title: The Effect of Hypoxia and Hyperoxia on Growth and Expression of Hypoxia-Related Genes and Proteins in Spotted Gar Lepisosteus oculatus Larvae and Juveniles.
abstract: We studied the molecular responses to different water oxygen levels in gills and swim bladder of spotted gar (Lepisosteus oculatus), a bimodal breather. Fish at swim-up stage were exposed for 71 days to normoxic, hypoxic, and hyperoxic water conditions. Then, all aquaria were switched to normoxic conditions for recovery until the end of the experiment (120 days). Fish were sampled at the beginning of the experiment, and then at 71 days of exposure and at 8 days of recovery. We first cloned three hypoxia-related genes, hypoxia-inducible factor 2α (HIF-2α), Na(+) /H(+) exchanger 1 (NHE-1), and NHE-3, and uploaded their cDNA sequences in the GeneBank database. We then used One Step Taqman® real-time PCR to quantify the mRNA copies of target genes in gills and swim bladder of fish exposed to different water O2 levels. We also determined the protein expression of HIF-2α and neuronal nitric oxide synthase (nNOS) in the swim bladder by using confocal immunofluorescence. Hypoxic stress for 71 days significantly increased the mRNA copies of HIF-2α and NHE-1 in gills and swim bladder, whereas normoxic recovery for 8 days decreased the HIF-2α mRNA copies to control values in both tissues. We did not found significant changes in mRNA copies of the NHE-3 gene in either gills or swim bladder in response to hypoxia and hyperoxia. Unlike in normoxic swim bladder, double immunohistochemical staining in hypoxic and hyperoxic swim bladder using nNOS/HIF-2α showed extensive bundles of HIF-2α-positive nerve fibers in the trabecular musculature associated with a few varicose nNOS immunoreactive nerve terminals.
authors.affiliation: Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Rimoldi
authors.affiliation: Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy.|Inter-University Centre for Research in Protein Biotechnologies, "The Protein Factory", Polytechnic University of Milan and University of Insubria, Varese, Italy.
authors.forename: Genciana
authors.initials: G
authors.lastname: Terova
authors.affiliation: Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Zaccone
authors.affiliation: School of Environment and Natural Resources, Ohio State University, Columbus, Ohio.
authors.forename: Tim
authors.initials: T
authors.lastname: Parker
authors.affiliation: Poison Information Centre, Jagiellonian University Medical College, Crakow, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Kuciel
authors.affiliation: School of Environment and Natural Resources, Ohio State University, Columbus, Ohio.
authors.forename: Konrad
authors.initials: K
authors.lastname: Dabrowski
mesh_terms: D000400:Air Sacs / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D005399:Fishes / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005786:Gene Expression Regulation; D005880:Gills / Q000254:growth & development / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D029941:Fish Proteins; D019001:Nitric Oxide Synthase; D010100:Oxygen; D012333:RNA, Messenger