PBOSSER 



metabolism of animals acclimated to extreme temperatures is mea- 

 sured over the entire curve, the two maxima are similar (Kanungo 

 and Prosser, 1959a) (Figure 5). Species differences maybe marked 

 as between Carassius carassius and C. gibelio (Suhrman, 1955 and 

 Roberts, 1960) ; G. carassius shows an inverse or type 5 acclimation, 

 _C. gibelio a positive or type 3 acclimation. 



Data for oxygen consumption by tissue slices, homogenates, and 

 whole gills are given in Table II. There is some disagreement for 

 the same tissue among investigators, and some tissues show more 

 temperature compensation than do others. Ingeneral, skeletal mus- 

 cle shows more change than does liver or heart. For brain, compen- 

 sation is reported by two authors and lack of compensation by two. 

 Gills of fish show marked metabolic compensation. For both gills and 

 muscle, Roberts (1960) reports higher daytime metabolic rates and 

 slightly greater differences between warm- and cold- acclimated 

 tissues when the fish have been on a short day (7-hour) photoperiod 

 than on a long day (17-hour) photoperiod. No attempt has been made 

 to equate the O consumption by various tissues to the total by the 

 intact animal arid to evaluate the relative contributions of each, but 

 the percentage of change found for isolated tissues is less than for 

 intact animals. 



Evidence for acclimatory effects on some enzymes of poikilo- 

 thermic vertebrates and not on other enzymes is summarized in 

 Table IE. The reported enzymatic effects are insufficient to account 

 for the observed changes in metabolism. Differences in some de- 

 hydrogenases and electron transport enzymes have been reported. 

 Gills from cold- acclimated goldfish were more sensitive to cyanide 

 (Ekberg, 1958) (and liver more sensitive to an timycin (Kanungo and 

 Prosser, 1959b)), while liver showed no significant differences with 

 respect to inhibition by cyanide, azide, carbon monoxide, or amytol 

 (Kanungo and Prosser, 19 59b) . Cocarboxylase showed some compen- 

 sation in liver and questionable effect in muscle (Garlsen, 1953). 

 Succinic dehydrogenase of eel liver as measured by methylene blue 

 reduction showed considerable change (Precht, 1951). In goldfish 

 this enzyme was altered in muscle and in liver when measured on a 

 protein (but not on a wet weight) basis (Murphy, 1961). Malic dehy- 

 drogenase of goldfish liver showed considerable inverse acclima- 

 tion (Precht's type 5) (Murphy, 1961). Cytochrome oxidase showed 



14 



