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 Antarctic Ice Sheet mass loss has increased
14.06.2018 | Technische Universität Dresden

nachricht WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf

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: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>