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Press Release 11-224
Suggested Explanation for Glowing Seas--Including Currently Glowing California Seas

Potential mechanism for dazzling blue flashes of light in oceans identified

Illustration showing how a flash of light is emitted when a dinoflagellate is mechanically agitated.

A proposed mechanism for bioluminescence in dinoflagellates.
Credit and Larger Version

October 18, 2011

It has long been known that spectacular blue flashes--a type of bioluminescence--that are visible at night in some marine environments (currently including coastal California waters) are caused by tiny, unicellular plankton known as dinoflagellates. However, a new study has, for the first time, detailed the potential mechanism for this bioluminescence.

The study, which was partially funded by the National Science Foundation, is reported by Susan Smith of Emory School of Medicine, Thomas DeCoursey of Rush University Medical Center and colleagues in the Oct. 17, 2011 issue of the Proceedings of the National Academy of Sciences (PNAS).

A key aspect of the potential mechanism for bioluminescence in dinoflagellates proposed in the PNAS study involves voltage-gated proton channels--channels in membranes that can be opened or closed by chemical or electrical events.

J. Woodland Hastings, a member of the Smith and DeCoursey research team and an author of the PNAS article, suggested the presence of voltage-gated proton channels in dinoflagellates almost forty years ago. But the Smith and Decoursey team only recently confirmed them by the identification and subsequent testing of dinoflagellate genes that are similar to genes for voltage-gated proton channels that had previously been identified in humans, mice and sea squirts.

According to the study, here is how the light-generating process in dinoflagellates may work: As dinoflagellates float, mechanical stimulation generated by the movement of surrounding water sends electrical impulses around an internal compartment within the organism, called a vacuole--which holds an abundance of protons. (See accompanying illustration.) These electrical impulses open so-called voltage-sensitive proton channels that connect the vacuole to tiny pockets dotting the vacuole membrane, known as scintillons.

Once opened, the voltage-sensitive proton channels may funnel protons from the vacuole into the scintillons. Protons entering the scintillons then activate luciferase--a protein, which produces flashes of light, that is stored in scintillons. Flashes of light produced by resulting luciferase activation would be most visible during blooms of dinoflagellates.

The red tide that is currently flashing off some California waters is almost certainly generated by dinoflagellates. Although the California species may be different from those included in this study, their mechanism for triggering flashes is believed to operate by the same mechanism.

This research illuminates the novel mechanisms underlying a beautiful natural phenomenon in our oceans, and enhances our understanding of dinoflagellates--some of which can produce toxins that are harmful to the environment.

-NSF-

Media Contacts
Lily Whiteman, National Science Foundation, (703) 292-8310, lwhitema@nsf.gov
John Pontarelli, Rush University Medical Center, (312) 942-5949, john_m_pontarelli@rush.edu

Program Contacts
Gregory Warr, National Science Foundation, (703) 292-8440, gwarr@nsf.gov

Principal Investigators
Thomas E. DeCoursey, Rush University Medical School, (312) 942-3267, tdecours@rush.edu

Co-Investigators
Susan Smith, Emory School of Medicine, (404) 727-5880, susan.m.smith@emory.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

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