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Sediments from Tibetan lakes in NW China are potentially sensitive recorders of climate change and its impact on ecosystem function. However, the important plankton members in many Tibetan Lakes do not make and leave microscopically diagnostic features in the sedimentary record. Here we established a taxon-specific molecular approach to specifically identify and quantify sedimentary ancient DNA (sedaDNA) of non-fossilized planktonic organisms preserved in a 5-m sediment core from Kusai Lake spanning the last 3100 years. The reliability of the approach was validated with multiple independent genetic markers. Parallel analyses of the geochemistry of the core and paleo-climate proxies revealed that Monsoon strength-driven changes in nutrient availability, temperature, and salinity as well as orbitally-driven changes in light intensity were all responsible for the observed temporal changes in the abundance of two dominant phytoplankton groups in the lake, Synechococcus (cyanobacteria) and Isochrysis (haptophyte algae). Collectively our data show that global and regional climatic events exhibited a strong influence on the paleoecology of phototrophic plankton in Kusai Lake.

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2,6-Dimethoxyphenol (DMP) as a substrate was widely used in determination of laccase activity. It is surprising, however, that its catalyzed oxidation products have not been completely determined until now. Studies were thus conducted on Rhus laccase (RL) and immobilized Rhus laccase (IRL)-catalyzed oxidation reactions of 2,6-dimethoxyphenol in water-organic solvent systems. These reactions proceeded well in water-(im)miscible organic solvent systems pre-saturated with water. Only one product, 3,3′,5,5′-tetramethoxy-1,1′biphenyl-4,4′-diol (TMBP), was produced by RL catalysis, and it was thoroughly characterized by FT-IR, NMR, GC-MS, etc. A simple enzymatic mechanism of this reaction is proposed.Rhus laccase, laccase-catalyzed oxidation, organic solvent, 2,6-dimethoxyphenol, COLOC Laccases (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductase), part of a large group of enzymes among the multicopper enzymes, widely occur in higher plants and fungi [1][2][3] . Simply based on the function of catalyzing the oxidation of substituted phenols and/or anilines-type substrates through four-electron reduction of O 2 to H 2 O [3][4][5][6][7] , these enzymes constitute a very prospective class of enzymes for physiological development and industrial utility, such as bioremediation, organic catalyzed synthesis, pulp and paper biobleaching, and analytic uses [4,[8][9][10] .Compared with fungal laccases which have been studied thoroughly and extensively [9,[11][12][13] , plant laccases, such as Rhus laccases (RL) which were isolated from the sap of Chinese lacquer tree (Rhus vernicifera) [14] , have only been marginally evaluated [3,[15][16][17] and it is still worthwhile to study the enzymatic activity of RL in various solvents, especially in nonaqueous solvents with the appreciated advantages [18] . This kind of will facilitate the investigation of the reaction mechanisms of phenolic substrates, such as urushiol and dioxins, which are insoluble or poorly soluble in water.2,6-Dimethoxyphenol was widely used as a substrate of laccases catalysis and activity determination in aqueous solution. However, no research on RL catalysis of 2,6-dimethoxyphenol (DMP) in organic solvents was reported. It was surprising that none of its catalyzed products was analyzed and characterized until now except for little insufficient analysis in aqueous solution.In the present study, reactions of DMP in various organic solvents catalyzed by RL and immobilized RL on chitosan (unpublished data) were studied. The products were thoroughly characterized by infrared (IR), nuclear magnetic resonance (NMR) spectroscopy especially correlation spectroscopy (COSY) and correlated spec-