A New Technique Allows Insertion of Genes in Non-dividing Cells

Until recently, the only method for modifying DNA was the CRISPR-Cas9 system. However, the new Salk technology is much more efficient than any other method because it allows the incorporation of DNA into non-dividing cells. The cells of the heart, brain, eye, and pancreas do not divide again and are locked in G₀. In order for this to be accomplished a specific pathway called NHEJ was targeted by researchers. This pathway repairs routine breaks in DNA sequences by rejoining original strand ends. Researchers constructed a new complex called HITI, homology-independent targeted integration, used to insert genes into the cells. The complex is made up of different nucleic acids. Then, they used a virus to implant the HITI inside the cell to transfer the genetic information to neurons that were derived from embryonic stem cells from humans.  Scientists then completed a genetic modification in adult mice and it was successful. After that, they tried to use the technique as a gene-replacement therapy method. The researchers decided to work with mice that were born blind. They successfully delivered the gene Mertk, one of the genes that, when damaged in humans, causes vision loss. The gene was inserted into the genome of the mice at just three weeks old and by the time they were eight weeks old the mice showed response to light. Furthermore, testing was continued and healing was observed in the retinal cells of the mice. I feel that many people will benefit from this new gene-replacement therapy process. Individuals can be assisted by a gene when having a disability, such as severe eye loss. Also, one that suffers from serious head trauma can gain some of his or her brain cells back. Consequently, he or she will recover from a concussion quicker. This is only the beginning of the great things science can do to help people suffering from genetic damage. Gene therapy is going to revolutionize healthcare in the future. 

Hormones Tick on Epigenetic Clock

    The reproductive cycle of mammals is controlled by reversible changes in DNA.  Siberian hamsters breed during the longest days of the year and the shortest days trigger hormonal changes, thus causing their gonads to shrink.  It has been unclear how melatonin, a nocturnal hormone, alters gene activity. 
   
    Tyler Stevenson of University of Aberdeen and Brian Prendergast of University of Chicago discovered that shorter days and changes in melatonin reduce a key gene, methylation which is in the hypothalamus, to activate the gonad shrinking.  This study that was performed was the first to show cycles of DNA modification underlie seasonal changes.  I found this very interesting because just a slight change in a hormone can trigger a whole cascade of events.  I personally didn't know that melatonin had that much of an impact on mammals. 

http://doi.org/nz8
http://www.newswise.com/articles/siberian-hamsters-show-what-helps-make-seasonal-clocks-tick
http://www.jstor.org/discover/10.1086/652243?uid=3739808&uid=2&uid=4&uid=3739256&sid=21102847425247