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 Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>