Meeting Abstract

P2.59  Monday, Jan. 5  A New, Non-Lethal Phenotype, the Blackburn College Floater (BC-Floater), in the Axolotl (Ambystoma mexicanum) POCKLINGTON, EM*; ZALISKO, EJ; MAXSON, KA; BROWN, L; Blackburn College; Blackburn College; Blackburn College; Blackburn College epock@blackburn.edu

Three generations of captive-bred axolotls (Ambystoma mexicanum) reveal a new, non-lethal phenotype that results in the sustained inflation of the lungs for weeks to months. Affected animals inhale but rarely exhale. Animals expressing this phenotype float inverted or listing for two or more consecutive weeks, with trunks breaking the water surface. The new phenotype, designated the Blackburn College Floater (BC-Floater), was first documented in crosses raised in Blackburn College laboratories. Over three years, crosses were raised under similar laboratory conditions (20-25 C with local photoperiods). A repeated cross produced 29% and 25% BC-Floaters in successive years. That same male crossed with a different female produced only 2% offspring that matched the floater phenotype. Subsequent crosses of BC-Floaters that had recovered to normal body posture exhibited an unclear pattern of incomplete penetrance. Two crosses of F₁ BC-Floaters produced 20% and 21% BC-Floater offspring. Two crosses of F₂ BC-Floaters produced 8% and 10% BC-Floater offspring. Axolotls first exhibited the floating phenotype at 21-80mm total length and 3-15 weeks post-hatching (mean=43mm and 8 weeks, N=55 representing animals from 3 crosses). By one year of age, most BC-Floaters either recovered to a normal body posture and ventilation of their lungs or died from the apparent stress of the continued inverted condition. In still, shallow water (5cm), recovery was slow and irregular; 8 of 29 (28%) BC-Floaters recovered by nine months. In 25cm deep water (with turbulence generated by a hanging power filter) 42 of 44 (93%) six month-old BC-Floaters reverted to a normal body posture within 10 days.