The results of chemical characterization of amino acid-containing particulate and dissolved organic matter in oceanic waters are briefly described. In both particulate and dissolved phases, there are high molecular mass proteins, while the majority of amino acid-containing organic matter comprises low molecular mass peptides. Two dissolved proteins were identified as porin P and ompA-like protein derived from bacteria and one particulate protein was heat shock protein 70 from photosynthetic organisms. They survive and accumulate from N-termini to, perhaps, C-termini without much alteration. Questions are raised as to why specific biomacromolecules survive and accumulate without alteration, and why partially degraded low molecular mass peptides also survive and accumulate in marine organic pool. Since marine organic pool is one of the three major organic reservoirs on earth's surface, changes in dynamics and subsequent ebb and flow of the marine organic pool may affect the global bioelement cycles over a certain time-scale. Clarification of the mechanistic processes by which the marine organic pool is maintained is one of the key areas of research in organic geochemistry.

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Lipids were analyzed for three different life forms of a marine planktonic diatom,Chaetoceros pseudocurvisetus, cultured in different nutrient media, in order to examine the influence of nutrient deficiency to the variation of the lipid distribution.
TLC-FID and GC-MS analyses show large differences in lipid composition between the vegetative cell (VC) cultured in a nitrate-rich medium and the resting spore (RS) and resting cell (RC) cultured in nitrate-poor media. TLC-FID profiles of total lipids showed that triacylglycerols are abundant in the VC, whilst free fatty acids and sterols are abundant in the RS and RC. The VC shows lack of n-alkanes, unsaturated fatty acids and sterols. In contrast, the RS and RC show a broad n-alkane distribution maximizing at C₁₇ with no odd/even carbon number preference, the presence of a C₂₁ polyunsaturated alkene, phytadienes, unsaturated fatty acids and Δ⁵-sterols. A C₃₀ sterol is specifically detected in the RS, while pristane in the RC.
These results indicate that the distribution of lipids from C. pseudocurvisetus is strongly affected by nutrient condition. This finding suggests the possibility of the use of lipids to indicate paleonutrient conditions of sea surface water, and also provides a new insight to explain lipid distributions in field samples investigated before.

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