| Natural metabolism condition, effects of environment factors on metabolism of Japanese flounder and turbot, the representative fishes of flatfish, were discussed in this paper. Osmoregulatory mechanism of fish was also researched in detail.1. Study on dai ly metabol ism level and rhythm of turbot ScophamusmaximusMetabolism rhythms on turbots of different sizes were studied. The results showed that, there were apparent effects of feeding on metabolism of turbot. Shortly after feeding, the metabolism rate had an increasing trend. The four specifications showed a same disciplinarian of oxygen consumption and ammonia excretion. The first peak level of metabolize rate appeared during the third hour to the 9th hour after feeding, and the second peak level appeared at 3:00-6:00 am (21~24hr after feeding). There were no distinct difference between metabolism rhythms in day and metabolism rhythms at night (P>0.05). The body weight had significant effect on metabolize of turbot (P< 0.05), the daily average rate of oxygen consumption of the four sizes (9.69?. 35g, 33. 34?. 34g, 130.18+26. 75g and 264.11+35. 79g) were 0. 2702?.0225, 0.1880+0. 0189, 0.1592+0. 0436, 0.1033 + 0.0184 mg02/g/h respectively; and the daily average rate of ammonia excretion were 0.6496?.0303, 0.4560+0.0669, 0.3744+0.0320, 0.2831+0.0662 mgN/lOOg/h respectively.2. Effects of salinity on metabolism of juvinile turbotThe metabolism changes of juvinile turbots ( Scophamus maximus Linnaeus) were determined when the salilnity changed abruptly from 34 tolow levels (28,23,18,12, 8ppt) and to a high level(40ppt). The results suggest that all of the oxygen consumption rates and ammonion exretion rates of juvinile turbots of the 6 groups have a slowly increasing trend, and the bigger extent salinity changed, the more distinct trend appeared. After salinity changing, it was about at the 24h of the experiment that the peak level of oxygen consumption rate was saw, however the highest ammonion exretion rate was seen only at 9~15h after the experiment began. And at the end of the experiment, oxygen consumption and ammonion exretion rates of juvinile turbot came back to the former level before salinity changing, and no marked differiences were seen in all groups (P>0. 05). 3. Characterization of gill NaHO-ATPase in Japanese flounder (.Paralichthys olivaceus)The characterization of gill Na+-K+-ATPase in Japanese flounder (Paralichthys olivaceus) was studied in this paper. The result shows that both of the two changing curves of gill NaMC-ATPase activity of Japanese flounder affected by reaction temperature and pH appeared peak value, the optimal reaction temperature is 30-35, above 40 the enzyme activity drops rapidly, at 50 the enzyme is deactivated. The optimal pH is 7. 5-8. 0, when the pH level is less than 7.5 or higher than 8.0, the enzyme activity drops rapidly. When pH level is less than 6.0, the enzyme activity was entirely inhibited. In the range of reaction time and ATP-Na2 concentration of this experiment, the gill Na+-K+-ATPase activity has a rising trend along with the time passing by and with the ATP-Na2 concentration rising, but the rising rapid decreased by degrees. The optimal concentration of Na+, K+and Mg2+ in the medium is 80, 30 and 6 mmol/L, respectively. If K+ or Mg2 was absent, gill Na-K-ATPase appears very low activity. As an inhibitor, ouabain has a distinctly inhibited effect on gill Na+-K+-ATPase activity. At 2mmol/L concentration of ouabain, the enzyme activity has been entirely inhibited.4. Effects of salinity on plasma osmolality and gill Na*-HO-ATPase activity of juvinile Japanese flounderThe changes of plasma osmolality and gill Na+-K*-ATPase activity of juvini le Japanese flounder (Paralichthys olivaceus) was studied when the salilnity changed abruptly from 30 to 6 (in 6ppt increments). The results suggest that effects of the salinity on plasma osmolality and activity of gill NaMC-ATPase of Japanese flounder was significant (P<0. 05). After the salinity changed, plasma osmolality and gill Na-K-ATPase activity of...
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