浑善达克沙地高西马格剖面5000年来化石盘星藻及其生态学意义(英文)

为了更好地了解浑善达克沙地5000年以来的古植被、古环境以及古气候的演变,在分析内蒙古浑善达克沙地境内高西马格剖面孢粉的同时发现了大量的具淡水指示意义的盘星藻,它们是短棘盘星藻(Pediastrum boryanum)和钝角盘星藻(P.muticum)。本文对该剖面的盘星藻化石组合进行了详尽的研究。该组合大致可以划分为三个阶段:阶段Ⅰ(约5000～3500 a BP),化石盘星藻零星出现,显示了高西马格湖当时可能为贫含有机质的淡水湖;阶段Ⅱ(3500～1500 a BP),化石盘星藻爆发性地发生,可能表明了该时期潮湿的条件和草原发展的阶段;和阶段Ⅲ(1500～200 a BP),化石盘星藻消失,显示湖水可能碱性化和湖面退缩。代表了一个日趋干旱的环境。这一结果表明,一种指相化石盘星藻在第二阶段化石组合中大量出现,有时甚至达到60％以上,高西马格湖在3500～1500a BP期间水体为富含有机质的淡水且水域面积较大。     

浑善达克沙地高西马格剖面孢粉分析及植被演化的初步探讨

 为了探讨浑善达克沙地5 000年以来的植被演化过程, 我们对内蒙古正蓝旗境内高西马格湖人工挖掘2.0 m深的剖面进行了较高时间分辨率的孢粉分析,并参考孢粉组合与植被之间的对应关系,得出: 该期的植被和气候演化大致可以划分为3个阶段：阶段 I（约5 010～4 040 aBP）,孢粉组合     

浑善达克沙地典型灌木和草本植物对模拟降雨的不同反应

为了探讨不同生活型对瞬时降雨的适应策略,比较了浑善达克沙地常见灌木羊柴(Hedysarum fruticosum Pall.)和其共生草本植物猪毛菜(Salsola callina Y.L. Chang)在降雨解除干旱后的生理生态反应.光合速率(Pn)、蒸腾速率(E)、气孔导度(gs)、PSⅡ最大光化学效率(Fv/Fm)和叶片水势(ψleaf)均随着模拟降雨量的增加而增大;羊柴的水分利用效率(WUE)随降雨量的变化不大,而猪毛菜的WUE却随降雨量的增加一直处于下降趋势.两种植物的Pn和Fv/Fm都在雨后3 d完全恢复,而gs和ψleaf却提前1或2 d恢复,这说明气孔和非气孔因素综合限制了羊柴和猪毛菜的同化速率.两种植物对模拟降雨量的反应方式不同,15 mm的雨量就使羊柴的Pn、E和gs达到最大值,而猪毛菜却随着雨量的增加一直增大.我们认为,羊柴和猪毛菜对于模拟降雨的反应在时间上具有同步性,但对雨量的反应方式却不一致,猪毛菜对水分的利用不经济且瞬时反应,而羊柴可以被认为是节约型用水植物.     

Ligand-based design,synthesis, computational insights,and in vitro studies of novel N-(5-Nitrothiazol-2-yl)-carboxamido derivatives as potent inhibitors of SARS-CoV-2 main protease

The global outbreak of the COVID-19 pandemic provokes scientists to make a prompt development of new effective therapeutic interventions for the battle against SARS-CoV-2. A new series of N-(5-nitrothiazol-2-yl)-carboxamido derivatives were designed and synthesised based on the structural optimisation principle of the SARS-CoV Mpro co-crystallized WR1 inhibitor. Notably, compound 3b achieved the most promising anti-SARS-CoV-2 activity with an IC₅₀ value of 174.7 µg/mL. On the other hand, compounds 3a, 3b, and 3c showed very promising SARS-CoV-2 Mpro inhibitory effects with IC₅₀ values of 4.67, 5.12, and 11.90 µg/mL, respectively. Compound 3b docking score was very promising (−6.94 kcal/mol) and its binding mode was nearly similar to that of WR1. Besides, the molecular dynamics (MD) simulations of compound 3b showed its great stability inside the binding pocket until around 40 ns. Finally, a very promising SAR was concluded to help to design more powerful SARS-CoV-2 Mpro inhibitors shortly.     

Effects of the comutagens, harman and norharman, on the interaction of a tryptophan pyrolysis product, 3-amino-1-methyl-5H-pyrido (4,3-b) indole with DNA.

Harman and norharman, known as comutagens of many chemicals, were tested for their effect on the binding to DNA of 3-amino-1-methyl-5H-pyrido(4,3-b)indole, (Trp-P-2), a potent mutagen found with harman and norharman in the pyrolysate of tryptophan (1). We demonstrated that the alteration of the DNA helix by intercalation of these comutagens to DNA does not affect the affinity of this potent mutagen for DNA. Covalent binding, however, was inhibited by the comutagens.