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First published online November 24, 2003
Journal of Experimental Biology 207, 95-112 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00708

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Effects of temperature acclimation on lactate dehydrogenase of cod (Gadus morhua): genetic, kinetic and thermodynamic aspects

Maxim Zakhartsev^1,*, Torild Johansen², Hans O. Pörtner³ and Ronny Blust¹

¹ Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
² Department of Fisheries and Marine Biology, University of Bergen, PO Box 7800, N-5020 Bergen, Norway
³ Marine Biology/Ecological Physiology, Alfred-Wegener-Institute, Postfach 12 01 61, Columbusstrasse, D-27568 Bremerhaven, Germany

View larger version (18K): [in a new window]   Fig. 1. Typical set of kinetic properties of the lactate dehydrogenase (LDH) isozyme mixture in crude homogenates prepared from muscle (M) and liver (L) of cod Gadus morhua. Values are means ± S.D.

View larger version (13K): [in a new window]   Fig. 2. (A) Temperature dependence of max (open circles) was used to calculate the Arrhenius activation energies (Ea) for lactate dehydrogenase (LDH) in crude tissue homogenates from the slope of Arrhenius plots [103/T K against ln(max)]. (B) The enthalpy–entropy compensation plot was compiled from different sources for purified LDH (Hochachka and Somero, 1984; Low et al., 1973; Place and Powers, 1984; Prosser, 1986; Somero and Low, 1976; Uvarov and Archakov, 1990) and used to calculate thermodynamic parameters (H, S, G). Results of linear regression are given ± S.E.M.

View larger version (22K): [in a new window]   Fig. 3. The change in growth kinetics of Norwegian coastal cod (Gadus morhua) throughout the year in terms of daily increments of (A) body mass (g day–1) and (B) length (mm day–1) for two acclimation groups (4°C and 12°C). The values are means ± S.E.M. After November 1999 (shaded area), growth rate became more or less similar at both acclimation temperatures.

View larger version (95K): [in a new window]   Fig. 4. Isoelectric focusing (IEF) and staining for lactate dehydrogenase (LDH) activity in crude homogenates of three individual cod (Gadus morhua). M, white muscle; L, liver; std, lane with pI calibration markers (IEF 3.5–9.3; Amersham Pharmacia Biotech). Ldh locus classification (A, B and C) is according to Zietara and Skorkowski (1993). a/a, a/b and b/b are Ldh-B phenotypes according to polymorphism in that locus. For more information, see Table 4.

View larger version (22K): [in a new window]   Fig. 5. Temperature dependence of max [expressed as units per mg of total protein (A) and units per g wet mass (B)] for pyruvate reduction by lactate dehydrogenase (LDH) in crude homogenates prepared from white muscle (circles) and liver (triangles) of cod (Gadus morhua) acclimated to different temperatures. Values are means ± S.E.M. (N=21 for 4°C and N=15 for 12°C). ns, not significant. The dotted line indicates the upper border of data accepted for regression analysis.

View larger version (21K): [in a new window]   Fig. 6. Temperature dependence of of lactate dehydrogenase (LDH) in crude homogenates prepared from muscle (circles) and liver (triangles) of cod (Gadus morhua) acclimated to different temperatures. Two-phase linear regression analysis of the temperature dependence of reveals that at temperatures below 16±1°C (shaded area) the is almost independent of temperature (the slope of the curve is 0.003 mmol l–1 deg.). Values are means ± S.E.M. (N=21 for 4°C and N=15 for 12°C). ns, not significant. The dotted line indicates the upper border of data accepted for regression analysis.

View larger version (17K): [in a new window]   Fig. 7. Temperature dependence of of lactate dehydrogenase (LDH) in crude homogenates prepared from muscle (A) and liver (B) of cod (Gadus morhua) acclimated to different temperatures. Values are means ± S.E.M. (N=21 for 4°C and N=15 for 12°C). Asterisks indicate that differences are significant (F-test, P<0.001). The dotted line indicates the upper border of data accepted for regression analysis.

View larger version (19K): [in a new window]   Fig. 8. Relationship between the relative catalytic efficiency of the overall lactate dehydrogenase (LDH) suite in crude homogenates and the total mass of muscle (A) and liver (B). / is the total tissue relative catalytic efficiency; Vmaxtotal is expressed in U g–1 wet mass; mass of muscle = 90% of the mass difference between fresh body mass and liver [Mmuscle=(Mfish–Mliver)x0.9]. Mean data are presented as larger symbols with bars representing S.D. (N=21 for 4°C acclimation and N=15 for 12°C acclimation). Broken lines are linear regressions. (A) 4°C, y=2670+1.079x (r2=0.02; N=21); 12°C, y=6121–0.61x (r2=0.02; N=15); (B) 4°C, y=4728–6.921x (r2=0.02; N=18); 12°C, y=7069–11.1x (r2=0.08; N=15). Asterisks indicate that differences are significant (unpaired t-test, P<0.05); ns, differences are not significant (unpaired t-test, P>0.05).