Snail gene in fruitfly embryo

The photograph shows a fruitfly embryo at a very early stage in development. The embryo was stained to visualize the expression of a specific gene, Snail. Although all 10,000 cells that comprise the embryo contain copies of the Snail gene, only those cells located in ventral regions (the future belly; bottom portion of image) activate the gene. This specific expression of Snail is one of the first steps in the formation of the mesoderm. The particular embryo shown here contains a foreign piece of D N A, or "transgene". The transgene contains Snail under the control of a regulatory D N A that causes the gene to be expressed in a stripe, in addition to the normal pattern of activity in the ventral mesoderm.

This image represents some of the work in the laboratory of Michael Levine in the Department of Molecular and Cell Biology.

Photo submitted by Michael Levine