Altered expression of Na/K-ATPase and other osmoregulatory genes in the gills of euryhaline

24 Recent advances in molecular techniques have allowed gene expression in euryhaline 25 animals to be quantified during salinity transfers. As these investigations transition from 26 studying single genes to utilizing genomics-based methodologies, it is an appropriate time to 27 summarize single gene studies. Therefore, a meta-analysis was performed on 59 published 28 studies that used quantitative polymerase chain reaction (qPCR) to examine expression of 29 osmoregulatory genes (the Na/K-ATPase, NKA; the NaK/2Cl cotransporter, NKCC; 30 carbonic anhydrase, CA; the cystic fibrosis transmembrane regulator, CFTR; and the H31 ATPase, HAT) in response to salinity transfer. Based on 887 calculated effect sizes, NKA, 32 NKCC, CA, and HAT are up-regulated after salinity transfer, while surprisingly, CFTR is 33 unchanged. Meta-analysis also identified influential factors contributing to these changes. For 34 example, expression was highest: 1) during transfers from higher to lower salinities comprising a 35 physiological transition from osmoconformity to osmoregulation, 2) 1-3 days following transfer, 36 3) during dissimilar transfers, and 4) in crustaceans rather than fishes. Methodological 37 characteristics (e.g., types of controls) were not important. Experiments lacking in the current 38 literature were also identified. Meta-analyses are powerful tools for quantitatively synthesizing a 39 large body of literature, and this report serves as a template for their application in other areas of 40 comparative physiology. 41 42