Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae)
As the Southern Ocean cooled to −1.8 °C over the past 40 My, the teleostean clade Notothenioidei diversified and, under reduced selection pressure for an oxygen-transporting apparatus, became less reliant on hemoglobin and red blood cells. At the extreme of this trend, the crown group of Antarctic i...
Published in: | Molecular Biology and Evolution |
---|---|
Main Authors: | , , , |
Format: | Text |
Language: | English |
Published: |
Oxford University Press
2012
|
Subjects: | |
Online Access: | http://mbe.oxfordjournals.org/cgi/content/short/msr278v2 https://doi.org/10.1093/molbev/msr278 |
id |
fthighwire:oai:open-archive.highwire.org:molbiolevol:msr278v2 |
---|---|
record_format |
openpolar |
spelling |
fthighwire:oai:open-archive.highwire.org:molbiolevol:msr278v2 2023-05-15T13:37:57+02:00 Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) Lau, Yuk-Ting Parker, Sandra K. Near, Thomas J. Detrich, H. William 2012-01-10 18:20:56.0 text/html http://mbe.oxfordjournals.org/cgi/content/short/msr278v2 https://doi.org/10.1093/molbev/msr278 en eng Oxford University Press http://mbe.oxfordjournals.org/cgi/content/short/msr278v2 http://dx.doi.org/10.1093/molbev/msr278 Copyright (C) 2012, Society for Molecular Biology and Evolution Research article TEXT 2012 fthighwire https://doi.org/10.1093/molbev/msr278 2013-05-27T16:05:55Z As the Southern Ocean cooled to −1.8 °C over the past 40 My, the teleostean clade Notothenioidei diversified and, under reduced selection pressure for an oxygen-transporting apparatus, became less reliant on hemoglobin and red blood cells. At the extreme of this trend, the crown group of Antarctic icefishes (Channichthyidae) lost both components of oxygen transport. Under the decreased selection scenario, we hypothesized that the Antarctic dragonfishes (Bathydraconidae, the red-blooded sister clade to the icefishes) evolved lower blood hemoglobin concentrations because their globin gene complexes (α- and β-globin gene pairs linked by a regulatory intergene) transcribe globin mRNAs less effectively than those of basal notothenioids (e.g., the Nototheniidae [notothens]). To test our hypothesis, we 1) sequenced the α/β-intergenes of the adult globin complexes of three notothen and eight dragonfish species and 2) measured globin transcript levels in representative species from each group. The typical nototheniid intergene was ∼3–4 kb in length. The bathydraconid intergenes resolved into three subclasses (long [3.8 kb], intermediate [3.0 kb], and short [1.5–2.3 kb]) that corresponded to the three subclades proposed for the taxon. Although they varied in length due to indels, the three notothen and eight dragonfish intergenes contained a conserved ∼90-nt element that we have previously shown to be required for globin gene transcription. Using the quantitative polymerase chain reaction, we found that globin mRNA levels in red cells from one notothen species and from one species of each dragonfish subclade were equivalent statistically. Thus, our results indicate that the bathydraconids have evolved adult globin loci whose regulatory intergenes tend to be shorter than those of the more basal nototheniids yet are equivalent in transcriptional efficacy. Their low blood hemoglobin concentrations are most likely due to reduction in hematocrit. Text Antarc* Antarctic Southern Ocean HighWire Press (Stanford University) Antarctic Southern Ocean The Antarctic Molecular Biology and Evolution 29 3 1071 1080 |
institution |
Open Polar |
collection |
HighWire Press (Stanford University) |
op_collection_id |
fthighwire |
language |
English |
topic |
Research article |
spellingShingle |
Research article Lau, Yuk-Ting Parker, Sandra K. Near, Thomas J. Detrich, H. William Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
topic_facet |
Research article |
description |
As the Southern Ocean cooled to −1.8 °C over the past 40 My, the teleostean clade Notothenioidei diversified and, under reduced selection pressure for an oxygen-transporting apparatus, became less reliant on hemoglobin and red blood cells. At the extreme of this trend, the crown group of Antarctic icefishes (Channichthyidae) lost both components of oxygen transport. Under the decreased selection scenario, we hypothesized that the Antarctic dragonfishes (Bathydraconidae, the red-blooded sister clade to the icefishes) evolved lower blood hemoglobin concentrations because their globin gene complexes (α- and β-globin gene pairs linked by a regulatory intergene) transcribe globin mRNAs less effectively than those of basal notothenioids (e.g., the Nototheniidae [notothens]). To test our hypothesis, we 1) sequenced the α/β-intergenes of the adult globin complexes of three notothen and eight dragonfish species and 2) measured globin transcript levels in representative species from each group. The typical nototheniid intergene was ∼3–4 kb in length. The bathydraconid intergenes resolved into three subclasses (long [3.8 kb], intermediate [3.0 kb], and short [1.5–2.3 kb]) that corresponded to the three subclades proposed for the taxon. Although they varied in length due to indels, the three notothen and eight dragonfish intergenes contained a conserved ∼90-nt element that we have previously shown to be required for globin gene transcription. Using the quantitative polymerase chain reaction, we found that globin mRNA levels in red cells from one notothen species and from one species of each dragonfish subclade were equivalent statistically. Thus, our results indicate that the bathydraconids have evolved adult globin loci whose regulatory intergenes tend to be shorter than those of the more basal nototheniids yet are equivalent in transcriptional efficacy. Their low blood hemoglobin concentrations are most likely due to reduction in hematocrit. |
format |
Text |
author |
Lau, Yuk-Ting Parker, Sandra K. Near, Thomas J. Detrich, H. William |
author_facet |
Lau, Yuk-Ting Parker, Sandra K. Near, Thomas J. Detrich, H. William |
author_sort |
Lau, Yuk-Ting |
title |
Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
title_short |
Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
title_full |
Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
title_fullStr |
Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
title_full_unstemmed |
Evolution and Function of the Globin Intergenic Regulatory Regions of the Antarctic Dragonfishes (Notothenioidei: Bathydraconidae) |
title_sort |
evolution and function of the globin intergenic regulatory regions of the antarctic dragonfishes (notothenioidei: bathydraconidae) |
publisher |
Oxford University Press |
publishDate |
2012 |
url |
http://mbe.oxfordjournals.org/cgi/content/short/msr278v2 https://doi.org/10.1093/molbev/msr278 |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
http://mbe.oxfordjournals.org/cgi/content/short/msr278v2 http://dx.doi.org/10.1093/molbev/msr278 |
op_rights |
Copyright (C) 2012, Society for Molecular Biology and Evolution |
op_doi |
https://doi.org/10.1093/molbev/msr278 |
container_title |
Molecular Biology and Evolution |
container_volume |
29 |
container_issue |
3 |
container_start_page |
1071 |
op_container_end_page |
1080 |
_version_ |
1766099907028975616 |