The researchers studied the behavior of the algal cell Karlodinium veneficum, known as a dinoflagellate and found in estuaries worldwide. Each year millions of dollars are spent on measures to control dinoflagellates around the globe. This particular species is known to release a substance called karlotoxin, which is extremely damaging to the gills of fish. Karlodinium veneficum has been known to form large algal blooms in the Chesapeake and elsewhere, triggering an immediate harmful impact on aquatic life, including fish kills.
"This new research opens the door to reducing bloom frequency and intensity by reducing the availability of its prey," said Allen Place of the Institute of Marine and Environmental Technology at the University of Maryland Center for Environmental Science. "As we reduce the nutrient load feeding Karlodinium's prey and bring back the bay's most prolific filter feeder, the Eastern oyster, we could essentially limit Karlodinium's ability to bloom."
Place, in whose laboratory karlotoxin was discovered and characterized, was a co-author of the new study, published this week in the online Early Edition of the Proceedings of the National Academy of Sciences. Other researchers involved in the study came from the University of Minnesota, The Johns Hopkins University and the University of Hawaii.
"This is a major environmental problem, but we didn't know why these microbes were producing the toxins in the first place," said Joseph Katz, the William F. Ward Sr. Professor in the Department of Mechanical Engineering at Johns Hopkins and a co-author of the paper. "Some people thought they were just using the toxins to scare away other predators and protect themselves. But with this new research, we've provided clear evidence that this species of K. veneficum is using the toxin to stun and capture its prey."
Historically, scientists have found it difficult to study the behavior of these tiny animals because the single-cell creatures can quickly swim out of a microscope's shallow field of focus. But in recent years this problem has been solved through the use of digital holographic microscopy, which can capture three-dimensional images of the troublesome microbes. The technique was pioneered by Katz.
In a study published in 2007, Katz, Place and Jian Sheng, who was Katz's doctoral student, were part of a team that reported the use of digital holographic microscopy to view the swimming behavior of K. veneficum and Pfiesteria piscicida. At the time, it appeared that K. veneficum slowed down into a "stealth mode" in order to ambush its prey while P. piscicida sped up to capture prey.
For the new paper, in which Sheng is lead author, the researchers used the same technique to more closely study the relationship between K. veneficum and its prey, a common, single-celled algal cell called a cryptophyte. They found that K. veneficum microbes release toxins to stun and immobilize their prey prior to ingestion, probably to increase the success rate of their hunt and to promote their growth.
This significantly shifts the understanding about what permits harmful algal blooms to form and grow, the researchers said. Instead of being a self-defense mechanism, the microbes' production of poison appears to be more closely related to growth through the ingestion of a "pre-packaged" food source, the cryptophyte cell, they concluded.
"In the paper, we have answered why these complicated [toxic] molecules are made in nature in the first place and identify a possible alternative mechanism causing massive bloom," said Sheng, who is now a faculty member in the University of Minnesota's Department of Aerospace Engineering and Mechanics.
Other co-authors of the PNAS paper are Edwin Malkiel, an adjunct associate research scientist in the Department of Mechanical Engineering at Johns Hopkins; and Jason E. Adolf, an assistant professor in the University of Hawaii's Department of Marine Science.
Funding for the research was provided by the National Science Foundation and the National Oceanic and Atmospheric Administration's Coastal Oceans Program.
The journal article maybe viewed online here: http://www.pnas.org/content/early/2010/01/14/0912254107.full.pdf+html.Related links:
Phil Sneiderman | EurekAlert!
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research