Hypoxia tolerance of New Zealand triplefin fish brains (Tripterygiidae): an enzymatic and metabolomic investigation

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dc.contributor.advisor Hickey, A en
dc.contributor.author James, Crystal en
dc.date.accessioned 2017-05-09T21:20:15Z en
dc.date.issued 2016 en
dc.identifier.uri http://hdl.handle.net/2292/32825 en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract The human brain is extremely sensitive to lack of oxygen failing within minutes of hypoxia. Hypoxia promotes a shift from aerobic to anaerobic metabolism which causes lactate accumulation, redox imbalance, glutamate accumulation leading to excitotoxicity, and altered calcium homeostasis which all lead to potential cell death. In comparison, aquatic animals are effective at routinely surviving levels of less than 3% atmospheric oxygen. Triplefins, especially intertidal rock pool species, repeatedly undergo periods of hypoxia or anoxia whilst still maintaining brain function. Therefore, investigations into mechanisms enhancing survival of the aquatic brain may be critical for understanding how humans could increase tolerance to cope with the vast array of conditions under which hypoxia arises. Five New Zealand triplefin species ranging from intertidal to subtidal zones were compared each with different hypoxia tolerances. Two key mechanisms thought to be impacting hypoxia tolerance were investigated. Firstly, the activity of key enzymes was assessed to determine their contribution to overall metabolism. The second mechanism to compliment this is analysis of abundance in metabolites between species subjected to a ~35 minute hypoxic event. Enzymatic activity was determined spectrophotometrically, whilst Gas Chromatography-Mass spectrometry (GC-MS) was used to determine concentrations of key metabolites (sugars, organic acids, fatty acids, lipids and proteins). Enzyme analysis showed significant differences in Adenylate kinase, Lactate dehydrogenase, Citrate Synthase, Glutamate dehydrogenase, Malate dehydrogenase and Pyruvate kinase (p≤0.05). Lactate dehydrogenase (LDH) activity was lower in hypoxia tolerant species than hypoxia sensitive species (420±27 & 520±20 umol/min/g respectively) with Pyruvate kinase (PK) following a similar trend. Additionally, hypoxia tolerant species had ~ 22% greater Creatine kinase (CK) activity compared to their relatives. Results from GC-MS show that hypoxia influences metabolite abundance. Citric acid cycle and glycolysis intermediates along with antioxidants, neurotransmitters and fatty acids showed variations between normoxia and hypoxia that are indicative of hypoxia tolerance. Additionally analysis of both enzyme activity and metabolite abundance showed strong rank correlations against Pcrit. Overall these results show hypoxia tolerant species have reduced metabolism under hypoxia and an ability to maintain energy stores in order to sustain extreme hypoxic events. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99264917113802091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ en
dc.title Hypoxia tolerance of New Zealand triplefin fish brains (Tripterygiidae): an enzymatic and metabolomic investigation en
dc.type Thesis en
thesis.degree.discipline Biological Science en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 624932 en
pubs.record-created-at-source-date 2017-05-10 en


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http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by-nc-sa/3.0/nz/

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