PR03SER 



ties independent of temperature. It is important, therefore, that pho- 

 toperiod be kept the same for different conditions of temperature 

 acclimation. 



Another difficulty in metabolic acclimation results from the 

 differences between active and rest (standard) metabolism and the 

 impossibility of controlling movement in poikilotherms. There is 

 evidence that active and rest metabolism follow slightly different 

 enzyme pathways. Data from anesthetized fish differ from those 

 from quiescent awake ones; hence anesthetics are usually avoided. 



Kinetic analyses have been useful in studies of enzyme induction 

 and of the role of amino acid pools in protein synthesis, but such a- 

 nalyses have not often been applied to problems of acclimation. 



The time -course of acclimation deserves more attention. One 

 related method is to compare the rate- temperature curves of stabil- 

 ized rate functions for poikilothermic animals that have been differ- 

 ently acclimated (Prosser, 1958). Such curves permit some specula- 

 tion concerning themechanismof acclimation (Figure 4). When there 

 is no acclimation, the rate-temperature curves coincide for animals 

 from either temperature (Figure 4a). This lack of acclimation has 

 been described for winter and summer Gunner (Haugaard and Irving, 

 1943) and for a variety of insects and shore invertebrates. One t)T)e 

 of acclimation to cold is a translation of the rate curve to the left or 

 upward (Figure 4b) without change in slope. Such simple translation 

 has been observed for O consumption by the scorpene trout (Gelin- 

 eo, 1959), cocarboxylaseoftheeel(Carlsen,1953),oxygen consump- 

 tion by salamanders, Eurycea (Vernberg, 1952) and Triturus (Riech 

 et al., 1960), for metabolism of some northern and southern species 

 of frogs (Tashian, 1957), of the lizard Sceloporus at 16 C and 23 C 

 (Dawson and Bartholomew, 1956) as well as for numerous inverte- 

 brates (Prosser, 1961). 



A third pattern (Figure 4c) is rotation about a midpoint, i. e., 

 change in slope or Q only. This occurs for O consumption by the 

 European eel with an intersection of curves for 11 C and 26 C 

 acclimation at about 21° C (Precht, 1951) and also for metabolism 

 by the salamander Plethedon (Vernberg, 19 52). The most common 

 pattern is a combination of translation with rotation. When the Q 

 of cold- acclimated animals is less than that of warm- acclimated 



10 



