Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fat chance for hosts

09.09.2003


New study shows parasitic flatworms take destiny by the tail



In the research article "Larval swimming overpowers turbulent mixing and facilitates transmission of a marine parasite," appearing in the September issue of the Ecological Society of America’s journal Ecology, Jonathan Fingerut of the University of California-Los Angeles and colleagues describe the results of the first study to examine larval behavior versus passive-transport processes under natural and simulated water flow conditions.

H. rhigedana is one of the most common parasitic flatworms found in southern California. Sexual reproduction takes place in definitive host birds, which defecate the parasite’s eggs into marshes. The first swimming larval stage (miracidia) infect the California horn snail, causing castration and other sublethal effects. Asexual reproduction ensues, producing tens of free-swimming cercariae per snail per day, which encyst on other snails and crabs as second intermediate hosts. Birds which eat the snails and crabs complete the parasite’s life cycle.


Fingerut and his colleagues Cheryl Ann Zimmer and Richard Zimmer, also of UC-Los Angeles, wanted to determine what explains the unusually high transmission rate of H. rhigedana’s cercariae (second larval stage). The larvae encyst up to 100 percent of the local snail and crab second intermediate hosts, an especially astonishing feat since this larval stage has but four hours to locate and infect its host.

The researchers examined the range of variation and effect on larval swimming of relevant physical factors (light, temperature, salinity and water flow). They also used new laser and digital video imaging technologies to identify active versus passive transport of the larvae.

"In our still water experiments, we found that exposure to light caused cercariae to swim straight toward the bottom of the water body where they were likely to encounter their hosts," says Fingerut. "And while salinity had no impact on either swim speed or direction, a 33 percent increase in water temperature led to a 71 percent increase in the larvae’s swim speeds, bringing the larvae to the bottom faster."

When the researchers looked at the same variables in slow-moving water conditions, they found similar results: the cercariae swam determinedly towards the bottom, prevailing over the slow-moving water currents. However, fast-moving water bodies overwhelmed the larvae’s ability to control their movements and they were distributed throughout the water column, much like passive particles. Water temperature had no effect in this setting.

"Our study indicates that whether adaptive or fortuitous, parasite transmission is largely controlled by the cercariae and not by the vagaries of flow," the investigators conclude.


Founded in 1915, the Ecological Society of America (ESA) is a scientific, non-profit, organization with 8000 members. Through ESA reports, journals, membership research, and expert testimony to Congress, ESA seeks to promote the responsible application of ecological data and principles to the solution of environmental problems. For more information about the Society and its activities, access ESA’s web site at: www.esa.org.

Annie Drinkard | EurekAlert!
Further information:
http://www.esa.org

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>