The most severe mass extinction in Earth's history occurred at the end of Permian Period, and recovery from this mass extinction extended until the subsequent Early Triassic. Organic geochemical works from many studies of shallow water platform sedimentary strata have indicated that increases in green sulphur bacterial and cyanobacterial biomasses as well as terrigenous organic material occurred in end-Permian to earliest Triassic shallow-marine environments. Additionally, recent studies on pelagic deep sea sedimentary rocks in accretionary complexes of Japan have increased understanding of the low latitudinal Panthalassic record through the Late Permian and into the Early Triassic. Correlations of conodont fossil occurrences and stable carbon isotope compositions of organic matter in the continuous deep-sea Permian-Triassic boundary section indicate that the mass extinction horizon is located at the onset of black claystone above microfossil-rich siliceous claystone beds. Although this black claystone bed suggests oxygen-poor conditions, bacterial blooms and terrigenous inputs in the pelagic region were not especially significant based on the detected smooth organic carbon isotope curve, which does not include any isotopically heavier signals. Subsequent recovery of radiolarian chert deposition occurred at the late Early Triassic-early Middle Triassic transition. Organic molecules have been detected from these strata. Considering their producing processes in the pelagic deep sea, highly concentrated dibenzothiophene in the latest Early Triassic black chert indicate sulfur-rich depositional conditions. Also, high concentrations of polycyclic aromatic hydrocarbons (PAHs) suggests a high flux of marine organic matter during the latest Early Triassic. As these occurrences coexist with changes in perhaps bacterial community and decreases in radiolarian fossil diversity, this event may be related to the delay in the recovery of life and environments after the end-Permian mass extinction.

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Coals and coaly shales from the Permian Gondwana sequence in the Barapukuria Basin (core GDH-40) of Bangladesh were investigated to determine the influence of rock type and organic source on methylphenanthrene (MP) maturity parameters such as methylphenanthrene ratio (MPR) and methylphenanthrene index 3 (MPI 3). The T_max (℃) depth profile of the coals is almost constant, and the T_max values (430-440 ℃) correspond to about 0.6-0.7% vitrinite reflectance, which suggests the early stage of oil generation. In the constant maturation stage, the MPR and MPI 3 values of coals are clearly different from those of coaly shales. The 9-MP/1-MP and 9-MP/2-MP ratios of the coals are higher than those of the coaly shales because the activated methylation preferentially leads to 9-MP in coals during the early stage of oil generation. Also, these ratios increase in the coals rather than coaly shales attributed to selective biodegradation of the MP and conifer-rich sources. A negative correlation observed between 9-MP and 2-MP compositions indicates methylation effect and/or change in organic source input into the paleomire. The 1,7-dimethylphenanthrene (DMP) isomer, gymnosperm-derived pimanthrene, is more abundant in the coals than the coaly shales. The relative abundances of the 1,7-DMP in the coals tend to be higher in middle part of the drill core, and decrease with depths. Anthracene (A) and methylanthracene (MA) also tend to be more abundant in the coals. The abundance of 1,7-DMP, A and MA in the coals may be related to Gondwana coals characterized by the predominance of coniferous gymnosperms.

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The green sulfur bacteria (GSB) are obligately anaerobic photosynthetic bacteria found in photic zone under euxinic condition with the presence of hydrogen sulfide. Photosynthetic pigments indigenous to GSB are bacteriochlorophylls c, d, and e. The most significant structural difference from chlorophylls a and b and from bacteriochlorophylls a and b is the side-chain alcohol other than phytol, primarily composed of farnesol. Hence the detection of farnesol in sediments, for example, implies that the sediments were deposited under the regime of photic zone anoxia. In the present study, alcohols were analyzed by GC and GC/MS for sediment core samples collected from six meromictic brackish water lakes with the different salinities. A strong positive linear correlation with a regression through the origin was observed among farnesol, and n-C_14:0, n-C_15:0, and n-C_16:1 alcohols for individual lake sediments. These results suggest that farnesol and those aliphatic alcohols in the sediments are commonly originated from GSB or their bacteriochlorophylls. Moreover, except for one case, the abundance ratio of farnesol: n-C_16:1 was large (16-17:1) in highly saline but small (8-11:1) in lower saline lake sediments. Hence a tentative hypothesis is proposed that the farnesol/n-C_16:1 ratio may employed as a potential proxy reflecting the salinity of the anoxic bottom water in meromictic brackish water lakes.

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The type II kerogen from the Miocene Onnagawa Formation Shale was analyzed by pyrolysis and thermochemolysis with tetramethylammonium hydroxide (TMAH) and trimethylsulfonium hydroxide (TMSH) under various thermal conditions. The results were compared with that by alkali hydrolysis. The n-alkanes and n-alkenes in products by pyrolysis and thermochemolysis might be generated from alkyl moieties in geomacromolecule by thermal cracking of C-C bonds. The n-alkanoic acids (as fatty acid methyl esters; FAMEs) were mainly detected in the compounds released from the kerogen by thermochemolysis, indicating that they have been preserved through polymerization of marine plankton-derived compounds. Noticeably, the short chain (<C₁₁) FAMEs were abundant in products by thermochemolysis, while those were hardly detected in hydrolysates. These short chain n-alkanoic acids might be mainly occluded in intra-aggregates within the geomacromolecule. In addition, the C₇ and C₉ FAMEs predominated in products by TMSH-using thermochemolysis, although the C₇ FAME was minor in TMAH method. It was suggested that the trapped and occluded compounds like C₇ and C₉ acids were more efficiently released from kerogen by TMSH thermochemolysis. On the other hand, total FAME/n-alkane ratios in the products by TMAH thermochemolysis were significantly higher than those by TMSH method. These results suggest that total recovery of the FAME released from kerogen by thermochemolysis can be lower in the presences of TMSH than TMAH.

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Kerogens from weathered and unweathered coals and coaly shales from Myanmar have been characterized based on Rock-Eval pyrolysis, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), CNS elemental composition, and Fourier transform infrared (FT-IR) spectroscopy. Three moderately weathered coaly shales and five unweathered coals/coaly shales were collected from relatively thin carbonaceous layers (15-150 cm) in the Upper Eocene sediments in the western margin of the Central Myanmar Basin. Although organic maturities are similar for all samples (T_max417-426℃; immature), kerogens from the weathered samples exhibit low Hydrogen Index (HI, 29-42 mgHC/gTOC) and high Oxygen Index (0I, 96-168 mgCO₂/gTOC), whereas those from unweathered samples have higher HI (86-250 mgHC/gTOC) and lower OI (25-115 mgCO₂/gTOC), respectively. Kerogens with high S₃ (pyrolysed at 300-400℃) by Rock-Eval also had high S₃' (pyrolysed at 400-650℃), and show strong correlation. The ratio of S₃' to S₃ is higher in the weathered samples, suggesting an increase in S₃' or a decrease in S₃ values. Py-GC-MS pyrolysates from the weathered kerogens showed that lighter n-alkanes/alkenes less than n-C₁₀ and methyl/dimethyl phenols are decreased. FT-IR analysis of the weathered kerogen showed lower peaks of aliphatic bonding at 2925-2850 cm^-1, and relatively constant peaks of C=0 and C-0 bonds at 1716 cm^-1 and 1000-1300 cm^-1, respectively. These trends in the FT-IR were more apparent in the bitumen samples. These results suggested that rapid decomposition of alkyl chain moieties in kerogen by weathering faster than that of organic oxygen group had caused an increase in OI.

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Organisms have complex metabolic networks, and their fluxes could be sensitive depending on various physiological and environmental conditions. As one of these factors, reproduction (e.g., egg production) is a common and essential process to create new individuals. However, little is known about the effect of reproduction in metabolic fluxes of organisms. In this study, we cultured the calanoid copepod Acartia steueri, and measured the stable nitrogen isotopic composition (δ¹⁵N) of amino acids in adult males and females and their eggs in order to demonstrate the effect of reproduction in amino acid metabolic fluxes of this species. The δ¹⁵N values of glutamic acid and phenylalanine and the estimated trophic position were 6.3‰, -2.6‰ and 1.73 for male adults; 7.0‰, -2.6‰ and 1.78 for female adults; and 7.3‰, -2.3‰ and 1.82 for eggs, respectively. These results demonstrate no substantial change in the isotopic signature of amino acids among the examined samples, implying that the balance in the amino acid metabolism between assimilation (i.e., absorbing input and biomass construction) and dissimilation (i.e., amino acid deamination) may not change with egg production in this copepod.

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We examined stable hydrogen (δD, ‰ relative to V-SMOW) and carbon isotopic compositions (δ¹³C, ‰ relative to V-PDB) of fatty acids extracted from beef, and compared them with those from feeds (mixtures of plant materials) for the cattle. The δD value of stearic acid in beef is similar to that in the feeds, whereas the palmitic and oleic acids in beef are both significantly depleted in D (by ca. 60‰) as compared with the corresponding acids in the feeds. On the other hand, these fatty acids in beef are enriched in ¹³C (by up to 5.7‰) relative to the corresponding acids in the feeds. Thus, the isotopic compositions of fatty acids in beef are not identical to those in the feeds. These results suggest that fatty acids in beef are an admixture of fatty acids derived from de novo biosynthesis in the cattle and from the feeds, and may imply that a considerable D-depletion process (e.g., hydrogenation of feed-derived fatty acids and/or dehydrogenation-hydrogenation cycling) occur in the fatty acids of the cattle.

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