ORIGIN 



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Fig. 10. 



Zymogram of the LDH pattern of a representative of 

 each of the classes of vertebrates. The representative 

 species are human (mammal), Adelie penguin (bird), 

 rattlesnake (reptile), Amphiuma (amphibian), fluke (bony 

 fish), sand shark (cartUagenous fish), and the lamprey. 

 Note the considerable variation in the number and mo- 

 bility of LDH isozymes present in each of these orga- 

 nisms. (From Markert, in The Harvey Lectures, Series 59, 

 187, 1965; reproduced with permission of the Academic 

 Press.) 



plementarity of the subunits of vertebrate LDH 

 is presented in Fig. 12, which shows the iso- 

 zyme patterns obtained when horse LDH is 

 hybridized with lamprey, fish, or salamander 

 LDH. These patterns are relatively simple. 

 More complex patterns are obtained in hybridi- 

 zations involving other organisms. This is 

 illustrated in Figs. 13 and 14 in which the 

 results of the hybridization of chicken LDH 

 with horse, snake, cow, or rabbit are shown. 



TILL: Why are you doing all this? 



MASSARO: For kicks: Seriously, one of 



our major interests is finding out how the LDH 

 tetramer is put together. We feel that a study 

 of various aspects of the phenomenon of inter- 

 specific hybridization is a valid approach to the 

 problem. 



McCARL: Do you always get the same 

 patterns of hybridization? 



MASSARO: Yes, they are very constantbe- 

 tween any two given species. 



It would be expected that the catalytic prop- 

 erties of the hybrid molecules differ from those 

 of the parental types. This is analogous to the 

 situation encountered with the heteropolymeric 

 isozymes formed by recombination of LDH-1 

 and -5 from the same species. From our data, 

 it appears that, in closely related animals, 



Fig. 11. 



Zymogram illustrating the hybrid Isozymes of LDH 

 formed between beef LDH- 1 and LDH from several classes 

 of vertebrates (lamprey, fish, rattlesnake, penguin LDH- 

 5, and pig LDH-5). The hybrids are indicated by small 

 circles. (From Markert, in Ideas in Modern Bi logy, 1965; 

 reproduced with permission of the National Academy of 

 Sciences). 



85 



