SEA 



SCIENCE 



from mast cells — the most common tissue 

 immune cell found in fish and other vertebrates, 

 including humans. 



Mast cells are present in many tissues, 

 including the skin, respiratory tract — gills or 

 lungs — and the gastrointestinal tract 



This is the first time that researchers have 

 isolated a peptide antibiotic from mast cells of 

 any animal, including humans. The study 

 appeared in a recent issue of the prestigious 

 scientific journal Nature. 



"The peptide antibiotics or 'piscidins' 

 have the potential to fight important bacterial 

 pathogens of both fish and mammals, including 

 multi-drug-resistant bacteria," says Noga. 'The 

 antibiotics could be a useful template for 

 designing new drugs because they are novel 

 structures and not related to any known 

 antibiotic. With the development of antibiotic- 

 resistant bacteria, there is an urgent need to find 

 new types of antibiotics that can fight these 

 resistant pathogens." 



Noga says it is unclear whether fish mast 

 cells are from the same lineage as mammalian 

 mast cells. 



"While mast cells are one of the most 

 common immune cells of vertebrates, their role 

 as a critical line of defense is uncertain," he adds. 

 "However, if any type of peptide antibiotic is 

 also present in human mast cells, it could have 

 important implications for treating human 

 diseases, including asthma, skin allergies and 

 certain types of arthritis, because of the 

 prominent role that mast cells play in these 

 diseases." 



The study also has important implications 

 for the U.S. aquaculture industry, which grew 

 from $45 million for value of products sold in 

 1974 to more than $978 million in 1998, 

 according to the U.S. Dept. of Agriculture. 



The N.C. Dept. of Agriculture & 

 Consumer Services reported that the state's 

 aquaculture sales exceeded $20.5 million in 

 2000. Hybrid striped bass was the second 

 highest product in the N.C. aquaculture industry, 

 generating more than $5.3 million in 2000, 

 according to the department. 



"The new discovery can lead to ways to 

 protect hybrid striped bass and other fish against 

 disease without using traditional antibiotics," 



Umaporn Silphaduang and Ed Noga check the health status of some fish. 



says Noga. "This could result in health-costs 

 savings and a higher quality and safer product." 



North Carolina Sea Grant Director Ronald 

 G. Hodson says the cutting-edge research has 

 tremendous potential for human medicine as 

 well as aquaculture and other areas of veterinary 

 medicine. "We believe this discovery is just the 

 beginning of a whole new approach to treating 

 bacterial diseases in humans and other animals." 



What's next? 



Silphaduang, who won one of NOAA's 

 2001 Walter B. Jones Memorial Awards in 

 Coastal and Marine Graduate Study, says they 

 will be determining if the mast cells of other 

 animals, including humans, contain antibiotics. 



"We hope to find an answer within the 

 next 12 months," adds Noga. 



New Stress Test 



As an aquatic medicine specialist, Noga 

 has done groundbreaking research on a variety 

 of fish, including channel catfish, tilapia and 

 rainbow trout. 



David Robinette, a former graduate student 

 at the NC State College of Veterinary Medicine, 

 attributes Noga's breakthroughs in fish antibiotic 

 studies to his creativity and attention to details. 



"Ed is one of the most thorough scientists I 



have ever known," says Robinette, winner of a 

 1999 Walter B. Jones Memorial Award in 

 Coastal and Marine Graduate Study. "He is 

 always on top of what his research assistants are 

 doing in the lab and helping them to develop 

 critical thinking skills. He never leaves a stone 

 unturned." 



In 1987, Noga's lab was the first to 

 develop a method for in vitro culture of the 

 parasite Amyloodinium ocellatwn, one of the 

 most important pathogens affecting marine fish. 



A year later, Noga and former NC State 

 College of Veterinary Medicine graduate student 

 Stephen Smith identified a toxic dinoflagellate 

 later named Pfiesteria, which has been 

 associated with numerous fish kills and health 

 problems in coastal waters. 



In 2000, Noga and Robinette used channel 

 catfish to develop a new stress test for fish. 



The researchers identified naturally 

 occurring antibiotics in channel catfish that may 

 be a promising indicator for monitoring fish 

 health in the expanding aquaculture industry. 



The scientists found that polypeptides 

 called histone-like proteins (HLPs) are likely an 

 important component of nonspecific immunity 

 in channel catfish. Nonspecific immunity 

 protects against many different diseases at once. 



24 WINTER 2002 



