228 



BELSER 



[CHAP. 9 



directly involved in the filtering rate in oysters, and Loomis (1955) showed that 

 glutathione triggers a feeding response in hydra. 



It seems quite reasonable that all of these compounds might be bioassayed 

 in the future. The basis for description of genus and species in bacteria resides 

 in differential utilization of carbohydrates. Why should it not be possible to 

 apply a spectrum of bacteria with different carbohydrate patterns to sea-water 

 in order to characterize the carbohydrate components of the organic material ? 



122 W 



121 W 



33 N 



SHIPS TRACK 



WATER MASS BOUNDARY- ANIMAL INDICATOR SPECIES 



INFERRED BOUNDARY- ANIMAL INDICATOR SPECIES 



STATIONS BIOASSAYED 



STATIONS NOT BIOASSAYED ,"' 



32°20'N 



Fig. 1. Plot of Zig Pac cruise data showing water-mass boundaries as defined by animal 

 indicator species. At the stations where bioassays were run, the results appear below 

 the station. + denotes presence and — denotes absence of specific biochemicals. 

 The number indicates depth of sample in meters, and the biochemicals are reported 

 in the order : isoleucine, glycine, tryptophane, uracil and peptone. The animal 

 indicator data are from unpublished work of L. Berner. 



The mutant isolation program with Serratia has produced five separate 

 mutants which respond to unidentified components of peptone, but to none of 

 the single amino acids. It is suspected that they cannot synthesize short chain 

 peptides, and efforts are being made to identify their requirements. Since 

 glutathione is a tri-peptide, it seems reasonable to suppose that one might be 

 able in the future to have a specific assay for this compound. 



Vishniac (1955) has devised an assay for steroids using Labyrinthula. This 

 might perhaps open a whole new area of bioassay for more complex substances 

 in sea-water, including the steroid vitamin D. 



