When An Arm is Really a Leg | DNA Science Blog

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A homeotic mutation mixes up body parts, so that a fly grows a leg on its head or antennae on its mouth. Assignment of body parts begins in the early embryo, when cells look alike but are already fated to become what they will become, thanks to gradients of “morphogen” proteins that program a particular region to elaborate particular structures. Mix up the messages, and a leg becomes an antenna, or an elbow a knee.

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Complex Controls to Make a Mouse Limb | DNA Science Blog

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As mutants tend to do, the homeotics teach us what happens normally, but with a special twist that drew me to devote my PhD years to them: the genes that control the sequential formation of body parts are themselves laid out in the exact sequence along the chromosome in which they are deployed as development proceeds.

jlinzel‘s insight:

This is development. Genes control the on and off of other genes. The dance provides the architecture of life. Development is awesome and beginning to be explainable. 

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Pandoravirus, bigger and unlike anything seen before

Pandoraviruses, which are physically and genetically unlike any previously known viruses, are now the biggest known viruses.The discovery of the giant Mimivirus and Megavirus amazed virologists (and also many others). Their virions (750 nanometers) and DNA genomes (1,259,000 base pairs) were the biggest ever discovered, shattering the notions that viruses could not be seen with a light microscope, and that viral genomes were smaller than bacterial genomes.

See on www.virology.ws