What is an artificial chromosome?

It’s a chromosome that’s made from scratch in the lab. It can have one or more genes on it, and it needs a centromere, so it gets replicated and divided up during cell division just like a regular chromosome.

How do you envision artificial chromosomes being used?

I definitely want to see artificial chromosome technology used in agriculture someday. Right now plant biotechnologists add one gene at a time [to plants]. When they made Bt corn, for instance, they put a Bt gene into corn, and that was that. The big argument in favor of the artificial chromosome is that it has a large capacity to carry genes—you can put as many genes on the chromosome as you want. You can put entire pathways.

Let’s say a crop plant doesn’t make vitamin B12, but you’d like it to. To make vitamin B12 you need something like 10 genes. It would be almost impossible to [engineer this plant] with current technology, but with an artificial chromosome it should be possible to do a manipulation like that.

Does your rice research have any implications for human health?

Centromeres exist on all eukaryotic chromosomes, so understanding the structure, function and evolution of centromeres in plants will definitely help on the human side. In humans, artificial chromosomes are seen as a promising way to deliver genes for gene therapy. Let’s say you have a patient who’s colorblind, and they need a single gene to correct the problem.

The basic theory of gene therapy is to put the needed gene into the affected tissue, so that the
gene can produce the protein that’s needed to correct the problem. Currently, doctors use a virus-based vector, which inserts the gene randomly in the genome. It’s already known, however, that this process can actually cause cancer, because sometimes the new gene will insert into the middle of an existing gene that regulates cell division or the cell cycle. But artificial chromosomes carry genes independently. They don’t integrate into the genome, and they don’t interfere with existing chromosomes. So you can express the gene you need, without interfering with the other 30,000 genes that you have. [Human gene therapy] is really the main drive behind artificial chromosome research, and understanding the centromere—how it behaves, how it functions—is the most important part of this effort.

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Tags: DNA, Genetics, Horticulture, Plant breeding and genetics, Rice
Posted in Agriculture, Health, Living Science, Spring 2011 | 1 Comment »