. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 50 100 150 200 250 300 350 400. 50 100 150 200 250 300 350 400 Pressure (atm) Figure 1. The effects of measurement temperature and pressure on the apparent Michaelis-Menten constant (Km) of NADH for M4-LDHs of the cosmopolitan deep-sea rattail fish Coryphaenoides armaim, the hydrothermal vent hythitid Bytlules hollisi. and the hydrothermal vent zoarcid Tlwrmanvs The dashed vertical line indicates the approximate habitat pressure at the two vent sites. nailer and Somero, 1978, with Yancey and Siebenaller, 1987).
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 0 50 100 150 200 250 300 350 400. 50 100 150 200 250 300 350 400 Pressure (atm) Figure 1. The effects of measurement temperature and pressure on the apparent Michaelis-Menten constant (Km) of NADH for M4-LDHs of the cosmopolitan deep-sea rattail fish Coryphaenoides armaim, the hydrothermal vent hythitid Bytlules hollisi. and the hydrothermal vent zoarcid Tlwrmanvs The dashed vertical line indicates the approximate habitat pressure at the two vent sites. nailer and Somero, 1978, with Yancey and Siebenaller, 1987). For the M4-LDHs of C. annatus and B hollisi, tem- peratures of 10 to 20°C increased the Km of NADH by ~ 15-20 /uM at in situ pressures (Fig. 2). In contrast, the Km of NADH for the M4-LDH of T. andersoni increased by only approximately 8 pM as temperature increased from 5 to 20°C. Therefore, temperatures characteristic of warm water vents perturbed the Km of NADH of the M4- LDHs of C. annatus and B. hollisi sufficiently to increase their values beyond the physiologically conserved range noted for other species. The M4-LDH of T. andersoni retained its Km of NADH within the physiologically con- served range across the span of measurement tempera- tures at in situ pressure. The different responses of the M4-LDHs of these three species to changes in temperature at in situ pressure lead us to propose two hypotheses concerning the relation- ship between species distribution patterns and tempera- ture and pressure influences on enzymatic function. First, we propose that the M4-LDHs of cold-adapted deep-sea fishes are not pre-adapted for function at the elevated temperatures found at the warm water vents. Thermal perturbation of the kinetic properties of en- zymes under pressure may restrict the endemic fauna of the cold deep sea from exploiting hydrothermal vent habitats. Thus, as much as interspecific differences in the pressure sensitivities of enzymes may be important in es- tabl
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
