and nutrition. Especially for comparative purposes, a thorough knowledge 

 of the intermediary metabolism of aquatic animals would be invaluable. 

 There would be great value in the application of this knowledge to better 

 commercial use of these marine resources. 



Research study of the intermediary metabolism of aquatic animals 

 is a fertile field for further scientific effort. Almost none of the 

 research reviewed herein has been directed toward the objective of de- 

 termining the pathways of intermediary metabolism, and the small amount 

 of information that is available applies to this objective only super- 

 ficially. Future studies should be directed to two broad objectives: 

 Firstly, extensive research will be required to map out the overall path- 

 ways of intermediary metabolism in aquatic animals, especially the fish. 

 Secondly, intensive research will be required to determine the exact mech- 

 anism of each metabolic transformation. 



We believe that the overall need for future research may be outlined 

 as follows: 



1. Ehzymes known to occur in pathways of general intermediary meta- 

 bolism should be identified and their activities measured. The identifica- 

 tion of a particular en2yme in the homogenates of tissue of the aquatic 

 animal under study will require specific assays in which the reaction sys- 

 tem consists of known chemical compounds. It will be preferable to have 

 the enzymes either fractionated from the major portion of the protein and 

 interfering enzymes or purified until all extraneous material has been 

 removed. 



e 



2. The intermediate compounds of metabolism should be studied in 

 such a way as to show the sequence in which they are formed. Several 

 ways of carrying out this study are known. Radiolabeled reaction com- 

 ponents may be added to the whole aquatic animal., to a given tissue, or 

 to a tissue preparation; and after reaction, the products may be separ- 

 ated on filter paper and an autoradiograph developed (Bassham et al. 195>3)« 

 The sequential transformation of metabolites also may be established by 

 adding a reactant to the tissue or tissue preparation of the aquatic ani- 

 mal and then separating the products by filter-paper chromatography to 

 determine the next member in the metabolic sequence (Avron and Biale 19!?7)« 



3. After enzymes and the metabolic intermediates have been identi- 

 fied, the pathways of intermediary metabolism should be checked at the 

 whole-animal level, using radioactive or mass isotope tracers. This re- 

 search can best be patterned after that which has already been done with 

 land animals, plants, and bacteria. The amount of carbohydrate metabolized 

 by the Embden-Meyerhof pathway and the amount metabolized by the hexose- 

 monophosphate shunt, for example, can be determined from studies of forma- 

 tion of C II K)2 following glucose-1-C-" 4 - and glucose-o-C 1 ^ injection into fish. 



U. As our knowledge of the pathways of intermediary metabolism de- 

 velops, attempts should be made to integrate this knowledge with that of 

 the nutrition and physiology of aquatic animals. There are a variety of 

 important questions in the nutrition and physiology of aquatic animals 

 that should be answered at the level of intermediary metabolism. How, 

 for example, are the characteristic highly unsaturated fatty acids of fish 



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