Meeting Abstract
Many fish face low oxygen concentrations (hypoxia) in their natural environments, and they respond to hypoxia through a variety of behavioral, physiological, and cellular mechanisms. Some of these responses involve changes in gene expression. In mammals, the hypoxia inducible factor (HIF) family of transcription factors are the “master regulators” of gene expression during hypoxia, but the study of HIF in fish has been hampered by the lack of reagents to detect this protein in non-mammalian vertebrates. In this study, we affinity purified antibodies against HIF-1α from the killifish Fundulus heteroclitus and used them to recover and quantify HIF-1α from killifish cells and tissues. Mass spectrometry analysis confirmed that these antibodies recognized HIF-1α in the killifish cell line, KFE-5. The protein was more abundant in nuclear extracts than cytoplasmic extracts but only minimally affected by exposure of KFE-5 cells to cobalt chloride, a hypoxic mimetic. In the closely related F. grandis exposed to low oxygen for 24 h HIF-1α was elevated in skeletal muscle, liver, brain, and gonad. There was considerable individual variability in the extent of the increase in tissue HIF-1α protein levels during hypoxia, suggesting individual differences in hypoxia responses among fish. These results indicate that fish respond to low oxygen exposure with increases in HIF-1α protein levels in multiple tissues and that this response varies among individuals within a species.
