Explore the vast range of titles available.

定量分析了赤道中、东太平洋MP2001-01和ES0103沉积岩样中有机碳、可溶有机质(氯仿抽提物)及其族组成(总烃、饱和烃、芳烃、非烃、沥青质)、生物标志物(正构烷烃、类异戊二烯、萜类化合物),在对两站区沉积岩样低熟烃的认定基础上,进行物源和源性的地球化学对比,研究它们的共性与差异性。研究发现,无论是在含量、族组成、演化程度、物质来源、沉积环境以及受控因子等方面都有明显的区别,这些差异主要是环境因素造成。两站柱样分别位于太平洋中心开阔深海盆地,它们之间被莱恩火山链隔开,它们的地理位置不同,两站区物质来源和沉积环境(氧化或还原)具有明显的差异,而南极底层流的影响是两站区低成熟烃组成特征、演化程度的主要环境受控因子。

The protein prenylation is one of the essential post-translational protein modifications, which extensively exists in the eukaryocyte. It includes protein farnesylation and geranylgeranylation, using farnesyl pyrophosphate （FPP） or geranylgeranyl pyrophosphate （GGPP） as the substrate, respectively. The prenylation occurs by covalent addition of these two types of isoprenoids to cysteine residues at or near the carboxyl terminus of the proteins that possess CaaX motif, such as Ras small GTPase family. The attachment of hydrophobic prenyl groups can anchor the proteins to intracellular membranes and trigger downstream cell signaling pathway. Geranylgeranyl biphosphate synthase （GGPPS） catalyzes the synthesis of 20-carbon GGPP from 15-carbon FPP. The abnormal expression of this enzyme will affect the relative content of FPP and GGPP, and thus disrupts the balance between protein farnesylation and geranylgeranylation, which participates into various aspects of cellular physiology and pathology. In this paper, we mainly review the property of this important protein post-translational modification and research progress in its regulation of cigarette smoke induced pulmonary disease, adipocyte insulin sensitivity, the inflammation response of Sertoli cells, the hepatic lipogenesis and the cardiac hypertrophy.

To determine geochemical indicators for depositional environment favored by terrestrial petroleum source rocks, we selected 40 source rock samples from the Late Cretaceous Qingshankou Formation （Kzqn） and the first member of Nenjiang Formation （K2n1） in the Songliao Basin to qualify saturate fraction and aromatic fraction using GC-HRT （gas chromatography high resolution time-of-flight mass spectrometry） and quantify important biomarkers using GC-MS. The results reveal that source rocks from the 1st member of Qingshankou Formation （K2qn1） are characterized by not only high contents of terpanes, regular steranes and 4-methylsteranes but also high contents of dinosteranes, C31 steranes and aryl isoprenoids. Presence of specific biomarkers like elementary sulfur and lanostanes indicates a depositional environment of lagoon characterized by water stratification and high salinity. In the 2nd-3rd members of Qingshankou Formation （K2qn2＋3）, source rocks contain lower contents of biomarkers, indicating a depositional environment of shallow fresh-water lake delta. Source rocks in the K2n1 contain high contents of terpanes, regular steranes and 4-methylsteranes but lower contents of dinosteranes, C31 steranes and aryl isoprenoids, indicating a depositional environment of fresh-brackish open lake characterized by low salinity and poor water stratification, where organic matter is seriously altered by bacteria. Overall analysis shows that primary geochemical indicators for terrestrial petroleum source rocks are as follows： 1） C30 hopanes 〉 1500 ppm; 2） gammacerane 〉190 ppm; 3） C27 steranes 〉200 ppm; 4） 4-methylsteranes 〉 100 ppm; 5） aryl isoprenoids 〉 3 ppm; 6） dehydroxyl-vitamin E 〉 10 ppm.

Catharanthus roseus is one of the most extensively investigated medicinal plants, which can produce more than 130 alkaloids, including the powerful antitumor drugs vinblastine and vincristine. Here we review the recent advances in the biosynthetic pathway of terpenoid indole alkaloids （TIAs） in C. roseus, and the identification and characterization of the corresponding enzymes involved in this pathway. Strictosidine is the central intermediate in the biosynthesis of different TIAs, which is formed by the condensation of secologanin and tryptamine. Secologanin is derived from terpenoid （isoprenoid） biosynthetic pathway, while tryptamine is derived from indole biosynthetic pathway. Then various specific end products are produced by different routes during downstream process. Although many genes and corresponding enzymes have been characterized in this pathway, our knowledge on the whole TIA biosynthetic pathway still remains largely unknown up to date. Full elucidation of TIA biosynthetic pathway is an important prerequisite to understand the regulation of the TIA biosynthesis in the medicinal plant and to produce valuable TIAs by synthetic biological technology.

We reconstruct the environmental evolution of the East China Sea in the past 14 kyr based on glycerol dialkyl glycerol tetraethers（GDGTs） in a sediment core from the subaqueous Yangtze River Delta. Two primary phases are recognized. Phase I（13.8–8 cal kyr BP） reflects a predominantly continental influence, showing distinctly higher concentrations of branched GDGTs（averaged 143 ng/g dry sediment weight, dsw） than isoprenoid GDGTs（averaged 36 ng/g dsw）, high BIT index（branched vs. isoprenoid tetraethers） values（〉0.78） and a fluctuating GDGT-0/crenarchaeol ratio（R_（0/5）, varied from 0.52 to 3.81）. Within this interval, temporal increases of terrestrial and marine influence are attributed to Younger Dryas（YD）（ca. 12.9–12.2 cal kyr BP） cold event and melt-water pulse（MWP）-1B（11.5–11.1 cal kyr BP）, respectively. The prominent transition from 8 to 7.9 cal kyr BP shows a sharp decrease in BIT index value（〈0.4） and increase in crenarchaeol, which marks the beginning of phase II. Afterwards, the proxies remain relatively constant, which indicates that phase II（7.9 cal kyr BP-present） is a shelf sedimentary environment with high stand of sea level. Overall, the BIT index in our record serves as a good marker for terrestrial influence at the site, and likely reflects the flooding history of the region. The TEX_（86）（Tetra Ether Index of tetraethers consisting of 86 carbons） proxy is not applicable in phase I because of an excess terrestrial influence; but it seems to be valid for revealing the annual SST in phase II（21.6±0.9°C, n=49）. In contrast, the MBT＇/CBT（Methylation of Branched Tetraethers and Cyclization of Branched Tetraethers） proxy appears to faithfully record the annual mean air temperature（MAT）（14.3±0.63°C, n=68） and presents an integrated signal over the middle and lower Yangtze River drainage basin.

We investigated the occurrence and distribution of terrestrial-derived hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers（OH-GDGTs） in the Han River system and their potential impact on the application of the ring index of OH-GDGTs（RI-OH） as a sea surface temperature（SST） proxy in the eastern Yellow Sea. Thereby, we analyzed various samples collected along the Han River and from its surrounding areas（South Korea, n = 34）. The OHGDGTs were found in all samples investigated. OH-GDGT-0 was the dominant OH-GDGT component in the estuary and marine samples while OH-GDGT-2 was generally dominant in the soils, the lake sediments and the river suspended particulate matter（SPM）. Our results thus suggests a possible warm bias of the RI-OH-derived summer SSTs in the coastal zone to which a large amount of terrestrial organic matter is being supplied. Further studies are necessary to better assess the applicability of the RI-OH proxy in the eastern Yellow Sea.

Branched and Isoprenoid Tetraether（BIT） index was considered as a proxy for terrestrial organic matter input in lake sediments, based on the assumption that branched glycerol dialkyl glycerol tetraethers（b GDGTs） are mainly derived from terrestrial soils. However, mounting evidences have showed that the in situ production of b GDGTs is widespread in lakes, challenging BIT as a reliable terrestrial input proxy. Recently, BIT has been proven to be a reliable proxy for paleohydrology in a small crater lake（Lake Challa） in accordance with a different mechanism. However, the response of BIT to paleohydrology variation may differ for different lakes. In this study, we investigate the variations in the BIT index and the concentrations of its related GDGTs in a 12-ka sediment core from Lake Qinghai, in combination with our previous results for surface sediments. We find that variations in BIT strongly depend on the concentration of crenarchaeol in both surface and ancient sediments of this lake, whereas b GDGT concentration varies much less remarkably. Considering that crenarchaeol production is positively correlated with water depth in Lake Qinghai, water depth may exert negative control on the BIT index in this lake. This case is inconsistent with the positive relationship between BIT and lake levels or rainfall intensity reported for Lake Challa, suggesting that the response of BIT to local paleohydrology is site specific in lacustrine systems. Hence, the application of sedimentary BIT as a paleohydrological proxy in a specific lake requires caution before confirming the environmental controls on BIT in that lake.