Meeting Abstract
Hemoglobins (Hbs), widespread in all living organisms, descended from an ancient ancestral gene and serve many functions, including transporting of oxygen. In the present study, frequency of occurrence and function of the unusual phenomenon of Hb polymerization, which can cause distortion or sickling of red blood cells (RBCs) similar to human sickle cell disease, was investigated in 47 species of fishes. In a 9 year survey of three ecosystems, east and west sides of the Atlantic Ocean, and Gulf of Mexico, 32% of species sampled (15 species in 5 orders, 9 families) exhibited Hb polymerization in RBCs under low O2 and pH conditions. Transmission Electron Microscopy (TEM) verified presence or absence of Hb polymers at the cellular level, in vitro for 12 species, and in vivo for Atlantic cod (Gadus morhua), revealing that while intensity and morphology of Hb polymers varied across species, they were not independent of phylogeny and present in all Gadiformes. Moreover, purification and recrystallization of Atlantic cod Hb validated previous results (Harosi et al., 1998) that Hb polymerized independent of other cellular components. Finally, effects of pH (6.99 – 7.99) on Hb polymerization intensity in two related boreal species, Atlantic cod (G. morhua) and Oyster toadfish (Opsanus tau) found strong, reversible pH dependence with ~ 50% of all RBCs containing Hb polymers at ~ pH 7.6 in both species. We propose; Hb polymerization in RBCs is wider spread than previously thought, and likely evolved independently across diverse fish taxa. Hb’s that polymerize may exhibit unusual physiological and structural plasticity, conferring innate immunity, as well as acting as an environmental sensor, sensitive to changing oceanic conditions.
