Weizmann Institute scientists discover: A 'risk distribution law' for...(genetic code responsible for activating ...)

Date:11/1/2007

genetic code responsible for activating the gene) contains a key to gene conservation: The expression of a gene that contains the sequence TATA in its promoter is more likely to have evolved than that of a gene that does not have TATA in its promoter. In other words, the level of risk appears to written in the genetic code, in a way thats similar to financial risk analysis: When the cost of error is high, an investors willingness to chance the risk is low, but if the cost of a mistake is negligible, even if the chance of making one is high, the possibility of gain may make the risk worthwhile. Evolution, it seems, discovered this principle millions of years before Wall Street.

In a different study, Barkai and her research team investigated the effects of a drastic evolutionary experiment that nature sometimes performs on living cells: the doubling of an entire genome. They looked at two related species of yeast, one of which (S. cerevisiae) had undergone genome doubling millions of years ago. After the duplication, Cerevisiae seem to have learned a new trick: They gained the ability to grow and multiply without oxygen.

To find out if this difference is connected to changes in gene expression, the team tested 50 genes that play a role in processing oxygen in both species. They discovered one gene segment a bit responsible for expression of these genes that had changed in the course of the genome doubling in cerevisiae. The effects of this change were seen in over 50 genes and dramatically affected the oxygen requirements of the yeast.

The ability to live without oxygen might give cerevisiae a clear advantage over its sister yeast if there were a radical change in the make-up of the Earths atmosphere. But it is exactly this combination of environmental change and genetic experimentation that has fueled evolution for millions of years and is still driving it today.

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Contact: Yivsam Azgad news@weizmann.ac.il 972-893-43856 Weizmann Institute of Science Source:Eurekalert

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