毛喉鞘蕊花的化学成分研究

本文报导了,从产于滇东北的毛喉鞘蕊花(Coleus forskohlii Brig)的根茎中分离到四个二萜化合物,经光谱分析鉴定,其结构分别为1α,6β,7α-triacetyl-coleonol—B(1),I-acetyl—forskolin(2),coleonol-B(3),和deacetyl-forskolin(4)。化合物(1)和(2)是首次从该植物中分离到。     

Stabilization of a HemA-LacZ hybrid protein against proteolysis during carbon starvation in atp mutants of Salmonella typhimurium.

Transposon insertions that stabilize the beta-galactosidase activity of a HemA-LacZ hybrid protein following carbon starvation were mapped to the atp operon of Salmonella typhimurium. This effect is similar to that seen with nuo mutants defective in the energy-conserving type I NADH dehydrogenase. Insertions in several other genes, including such highly pleiotropic mutants as rpoS, polA, and hfq, were isolated with the same phenotypic screen, but they do not affect the beta-galactosidase activity of HemA-LacZ. All of these mutants act indirectly to alter the colony color of many different fusion strains on indicator plates.     

A Bacillus subtilis malate dehydrogenase gene.

A Bacillus subtilis gene for malate dehydrogenase (citH) was found downstream of genes for citrate synthase and isocitrate dehydrogenase. Disruption of citH caused partial auxotrophy for aspartate and a requirement for aspartate during sporulation. In the absence of aspartate, citH mutant cells were blocked at a late stage of spore formation.     

Cellobiose-oxidizing enzyme from a newly isolated cellulolytic bacterium Cytophaga sp. LX-7

Summary The cellobiose oxidizing enzyme of the newly isolated cellulolytic bacterium Cytophaga sp. LX-7 was produced extracellularly when grown on cellulose or other saccharides, which was previously noted only in fungi. The enzyme could use not only cellobiose, maltose, glucose and other saccharides but also cellulose as substrates, and use dichlorophenol indophenol and oxygen as electron acceptors.     

Comparative study of nickel toxicity to growth and photosynthesis in nickel-resistant and -sensitive strains of Scenedesmus acutus f. alternans (Chlorophyceae)

Nickel (Ni) toxicity to growth and photosynthesis was studied in four strains of Scenedesmus acutus f. alternans. Effects of Ni dosage and duration of exposure on growth and photosynthesis were strain specific. Large differences in responses of both growth and photosynthesis to Ni were detected between three resistant strains (B4, Cu-Tol, and Ni-Tol) and one sensitive strain (UTEX 72). Growth of UTEX 72 was 18 times more sensitive to Ni than those of the three resistant strains. The order of Ni dosages (fmol Ni/pg cell dry weight) causing 50% inhibition (D₁₅₀) of growth rates in the four strains was Ni-Tol (10.5) > B4 (8.19) > Cu-Tol (4.60) > UTEX 72 (0.25). The effect of Ni dosage on photosynthetic rate as percentage of control corresponded to a saturation curve and was a strong function of duration of exposure. The DI₅₀s of photosynthetic rates were 3.5 times lower in UTEX 72 than in the three resistant strains, and in all four strains they decreased sharply with the increase in duration of exposure. The order of the four strains in DI₅₀s of photosynthetic rate was B4 (58.2) > Cu-Tol (38.0) > Ni-Tol (28.9) > UTEX 72 (8.24) for 6-h exposure and Ni-Tol (2.88) > Cu-Tol (1.30) > B4 (1.01) > UTEX 72 (0.15) for 24-h exposure. The DI₅₀s of photosynthetic rate for 6-h exposure were higher than those of growth rate in all four strains, and for 24-h exposure they were lower, except in UTEX 72. Thus, the relative Ni sensitivity of growth and photosynthesis of the four strains depends on the duration of exposure. The results of factorial analysis of variance suggested that Ni toxicity to photosynthesis is a consequence of a strong interaction among strain, Ni dosage, and duration of exposure.     

生物复苏——大绝灭后生物演化历史的第一幕

生命史是一部生物界短期,快速剧变与长期,慢速稳定相互交替的历史。大绝灭（即集群绝灭）事件反映了全球环境的大突变,点断了地质历史中的生命记录及其发展历程,预示着生物界的演化出现了最有意义的飞跃,近年来尝试研究大绝灭后全球生物界的残存－复苏及其基本型式,并探索复苏的控制因素,标志着地质科学中一个重心的转移（即从大绝灭转向其后的生物残存与复苏的研究）。生物复苏揭示了大绝灭后生物演化历史的第一幕,其研究的     

向日葵幼苗环旋运动的三维轨迹

采用光学显微镜标尺和垂线原理制作的三维空间点测定仪,对向日葵（Ｈｅｌｉａｎｔｈｕｓ ａｎｎｕｕｓＬ．）幼苗的环旋运动进行了连续测量。结果表明：向日葵环旋运动的轨迹有椭圆型、摆动型和不规则型;同一植株在不同生长阶段所表现的环旋运动轨迹不一定相同,同一株龄的不同个体也不一定具有相同的运动轨迹;运动的方向有左旋和右旋,圆周运动光源可以显著地改变运动方向;从三维角度看,在整个下胚轴生长阶段,环旋运动的振幅存在一个由小变大再由大变小的变化规律     

生态环境对川芎产、质量的影响

生态环境对川芎产、质量的影响丁德蓉,陈兴福,卢进,黄文秀,刘岁荣（四川省中医药研究院药物种植研究所,南川６４８４０８）ＩｎｆｌｕｅｎｃｅｏｆＥｃｏｅｎｖｉｒｏｎｍｅｎｔｏｎｔｈｅＹｉｅｌｄａｎｄＱｕａｌｉｔｙｏｆＬｉｇｕｓｔｉｃｕｍｃｈｕａｎｘｉｏｎ...     

磁水对蕃茄酯酶同工酶的影响

蕃茄（ＬｙｃｏｐｅｒｓｉｃｏｍｅｓｃｕｌｅｎｔｕｍＭｉｌｌ）在各生长发育期酯酶同工酶谱带无明显变化,但经磁水处理后各生长发育阶段功能叶中酯酶同工酶酶谱及磷素含量与对照组相比存在显著差异,且具有酶谱负极端带数增加,正极端带数减少的趋势。总磷含量测定结果表明处理组均比对照组显著提高。这些变化在磁水处理著前后代中不存在,故认为磁水只是致使非编码顺序局部复制引起ＤＮＡ分子高级结构改变或是通过活化调节基因来调控酯酶同工酶,活化磷代谢,达到促进生长和增产的效果,而并非导致可遗传变异的结果。