One wonders what force Dylan Thomas was pondering when he wrote: "The force that through the green fuse drives the flower/ Drives my green age." Chances are the poet wasn't considering genetics, but that shouldn't bother researchers Paul Kulesa and Scott Fraser. They've discovered that physical forces may be more important than gene expression during the development of chick somites, or embryonic segments.
The prevailing view has been that molecular biology drives cells in a single direction, from the presomite region into regions where somites are forming. However, by following individually stained cells in time-lapse, Kulesa, of the Stowers Institute for Medical Research, Kansas City, Mo., and Fraser, of the California Institute of Technology, found that cells move in two directions, across apparent expression boundaries. Furthermore, the movement precedes, rather than follows, the expression of genes believed to be involved with this process, leading the researchers to conclude that the ...
