AbstractDifferential screening of a hepatopancreas cDNA library derived from the marine snail Littorina littorea yielded a 421‐bp clone coding for ribosomal protein L26 that was up‐regulated during anoxia exposure. The deduced amino acid sequence, containing 144 residues with a predicted molecular weight of 17 kDa, showed 80% amino acid sequence identity to the mammalian ribosomal protein L26. Analysis of hepatopancreas and foot muscle samples from a time course of anoxia exposure showed a maximal transcript increase of 4‐ and 3‐fold after 96 hr and 48 hr, respectively, relative to normoxic animals, with a subsequent decrease in transcript levels during normoxic recovery. Nuclear run‐off assays confirmed the observed transcriptional up‐regulation of L26 during anoxia. Organ culture experiments were performed to determine a possible pathway of up‐regulation of L26, with data indicating a putative role for cGMP in signal transduction. The transcriptional up‐regulation of L26 during anoxia may stabilize the existing mRNA pool, via a possible cGMP‐mediated signaling cascade, until oxygen reappears and protein synthesis resumes. J. Exp. Zool. 290:759–768, 2001. © 2001 Wiley‐Liss, Inc.