Dictyostelid cellular slime molds use of cyclic AMP serves as a model organism in cell to cell commu

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Dictyostelid cellular slime molds use of cyclic
AMP serves as a model organism in cell to cell
communication.

• Aaron M. Owens
• Department of Biological Sciences, Arkansas State
  University
• Jonesboro, AR 72467 U.S.A.
• 22 April 2007

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Agenda

• Introduction
• Dictyostelids
• Cyclic AMP
• Research
• Questions

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IntroductionDictyostelids
sorocarps
pseudoplasmodium (slug)
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Dr. Kenneth Raper

• First described in late 19th century
• Mycologist for USDA
• First isolated them in 1933
• 1st to see potential as model organisms
• Published 4 papers

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Cyclic adenosine monophosphate(cAMP)

• Acts as a chemical signal or intracellular second
  messenger
• Product of cytosolic ATP by enzyme adenylyl
  cyclase
• Phosphodiesterase degrades cAMP
• Targets protein kinase A
• One regulatory subunit/ one catalytic in
  dictyostelids
• Intracellular cAMP

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Cyclic adenosine monophosphate(cAMP) (cont.)

• Extracellular cAMP signal controls movement and
  differentiation
• Spore cell or stalk cell
• Move up cAMP concentration gradient
• Dictyostelids secrete cAMP in pulsating fashion
• Excitable medium
• -cAMP is relayed
• Dictyostelids have several different cAMP
  receptors
• Genetic studies
• Belong to family of seven transmembrane domain
  receptors
• Starvation causes them to express surface cAMP
  receptors
• Sensitive to cAMP

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Cyclic adenosine monophosphate(cAMP) (cont.)

• The control of chemotactic cell movement during
  Dictyostelium morphogenesis
• Dorman in 2000

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Research

• Numerous studies
• cAMP waves in Dictyostelium discoideum
• Tomchik and Devreotes published in Science
• Used an isotope dilution fluorographic technique
  to see distribution of cAMP
• Supported hypothesis that cAMP mediates
  aggregation
• Methods are complicated
• Results support hypothesis

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Research
Fluorographic image of cyclic AMP waves
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References
Bouzid, S., Harwood, J., Hopper, N. A., Simon,
M., Vernon, M., and Williams, J. G. 1993.
Regulation of Dictyostelium morphogenesis by
cAMP-dependent protein kinase.
Dormann, D., Vasiev, B., and Weijer, C. J. 2000.
The control of chemotactic cell movement during
Dictyostelium morphogenesis.
Tomchik, K. J. and Devreotes, P. N. 1981.
Adenosine 3,5-monophosphate waves in
Dictyostelium discoideum a demonstration by
isotope dilution-fluorography technique.
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QUESTIONS?