equilibration. 



The importance of the intracellular location of carbonic 

 anhydrase in prokaryotic autotrophs to their ability to take up and 

 concentrate CO^ for photosynthesis has been established recently by 

 the controlled expression of the foreign gene in these organisms. 

 The C0 ? concentration mechanisms in these organisms and other 

 phytoplankton are essential to their role in global carbon flux. 



More research is needed on: 



(1) the COp concentrating mechanisms of 

 prokaryotic/ eukaryotic phytoplankton ; 



(2) the role of carbonic anhydrase in these mechanisms; and 



(3) the role of extracellular carbonic anhydrase and excreted 



active carbonic anhydrase in facilitating C0 ? < > HCC, < > H ? 



exchange in the ocean. 



This research is ripe for transformation technology, and 

 probing of/screening for carbonic anhydrase at the 

 process/physiological level, both supported by mass spectrometry. 



(4) Analysis of photosynthetic respiratory activities of 

 mixed populations of phytoplankton using fluorescence quenching and 

 analyses of stable isotope exchange. 



All of these research areas are of basic importance in 

 understanding ecosystem energy balance, whether it be concerned 

 with balance of C0 2 fluxes, residence time of carbon, or seasonal 

 and annual trends in greenhouse C0 ? . 



Sequestration of Carbon: Suggested Techniques and Approaches 



There is a need to examine carbon isotopic discrimination of 

 the C-fixation enzymes and enzyme systems in autotrophs: 

 specifically, isotope ratios in specific cellular and subcellular 

 components: 



a. Examination of humics, tannins, and "black" muds with 

 gentle extraction and tagging procedures, coupled with chemical 

 analysis. Coupled with separation techniques and high resolution 

 isotope ratio mass spectrometry, this approach could yield valuable 



II-5 



