Temperature‐adaptive differences between the M₄ lactate dehydrogenases of stenothermal and eurythermal sciaenid fishes

Abstract

The effects of temperature on the apparent Michaelis-Menten constant (K,) of pyruvate were determined for M,-lactate dehydrogenases (LDHs) of 15 species of the teleost family Sciaenidae from habitats differing in average temperature and temperature range. The central question addressed was whether adaptive differences in the effect of temperature on an important kinetic parameter, K,, reflect selection based on the range of temperatures experienced by the species, the highest temperature encountered by the species, or both of these factors.For the M,-LDHs of all 15 species, the K, of pyruvate was conserved between 0.1 and 0.4 mM pyruvate over the species' physiological temperature range. However, large increases in K, of pyruvate commonly were found at temperatures a few degrees C above the species' upper habitat temperature. Distinctions were found between the responses of the enzymes of eurythermal and stenothermal sciaenids. For the most eurythermal species, e.g., Sciaenops ocellatus, Micropogonias undulatus, and Roncador stearnsii, K, of pyruvate varied only about twofold between 10 and 30"C, the temperatures which encompass most of the habitat ranges of these species. For the most stenothermal species, e.g., Cynoscion striatus and Micropogonias furnieri, with habitat temperature ranges of 14-18"C, sharp increases in K, occurred a t temperatures above 20°C. We hypothesize that thermal stability of K, values is more strongly selected by maximal habitat temperature than by the amount of variation in habitat temperature, and that adaptation to high temperatures may pre-adapt enzymes for eurythermal function.

Evolution of Lactate Dehydrogenase-A Homologs of Barracuda Fishes (Genus Sphyraena) from Different Thermal Environments: Differences in Kinetic Properties and Thermal Stability Are Due to Amino Acid Substitutions Outside the Active Site,

“…We found that species differences in the relationship of K m Versus temperature for LDH-As favor conservation of K m for substrate and cofactor at physiological temperatures. These results agree with previous findings for dehydrogenase enzymes of other vertebrates and invertebrates (Graves & Somero, 1982;Coppes & Somero, 1990;Dahlhoff & Somero, 1993), and show that even relatively minor changes in temperature, such as those predicted by some models of global warming, appear adequate to favor selection for adaptive change in proteins.…”

Lactate dehydrogenase of Mugil sp. (Mugilidae, Perciformes). Lack of electrokinetic, thermostability and kinetic differences among individuals with different number of scales

“…On the other hand, B-isoforms are characteristically more susceptible to substrate inhibition, channeling more pyruvate into the Kreb's cycle and functioning mainly as lactate oxidases. The apparent K m (pyr) values obtained here have been compared with other fish LDH K m values (Wuntch and Goldberg, 1970;Panepucci et al, 1987;Coppes and Somero, 1990;Almeida-Val et al, 1991). All were found to be similar to K m values obtained for muscle and heart LDH or their purified isoforms.…”

Fertilizer Industry Effluent Induced Biochemical Changes in Fresh water Teleost, Channa striatus (Bloch)

“…Some components present in the fertilizer industrial effluent interact together and produce toxicity to aquatic organisms for example the interaction between dissolve oxygen and elevated ammonia has been shown to alter the respiratory physiology of fresh water fish (Pickering and Pottinger 1987). These findings indicated that the inhibitory effect of industrial effluent on the activity of LDH may be mediated via formation of enzyme-inhibitor complex leading to impairment of carbohydrate metabolism (Panepucci et al 1984(Panepucci et al , 1987Copper and Somero 1990;Sharma and Gopal 1995).…”