SECRETARY'S REPORT 185 



suggest a different molecular environment for carotenoids and 

 chlorophylls. 



In the area of phosphorus metabolism the structure and physiology 

 of ribonucleic acid-polyphosphates in algae have been studied. Ex- 

 tracts have been obtained from synchronous algal cultures, and poly- 

 mers have been hydrolyzed by various means; the low molecular- 

 weight products have been investigated to ascertain the linkage group 

 which connects the ribonucleic acid to polyphosphates. In December 

 1963 through February 1964, an extensive Antarctic collecting trip 

 aboard the U.S.S. Eltanin was made. Algal and diatom collections 

 were made in the Humboldt current off the coast of Chile and in a 

 great circle arc from Valparaiso to Peter I Island. From these plank- 

 ton, sample determinations were made on total phosphorus and 

 organic nitrogen. The distribution of phosphorus within certain 

 compounds and relative rates of radioactive phosphate incorporation 

 into various fractions were determined. Concurrently, sea- water 

 samples were obtained at the same sites at which organisms were 

 collected to determine the major nutrients to which the plankton 

 were exposed. 



A glycopeptide was isolated, purified, and characterized from the 

 green alga Chlorella pyrenoidosa. This glycopeptide contains sialic 

 acid, a sugar derivative which has not previously been reported in 

 any photosynthetic organism. Sialic acid confers antigenic speci- 

 ficity upon such macromolecules as blood-group substances and bac- 

 terial cell-wall sheaths. 



The continued investigation of intracellular, phytochrome-mediated 

 responses in corn-leaf sections has demonstrated a light catalyzed 

 utilization of carbohydrates more closely associated with the radiant- 

 energy stimulus than any other phytochrome-mediated biochemical 

 response reported heretofore. Increase in utilization occurs well be- 

 fore any growth response is detectable. Total sugar loss is the first 

 change observable, preceding starch disappearance. Specific sugar 

 changes occurring during the first hours immediately following the 

 light pretreatment reveal major changes in both nonreducing and 

 reducing sugars. 



Continuation of the studies on the correlation between measured 

 in vivo changes in phytochrome pigment concentrations and observed 

 physiological responses induced by red or far-red irradiation show 

 that the logarithmic change in pigment concentration correlates ex- 

 actly with the physiological dose-response curve for initial light 

 treatments. The time rate of bean hypocotyl hook opening has been 

 measured by time-lapse photography. The rate of hook opening is 

 directly proportional to the intial dose of red light. The onset of 

 opening occurs after about 5 hours and is the same for all exposures. 



