The things we do to animals

We've started out our semester in "Biology of Disease" with a tedious review of some genetic engineering and recombinant DNA techniques. Yesterday we got into a discussion on transgenic animals - when you take genetic material from one animal and insert it into the genome of an animal of a completely different species. This is a pretty interesting - and controversial - topic. Here are some of the examples mentioned in class:

• Take out the luminescence gene that allows fireflies to glow, and insert it into a fish embryo. When the fish grows up, the luminescence gene will be incorporated into all of its cells, so it will glow in the dark. Result: make a lot of money selling glow-in-the-dark fish from pet stores.
• Take out a human gene for a hormone or enzyme, and insert it into some of the cells in a goat that are responsible for milk production. As the goat produces milk, the cells will express the gene and produce the hormone or enzyme in its milk. Result: collect the goat's milk and purify it to get a whole bunch of the hormone or enzyme that you need, which will be exactly the same as the human hormone or enzyme.
• Take out an oncogene (a gene that, when "turned on," will cause the cells it's in to become cancerous) from a human cell and insert it into mammary cells of a mouse. If you put it in the right place, it will automatically get "turned on." Result: a mouse that will predictably get mammary tumors so you have a substitute model for studying human breast cancer.
• Take out a gene for a growth hormone from one species, and insert it into salmon. Result: gigantic salmon.
• Insert a gene that causes huge muscle growth into certain muscle cells of a cow. Result: a cow that grows enormous muscles (which are not very healthy) and is so huge as a fetus that it can't be born normally because its muscles won't fit through the birth canal.

So, there are obviously a lot of applications for genetic engineering and transgenic animals. I think sometimes scientists get excited about what they can do and forget to even ask if they should do it. In some of these cases, the genetic alteration is clearly really detrimental to the animal's health and happiness (e.g. the cow with huge muscles). In other cases, the animal isn't really affected at all (e.g. the glow-in-the-dark fish). In what I think are the best cases, the animal can provide something that will help save and improve human lives, without causing any real harm to the transgenic animal (e.g. the goat producing a human enzyme in its milk). Less appealing are some of the animals designed to provide research models for human diseases, like the mouse with breast cancer. This obviously isn't great for the animal, but we really need this kind of research resource, so what else are you going to do? Get a whole bunch of mice and hope they happen to get breast cancer? I do find a bit of a problem with things like making fish glow in the dark just because we can, even if it doesn't harm the animal in any noticeable manner.

Anyway, that's my random thoughts from biology of disease...