Gene by Gene

[groovedaddy]

Over the years, scientists have developed many strains of genetically modified mice, many of which incorporate human versions of similar mouse genes. But there is something different in a recent experiment performed at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Scientists there have created a strain of mouse that contains the human variant of a gene, called FOXP2, associated with several critical tasks, including the human capacity for language.

What makes this different is how fundamentally human — and unmouse-like — language really is. Something essential to us, something defining in our species, has been implanted in a rodent.

FOXP2 happens to work pretty well in mice. Those with the new gene in place do in fact communicate differently with each other, by using slightly lower-pitched ultrasonic whistles. The nerve cells they grow in one region of the brain are also more complex than those in unaltered mice. These may sound like modest results, but they are striking. They help clarify the function of FOXP2, and, in doing so, they help scientists better understand what constellation of genes produces the capacity for language in humans and, thus, how we differ from our nearest primate relative, the chimpanzee.

What takes some getting used to is the idea of exploring what humanness really is — how complex and how little understood — by transplanting our genetic signatures, gene by gene, into other species. And there is another question hovering over this experiment: Just how alien to themselves do these transgenic mice become? To that question, scientists are bound to find no answers, until, perhaps, mice can speak for themselves.

http://www.nytimes.com/2009/06/05/opinion/05fri4.html?th&emc=th

[phantom power]

1. Interesting, but we need to keep the nature of toolkit proteins in perspective.

The function of toolkit proteins like FOXP2 is highly context dependent -- where and when is it activated, and what developmental sub-routines does it activate. All of those things will be different in a mouse. Giving it a FOXP2 gene will not cause a developing mouse brain to develop language centers.

[groovedaddy]

2. I've met plenty of rat bastards in my life, but they were the 2 legged kind! n.t

[phantom power]

3. And some humans are definitely street-rat crazy!

I just finished reading this book on developmental and evolutionary plasticity called "The Plausibility of Life." One of the key topics of the book was the robustness of organisms in the face of mutations to developmental genes. It's pretty remarkable that you can insert a human gene into a mouse, and (a) it develops successfully, and (b) the development is viable. These mice have altered brains, and yet they are viable mutations.

In this case, there are probably at least two robustness mechanisms in play. The first is modularity in gestation. Altering the brain development pathways did not alter the entire brain, only the subroutines for creating certain regions. The second mechanism is the wiring of the brain connections, which is mostly separate from basic brain anatomy layout. The wiring mechanisms are highly exploratory and adaptable. The consequence is that when you change anatomy, either in the brain or in other tissues, the actual neural wiring mechanisms intrinsically adapt to the new anatomy. The result is that alterations to anatomy remain viable across a much larger range than one would otherwise suspect.