Sept. 12, 2011
Hard to lose this kitty in the dark, since it fluoresces a green color. Mayo clinic researchers have created a transgenic cat, genetically engineered to glow green. They used a technique called gamete-targeted lentiviral transgenesis, inserting genes into cat oocytes before fertilization with normal sperm. This was the first time the technique had succeeded with a carnivore. Besides inserting the GFP (green fluorescent protein) gene, which was actually used for tracking purposes, they also inserted a gene from rhesus monkeys--TRIMCyp--that is a "restriction factor", known to block Feline Immunodeficiency Virus (FIV), the feline equivalent of the human AIDS virus (HIV). When some of the kittens glowed green, it was evidence that the FIV-blocking gene had been successfully transferred. The successful gene transfer was also verified by the ability of the transgenic cats to pass on their glowing personality to their offspring (F1 generation), showing that the transferred genes were present in the germline.
According to researchers, cats are valuable models for the study of numerous human conditions. This line of cats will help studies related to FIV and HIV infection. Initial tests already show that the blood cells of the transgenic cats are resistant to growth of the FIV virus.
Previous attempts to generate genetically-engineered cats tried to use cloning techniques (somatic cell nuclear transfer; SCNT), but the authors note in relation to SCNT cloning:
"However, the efficiency of animal cloning is extremely low, and SCNT results in faulty epigenetic reprogramming in most embryos. Cloned mammals with apparently normal gross anatomy can have many abnormalities resulting from failure to erase and reprogram epigenetic memory completely."
In short, SCNT cloning has been an abysmal failure. But the technique used by the Mayo Clinic scientists is supposedly much better. According to senior author Dr. Eric Poeschla:
"The 23% success rate is much higher than the typical 3% seen with somatic cell nuclear transfer. Almost all of our pregnancies were transgenic, and that efficiency is important so you dont have to extensively screen these large animals. The really great thing is that the animals were healthy and fertile and their kittens were healthy.
The article is published in the journal Nature Methods.