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 Foxes in the city: citizen science helps researchers to study urban wildlife
14.12.2018 | Veterinärmedizinische Universität Wien

nachricht Machine learning helps predict worldwide plant-conservation priorities
04.12.2018 | Ohio State University

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: Data storage using individual molecules

Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.

Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Pressure tuned magnetism paves the way for novel electronic devices

18.12.2018 | Materials Sciences

New type of low-energy nanolaser that shines in all directions

18.12.2018 | Physics and Astronomy

NASA research reveals Saturn is losing its rings at 'worst-case-scenario' rate

18.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>