Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'Home run' study on spread of disease published

20.12.2006
A paper that authors are calling a "home run" study on the spread of disease is published in this week’s issue of the Proceedings of the National Academy of Sciences (PNAS).

The study traces -- through genetic analysis -- the accidental introduction of invasive snails with parasitic flatworms. The invaders were probably transported with Japanese seed oysters imported into the waters of the Pacific Northwest over a century ago. It is the first comprehensive genetic analysis of an invasive marine host and its parasites. The study points to broad implications for identifying and mitigating spreading disease in a globalized economy.

Understanding the invasion pathways of disease-causing organisms and their hosts is key in limiting future disease outbreaks — in humans, in agriculture, and in wildlife.

Co-author Armand Kuris, professor of zoology in the Department of Ecology, Evolution and Marine Biology at the University of California, Santa Barbara, is one of a handful of experts who have been studying the ecology of parasites since the 1960s, an area of research that Kuris reports is understudied because parasites are so often invisible. He calls this PNAS paper a home run because it describes a complete picture of biological invasions. He explained that the imported snail has wiped out the native snails, changing the ecosystems of the Northwest.

"Little did the American oystermen of the early 1900s know that their activities could impact local fisheries one hundred years later," said Kuris. "Oyster aquaculture brought in many exotic species, including clams, worms, and snails. Importation was done in a crude and sloppy manner; there was little government regulation of these things at the time."

Invasive North American populations of Asian mud snails, Batillaria attramentaria, probably arrived with Pacific oysters, Crassostrea gigas, imported from northern Japan in the early 1900s, according to the scientists. Genetic research has now confirmed this. The team included first author Osamu Miura, a scientist with Tohoku University in Sendai, Japan; colleagues from the Smithsonian Tropical Research Institute in Panama (STRI); and, scientists from UC Santa Barbara.

"We saw a lot of genetic variation among snail populations in Japan but the North American snails are genetically most similar to those from northern Japan, the source of the imported oysters," Miura reports.

"Using genetics we have shown how the pest snail was introduced and that it came with a parasite that infects fishes and birds," said Mark Torchin, a biologist with STRI. Later, a second parasite came that was spread by migratory birds that ate the infected fish in Japan. The process shows that establishment of an invasive pest can lead to later establishment of disease organisms.

Ryan F. Hechinger, a doctoral student at UCSB, explained how the parasitic flatworm, or trematode, castrates the snail, replacing the gonads with its own mass. "The infected snail will never again make snail babies," said Hechinger. "It is now a parasite making machine. It’s basically a robot driven by the parasite."

Hechinger explained that this is the first time that scientists have examined an invasion of a host and a parasite. Migrating birds are bringing one of the trematode parasites; they ingest them when they eat infected fish. The host is a particular snail –- only one species is vulnerable –– and it is used as an intermediate host. The trematode moves on from the snail to burrow into fish. The trematode has permeated the ecosystem’s fish.

Of the eight species of trematode parasites that plague the snails in Japan, only the most common, Cercaria batillariae, has arrived in America. Gene sequencing showed that this single species actually consisted of several cryptic, or similar looking but genetically distinct, species in its home range in Japan. In North America, they commonly found two of the species. One parasite shows much less genetic diversity in America than in Japan, whereas the other parasite is equally diverse in both regions.

"Genetic evidence suggests that while one cryptic parasite species experienced a bottleneck and probably came with the snails, the other was probably historically dispersed by migratory birds and could only establish in North America after the snail hosts arrived," added Torchin. "This is because these trematode parasites have complex life cycles, using snails as first intermediate hosts, fishes as second intermediate hosts and birds as final hosts. As we homogenize biotas as a result of repeated species invasions through global trade, we increase the chances of reuniting infectious agents with suitable hosts."

Parasites which may have historically gone unnoticed as "tourists" in some regions may become pervasive residents after invasion of their missing hosts.

Gail Gallessich | EurekAlert!
Further information:
http://www.ucsb.edu

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>