Format: Journal Article
• Language: English
• Published: Orlando, FL Elsevier Inc 01.01.1983; Elsevier
• Subjects: Azure Stains; Biological and medical sciences; Chromosomes - ultrastructure; Cytogenetics; Fluorescence; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Methods; plant breeding; plant genetics; Plants - genetics; Vegetals and fungi; Molecular arrangement; Allium cepa; Liliaceae; Monocotyledones; Vegetals; Angiospermae; Cytogenetics; Fluorescence; Chromosome; Spermatophyta; Method; Coloration
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/0014-4827(83)90288-4

The high resolution afforded by the fluorescence plus Giemsa (FPG) labelling method has allowed us to visualize three main features in BrdU-substituted A. cepa chromosomes. These are (1) exchanged segments smaller than the width of the chromatid detected after BrdU substitution for two S periods; (2) late-replicated chromosome segments (LRS) of similar characteristics; (3) discontinuous or ‘step-wise’ exchanges (SWE). A variation in longitudinal dimension has not been observed in any case; all these features have a roughly constant longitudinal dimension of about 0.5 μm. These results suggest that arrangements of the chromatin fibres having a diameter detectable under the light microscope following a longitudinal pattern can be ignored. In addition, our observations seem to support the model of a coiled structure of metaphase chromosomes. On the other hand, the analysis of the morphological pattern shown by the SWE along a chromatid and in sister chromatids has provided us with what could be evidence of a direction of the hypothetical gyres.