Alzheimers and tangles and neat techniques

Karen Ashe, a neurologist at the University of Minnesota in Twin Cities did work published in the journal Science Science, Vol 309, Issue 5733, 476-481 , 15 July 2005 that suggested that the neurofibrillary tangles seen in Alzheimer’s may not be the cause of the dementia. She was able to put a defective tau protein in mice and turn it on or off. When turned on the tangles appeared and the mental performance of the mice decreased. However, when they turned the defective gene off the tangles remained but the mice regained some memory skills. Thus tangles but themselves don’t cause memory loss. The defective tau protein must do something else. These results are interesting but the ability to insert a mutant gene and turn it on or off at will is an amazing and very powerful technique.

To turn a gene on or off they attached it to a transgene that was responsive to the chemical antibiotic-like doxycycline. So when they added the doxycycline the gene for the mutant tau protein was turned off. The were also able to direct where in the mouse’s body the gene turned on by attaching this complex to another gene controlling sequence that is express only in the mouse’s forebrain. Thus they directed mutant tau to the forebrain and could turn it off at will to see what happens.

Control is the key. When the human genome was sequenced we had fewer genes than expected and more “junk” DNA that anything else. People age beginning to think that our secret is very fine control of what we have rather than having more than anything else.