Artificial Plasmids

Dateline: 09/03/98

Scientists at the University of North Carolina Chapel Hill announced this week that they have successfully inserted an artificial plasmid into a cultured human cell. Plasmids are small, circular pieces of DNA. This announcement is significant because this plasmid was approximately 20 times larger than previously used plasmids. Scientists hope this research will lead to a successful in vivo procedure.

The genes transferred were responsible for the production of Beta-globin, a component of hemoglobin. The transplanted genes also replicated when the constituent cell replicated. The DNA plasmids went from double-stranded DNA to single-stranded RNA, which indicated that the traditional protein production model was being followed.

Scientists indicated that the genes were stable and replicable for more than a year, an indication that the plasmid was well integrated into the cellular apparatus.

Using bacteria to replicate portions of DNA produced the genes. The portion was inserted into a harmless part of the Epstein-Barr virus. Epstein-Barr was used because it can sustain itself in a human cell without degrading. Thus the virus served as a vector.

Interestingly enough, the plasmids didn't insert themselves into existing chromosomes. Instead, they functioned independently, hence the moniker "artificial chromosome." Each time the regular chromosomes in the cell were replicated, the plasmids were replicated.

Assuming a similar procedure works in the human body, independent chromosomes offer several advantages. They are inherently more stable than insertions, and scientists don't have to worry about a gene attaching to a chromosome and not functioning due to the location of the attachment.

What do you think? Might this be a successful treatment method for a host of defective gene conditions? In what other applications might this method be used? Come over to the Biology Forum and share your thoughts, opinions, and feelings.