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JSU Researchers Find |
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May 23, 2003 --
Researchers in the department of biology at Jacksonville State
University are examining the use of photoactive dyes to treat fish
parasites. In the past, photoactive dyes have been effective against insects, which led JSU researchers to explore their use against aquatic parasites. Disease is of major concern to the aquaculture industry. Losses in aquarium and foodfish industries are likely to exceed $100 million annually. One of the most common disease causing external protozoan parasites is Ichthyophthirius multifiliis ("Ich"), which causes white spot disease and is responsible for nearly 50% of catfish losses and up to 80% of ornamental fish losses annually. Microbiologist Dr. Benjie Blair and aquaculturist Dr. Mark Meade have found that several photoactive dyes are effective against Ich and other aquatic protozoans. Researchers expect at the end of the project that photodynamic dyes will become a viable alternative to classical treatments for parasitic diseases and may even reduce the occurrence of subsequent infections. "Treatment is aimed at decreasing or eliminating primary infestations and reducing the occurrence of secondary infestations", according to Blair. "These dyes may also prove to be useful as an attenuating agent for protozoa infections and provide enhanced immune responses in fish." Phloxine B, a type of photoactive dye, has been successful in trials against a variety of protozoa (Tetrahymena and Ichthyophthirius). Little is known about the function of these Halogenated xanthenes dyes but it has been suggested that when the dye becomes activated by sunlight they collect light energy and transforming oxygen to reactive single oxygen and superoxide. The results are that damage occurs randomly throughout the organism that has ingested or absorbed the dye. In general, the dyes are toxic to organisms that do not have strong pigmentation or layers of skin and therefore, do not harm most animals. In fact, the FDA has approved phloxine B for use as a coloring agent for food and cosmetics. "Use of photoactive dyes poses no potential threat to the environment," says Meade. "Most treatments used today involve harsh chemicals, many of which can be both mutagenic and carcinogenic. We are conducting toxicity assays in conjunction with other faculty in our department along with treatment assays to insure the safety of photoactive dyes." Rapid photodegradation of most of these dyes occurs in sunlight within a few hours. Degradation products of this dye are also not harmful and do not produce a substantial increase in toxicity and have extremely low toxicity to mammals, birds, fish, reptiles and amphibians. Blair and Meade have received a U.S. patent (U.S. Patent No. 6,506,79) and are currently seeking funding to support graduate students working on this project. |
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