Neural control of dynamic structural coloration in squid iridophores.
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1
Marine Biological Laboratory, Marine Resources Center, United States
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2
University of Texas Medical School, Department of Integrative Biology and Pharmacology, United States
Fast dynamic control of skin coloration is rare in the animal kingdom, whether it be pigmentary or structural. Iridescent structural coloration results when nanoscale structures disrupt incident light and selectively reflect specific colors. Unlike animals with fixed iridescent coloration (e.g. butterflies), squid iridophores produce dynamically tunable structural coloration, as exogenous application of the acetylcholine (ACh) changes the color and brightness output. However, previous efforts to stimulate iridophores neurally or to identify the source of the ACh were unsuccessful, leaving researchers to question the activation mechanism. We developed a novel neurophysiological preparation in the fin of Doryteuthis pealeii (aka. Loligo pealeii) and demonstrated, for the first time, that electrical stimulation of neurons in the skin shifts the color spectrum (>145 nm) and increases the luminosity (>245 %) of innervated iridophores. By forward filling the stimulated nerves, we traced extensive nerve branching within the convoluted iridophore platelets. We show the dynamic color shift is significantly faster (17 s) than the luminosity increase (32 s) revealing two distinct mechanisms. Responses from a structurally altered preparation indicate that the reflectin protein condensation mechanism explains luminosity change, while an undiscovered mechanism causes the fast color shift.
Acknowledgements
TJW and PTGB share first authorship. We thank Hanlon lab members for discussion and in particular Lydia Mathger for help with spectrometry and advice. We thank MBL equipment resources and Zeiss Microscopes for assistance with equipment. We thank MBL Central Microscopy for imaging resources and MBL Aquatic Resources Division for supplying squid. We are very grateful for funding from ONR Basic Research Challenge grant # N00014-10-1-0989, DARPA grant W911NF-10-1-0113 and AFOSR grant FA9950090346.
Keywords:
Acetylcholine,
Electrophysiology,
Iridescence,
Neural Stimulation,
Whole-mount microscopy
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for Participant Symposium)
Topic:
Neuromodulation
Citation:
Wardill
TJ,
Gonzalez Bellido
PT,
Crook
R and
Hanlon
RT
(2012). Neural control of dynamic structural coloration in squid iridophores..
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00264
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Received:
30 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Dr. Trevor J Wardill, Marine Biological Laboratory, Marine Resources Center, Woods Hole, MA, 02543, United States, twardill@umn.edu
Dr. Paloma T Gonzalez Bellido, Marine Biological Laboratory, Marine Resources Center, Woods Hole, MA, 02543, United States, paloma@mbl.edu