Figure from Temperature compensation of enzymatic activities in brain of antarctic fishes: Evidence for metabolic cold adaptation

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Activities of citrate synthase (CS) and lactate dehydrogenase (LDH) in brain tissue of antarctic, temperate, and tropical teleost fishes. Activities were measured at 10°C following protocols given in Torres and Somero (1988a), except that for the CS assays the concentration of dithionitrobenzoic acid was 1 millimolar (mM). Uncentrifuged homogenates were used. Activities are expressed as I.U. of activity (micromoles of substrate converted to product per minute) per gram wet mass of tissue. Duplicate measurements were made for each brain homogenate. The average values of CS and LDH activity for each brain were used to calculate the mean activities for each geographical group. The group means are given with the SEM and, in parentheses, the total number of brains analyzed for each geographical group. Variances were tested with Cochran's C test. In comparing mean CS activities (A), variances were unequal, so a Kruskal-Wallis analysis was applied. In B, one-way analysis of variance was applied for comparisons of means of LDH activities. In all comparisons of effect of habitat, significant differences (p<0.05) were observed for both enzymes. Antarctic species studied were Pagothenia borchgrevinki, Trematomus bernacchii, Trematomus hansoni, Trematomus newnesi, Trematomus pennelli, Chaenocephalus aceratus, Champsocephalus gunnari, and Chianodraco rastrospinosus. Temperate species studied were Sebastes mystinus, Sebastes carnatus, and Leptocottus armatus. Tropical species studied were Halichoeres bivittatus, Halichoeres radiatus, Pomacentrus sp., Centropomus undecimalis, and Oreochromis sp.