title: Effects of elevated seawater pCO(2) on gene expression patterns in the gills of the green crab, Carcinus maenas.
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 pCO(2) as predicted for the future. In order to promote our understanding of the responses of green crab acid-base regulatory epithelia to high pCO(2), Baltic Sea green crabs were exposed to a pCO(2) 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 pCO(2). However, 2% of all investigated transcripts were significantly regulated 1.3 to 2.2-fold upon one-week exposure to CO(2) 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 pCO(2). 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(-)/HCO(3)(-) 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.
authors: Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada R3T2N2. umfehsen@cc.umanitoba.ca
authors: Sandra
authors: S
authors: Fehsenfeld
authors: Rainer
authors: R
authors: Kiko
authors: Yasmin
authors: Y
authors: Appelhans
authors: David W
authors: DW
authors: Towle
authors: Martin
authors: M
authors: Zimmer
authors: Frank
authors: F
authors: Melzner
mesh_terms: D000818:Animals; D003386:Brachyura / Q000235:genetics / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry*; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters / Q000235:genetics / Q000378:metabolism; D005740:Gases / Q000737:chemistry; D020869:Gene Expression Profiling; D005880:Gills / Q000378:metabolism*; D016023:Integrins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D059470:Tetraspanins / Q000235:genetics / Q000378:metabolism
chemical_list: D018118:Chloride Channels; D027963:Chloride-Bicarbonate Antiporters; D005740:Gases; D016023:Integrins; D008565:Membrane Proteins; D015221:Potassium Channels; D059470:Tetraspanins; D002245:Carbon Dioxide