Researchers are enthusiastically watching the chromosomes of the fruit fly in action over the specialized microscope. These fruit fly larvae, warmed in a toasty lab chamber, are giving clues to the gene expression and chromosome interactions. Scientists from Cornell scientists take these actions very seriously.

They are using multiphoton fluorescence microscopy, which is a technique pioneered at Cornell University by physicist Watt W. Webb. These scientists from Cornell have for the first time witnessed chromosomes change their form in order to activate their genes to synthesize key proteins in fruit fly cells. They say that this is a very important step toward understanding the basic processes that underlie gene expression.

The discovery was the result of cross-disciplinary collaboration between Webb and John Lis, Cornell's Barbara McClintock Professor of Molecular Biology and Genetics.

"This technology will revolutionize the way we see gene expression in organisms," said Lis. "We're watching transcription in real time in living cells".

These scientists have published their findings in the Aug. 31 issue of the journal Nature.

The research team focused their attention on gene regulatory mechanisms: specifically, what happens in a cell's nucleus when an external stimulus prompts specific genes to activate, and how those activated genes direct the production of proteins that protect the fly against the stress of heating.

"Whenever a cell is stressed, it will produce proteins that will help the cell resist stress," said Webb, Cornell professor of applied physics and the S.B. Eckert Professor in Engineering. This process of stress reduction is carried out by a protein called heat shock factor (HSF). HSF interacts with genes to cue the synthesis of new proteins. But this well-known process had never been seen in living cells.

Unlike other methods, which lack penetrating power and can damage the specimen, MPM delivers crisp, clear images, even in thicker tissue samples like Drosophila salivary glands.

The results were astonishing. "Within two weeks we had spectacular pictures," said Lis. The images included pictures of the genes (hsp70 genes) that protect flies from the effects of extreme heat. By cranking up the heat, the scientists could activate these genes, and by using fruit flies specifically bred to carry fluorescent proteins on HSF, they could watch the transcription factors in action.

"This is the first time ever that anyone has been able to see in detail, at native genes in vivo, how a transcription factor is turned on, and how it then is activated," said Webb.

The technique also promises to offer a new tool for scientists across the biological sciences. Webb says it marks the success of an interdisciplinary trend that offers new potential for scientists in a variety of fields.

"Interaction between the physical sciences and the life sciences is very powerful," said Webb. "And it's becoming more powerful as a tool for advancing our understanding of the life sciences".


Posted by: Beverly    Source

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