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 Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

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: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

The material that obscures supermassive black holes

26.09.2017 | Physics and Astronomy

Ageless ears? Elderly barn owls do not become hard of hearing

26.09.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>