Open Access Research article

Effects of elevated seawater pCO2 on gene expression patterns in the gills of the green crab, Carcinus maenas

Sandra Fehsenfeld12*, Rainer Kiko2, Yasmin Appelhans3, David W Towle4, Martin Zimmer35 and Frank Melzner2

Author Affiliations

1 Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T2N2

2 Biological Oceanography, Leibniz-Institute of Marine Sciences (IFM-GEOMAR) Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany

3 Marine Ecology, Leibniz-Institute of Marine Sciences (IFM-GEOMAR) Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany

4 Center for Marine Functional Genomics, Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672 USA

5 Paris-Lodron-Universität Salzburg, FB Organismische Biologie, Hellbrunnerstr. 34, 5020 Salzburg, Austria

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BMC Genomics 2011, 12:488  doi:10.1186/1471-2164-12-488

Published: 6 October 2011

Abstract

Background

The green crab Carcinus maenas is known for its high acclimation potential to varying environmental abiotic conditions. A high ability for ion and acid-base regulation is mainly based on an efficient regulation apparatus located in gill epithelia. However, at present it is neither known which ion transport proteins play a key role in the acid-base compensation response nor how gill epithelia respond to elevated seawater pCO2 as predicted for the future. In order to promote our understanding of the responses of green crab acid-base regulatory epithelia to high pCO2, Baltic Sea green crabs were exposed to a pCO2 of 400 Pa. Gills were screened for differentially expressed gene transcripts using a 4,462-feature microarray and quantitative real-time PCR.

Results

Crabs responded mainly through fine scale adjustment of gene expression to elevated pCO2. However, 2% of all investigated transcripts were significantly regulated 1.3 to 2.2-fold upon one-week exposure to CO2 stress. Most of the genes known to code for proteins involved in osmo- and acid-base regulation, as well as cellular stress response, were were not impacted by elevated pCO2. However, after one week of exposure, significant changes were detected in a calcium-activated chloride channel, a hyperpolarization activated nucleotide-gated potassium channel, a tetraspanin, and an integrin. Furthermore, a putative syntaxin-binding protein, a protein of the transmembrane 9 superfamily, and a Cl-/HCO3- exchanger of the SLC 4 family were differentially regulated. These genes were also affected in a previously published hypoosmotic acclimation response study.

Conclusions

The moderate, but specific response of C. maenas gill gene expression indicates that (1) seawater acidification does not act as a strong stressor on the cellular level in gill epithelia; (2) the response to hypercapnia is to some degree comparable to a hypoosmotic acclimation response; (3) the specialization of each of the posterior gill arches might go beyond what has been demonstrated up to date; and (4) a re-configuration of gill epithelia might occur in response to hypercapnia.