Aliphatic hydrocarbons were analyzed in 3 species (Cladonia vulcani, Cladonia scabriuscula, and Xanthoria sp.) of lichens collected from Hokkaido and Hyogo Prefectures, Japan. Molecular composition of n-alkanes is likely influenced by precipitation, as the long chain n-alkanes are produced under arid environments. Alkenes such as heptadecene are also detected as major components in these samples. Molecular composition of these alkanes is different between the genus Xanthoria and Cladonia, suggesting that the composition is influenced by taxonomic diversity. Molecular composition of the aliphatic hydrocarbons other than n-alkanes and alkenes detected are far different between the genera Xanthoria and Cladonia, but are almost similar in these 2 species of the genus Cladonia, potentially depending on taxonomy at the genus level. From these results, we predict that the alkenes, as well as other aliphatic hydrocarbons, can be useful as a chemotaxonomic marker, while the composition of n-alkanes can be an environmental indicator.
Nitrogen isotope ratios of amino acids have been widely used to estimate the trophic position of organisms in ecological food webs. However, un-explainable compression/expansion of the trophic discrimination factor (TDF) has been reported in diverse consumer species. In particular, significant compression has been reported in herbivorous gastropods and bivalves, resulting in the estimated trophic position of them is lower than 2.0. In the present study, we report three diverse TDF for the gastropods Turbo sazae (7.5 ± 0.5‰), Haliotis discus (5.3 ± 1.0‰), and Lyncina vitellus (3.0 ± 0.7‰), as TDF found in H. discus and L. vitellus is considerably smaller than that generally found in many species (7.6 ± 1.3‰). The compression of TDF, however, well corresponds to the amount of proteinous mucus released from these species, implying that a part of the metabolic flux of amino acids is used for the production of proteinous mucus. Therefore, we suggest that understanding of TDF for consumer species with respect to ‘balance of metabolic flux’ between deamination of amino acids (i.e., energy production) and construction of own proteins including additional proteinous materials is required, to enhance accuracy in the application of nitrogen isotope ratios of amino acids to the food web studies.
Ester-bound compounds (compounds released by saponification) from the resistant macromolecules (RMMs) were analyzed in the extant and Pliocene fossil Liquidambar fruit from the Tokai Group distributed in Gifu Prefecture, central Japan. We compared the distributions of the ester-bound triterpenoids from the fossil with those of free and ester-bound triterpenoids of the extant fruits. The series of triterpenoid acids such as oleanolic and ursolic acids were identified in free compounds but hardly detected in ester-bound compounds from the extant Liquidambar samples. Most of free triterpenoids identified in the extant Liquidambar were also present in the fossil Liquidambar sample as the ester-bound compounds. These results indicate the occurrence of post-depositional incorporation of the free triterpenoids into the macromolecules such as the RMMs via ester bonds. Thus, it is suggested that the ester-bound triterpenoids in RMMs serve as excellent archives of the indigenous assemblage of triterpenoids. The class distributions of the oleanoids and ursanoids in the ester-bound compounds from the fossil sample are considerably different from those in the free polar compounds of the extant samples. Selective preservation of C-28 carboxyl group compared to C-3 oxygenated functions indicates that the triterpenoid acids were incorporated into RMM via ester-bound formed between C-28 carboxyl and hydroxyl groups of the RMM. These results indicate that the ester-bound triterpenoid acids obtained from the fossil sample are selectively preserved by incorporation into the RMM of the fruits.