Monthly Archives: April 2014

Today, April 25, 2014 is National Arbor Day and a reminder of the importance that individuals and groups need to plant and care for trees. This means ensuring that arboriculturists and foresters have access to the most up to date agricultural technologies. The American Chestnut blight is recent example of how genetic engineering has served as one of these vital technologies.

A recent piece published in Scientific American told of the blight of the American Chestnut nearly wiped out by a fungal disease and efforts to genetically engineer the trees to resist the fungus and reintroduce healthy trees back into America forests. Ferri Jabrs A New Generation of American Chestnut Trees May Redefine Americas Forests examines the history of the American Chestnut going from its role of providing food and shelter for animals and people to nearly becoming obsolete.

Before the early 1900s, one in every four hardwood trees in North Americas eastern forests was an American chestnut, providing copious food and shelter for animals and people alike.

A New York City nurseryman named S. B. Parsons imported Japanese chestnut trees in 1876, which he raised and sold to customers who wanted something a little exotic in their gardens. Other nurseries in New Jersey and California soon did the same.

One or perhaps allof these shipments concealed the pathogenic fungusCryphonectria parasitica, which chokes chestnut trees to death by wedging itself into their trunks and obstructing conduits for water and nutrients. Asian chestnut trees had long evolved resistance toC. parasitica, but their American relativeswhich had never encountered the pathogen beforewere extremely susceptible to the fungal disease known as chestnut blight.

In 1904 the fungus was first discovered in New York State and soon spread to New Jersey, Connecticut, Massachusetts and Pennsylvania. Within 50 years,C. parasitica killednearly four billion chestnut trees.

Since the 1980s several generations of researchers at the State University of New York College of Environmental Science and Forestry (S.U.N.Y.ESF) have toiled to restore the American chestnut to its native habitat. Genetic engineering has offered a successful route to restoration.

By taking genes from wheat, Asian chestnuts, grapes, peppers and other plants and inserting them into American chestnut trees, William Powell of S.U.N.Y.ESF and scores of collaborators have created hundreds of transgenic trees that are almost 100 percent genetically identical wild American chestnut yet immune to C. parasitica.

The scientists hope to get federal approval to begin planting these trees in the forest within the next five years (See The American Chestnuts Genetic Rebirth in the March 2014 issue of Scientific American).

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Remember the American Chestnut Tree on Arbor Day

4 hours ago

Contrary to common scientific belief, many genes are switched "on" by default. These findings are from a study by Prof. Dr. Frank Holstege of University Medical Center (UMC) Utrecht that has been published in the April 24 edition of Cell.

Genetic differences between individuals affect the origin and treatment of diseases, a fact that has prompted more and more wide-scale genetic research. However, it seems that we sometimes lack very basic genetic knowledge.

Holstege's research shows that contrary to common opinion, many genes are by default actually switched "on". Given that DNA is wrapped in proteins, most scientists assumed that it could not be read by the cell. Transcription can only begin when so-called transcription factors bind to the DNA. Holstege and his colleagues show that nearly half of the transcription factors actually prevent the DNA from being read. It would seem that in most circumstances these genes should first be actively switched "off".

1,600 genes analyzed

Holstege and his colleagues used yeast as the model organism for their research. Yeast may seem far removed from humans, but its genes are controlled in exactly the same way as in human cells. Holstege et al. analyzed the role played by 1,600 genes, a quarter of all known yeast genes. They studied the effect that mutations in all those genes have on the gene expression of all other genes. This is the largest systematic study of the effect of mutation on gene expression to date.

Holstege has previously demonstrated that it is actually not necessarily useful to look at the effect of changes in just one gene. All genes are active in networks that are often organized in such a way that they can replace defective genes (Cell, December 10, 2010). The new study is the first step to mapping out the entire genetic control network.

"Comparative genetic research into patients and healthy subjects is very important," says Holstege. "It provides information on the cellular pathways associated with diseases. Our research shows, however, that it's hard to understand cells if you don't take the simultaneous activity of all genes into account."

Explore further: Research brings significant improvement in genetic analysis of tumours

Every tumour is unique and requires specific treatment. A thorough and complete analysis of the genetic activity in the tumour cells is necessary to determine the appropriate treatment. Researchers at TU ...

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Many genes are switched on by default