Meeting Abstract

35.4  Friday, Jan. 4  Short- term mechanism of seawater adaptation in Mozambicus tilapia (Oreochromis mossambicus): The effect of salinity exposure on cell cycle and Na/K ATPase content in gill cells assessed using laser scanning cytometry (LSC) KAMMERER, B.D.**; SARDELLA, B.A.; K�LTZ, D.; University of California, Davis; University of California, Davis; University of California, Davis bdkammerer@ucdavis.edu

We have developed a new method for analysis of teleost gill cells using cellular and immunocytochemical staining for LSC. Epithelial cells were isolated from gills of whole tilapia acclimated to (2/3) seawater (SW) and their preparation optimized for spinning gill cells down on to coverslips. Freshwater-acclimated tilapia were transferred to 2/3-strength SW over a time course: 0 (FW-control), 2, 4, 8, 16, 24, 72, and 168 (1-week) hours. Multivariate LSC analysis based on propidium iodide staining and histone H3 Ser10 immunocytochemistry indicated a changeover from the majority of cells being in G1 cell cycle phase to G2 phase at around 72 hours. Furthermore, our analysis demonstrates that gill cells show a rapid increase in mitotic cells during the first 2 hours of SW exposure, an effect which is exacerbated in chloride cells (CC) at 8 hours. Na/K ATPase levels also tended to increase per CC in response to SW acclimation. We conclude from these data that SW-exposure results in rapid transient cell cycle arrest initially at an intra-mitotic and then at the G2 checkpoint. These results together with the observed increase in Na/K ATPase in CC indicate rapid remodeling of gill epithelium during SW acclimation of tilapia.