Isolation and Identification of the Abnormal Opaque material in the White Mutant of Siamese Fighting Fish, Betta Splendens

Abstract

The problem. White purine pigments commonly occur as iridophore coloration in a variety of animals. These purines may also be abnormally stored in body integuments. A new mutation, opaque (Op), has been described for the Siamese Fighting Fish, Betta splendens. A build-up of the white material occurs as the fish ages especially in the head and eyes. Unlike a disease, the condition seems to be irreversible. The purpose of this research was to isolate and identify the constituents of the opaque white material. Procedure. Any determination of purines in Op white Bettas must account for the guanine in iridophores. Three phenotypes, (i) Op, (ii) spread iridocytes (Si), and (iii) normal, were compared to distinguish between iridophore purines and the white material of the Op Bettas. A fourth phenotype, a hybrid (Op x Si), was included to determine possible differences in genetic expression. The fish were microscopically inspected both externally and internally. Then various tissue samples were extracted (O.1N HCl) and components of the extracts separated by thin layer chromatography (1M NaCl). These separated components were then extracted (O.1N Hel) and the ultraviolet and fluorescent spectra were determined. Findings. Microscopic inspection of the Op Bettas indicated iridophores were spread over the body and fins but not on the head as a result of the Si mutation. The white material covered the entire body and fins including the head and eyes. Thin layer chromatography, U.V., and fluorescence spectra indicated guanine was present in Op, Si, and hybrid Bettas. Comparison of guanine in head extracts showed 3.5 and 2 times more guanine in Op Bettas than in Si and hybrid Bettas, respectively. Conclusions and Recommendations. The Op mutation may occur as a metabolic malfunction or as a purine-pteridine chromatophore inter-relationship. Guanine gout may result when a lack of xanthine dehydrogenase or guanase prevents guanine destruction to normal by-products. Alternately, increased enzyme activity by guanine deaminase may produce excess guanine that is not normally catabolized and eliminated. A malfunction in chromatophore metabolish might also cause this mutation. An inverse relationship is observed in that purines increase in chromatophores when pteridines decrease. This may be either an enzymatic or hormonal disorder of the chromatophore. Enzymic and hormonal analyses should be done on the Op Bettas. Several genetic crosses are also needed with subsequent pigment, enzyme, and hormone analyses of the hybrids.