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To: Nebullis
I've found some interesting things in researching geotropism. For Lurkers interested in the subject of when or how gravity is 'sensed' rather than ‘learned’ (conversely, motion sickness or motion maladaptation syndrome):

Transcription Profiling of Early Gravitropic Response in Arabidopsis

This experiment identified transcripts present or absent under gravitropic stimulation. That many of them were also present under mechanical perturbation was unexpected.

The effect of microgravity environment on the expression of expansins from the peg and root tissue of Cucumis Sativus

This space biology experiment had the unexpected result of precious little difference between peg growth at space gravity v. ground.

I also found and then promptly lost (must be the excitement of the elections tonight) - a list of proposed space biology experiments to explore gravity vis a vis genetics.

On first blush, it appears that although it has been known for 100 years that roots know "down" and leaves know "up" (etc.) - that the actual work to determine what part of that it is genetic “knowledge" or “memory” of gravity – versus dynamic adaptation to gravity/motion stimuli - must wait for experiments which can only be done in space.

Am I close, Nebullis?

414 posted on 10/07/2003 11:50:43 PM PDT by Alamo-Girl
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To: Alamo-Girl
Roots vs leaves may also be a water-tropism vs a solar-tropism.
416 posted on 10/08/2003 6:10:41 AM PDT by Doctor Stochastic (Vegetabilisch = chaotisch is der Charakter der Modernen. - Friedrich Schlegel)
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To: Alamo-Girl
On first blush, it appears that although it has been known for 100 years that roots know "down" and leaves know "up" (etc.) - that the actual work to determine what part of that it is genetic “knowledge" or “memory” of gravity – versus dynamic adaptation to gravity/motion stimuli - must wait for experiments which can only be done in space.

There's a lot that is and can be done by increasing Gs by centrifugation. Most of the candidate genes and proteins that are involved in gravitropism are discovered this way. Plants are a good model to study tropisms. But gravity affects all living cells, not just plants and bacteria with flagella. It isn't so remarkable that something that has a definite physical effect on living organisms is part and parcel of what that organism is about.

420 posted on 10/08/2003 10:21:51 AM PDT by Nebullis
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