Fish may offer distinct benefits in such determinations due to  ease  with  which  they  can  be  held  in  certain  chronic regimes, and some complex chemical mixture exposures. In addition, since the transgenic targets permit mutations in a single  gene  to  be  detected,  the  precise  mutation  can  be described and inferences drawn about the potential mecha- nisms of the mutagen’s action. The  medaka  and  mummichog  were  chosen  for  trans- genic  applications  because  each  species  offers  benefits  for environmental toxicology and they are well suited to a wide range  of  studies  in  mutagenesis,  carcinogenesis,  anticar- cinogenesis,  and  hazard  assessment  using  chronic  expo- sures, complex chemical mixtures, or radiation. Mutations can be detected in virtually any tissue from which DNA can be isolated. A new aquatic resource center, the Aquatic Biotechnol- ogy  and  Environmental  Laboratory  (ABEL),  is  being  con- structed at the University of Georgia. The 8500 sq ft facility combines,  in  a  single  building,  the  molecular  and  toxico- logical laboratories with the aquatic animal husbandry wet labs,  thereby  enhancing  the  efficiency  of  animal  care  and use  and  of  laboratory  analyses.  The  laboratories  are equipped  with  state-of-the-art  instrumentation,  including that  for  DNA  sequencing  and  quantitative  PCR;  the  toxi- cological  exposure  laboratories  have  proportional  flow- through  chemical  diluters  and  gene-transfer  equipment. Both freshwater and saltwater organisms can be cultivated. Under  special  arrangements,  transgenic,  mutant  or  other specialized  strains  of  fish  from  other  laboratories  will  be accommodated in the facility. Contact Richard  N.  Winn,  PhD:  rwinn@smokey.forestry. uga.edu;  University  of  Georgia,  Aquatic  Biotechnology Laboratory,  458  Animal  Science  Complex,  Athens,  GA 30602, USA; telephone: 706-542-6227; fax: 706-542-7925. SMALL  FISH  CARCINOGENESIS  RESOURCES AT  THE   INSTITUTE  OF   MARINE   SCIENCES, THE  UNIVERSITY  OF  SOUTHERN MISSISSIPPI  (USM) Program  Description Small fish have been used in studies of carcinogenicity at the Gulf  Coast  Research  Laboratory  of  the  College  of  Marine Sciences (USM) since about 1984. The program began with a  contract  with  the  National  Cancer  Institute  and  the  US Army  to  use  small  fish  species  (primarily  the  Japanese medaka, Oryzias latipes) to test the carcinogenicity of con- taminants and by-products from the processing of drinking water.  Studies  have  dealt  with  the  responses  of  small  fish species  to  different  classes  of  carcinogens,  the  carcinogen dose–response  curve,  the  feasibility  of  using  small  fish  in regulatory   testing,   and   the   processes   of   initiation/ promotion  of  tumorigenesis.  Good  Laboratory  Practice (GLP) guidelines are followed that require highly controlled conditions  of  planning,  execution,  and  accountability.  Di- rected toward answering practical questions about environ- mental  risks,  these  studies  have  shown  that  the  small  fish models, particularly the Japanese medaka, are rapid, accu- rate, and economical indicators. Because large numbers of animals  can  be  used  without  great  expense,  these  studies encompass a high level of statistical support not practical in ones  using  traditional  rodent  models.  The  approach  and rationale  for  the  carcinogenesis  studies  (Hawkins  et  al., 1995) and animal care and maintenance (Overstreet et al., 2000) have been reviewed. Work centers around rearing and maintaining experi- mental fish, exposing them under highly controlled condi- tions to test compounds for lengthy periods, and evaluating cellular  and  tissue  responses.  A  large-scale  dose–response study  required  that  36,000  fish  were  spawned  within  two days. Exposures can be conducted for more than 12 months with  test  concentrations  maintained  consistently  at  envi- ronmental levels. Pathological analyses are facilitated by the small size of the fish so that the entire animal can be pro- cessed  and  most  major  organs  and  tissues  examined  in  a single histological section. The  toxicology  laboratory  occupies  a  12,000-sq-ft building devoted to animal husbandry and exposure. Almost half  of  the  space  is  used  in  animal  production  and  mainte- nance. Cultue of the fish is physically separated from experi- mental exposure areas. The facility is equipped to produce and maintain  saltwater  and  freshwater  fish  and  invertebrates  in several  systems  including:  (1)  flow-through  freshwater  race- ways and aquaria receiving water from a 480-ft nonchlorinated well on the GCRL campus; (2) flow-through natural seawater systems receiving water from the Mississippi Sound, an estua- rine ecosystem bordering the campus; (3) recirculating natural and artificial seawater systems; and (4) static systems. In ad- dition  to  the  medaka,  a  variety  of  freshwater  and  saltwater species are kept as test animals. Fish Resource Centers S243 Next >>