{"id":{"repo_id":"ohiolink","oai_identifier":"oai:etd.ohiolink.edu:ohiou1362666619"},"canonical_url":"https://search.dev.ndltd.org/etd/ohiolink/oai:etd.ohiolink.edu:ohiou1362666619","repository":{"repo_id":"ohiolink","name":"OhioLINK","base_url":"https://etd.ohiolink.edu/acprod/odb_etd/ws/oai/oai"},"display":{"title":"Effects of Hyperoxia on Thermal Tolerance and Indicators of Hypoxic Stress in Antarctic Fishes That Differ in Expression of Oxygen-Binding Proteins","abstract":"Antarctic icefishes (Family Channichthyidae) are unique in lacking the oxygen carrier hemoglobin (Hb) in their blood, leaving them with only 10% of the oxygen-carrying capacity observed in closely related red-blooded fishes. Previous studies have shown that icefishes have lower critical thermal maxima (CT<sub>MAX</sub>) than red-blooded notothenioids and that there is a positive correlation between CT<sub>MAX</sub> and hematocrit, indicating that oxygen-carrying capacity may contribute to thermal tolerance. I tested the hypothesis that the lower CT<sub>MAX</sub> of icefishes is associated with their reduced oxygen-carrying capacity. I also hypothesized that, as temperature rises, correlates of oxygen limitation (hypoxia inducible factor-1α and lactate) would increase to a greater extent in icefishes compared to red-blooded fishes and that this increase would be minimized under hyperoxic conditions. I sampled <i>Chaenocephalus aceratus</i> (Hb-) and <i>Notothenia coriiceps</i> (Hb+) at three temperatures (ambient, 8°C, and CT<sub>MAX</sub>) during an experimental heat ramp (4°C * hr<sup>-1</sup>) under normoxia and environmental hyperoxia. I have determined that a 3- to 4-fold elevation in environmental oxygen does not extend CT<sub>MAX</sub> in either species despite a 1.7-fold reduction in plasma lactate accumulation and a 2- to 3-fold increase in oxygen utilization as indicated by the differences in arterial and venous oxygen (PaO<sub>2</sub>-PvO<sub>2</sub>). The absence of an effect of hyperoxia on thermal tolerance may be explained by the lack of increased cardiac (venous) oxygen supply. I have determined that cardiac lactate increases with temperature in the icefish, <i>C. aceratus</i> but not in <i>N. coriiceps</i> and that HIF-1α mRNA levels in the heart are insensitive to increases in both temperature and oxygen. My results indicate that the hearts of icefishes may be especially hypoxia-sensitive and that the inability to maintain cardiac metabolism may contribute to the relatively low thermal tolerances of channichthyid fishes.","abstract_html":"Antarctic icefishes (Family Channichthyidae) are unique in lacking the oxygen carrier hemoglobin (Hb) in their blood, leaving them with only 10% of the oxygen-carrying capacity observed in closely related red-blooded fishes. Previous studies have shown that icefishes have lower critical thermal maxima (CT&lt;sub&gt;MAX&lt;/sub&gt;) than red-blooded notothenioids and that there is a positive correlation between CT&lt;sub&gt;MAX&lt;/sub&gt; and hematocrit, indicating that oxygen-carrying capacity may contribute to thermal tolerance. I tested the hypothesis that the lower CT&lt;sub&gt;MAX&lt;/sub&gt; of icefishes is associated with their reduced oxygen-carrying capacity. I also hypothesized that, as temperature rises, correlates of oxygen limitation (hypoxia inducible factor-1α and lactate) would increase to a greater extent in icefishes compared to red-blooded fishes and that this increase would be minimized under hyperoxic conditions. I sampled &lt;i&gt;Chaenocephalus aceratus&lt;/i&gt; (Hb-) and &lt;i&gt;Notothenia coriiceps&lt;/i&gt; (Hb+) at three temperatures (ambient, 8°C, and CT&lt;sub&gt;MAX&lt;/sub&gt;) during an experimental heat ramp (4°C * hr&lt;sup&gt;-1&lt;/sup&gt;) under normoxia and environmental hyperoxia. I have determined that a 3- to 4-fold elevation in environmental oxygen does not extend CT&lt;sub&gt;MAX&lt;/sub&gt; in either species despite a 1.7-fold reduction in plasma lactate accumulation and a 2- to 3-fold increase in oxygen utilization as indicated by the differences in arterial and venous oxygen (PaO&lt;sub&gt;2&lt;/sub&gt;-PvO&lt;sub&gt;2&lt;/sub&gt;). The absence of an effect of hyperoxia on thermal tolerance may be explained by the lack of increased cardiac (venous) oxygen supply. I have determined that cardiac lactate increases with temperature in the icefish, &lt;i&gt;C. aceratus&lt;/i&gt; but not in &lt;i&gt;N. coriiceps&lt;/i&gt; and that HIF-1α mRNA levels in the heart are insensitive to increases in both temperature and oxygen. My results indicate that the hearts of icefishes may be especially hypoxia-sensitive and that the inability to maintain cardiac metabolism may contribute to the relatively low thermal tolerances of channichthyid fishes.","abstract_has_math":false,"creators":["Devor, Devin Patrick"],"institution":"Ohio University","degree_name":"Master of Science (MS)","degree_level":"masters","degree_discipline":"Biological Sciences (Arts and Sciences)","degree_department":null,"school":null,"contributors":["Crockett, Elizabeth"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-06-12","date_published":"2013-06-12","updated_at":"2026-07-24T03:36:39Z","subjects":["Animal Sciences","Biology","Zoology","Molecular Biology","Experiments","Animals","Antarctic fish","thermal stress","hyperoxic treatment","icefish","Notothenioidei"],"languages":["English"],"rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1362666619","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Crockett, Elizabeth"]},{"key":"dc:creator","label":"Author","values":["Devor, Devin Patrick"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2013-06-12"]},{"key":"dc:publisher","label":"Institution","values":["Ohio University / OhioLINK"]},{"key":"dc:type","label":"Dc Type","values":["Electronic Thesis or Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biological Sciences (Arts and Sciences)"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Ohio University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Animal Sciences","Biology","Zoology","Molecular Biology","Experiments","Animals","Antarctic fish","thermal stress","hyperoxic treatment","icefish","Notothenioidei"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1362666619"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Antarctic icefishes (Family Channichthyidae) are unique in lacking the oxygen carrier hemoglobin (Hb) in their blood, leaving them with only 10% of the oxygen-carrying capacity observed in closely related red-blooded fishes. Previous studies have shown that icefishes have lower critical thermal maxima (CT<sub>MAX</sub>) than red-blooded notothenioids and that there is a positive correlation between CT<sub>MAX</sub> and hematocrit, indicating that oxygen-carrying capacity may contribute to thermal tolerance. I tested the hypothesis that the lower CT<sub>MAX</sub> of icefishes is associated with their reduced oxygen-carrying capacity. I also hypothesized that, as temperature rises, correlates of oxygen limitation (hypoxia inducible factor-1α and lactate) would increase to a greater extent in icefishes compared to red-blooded fishes and that this increase would be minimized under hyperoxic conditions. I sampled <i>Chaenocephalus aceratus</i> (Hb-) and <i>Notothenia coriiceps</i> (Hb+) at three temperatures (ambient, 8°C, and CT<sub>MAX</sub>) during an experimental heat ramp (4°C * hr<sup>-1</sup>) under normoxia and environmental hyperoxia. I have determined that a 3- to 4-fold elevation in environmental oxygen does not extend CT<sub>MAX</sub> in either species despite a 1.7-fold reduction in plasma lactate accumulation and a 2- to 3-fold increase in oxygen utilization as indicated by the differences in arterial and venous oxygen (PaO<sub>2</sub>-PvO<sub>2</sub>). The absence of an effect of hyperoxia on thermal tolerance may be explained by the lack of increased cardiac (venous) oxygen supply. I have determined that cardiac lactate increases with temperature in the icefish, <i>C. aceratus</i> but not in <i>N. coriiceps</i> and that HIF-1α mRNA levels in the heart are insensitive to increases in both temperature and oxygen. My results indicate that the hearts of icefishes may be especially hypoxia-sensitive and that the inability to maintain cardiac metabolism may contribute to the relatively low thermal tolerances of channichthyid fishes."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","p.72","1.14 MB"]},{"key":"dc:title","label":"Title","values":["Effects of Hyperoxia on Thermal Tolerance and Indicators of Hypoxic Stress in Antarctic Fishes That Differ in Expression of Oxygen-Binding Proteins"]}]}],"canonical_facts":{"dc:contributor":["Crockett, Elizabeth"],"dc:creator":["Devor, Devin Patrick"],"dc:date":["2013-06-12"],"dc:description":["Antarctic icefishes (Family Channichthyidae) are unique in lacking the oxygen carrier hemoglobin (Hb) in their blood, leaving them with only 10% of the oxygen-carrying capacity observed in closely related red-blooded fishes. Previous studies have shown that icefishes have lower critical thermal maxima (CT<sub>MAX</sub>) than red-blooded notothenioids and that there is a positive correlation between CT<sub>MAX</sub> and hematocrit, indicating that oxygen-carrying capacity may contribute to thermal tolerance. I tested the hypothesis that the lower CT<sub>MAX</sub> of icefishes is associated with their reduced oxygen-carrying capacity. I also hypothesized that, as temperature rises, correlates of oxygen limitation (hypoxia inducible factor-1α and lactate) would increase to a greater extent in icefishes compared to red-blooded fishes and that this increase would be minimized under hyperoxic conditions. I sampled <i>Chaenocephalus aceratus</i> (Hb-) and <i>Notothenia coriiceps</i> (Hb+) at three temperatures (ambient, 8°C, and CT<sub>MAX</sub>) during an experimental heat ramp (4°C * hr<sup>-1</sup>) under normoxia and environmental hyperoxia. I have determined that a 3- to 4-fold elevation in environmental oxygen does not extend CT<sub>MAX</sub> in either species despite a 1.7-fold reduction in plasma lactate accumulation and a 2- to 3-fold increase in oxygen utilization as indicated by the differences in arterial and venous oxygen (PaO<sub>2</sub>-PvO<sub>2</sub>). The absence of an effect of hyperoxia on thermal tolerance may be explained by the lack of increased cardiac (venous) oxygen supply. I have determined that cardiac lactate increases with temperature in the icefish, <i>C. aceratus</i> but not in <i>N. coriiceps</i> and that HIF-1α mRNA levels in the heart are insensitive to increases in both temperature and oxygen. My results indicate that the hearts of icefishes may be especially hypoxia-sensitive and that the inability to maintain cardiac metabolism may contribute to the relatively low thermal tolerances of channichthyid fishes."],"dc:format":["application/pdf","p.72","1.14 MB"],"dc:identifier":["http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1362666619"],"dc:language":["English"],"dc:publisher":["Ohio University / OhioLINK"],"dc:rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"dc:subject":["Animal Sciences","Biology","Zoology","Molecular Biology","Experiments","Animals","Antarctic fish","thermal stress","hyperoxic treatment","icefish","Notothenioidei"],"dc:title":["Effects of Hyperoxia on Thermal Tolerance and Indicators of Hypoxic Stress in Antarctic Fishes That Differ in Expression of Oxygen-Binding Proteins"],"dc:type":["Electronic Thesis or Dissertation"],"thesis:degree_discipline":["Biological Sciences (Arts and Sciences)"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science (MS)"],"thesis:institution_name":["Ohio University"]},"updated_at":"2026-07-24T03:36:39Z"}