KINETIC AND STRUCTURAL ADAPTATIONS OF CYTOPLASMIC MALATE-DEHYDROGENASES OF EASTERN PACIFIC ABALONE (GENUS HALIOTIS) FROM DIFFERENT THERMAL HABITATS - BIOCHEMICAL CORRELATES OF BIOGEOGRAPHICAL PATTERNING

Citation
E. Dahlhoff et Gn. Somero, KINETIC AND STRUCTURAL ADAPTATIONS OF CYTOPLASMIC MALATE-DEHYDROGENASES OF EASTERN PACIFIC ABALONE (GENUS HALIOTIS) FROM DIFFERENT THERMAL HABITATS - BIOCHEMICAL CORRELATES OF BIOGEOGRAPHICAL PATTERNING, Journal of Experimental Biology, 185, 1993, pp. 137-150
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology
ISSN journal
0022-0949
Volume
185
Year of publication
1993
Pages
137 - 150
Database
ISI
SICI code
0022-0949(1993)185:<137:KASAOC>2.0.ZU;2-R
Abstract
We measured the effects of temperature on cytosolic malate dehydrogena ses (cMDHs) from the shell muscle of five species of eastern Pacific a balone, genus Haliotis, found at different latitudes and/or tidal heig hts. The apparent Michaelis-Menten constant (K(m)) of coenzyme (nicoti namide adenine dinucleotide, NADH) was conserved within a narrow range (11-21 mumol l-1) at physiological temperatures for all species. Howe ver, elevated temperatures perturbed the K(m) of NADH for cMDHs of the two species living at higher latitudes and/or lower tidal heights [Ha liotis rufesens (red) and H. kamtschatkana kamtschatkana (pinto)] to a much greater extent than for cMDHs of congeners from lower latitudes and/or higher tidal heights [H. fulgens (green), H. corregata (pink) a nd H. cracherodii (black)]. The apparent Arrhenius activation energies for the cMDHs of these five species showed a similar interspecific di vergence. Furthermore, green, pink and black abalone have cMDHs that a re more resistant to thermal denaturation than are cMDHs of red and pi nto abalone. Native gel electrophoresis showed that cMDHs of red and p into abalone had identical mobilities, whereas cMDHs of green, pink an d black abalone are distinct both from each other and from that of the two cold-adapted species. These data suggest that cMDHs from the abal one species living in warm habitats are adapted to function optimally at higher temperatures than are the cMDHs of the two species living in cooler habitats. The relationships suggested by these criteria are in agreement with other studies that used morphological and molecular in dices to predict abalone phylogeny. These results therefore provide fu rther evidence that interspecific variation in protein structure and f unction may be driven by natural selection based on only small (i.e. s everal degrees Celsius) differences in average body temperature, and t hat such selection is an important element of the mechanisms of specie s formation and the maintenance of biogeographic patterning.