"We used existing technology and we applied it in a novel way" to illuminate simultaneously where three genes are "expressed" or active, Mauch says.

The new study is the first time any method has been used to simultaneously show the activity of three genes in a whole chicken embryo. Another method colorimetric detection has been used to detect three genes at once in fruit flies. A type of ISH known as FISH fluorescent in situ hybridization was used previously to show simultaneous action of two genes in frogs and in zebrafish by painting the genes with florescent dyes. Mauch's method is an improved version of FISH. Her study's title refers to it as "FISHing for chick genes."

An Aid to Studies of Embryo Development and Birth Defects

The chicken "is a good model for human kidney development because, unlike frogs and fish, the chicken kidney develops in three stages like the human kidney," says Mauch.

She says her method detects the expression of three genes even when they are active in the same tissue or within one cell. That helps researchers because "genes usually don't act alone. Each step in embryo development involves more than one gene being turned on."

When two or three genes are active in one tissue or cell, the fluorescent colors overlap to form other colors. When genes labeled red and green overlap, the image is yellow. Red- and blue-tagged genes overlap to form purple. Overlapping blue- and green-tagged genes appear turquoise. When three genes overlap, red, green and blue combine to produce white.

Mauch's improvement of the FISH method was combined with use of a "confocal" microscope a microscope that focuses on
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8-Mar-2004