[Coral-List] Announcing New Paper: Symbiophagy as a Cellular Mechanism for Coral Bleaching

[Cheryl Woodley]

Dear Coral List Members

I would like to let you know of a new publication that may be of 
interest. The citation and abstract are provided below.
All the best
Cheryl

Autophagy 5:2, 211-216; 16 February 2009

Symbiophagy as a Cellular Mechanism for Coral Bleaching
Craig A. Downs, Esti Kramarsky-Winter, Jon Martinez, Ariel Kushmaro,
Cheryl M. Woodley, Yossi Loya and Gary K. Ostrander

Abstract
Coral bleaching is a major contributor to the global declines of coral
reefs. This phenomenon is characterized by the loss of symbiotic algae,
their pigments or both. Despite wide scientific interest, the mechanisms
by which bleaching occurs are still poorly understood. Here we report
that the removal of the symbiont during light and temperature stress is 
achieved using the host’s cellular autophagic-associated machinery. Host 
cellular and subcellular morphologies showed increased vacuolization and 
appearance of autophagic membranes surrounding a variety of organelles 
and surrounding the symbiotic algae. Markers of autophagy (Rab 7 and 
LAS) corroborate these observations. Results showed that during stress 
the symbiont vacuolar membrane is transformed from a conduit of nutrient 
exchange to a digestive organelle resulting in the consumption of the 
symbiont, a process we term symbiophagy. We posit that during a stress 
event, the mechanism maintaining symbiosis is destabilized and 
symbiophagy is activated, ultimately resulting in the phenomenon of 
bleaching. Symbiophagy may have evolved from a more general primordial 
innate intracellular protective pathway termed xenophagy.


-- 
Cheryl Woodley, Ph.D.
Coral Health and Disease Program

DOC/NOAA/NOS/NCCOS
Center for Coastal Environmental Health and Biomolecular Research
Hollings Marine Laboratory
331 Fort Johnson Rd
Charleston, SC 29412
843.762.8862 Phone
843.762.8737 Fax
cheryl.woodley at noaa.gov