Featured Research

from universities, journals, and other organizations

Discovery illuminates elusive proton channel gene in dinoflagellates

Date:
October 24, 2011
Source:
Rush University Medical Center
Summary:
A 40-year search for a gene that causes some one-celled sea creatures to flash at night and is also found in others that produce deadly red tides has successfully ended.

A 40-year search for a gene that causes some one-celled sea creatures to flash at night and is also found in others that produce deadly red tides has successfully ended, thanks to research by a group of scientists led by Thomas E. DeCoursey, PhD, professor of biophysics and physiology at Rush University Medical Center.

The gene, discovered in a tiny marine organism called a dinoflagellate (Karlodinium veneficum), controls voltage-gated proton channels, which, in addition to triggering luminescence in certain single-cell sea creatures, activate many important biological mechanisms in other species, including humans.

Results of the study by DeCoursey, Susan M. E. Smith and co-researchers were published in the Oct. 17, 2011 issue of the Proceedings of the National Academy of Sciences. The study was funded in part by grants from the National Science Foundation and the National Institutes of Health.

The existence of a voltage-gated proton channel in bioluminescent dinoflagellates was proposed in 1972 by J. Woodland Hastings, a co-author on the current study, and his colleague Margaret Fogel. They hypothesized that proton channels helped trigger the flash by activating luciferase, an enzyme that helps produce luminescence. But until now, the genetic code responsible for the proton channels in dinoflagellates had not been identified, although it had been decrypted in humans, mice, algae and sea squirts.

Voltage-gated proton channels are extremely versatile. In humans, they are involved in several basic biological processes, including release of histamine in basophils, a type of white blood cell. Proton channels also play a role in the production of reactive oxygen species such as hydrogen peroxide that kill bacteria in phagocytes, another kind of white blood cell, and in maturation of sperm immediately before fertilization.

In the current study, DeCoursey and co-researchers mined the gene sequence library of a K veneficum dinoflagellate and found a gene named kHv1 that is similar to those already known to code for proton channels in other species. Not surprisingly, there were many differences in the make-up of the proton channel molecules in humans and tiny sea creatures, but the most important parts of the molecules turned out to be almost identical. Electrophysiologic tests confirmed that the genetically coded protein was indeed a proton channel -- but one with an unprecedented quality.

Proton currents in K veneficum differ from all known proton currents in having large inward currents -- a result of the channels opening at membrane potentials about 60 mV more negative than in other species, the researchers found.

"Vertebrate proton channels open to allow acid extrusion, while dinoflagellate proton channels open to allow proton influx into a cell's cytoplasm, making the channel ideally suited to trigger bioluminescence," DeCoursey explained.

When dinoflagellates floating in water are mechanically stimulated by movement, an impulse (action potential) is sent along the membrane of an internal compartment called a vacuole. Clustered along the inside of this membrane are tiny pockets called scintillons, containing a combination of luciferin and luciferase -- proteins that are able to produce a light flash under the right circumstances. The inside of the vacuole compartment is very acidic and has an abundance of protons.

As the electric impulse travels along the membrane, it causes the voltage-sensitive proton channels to open. Protons then flow from the vacuole into the scintillon, where they react with the luciferase and a flash of light results.

In nonbioluminescent mixotrophic species like K veneficum, proton influx might be involved in prey digestion (e.g., signaling prey capture) or prey capture (e.g., extrusion of stinging trichocysts).

Co-investigator Susan Smith carried out a phylogenetic analysis of known Hv1 sequences, finding high sequence diversity among the single-celled species and among invertebrates. She interpreted this finding to suggest the possibility of other novel functions of Hv1 in these species.

"As in multicellular organisms, ion channels in dinoflagellates play various roles in regulating basic life functions, which make them targets for controlling dinoflagellate populations and behavior," the authors suggested.

Future research will show whether targeting proton channels might give us a handle on controlling dinoflagellate blooms that cause deadly red tides and are responsible for massive fresh kills. Certain dinoflagellate species produce some of the most deadly poisons known, such as saxitoxin, a neurotoxin 100,000 times more potent than cocaine. Paralytic shellfish poisoning occurs in humans who eat shellfish that have consumed toxic dinoflagellates.

In addition to DeCoursey, Smith (Emory School of Medicine) and Hastings (Harvard University), the authors of this paper include Deri Morgan, Boris Musset and Vladimir V. Cherny of Rush University Medical School, and Allen R. Place of the University of Maryland Center for Environmental Sciences.


Story Source:

The above story is based on materials provided by Rush University Medical Center. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. M. E. Smith, D. Morgan, B. Musset, V. V. Cherny, A. R. Place, J. W. Hastings, T. E. DeCoursey. Voltage-gated proton channel in a dinoflagellate. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1115405108

Cite This Page:

Rush University Medical Center. "Discovery illuminates elusive proton channel gene in dinoflagellates." ScienceDaily. ScienceDaily, 24 October 2011. <www.sciencedaily.com/releases/2011/10/111024133035.htm>.
Rush University Medical Center. (2011, October 24). Discovery illuminates elusive proton channel gene in dinoflagellates. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/10/111024133035.htm
Rush University Medical Center. "Discovery illuminates elusive proton channel gene in dinoflagellates." ScienceDaily. www.sciencedaily.com/releases/2011/10/111024133035.htm (accessed October 2, 2014).

Share This



More Plants & Animals News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) — Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
Powered by NewsLook.com
Cultural Learning In Wild Chimps Observed For The First Time

Cultural Learning In Wild Chimps Observed For The First Time

Newsy (Oct. 1, 2014) — Cultural transmission — the passing of knowledge from one animal to another — has been caught on camera with chimps teaching other chimps. Video provided by Newsy
Powered by NewsLook.com
Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Earth Has Lost Half Its Vertebrate Wildlife Since 1970: WWF

Newsy (Sep. 30, 2014) — A new study published by the World Wide Fund for Nature found that more than half of the world's wildlife population has declined since 1970. Video provided by Newsy
Powered by NewsLook.com
Annual Dog Surfing Competition Draws California Crowds

Annual Dog Surfing Competition Draws California Crowds

AFP (Sep. 30, 2014) — The best canine surfers gathered for Huntington Beach's annual dog surfing competition, "Surf City, Surf Dog." Duration: 01:15 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins