Chromosomal Banding Patterns Produced by Methyl Green-Pyronin Staining After Trypsin Treatment

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Abstract
A method is described for producing banding patterns with methyl green-pyronin (MGP) stain in chromosomes of [mouse] fibrosarcoma cells. The stain was made by mixing equal volumes of 2% aqueous pyronin G, 2% aqueous methyl green, distilled water and 0.1 M acetate buffer (pH 5.7). Treatment with colcemide and hypotonic KCl (0.075 M) was performed as usual. Metaphase chromosomes were prepared using flame-drying technique and treated with 0.25% trypsin at 37.degree. C for 45-90 s. Before staining, the slides were rinsed in PBS [phosphate buffered saline], in distilled water, and then were dipped in 0.05 M acetate buffer. Chromosomes were stained for more than 20 min, rinsed in distilled water and hot-air dried. Satisfactory results were obtained in uncontracted metaphase chromosomes. MGP stain has the advantage of permitting much longer trypsin treatment and staining time than the trypsin-Giemsa method while providing satisfactory banding patterns.