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Killer algae's "fingerprints" wrap up the case

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27.05.2008

Phytoplankton are microscopic plants that are the base of the food chain in oceans and lakes.

Some phytoplankton can produce toxins that are harmful to other marine organisms, including fish. Holly A. Bowers of the University of Kalmar in Sweden has studied the DNA of phytoplankton in order to identify and quantify different types of harmful phytoplankton species.

Her work is a key piece of the puzzle when it comes to understanding when and how harmful phytoplankton species, such as e.g. the "killer algae" become dominant and threaten to kill off fish.

Just like plants on land, phytoplankton is an important source of nutrition for other organisms and is responsible for the major part of the global primary production. Sometimes the phytoplankton toxins can be so potent that they can cause severe illness and even death in humans.

Authorities, administrators, and researchers are interested in methods that can rapidly locate harmful phytoplankton species. Since phytoplankton species are tiny, 1-100 thousandths of a mm, and several of them look similar, it is difficult to distinguish various species in a microscope. One way to get around this is to analyze their DNA.

"DNA is species-specific and is similar to a fingerprint, which makes it possible to distinguish between different species", says Holly A. Bowers.

One way to analyze DNA is through real-time PCR, where you dye the DNA of a single species with a fluorescent preparation. The light can then be measured, and more light means more cells of the species there are in the water sample.

Holly A. Bowers' doctoral thesis describes how real-time PCR has been adapted to quickly and reliably identify and estimate a number of harmful phytoplankton species quantities present in the water. The DNA tests that Holly A. Bowers developed for her thesis are now used in several places around the world, especially in the Chesapeake Bay, Maryland, U.S. The findings of the DNA tests have helped researchers, authorities, and administrators to understand the spread of harmful phytoplankton species. The part of the doctoral work carried out in the U.S. mainly focused on identifying harmful species as part of a state-sponsored monitoring program. In Kalmar, Sweden, the DNA tests were used to study the feeding behavior of a phytoplankton species responsible for fish kills in coastal waters around the world, including the Baltic outside Kalmar.

The external examiner was Professor Lisa Campbell, Texas A&M University, USA.

For more information:
Professor Edna Granéli; Tel: +46- 480 44 73 07; Mobil: +46-70 674 9415 ?
E-post: edna.graneli@hik.se

Pressofficer Karin Ekebjär; +46-709229 435; karin.ekebjar@hik.se

Karin Ekebjär | Source: Informationsdienst Wissenschaft
Further information: www.vr.se

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