Effect of Hypoxia on the Respiratory Burst and Associated Bactericidal Activity in the Pronephritic Cells of the Mummichog, Fundulus heteroclitus

Estuaries provide habitat and spawning grounds for numerous species of plants, birds, fish and shellfish. Levels of dissolved oxygen, carbon dioxide and pH in estuarine waters vary with diurnal, tidal and seasonal cycles. Anthropogenic factors may further exacerbate these variations in water quality. The studies presented here tested the hypothesis that hypoxia, including hypercapnia and acidosis, suppresses antibacterial defenses provided by phagocytic cells. The respiratory burst of phagocytic cells was stimulated with zymosan and Vibrio parahaemolyticus to produce Reactive Oxygen Species (ROS) which are potent antibacterial agents. The respiratory burst is oxygen dependent and therefore may be inhibited by hypoxic conditions. Hypoxic conditions within physiologically relevant conditions (Po2 = 15 Torr, Pco2 = 8.0 Torr, pH = 7.0) significantly suppressed ROS production measured by the luminol-enhanced chemiluminescence assay. Hypoxic conditions also significantly suppressed superoxide production, measured by the reduction of NBT, when stimulated with both zymosan and V. parahaemolyticus. Furthermore, while ROS mediated bactericidal activity was not significantly suppressed under hypoxia at the 1:1 phagocyte:bacterium ratio, there was a significant suppression when the bacterial challenge was increased to 1:10. It can be concluded from these results that hypoxia plays a critical role in maintaining antibacterial defense mechanisms of the mummichog, F. heteroclitus against the opportunistic marine pathogen V. parahaemolyticus

Fundulus as the premier teleost model in environmental biology : opportunities for new insights using genomics

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Comparative Biochemistry and Physiology Part D: Genomics and Proteomics 2 (2007): 257-286, doi:10.1016/j.cbd.2007.09.001.A strong foundation of basic and applied research documents that the estuarine fish Fundulus heteroclitus and related species are unique laboratory and field models for understanding how individuals and populations interact with their environment. In this paper we summarize an extensive body of work examining the adaptive responses of Fundulus species to environmental conditions, and describe how this research has contributed importantly to our understanding of physiology, gene regulation, toxicology, and ecological and evolutionary genetics of teleosts and other vertebrates. These explorations have reached a critical juncture at which advancement is hindered by the lack of genomic resources for these species. We suggest that a more complete genomics toolbox for F. heteroclitus and related species will permit researchers to exploit the power of this model organism to rapidly advance our understanding of fundamental biological and pathological mechanisms among vertebrates, as well as ecological strategies and evolutionary processes common to all living organisms.This material is based on work supported by grants from the National Science Foundation DBI-0420504 (LJB), OCE 0308777 (DLC, RNW, BBR), BES-0553523 (AW), IBN 0236494 (BBR), IOB-0519579 (DHE), IOB-0543860 (DWT), FSML-0533189 (SC); National Institute of Health NIEHS P42-ES007381(GVC, MEH), P42-ES10356 (RTD), ES011588 (MFO); and NCRR P20 RR-016463 (DWT); Natural Sciences and Engineering Research Council of Canada Discovery (DLM, TDS, WSM) and Collaborative Research and Development Programs (DLM); NOAA/National Sea Grant NA86RG0052 (LJB), NA16RG2273 (SIK, MEH,GVC, JJS); Environmental Protection Agency U91620701 (WSB), R82902201(SC) and EPA’s Office of Research and Development (DEN)