Dr' Stuart Reichler

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• Dr. Stuart Reichler
• Lectures posted on class website
• No class W 11/22

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Signal Transduction
such as changes in cellular components or
production of new cellular components
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Multiple steps allow for signal amplification
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Multiple steps allow for signal specificity.
Different relay molecules lead to different
responses
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General model of Ca signaling
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How can calcium be involved in so many different
responses? How can changes in calcium give rise
to specificity?
Tbl 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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2 hypotheses about how Ca signals are
transduced Signatures vs. Switches
Fig 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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Stomata
closed
open
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Ca fluxes in guard cells in response to hormone
or stress that cause stomatal closing. Wildtype
vs. det3 and gca2 mutants that fail to close
stomata following treatment
Fig 5. Sanders et al., The Plant Cell, S401S417,
Supplement 2002
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Spike timing is critical for response
Fig 2. Allen et al., Nature, Vol 4111053-1057,
28 June 2001
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Duration of spikes for stomata closing
Fig 2. Allen et al., Nature, Vol 4111053-1057,
28 June 2001
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2 hypotheses about how Ca signals are
transduced Signatures vs. Switches
Fig 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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Ca agonists, which do not induce calcium
fluxes,can cause the natural responses (in some
systems)
Tbl 2. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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Root nodules Nitrogen fixation
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The nitrogen cycle
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Nitrogen as part of amino acids and nucleotides
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Bacteria and Plants Symbiosis
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Signaling between bacteria and plants
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1nM Nod
10nM Nod
A biphasic Ca response to Nod factor 1nM Nod -
toward nucleus 10nm Nod - away from nucleus
Fig 3. Shaw and Long, Plant Physiology, March
2003, Vol. 131, pp. 976984
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1nM Nod
10nM Nod
10nM Nod
1nM Nod
A biphasic Ca response to Nod factor 1nM Nod -
toward nucleus 10nm Nod - away from nucleus
Fig 3. Shaw and Long, Plant Physiology, March
2003, Vol. 131, pp. 976984
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Everything has its place
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Some Ca channels have specific effectors
associated with them Micro-domains
Ikeda, Science 12 Oct 2001 Vol 294318-319
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2 hypotheses about how calcium signals are
transduced Signatures vs. Switches
Fig 1. Scrase-Field and Knight, Current Opinion
in Plant Biology 2003, 6500506
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Signal Transduction
such as changes in cellular components or
production of new cellular components