Branchial expression of an aquaporin 3 (AQP-3) homologue is downregulated in the European eel Anguilla anguilla following seawater acclimation.
A cDNA encoding the homologue of mammalian aquaporin 3 (AQP-3) was isolated by reverse transcription-polymerase chain reaction from the gill of the European eel. The derived amino acid sequence shares 67-70% homology with other vertebrate AQP-3 homologues. Northern blot analysis revealed two AQP-3-specific mRNA species of 2.4 kb and 7 kb. AQP-3 mRNA is expressed predominantly in the eye, oesophagus, intestine (as found in mammals) and the gill; no expression could be demonstrated in the stomach and only low and sporadic levels in the kidney. Quantitative studies demonstrated that, following the 3-week acclimation of freshwater (FW)-adapted yellow and silver eels to seawater (SW), transcript abundance in the gill was reduced by 76% and 97%, respectively. The half time of branchial AQP-3 mRNA downregulation in yellow eels was approximately 10 h, with a maximal 94% decrease in expression after 2 days in SW (compared to time-matched FW controls). However, in fish acclimated to SW for more than 4 days, the fall in AQP-3 mRNA abundance recovered slightly, such that after 3 weeks, expression was 16% of that in time-matched FW controls. The potential roles for this aquaporin isoform in water or solute transport in the eel gill are discussed.
Cutler
Christopher P
CP
School of Biology, Bute Medical Buildings, University of St Andrews, St Andrews, Fife KY16 9TS, Scotland. cpc@st-andrews.ac.uk
Cramb
Gordon
G
D000064:Acclimatization / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D000811:Anguilla / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D051400:Aquaporin 3; D020346:Aquaporins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D005880:Gills / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012623:Seawater; D017386:Sequence Homology, Amino Acid
D020346:Aquaporins; D018076:DNA, Complementary; D012333:RNA, Messenger; D051400:Aquaporin 3