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Ion regulation in eurythermic teleost fish Fundulus heteroclitus: Cold shock vs. cold acclimation
Author(s) -
Marshall William S,
Barnes Kaitlyn R,
Malone Alicia M,
Buhariwalla Hannah EC,
Osmond Emily M
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.728.4
Subject(s) - ibmx , fundulus , acclimatization , chemistry , killifish , biophysics , shock (circulatory) , fish <actinopterygii> , biology , biochemistry , in vitro , medicine , botany , fishery , forskolin
Killifish overwinter (0–5°C) by decreasing activity and metabolic rate and yet they retain ability to ion/osmoregulate. Fish were acclimated to seawater (32 ppt) at 5°C and 20°C (8+ weeks); cold shock of 20°C opercular epithelia in vitro reversibly decreased Clsecretion by 90% (as short‐circuit current, SCC) and membranes failed to respond to hypotonic shock, IBMX/db‐cAMP (0.1 mM) or isoproterenol (1.0 μM). Opercular epithelia from cold‐acclimated fish also had low transport rates, but were able to respond normally, i.e. rapid inhibition of SCC by hypotonic shock and SCC stimulation by IBMX/db‐cAMP and isoproterenol. Cold acclimation caused homeoviscous adaptive changes, increased fatty acid unsaturation and increased short chain ( e.g. reduced C18:0 and increased C14:0, C18:1) to maintain membrane fluidity. Cooling in vitro to 1°C induced a sharp bend in Arrhenius plots below 8°C for warm (Q 10 = 6.9) and cold (Q 10 = 4.2) acclimated fish, but these nonlinearities were markedly reduced (to Q 10 = 2.9) by anaerobiosis and cyanide (0.5 mM), indicating mitochondrial inner membrane ATP production as source of the transition. In the cold, Fundulus markedly reduce ion transport rates but maintain regulatory control of ion transport through homeoviscous adaptation. Supported by NSERC, CFI and UCR.