A NEW VISIBLE-LIGHT DNA FLUOROCHROME FOR CONFOCAL MICROSCOPY

We have developed a new DNA-specific fluorochrome that is excited by v isible light. This chemically uncharacterized fluorochrome readily pen etrates tissue in whole mounts, gives a strong signal, is inexpensive to make and very easy to use. This preparation has several advantages over existing DNA fluorochromes in confocal laser microscopy applicati ons. Many DNA fluorochromes are excitable by ultraviolet light. These have limited utility in confocal microscopy, where commonly used laser s produce only visible wave-lengths of light. Other DNA fluorochromes are available that are excitable by visible light, but some have diffi culty penetrating all cell types, while others have high back-ground o r fade quickly. This new fluorochrome overcomes these problems and has an emission spectra that makes it compatible with either rhodamine or Texas Red(R) labeled reagents for double-label experiments. The abili ty to label all nuclei in a tissue and make three-dimensional reconstr uctions by confocal microscopy is extremely useful in examining cellul ar distributions within specific tissues.