Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii
The Antarctic teleost Trematomus bemacchii lives in the waters surrounding Antarctica which are a constant -1.8??C. As an adaptive property they possess a uniquely high serum osmolality of -600 mOsm kg"1 which is nearly double that of temperate teleosts. Acclimation of the T. bemacchii to +4??C...
Main Author: | |
---|---|
Other Authors: | |
Format: | Thesis |
Language: | English |
Published: |
Creighton University
|
Subjects: | |
Online Access: | http://hdl.handle.net/10504/55719 |
id |
ftcreightonuniv:oai:dspace.creighton.edu:10504/55719 |
---|---|
record_format |
openpolar |
spelling |
ftcreightonuniv:oai:dspace.creighton.edu:10504/55719 2023-05-15T13:37:16+02:00 Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii Morrison, John Francis Petzel, David Morrison, John Francis http://hdl.handle.net/10504/55719 en_US eng Creighton University Omaha, Nebraska http://hdl.handle.net/10504/55719 John Francis Morrison Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above. Thesis ftcreightonuniv 2015-07-04T22:25:34Z The Antarctic teleost Trematomus bemacchii lives in the waters surrounding Antarctica which are a constant -1.8??C. As an adaptive property they possess a uniquely high serum osmolality of -600 mOsm kg"1 which is nearly double that of temperate teleosts. Acclimation of the T. bemacchii to +4??C results in a 25% decrease in serum osmolality and a doubling of activity of the ion pump in the gill, the Na+,K+-ATPase, that is energetically responsible for osmoregulation. The Na+,K+-ATPase consists of two obligate subunits (a catalytic a and membrane trafficking ??), however in some systems an accessory (y) subunit has also been shown to colocalize with the obligate subunits. The a subunit is the active enzymatic portion and consists of 4 isoforms with differing biochemical properties. The affinity of the a3 for Na+ is less than that of the al and a2. However, all isoforms have similar affinities for K+ and ATP. Protein and mRNA of the al, a2, and a3 isoforms of Na+,K+-ATPase were previously reported in T. bemacchii gill. The effects of +4??C acclimation were investigated by measuring serum osmolality, oxygen consumption, substrate concentration dependent activation of the Na+,K+- ATPase, and ouabain inhibition of phosphoenzyme intermediate formation. Acclimation to +4??C caused the T. bemacchii to significantly decrease its serum osmolality from 581 + 11 mOsm kg"1 at -1.5??C to 477 + 4 mOsm kg'1 at +4??C. The apparent affinity of the enzyme for sodium increased significantly (K'Na of 2.3 + 0.2 mM to 1.5 + 0.3 mM) with +4??C acclimation but the apparent affinity for potassium and ATP showed no change. Concentration dependent inhibition of the formation of phosphoenzyme intermediate of Na+,K+-ATPase by ouabain indicated the contribution of a3 to total Na+,K"l"-ATPase decreased from 33.72 + 13.03% to 0 + 6.67% while al and a2 increased from 33.12 + 12.72% and 33.15 + 0.30% to 44.87 + 6.67% and 55.12 + 6.67%, respectively upon +4??C acclimation. This is the first report of the application of a functional biochemical assay to characterize an environmental physiological change in this organism. The a3 isoform of Na+,K+-ATPase was of particular interest. Gene specific primers for the a3 were designed and the sequence of the a3 determined. The T. bernacchii a3 isoform amino acid sequence showed 86% identity to the a3 isoform sequence from mammals and 87% to the sequence of the a3 isoform from other fishes (individual identity was as high as 91% when compared to Tilcipia mossambica). These results suggest that the T. bernacchii reduce serum osmolality in response to increased environmental temperature by altering the cell surface Na+,K+-ATPase a subunit composition. Thesis Antarc* Antarctic Antarctica Creighton University: Creighton Digital Repository (CDR) Antarctic The Antarctic |
institution |
Open Polar |
collection |
Creighton University: Creighton Digital Repository (CDR) |
op_collection_id |
ftcreightonuniv |
language |
English |
description |
The Antarctic teleost Trematomus bemacchii lives in the waters surrounding Antarctica which are a constant -1.8??C. As an adaptive property they possess a uniquely high serum osmolality of -600 mOsm kg"1 which is nearly double that of temperate teleosts. Acclimation of the T. bemacchii to +4??C results in a 25% decrease in serum osmolality and a doubling of activity of the ion pump in the gill, the Na+,K+-ATPase, that is energetically responsible for osmoregulation. The Na+,K+-ATPase consists of two obligate subunits (a catalytic a and membrane trafficking ??), however in some systems an accessory (y) subunit has also been shown to colocalize with the obligate subunits. The a subunit is the active enzymatic portion and consists of 4 isoforms with differing biochemical properties. The affinity of the a3 for Na+ is less than that of the al and a2. However, all isoforms have similar affinities for K+ and ATP. Protein and mRNA of the al, a2, and a3 isoforms of Na+,K+-ATPase were previously reported in T. bemacchii gill. The effects of +4??C acclimation were investigated by measuring serum osmolality, oxygen consumption, substrate concentration dependent activation of the Na+,K+- ATPase, and ouabain inhibition of phosphoenzyme intermediate formation. Acclimation to +4??C caused the T. bemacchii to significantly decrease its serum osmolality from 581 + 11 mOsm kg"1 at -1.5??C to 477 + 4 mOsm kg'1 at +4??C. The apparent affinity of the enzyme for sodium increased significantly (K'Na of 2.3 + 0.2 mM to 1.5 + 0.3 mM) with +4??C acclimation but the apparent affinity for potassium and ATP showed no change. Concentration dependent inhibition of the formation of phosphoenzyme intermediate of Na+,K+-ATPase by ouabain indicated the contribution of a3 to total Na+,K"l"-ATPase decreased from 33.72 + 13.03% to 0 + 6.67% while al and a2 increased from 33.12 + 12.72% and 33.15 + 0.30% to 44.87 + 6.67% and 55.12 + 6.67%, respectively upon +4??C acclimation. This is the first report of the application of a functional biochemical assay to characterize an environmental physiological change in this organism. The a3 isoform of Na+,K+-ATPase was of particular interest. Gene specific primers for the a3 were designed and the sequence of the a3 determined. The T. bernacchii a3 isoform amino acid sequence showed 86% identity to the a3 isoform sequence from mammals and 87% to the sequence of the a3 isoform from other fishes (individual identity was as high as 91% when compared to Tilcipia mossambica). These results suggest that the T. bernacchii reduce serum osmolality in response to increased environmental temperature by altering the cell surface Na+,K+-ATPase a subunit composition. |
author2 |
Petzel, David Morrison, John Francis |
format |
Thesis |
author |
Morrison, John Francis |
spellingShingle |
Morrison, John Francis Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
author_facet |
Morrison, John Francis |
author_sort |
Morrison, John Francis |
title |
Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
title_short |
Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
title_full |
Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
title_fullStr |
Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
title_full_unstemmed |
Physiological, Biochemical, and Molecular Biological Effects of +4???C Acclimation on the Antarctic Teleost Trematomus bernacchii |
title_sort |
physiological, biochemical, and molecular biological effects of +4???c acclimation on the antarctic teleost trematomus bernacchii |
publisher |
Creighton University |
url |
http://hdl.handle.net/10504/55719 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
http://hdl.handle.net/10504/55719 |
op_rights |
John Francis Morrison Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above. |
_version_ |
1766089868772900864 |