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News Release - Understanding Viruses in Lake Superior

                                 MN SEA GRANT
                                 NEWS RELEASE
Date: 1/12/99                                       Contact: Marie Zhuikov
                                                    Phone: (218) 726-7677

                 Understanding Viruses in Lake Superior - 
                Effects of Ultraviolet (UV) Light Probed

For the first time, scientists are looking at the abundance of viruses in one of
the Great Lakes.  Minnesota Sea Grant researchers Randall Hicks, associate 
professor and head of the University of Minnesota Duluth's (UMD) Department of 
Biology, and Mark Tapper, a UMD graduate student, recently completed a study 
that began to address how global climate change may affect viruses in the waters
of Lake Superior.  Because of the difficulty of identifying and counting these 
microscopic particles, little is known about the abundance of viruses or how 
various environmental factors affect them.

"We wanted to determine how many dormant viruses infect bacteria in the lake so 
we would have some idea of what the potential problems might be if UV light does
increase as a result of thinning of the ozone layer," said Hicks.  "Some types 
of UV light can damage DNA and can also cause dormant viruses to become active. 
If there are many dormant viruses, we might see major impacts on bacterial 
populations and, in turn, nutrient cycling and food webs," said Hicks.

Hicks and Tapper collected water samples from Lake Superior in the spring, 
summer, and fall of 1993, then counted the number of free viruses in the water 
samples. They also exposed other water samples to UV light in order to activate 
and count dormant viruses. 

They concluded that less than 7.5 percent of the bacteria in the samples 
contained dormant viruses. Even if all these dormant viruses were triggered, 
this level of infection does not appear to be a significant threat to bacterial 

But that doesn't mean the research is done. As Hicks explained, "We're better 
able to see and recognize more viruses now that we have better technology for 
observing them." So this project was just a start.  To build a more complete and
accurate picture of the universe of aquatic bacteria and their viruses, 
researchers will have to study other freshwater lakes as well as the oceans. 
This Sea Grant-funded research has already stimulated similar studies in coastal
oceans in other parts of the world.

The results of this research project were published in the January 1998 issue of
the journal Limnology and Oceanography. To find out more, you can order a 
reprint of the article,  "Temperate Viruses And Lysogeny In Lake Superior 
Bacterioplankton," from Minnesota Sea Grant by calling (218) 726-6191.


Note:  An image of a Lake Superior virus is available on Minnesota Sea Grant's 
Web site:  http://www.d.umn.edu/seagr/news/1999.html


Marie Zhuikov (pronounced zwee-cough)
Communications Coordinator
MN Sea Grant, University of MN - Duluth
(218) 726-7677   Fax: (218) 726-6556
MN Sea Grant Home Page: www.d.umn.edu/seagr

"Superior Science for You"