Propidium iodide for making heterochromatin more evident in the C-banding technique

Abstract

The detection of regions of heterochromatin has been the subject of intense investigation. We investigated an adaptation of the commonly used technique by replacing the nonfluorescent dye, Giemsa, by a fluorescent one, propidium iodide. This adaptation produces greater contrast of the heterochromatic bands in metaphase chromosomes and can be especially valuable when the organisms studied possess heterochromatin that is pale and difficult to visualize. We discuss the interactions of these two dyes with DNA and the excitation of the fluorescent dye when irradiated with ultraviolet light.

Key words::

• C-banding
• euchromatin
• fluorescence
• fluorochromes
• Giemsa
• heterochromatin

Acknowledgments

The authors are grateful for the valuable contributions of Dr. Marcelo Guerra to the preparation of the manuscript. Funding was provided by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, proc. 09/15780-6), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, proc. 083/2007) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). We thank also the Instituto Estadual de Florestas (IEF/MG) and the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) for their support during data collection.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.