Scientists Discover Astonishing "Genomic Variability" in Human Brains

Results of a new study by scientists at the Salk Institute for Biological Studies reports that rather than sticking to a single DNA script, human brain cells harbor astonishing genomic variability. The findings could help explain brain development and individuality, as well as lead to a better understanding of neurological disease.

The team, led by Fred Gage, Ph.D., a professor in the Salk's Laboratory of Genetics, found that human brain cells contain an unexpected number of so-called mobile elements--extraordinary pieces of DNA that insert extra copies of themselves throughout the genome using a "copy and paste" mechanism.

"This is a potential mechanism to create the neural diversity that makes each person unique," says Gage. "The brain has 100 billion neurons with 100 trillion connections, but mobile pieces of DNA could give individual neurons a slightly different capacity from each other."

The only other human cells known to remodel their genome are the cells of the immune system. There the genes coding for antibodies are shuffled to create the necessary variety of antibodies capable of recognizing an infinite number of distinct antigens.

When Coufal measured matched samples (brain versus other body tissues) from numerous individuals, she found that some brain samples had as many as 100 extra copies per cell. "This was proof that these elements really are jumping in neurons," explains Coufal. Strikingly, it also means that not all cells are created equal--humans are true chimeras since the DNA in their brain cells is different from the DNA in the rest of their cells.

Trying to explain why only brain cells harbor truly "mobile" elements, Coufal looked at the LINE-1 promoter, which is the switch that turns LINE-1 elements on and off, and she discovered that in the brain, the switch is generally on, whereas in other tissues it is permanently locked in the "off" position.

The entire report can be read by following the link provided. Source: Salk Institute/Science Daily

Source: Breaking Christian News

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