. The Biological bulletin. Biology; Zoology; Marine biology. 92 M. E. KRIEBEL ET AL. Table I Biochemical characteristics of skate and Torpedo electric organs Units/g Torpedo Skate Activity Mean SEM n % ChAT AChE ACh LDH nmol/h ^mol/min nmol /xmol/min 7500= 137-274' 1475" ; 235 ' 26 11 10 10 Enzyme activities for skate are from the present study. Other values are from the literature as follows: ' Dowdall (1977); " Volknandt and Zimmerman (1986);' Fox et al. (1990); " Dowdall (unpub. data). In the final column, skate values are
. The Biological bulletin. Biology; Zoology; Marine biology. 92 M. E. KRIEBEL ET AL. Table I Biochemical characteristics of skate and Torpedo electric organs Units/g Torpedo Skate Activity Mean SEM n % ChAT AChE ACh LDH nmol/h ^mol/min nmol /xmol/min 7500= 137-274' 1475" ; 235 ' 26 11 10 10 Enzyme activities for skate are from the present study. Other values are from the literature as follows: ' Dowdall (1977); " Volknandt and Zimmerman (1986);' Fox et al. (1990); " Dowdall (unpub. data). In the final column, skate values are expressed as a percentage of those of Tor- pedo. values for ACh from both organs are shown for compar- ison. The activities of all three enzymes were much lower in skate than in Torpedo, and the resuhs for ChAT, in particular, closely parallel the previously reported con- centrations for ACh (Fox et al., 1990). AChE activity was comparable to that previously reported for R. undulata (Nachmansohn and Meyerhof, 1941). Taken together, these findings show that the terminal volume in skate electric organ would be 3%-5% of that in Torpedo. If al- lowance is made for the lower cellular density in skate and the larger volume of individual electrocytes (as in- dicated by LDH activity), then the terminal volume of skate electric organ is between 10% and 18% of that found in Torpedo. both activities after 4 days suggests lower yields of nerve terminals after extended periods of collagenase digestion. The difference in tissue dissociation rates at 6°C (this study) and 26°C (Fox et a!., 1990) was surprisingly large (~40-fold) and much greater than the expected for a single enzyme reaction with a Qio of The ob- served temperature dependence is, however, consistent with cooperative enzyme action. Collagenase, by itself, is known to be ineffective for total tissue dissociation and is therefore used in conjunction with other proteases. The collagenase preparation from Clostridiu
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