Meeting Abstract

77-3  Monday, Jan. 6 08:30 – 08:45  The effect of hypoxia induced hemoglobin switching on aerobic performance in red drum, Sciaenops ocellatus NEGRETE JR, B*; ACKERLY, KL; ESBAUGH, AJ; The University of Texas at Austin Marine Science Institute; The University of Texas at Austin Marine Science Institute; The University of Texas at Austin Marine Science Institute bnegrete@utexas.edu http://www.bnegretejr.com

The Gulf of Mexico experiences one of the largest seasonal hypoxic zones in the world, exposing endemic fish to chronically O₂-limited waters. Previous work on red drum – a resident of the coastal waters of the Gulf of Mexico – has demonstrated they can dynamically regulate specific hemoglobin subunits in response to chronic hypoxia exposure, which result in lower blood oxygen binding affinity and a reduced whole animal critical oxygen threshold. Here, we will build upon this prior work by exploring the time course of red blood cell plasticity, and assess the impacts on maximum metabolic rate. Fish were acclimated to 30% air saturation for 1, 4, 8, 14, or 42 days, and red blood cells were collected for gene expression and biochemical profiling. Relative hemoglobin isoform abundance was assessed using real-time PCR and thin-layer isoelectric focusing. Additionally, hematocrit (red blood cell concentration) and NTP concentration were measured. Hb patterns showed up-regulation in Hbα 2 by 50-fold relative to control in response to hypoxia starting at 4 days. Hematocrit showed a difference in treatment at 8-days, with no change over other time points between treatments. Red drum do not show changes in [NTP] in hypoxia, suggesting they regulate Hb-O₂affinity through other changes in the red blood cell such as hematocrit and Hb. Thus, the effects of the observed red blood cell plasticity on whole animal performance were tested by assessing maximum metabolic rate of hypoxia and normoxia acclimated individuals at 50% oxygen saturation for at least 8-days.