VEGETATION CHANGES OF THE TAIHANG MOUNTAINS SINCE THE LAST GLACIAL

The vegetation of the Taihang Mountains was dominated by grass with less than 10％ forested area during the last pleniglacial. During the period of 17 000－ 10 000 a B.P. the forested area reached to 20％ － 30％ , and reached to 20％ － 40％ during the Early Holocene in the period of 10 000－ 8 000 a B.P. followed by the temperature increasing rapidly. But the northern part had more forested area than that of the southern part. During the period of 8000－ 5000 a B.P. forests developed further to 50％ or more. It was the highest period of the forest cover degree. After then, the forests began to be destroyed first in the southern part of the Taihang Mountains by people. Since 2500 a B.P. the forests were destroyed deadly. The forest cover decreased to less than 5％ before 1949. Since 1949 , although the government hold the policy of close hillsides to facilitate afforestation, the forest cover of Taihang Mountains could not exceed 11.6％ . So afforestation is an important work to keep economic and ecological sustainable development.

The Chromosome-Level Reference Genome of Tea Tree Unveils Recent Bursts of Nonautonomous LTR Retrotransposons in Driving Genome Size Evolution

Dear Editor,The tea tree Camellia sinensis,a member of the genus Camellia in the Theaceae family,includes two major cultivated varieties,C.sinensis var.assamica(CSA\Assam type)and C.sinensis var.sinensis(CSS;Chinese type)(Ming and Bartholomew,2007).Due to the high economic importance of the tea tree,considerable efforts have been made to explore genetic basis of the biosynthesis of natural metabolites that determine health benefits and diverse tea flavors(Shi et al.,2011;Li et al.,2011;Li et al.,2015;Xia et aL,2017;Liu et al.,2019).

Kinetic analysis of γ-glutamyltransferase reaction process for measuring activity via an integration strategy at low concentrations of γ-glutamyl p-nitroaniline

At 0.12 mmol/L γ-glutamyl p-nitroaniline(GGPNA),an improved integrated method was developed for kinetic analysis of γ-glutamyltransferase(GGT) reaction process and the integration with the classical initial rate method to measure serum GGT.For the improved integrated method,an integrated rate equation,which used the predictor variable of reaction time and considered inhibitions by both GGPNA and products,was nonlinearly fit to GGT reaction processes.For the integration strategy,classical initial rates were estimated when GGPNA consumption percentages were below 50%;otherwise,maximal reaction rates of GGT were estimated by the improved integrated method and converted into initial rates according to the differential rate equation at 0.11 mmol/L GGPNA.The inte-gration strategy was validated using optimized GGT kinetic parameters and 10-s intervals to record reaction curves within 8.0 min.By the integration strategy,there was a linear response from 0.9 to 32.0 U/L GGT,coefficients of variation were below 3.5%for GGT from 8.0 to 32.0 U/L(n=5) ,and GGT activities in clinical sera responded linearly to their classical initial rates at 2.00 mmol/L GGPNA with an expected slope.Therefore,the integration strategy was successful in measuring GGT at 0.12 mmol/L GGPNA.