title: Levels of choroidal body carbonic anhydrase activity and glycogen in farmed halibut.
abstract: We postulate that ocular abnormalities in farmed Atlantic halibut occur following aberrant gas production in the choroidal body associated with the enzyme carbonic anhydrase. We investigated choroidal body carbonic anhydrase activity in affected and normal halibut. Immunohistochemical detection of carbonic anhydrase allowed neither quantification of enzyme levels nor determination of enzyme activity. Histochemical detection of carbonic anhydrase, however, allowed microdensitometric quantification of enzyme activity. Mean enzyme activity in affected individuals was over twice that in normal fish. Glycogen, which we suggest is used to fuel oxygen production in the choroidal body, was evaluated by Best's carmine staining. Microdensitometry demonstrated glycogen levels of be significantly higher in affected fish. These findings show that posterior segment gas bubble and cyst formation is associated with aberrantly high choroidal enzyme activity and high choroidal glycogen concentrations.
authors.affiliation: Animal Health Trust, Kentford, Newmarket, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Williams
authors.forename: T
authors.initials: T
authors.lastname: Hopcroft
authors.forename: U
authors.initials: U
authors.lastname: Pantel
authors.forename: W M
authors.initials: WM
authors.lastname: Brancker
mesh_terms: D000818:Animals; D002256:Carbonic Anhydrases / Q000378:metabolism*; D002829:Choroid / Q000201:enzymology / Q000378:metabolism*; D015862:Choroid Diseases / Q000201:enzymology / Q000378:metabolism / Q000662:veterinary*; D005393:Fish Diseases / Q000201:enzymology* / Q000378:metabolism; D005398:Fisheries; D005412:Flatfishes / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism*; D007150:Immunohistochemistry
chemical_list: D006003:Glycogen; D002256:Carbonic Anhydrases