Sedimentary rocks from the boreholes of MITI Rumoi, Soma-oki and Nikaho were analyzed for maleimides and phthalimides by the chromic acid oxidation method. These compounds have been obtained from the diagenetic products (i.e., alkylporphyrins) of sedimentary chlorophylls. Because alkylporphyrins were shown to be converted to benzoporphyrins by heating experiments, phthalimides obtained by the oxidation of sediments are likely to be of chlorophyll origin. The ratio of total phthalimides to total maleimides in these sediments is increased with the depth of sediments, which has a strong positive correlation with the vitrinite reflectance of the sediments. Therefore, we propose that the ratio of total phthalimides to total maleimides in sediments may be useful as a maturity indicator for the sedimentary organic matter.

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Distinctive plant fragment-concentrated sandstones are found in a turbiditic sequence deposited under deep sea environment in the Miocene Kawabata Formation distributed along the Higashiyama-gawa River, Yubari, central Hokkaido, Japan. We observed microscopically the plant fragments and analyzed terrestrial higher plant biomarkers in the sediments to evaluate sedimentological and hydrodynamic behaviors of plant particles by gravity flow depositional processes. Biomarker compositions such as pristane/phytane and regular sterane ratios indicate a large contribution of terrestrial organic matter, especially woody fragments, in the sandstone layer. The relative abundances of terrestrial higher plant terpenoids (pentacyclic triterpenoids, des-A-triterpenoids and diterpenoids) are high in all parts of the sandstone layer, while long-chain n-alkane concentrations are remarkably higher only at the uppermost part. Also, leaf cuticle fragments are mainly found in the uppermost part. These results suggest that plant leaves are mainly deposited in the uppermost part of the sandstone layer. Thus, it is concluded that the variations in plant fragment types (tissues) deposited are thought to be resulted from various hydrodynamic behavior in gravity flow.

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Sedimentary rocks from the boreholes of MITI Rumoi, Soma-oki, and Nikaho were analyzed for 3-ethyl-4-methylmaleimide (EMMi) and 3,4-dimethylmaleimide (DMMi) by the chromic acid oxidation method. It had been demonstrated that a 3-ethyl-4-methylpyrrole unit in alkylporphyrins (e.g., etioporphyrin) was converted to a 3,4-dimethylpyrrole unit by heating experiments. The ratio of DMMi to EMMi (i.e., demethylation index) had been shown to have a strong positive correlation with the vitrinite reflectance of the Shinjo region sediments. The demethylation indices in the sediments analyzed in this study were increased with the depth of sediments and also proved to have a strong positive correlation with the vitrinite reflectance of the sediments. Therefore, we support that the demethylation index in sediments is useful as a maturity indicator for the sedimentary organic matter.

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Sweet potatoes sometimes sprout the purple color of stems with several small leaves in the house pantry. In the present study, we investigated the trophic hierarchy between a mother sweet potato and its baby sprouts grown without any light in a dark house pantry, based on stable nitrogen isotopic composition (δ¹⁵N,‰ vs. AIR) of glutamic acid and phenylalanine. The isotope data reveal that glutamic acid has a significant ¹⁵N-enrichment (by 6.9‰) from the mother sweet potato to its baby sprout while phenylalanine has a little ¹⁵N-enrichment (by 0.6‰) between them. Interestingly, the isotopic heterogeneity found within the sweet potato is very similar to the isotopic discrimination generally found in the combination between plants and herbivores during grazing food webs (ca. 8.0‰ for glutamic acid and ca. 0.4‰ for phenylalanine). These results suggest that the proteins in the mother sweet potatoes are major resources for not only proteins in their baby sprouts but also growth energy in the sprouting, when they are grown heterotrophically without any light.

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A mixture of 2-hydroxyarchaeol isomers is chemically synthesized from commercially available racemic isophytol. In the gas chromatogram of TMS-derivative of the synthesized material, two peaks of equal intensity are observed, suggesting the occurrence of two stereoisomers at C-3 (hydroxylated carbon in the isoprenoid chain). The ¹³C NMR spectrum of the synthesized material is slightly different from that of 2-hydroxyarchaeol from microbial origin, which is also consistent with the occurrence of two isomers in the former. By contrast, natural 2-hydroxyarchaeol from microbes and sediments is inferred to consist of a single stereoisomer at C-3.

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