Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Discovery illuminates elusive proton channel gene in dinoflagellate

25.10.2011
Mechanism in tiny, one-celled sea creature also present in higher vertebrates and humans

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 been successfully culminated 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 October 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.

Deb Song | EurekAlert!
Further information:
http://www.rush.edu

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>