Such gene transfer and gene splicing is routinely used by researchers who study microbes, plants, mice, rats, cattle, pigs and other animals. The gene transfer technology helps researchers figure out the function of genes in health and in disease.

This is the first time that a primate has been grown from an egg or fertilized egg carrying an inserted copy of a gene from another species. The researchers call the monkey ANDi, a reverse acronym for "inserted DNA."

For over a decade, researchers have known how to splice genes into cells of primates, including humans. Genetically engineered cells are the basis of gene therapy in humans, in which cells from a patient are collected, grown in a test tube, and a gene is added to the cells before the cells are placed back in the patient.

In the case of such gene therapy, only the cells put back into the patient (and the cells that grow from them) have the added gene. All the other cells in the patient do not.

Furthermore, since the engineered cells are not the cells that make eggs or sperm, the added gene is not passed on to children.

But in the case of ANDi, researchers inserted the gene into the egg cell, and as the fertilized egg divided from one into two, two into four, four into eight, and so forth through embryo stages into fetal development, every cell made and carried a copy of the inserted gene.

When ANDi reaches sexual maturity, researchers will be able to test if the gene is found in ANDi's sperm. If so, then the inserted gene can be passed on to ANDi's offspring.

News accounts of ANDi made a big deal that the inserted gene encoded a protein that glows or fluoresces green under UV light. However, ANDi doesn't glow green under UV light, because while the gene is present in every one of his cells, the gene is turned off and no protein is detectable yet. Researchers will watch for production of the glowing protein as ANDi ages.

Researchers commonly use the gene because it makes a protein originally found in a jellyfish and called Green Fluorescent Protein (or GFP). It's a good "reporter protein" because it is generally stable, non-toxic and easily detected in living cells just by shining UV light on cells, tissues or an animal making the protein. It's roughly the equivalent of putting a reflective collar on a dog to make it easier at night for drivers to spot the dog.

In the case of ANDi, the gene is detectable using probes specific for the DNA that makes up the genetic recipe card that encodes the green fluorescent protein. However, the protein is not detectable. This is the equivalent of having the recipe card but without making any cookies. The researchers reported that twin stillborn transgenic monkeys did glow green under UV light, indicating the fetuses not only had the gene but made the protein.

That leaves another step to go: getting a gene inserted into a primate egg cell to be expressed in a live-born animal that grows from the fertilized egg.

Biologists develop such transgenic animals so they can figure out the function of an added gene from any source. Furthermore, when combined with Dolly Technology, the approach can eventually be useful in figuring out the function of existing genes of the rhesus monkey.

This work again brings to the forefront the issues swirling around the ethics of treating genetic diseases of humans by either adding a gene to, or by deleting a faulty gene from, an egg that when fertilized then develops into a healthier baby.

Beyond the question of treating an existing disease are questions of the ethics of trying to improve an otherwise normal baby (for example by inserting genes intended to increase intelligence, creativity or athletic ability).

Because such added genes--whether to fix a genetic disease or to design a better baby--are likely to be passed on to future generations, some ethicists question the propriety of taking the risk that the inserted gene will somehow backfire and irreversibly threaten all future generations. Others question the ethics of choosing to refuse to try to treat or cure a disease. This illustrates the dilemma of weighing the ethics of acts of commission versus acts of omission.

Link: http://www.ohsu.edu/news/011001monkey.shtml