Differential responses in gills of euryhaline tilapia, Oreochromis mossambicus, to various hyperosmotic shocks

• Published in: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
• Main Authors: Wang, P.J., 李宗翰, Lin, C.H., Hwang, L.Y., Huang, C.L., Lee, T.H., Hwang, P.P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Euryhaline teleost; Gill; Mitochondrion-rich cells; Na plus /K plus; -ATPase; Osmolality; Tilapia; mitochondria-rich cells; na+-k+-atpase; killifish fundulus-heteroclitus; branchial chloride cells; atlantic salmon smolts; bass morone-saxatilis; time-course changes; rainbow-trout gill; yolk-sac membrane; fresh-water; Atlantic salmon
• Online Access: http://hdl.handle.net/11455/37750; https://doi.org/10.1016/j.cbpa.2008.12.012

Euryhaline tilapia (Oreochromis mossambicus) survived in brackish water (BW; 20 parts per thousand) but died in seawater (SW; 35 parts per thousand) within 6 h when transferred directly from fresh water (FW). The purpose of this study was to clarify responses in gills of FW tilapia to various hyperosmotic shocks induced by BW or SW. In FW-acclimated tilapia, scanning electron micrographs of gills revealed three subtypes of MR cell apical surfaces: wavy-convex (subtype I), shallow-basin (subtype II), and deep-hole (subtype III). Density of apical surfaces of mitochondrion-rich (MR) cell in gills of the BW-transfer tilapia decreased significantly within 3 h post-transfer due to disappearance of subtype I cells, but increased from 48 h post-transfer because of increasing density of subtype III cells. SW-transfer individuals, however, showed decreased density of MR cell openings after 1 h post-transfer because subtype I MR cell disappeared. On the other hand, relative branchial Na(+)/K(+)-ATPase (NKA) alpha 1-subunit mRNA levels, protein abundance, and NKA activity of the BW-transfer group increased significantly at 6,12, and 12 h post-transfer, respectively. In the SW-transfer group, relative mRNA and protein abundance of gill NKA alpha 1-subunit did not change while NKA activity declined before dying in 5 h. Upon SW transfer, dramatic increases (nearly 2-fold) of plasma osmolality, [Na(+)], and [Cl(-)] were found prior to death. For the BW-transfer group, plasma osmolality was eventually controlled by 96 h post-transfer by enhancement of NKA expression and subtype III MR cell. The success or failure of NKA activation from gene to functional protein as well as the development of specific SW subtype in gills were crucial for the survival of euryhaline tilapia to various hyperosmotic shocks. (C) 2008 Elsevier Inc. All rights reserved.