海洋生物体发光之潜在机制

It has long been known that distinctive¹ blue flashes--a type of bioluminescence--that are visible at night in some marine² environments are caused by tiny, unicellular（单细胞的） plankton³ known as dinoflagellates（鞭毛藻类） . However, a new study has, for the first time, detailed⁴ the potential mechanism⁵ for this bioluminesence. The study, which was partially⁶ 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 Proceedings⁷ 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 membranes⁹ 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 genes¹⁰ that are similar to genes for voltage-gated proton channels that had previously¹¹ been identified in humans, mice and sea squirts（海鞘） .

According to the study, here is how the light-generating process in dinoflagellates may work: As dinoflagellates float, mechanical stimulation¹² generated by the movement of surrounding water sends electrical impulses around an internal compartment¹³ within the organism, called a vacuole--which holds an abundance of protons. These electrical impulses open so-called voltage-sensitive proton channels that connect the vacuole（胞液） to tiny pockets dotting the vacuole membrane⁸, known as scintillons.

Once opened, the voltage-sensitive proton channels may funnel¹⁴ protons from the vacuole into the scintillons. Protons entering the scintillons then activate¹⁵ luciferase--a protein, which produces flashes of light, that is stored in scintillons. Flashes of light produced by resulting luciferase activation¹⁶ would be most visible during blooms of dinoflagellates.

This research illuminates¹⁷ the novel mechanisms¹⁸ underlying¹⁹ a beautiful natural phenomenon in our oceans, and enhances our understanding of dinoflagellates--some of which can produce toxins²⁰ that are harmful to the environment.