Plant Photosynthesis-Irradiance Curve Responses to Pollution Show Non-Competitive Inhibited Michaelis Kinetics

Photosynthesis-irradiance (PI) curves are extensively used in field and laboratory research to evaluate the photon-use efficiency of plants. However, most existing models for PI curves focus on the relationship between the photosynthetic rate (Pn) and photosynthetically active radiation (PAR), and do not take account of the influence of environmental factors on the curve. In the present study, we used a new non-competitive inhibited Michaelis-Menten model (NIMM) to predict the co-variation of Pn, PAR, and the relative pollution index (I). We then evaluated the model with published data and our own experimental data. The results indicate that the Pn of plants decreased with increasing I in the environment and, as predicted, were all fitted well by the NIMM model. Therefore, our model provides a robust basis to evaluate and understand the influence of environmental pollution on plant photosynthesis.     

Mechanism of How Salt-Gradient-Induced Charges Affect the Translocation of DNA Molecules through a Nanopore

Experiments using nanopores demonstrated that a salt gradient enhances the capture rate of DNA and reduces its translocation speed. These two effects can help to enable electrical DNA sequencing with nanopores. Here, we provide a quantitative theoretical evaluation that shows the positive net charges, which accumulate around the pore entrance due to the salt gradient, are responsible for the two observed effects: they reinforce the electric capture field, resulting in promoted molecule capture rate; and they induce cationic electroosmotic flow through the nanopore, thus significantly retarding the motion of the anionic DNA through the nanopore. Our multiphysical simulation results show that, during the polymer trapping stage, the former effect plays the major role, thus resulting in promoted DNA capture rate, while during the nanopore-penetrating stage the latter effect dominates and consequently reduces the DNA translocation speed significantly. Quantitative agreement with experimental results has been reached by further taking nanopore wall surface charges into account.     

Cytological and mapping analysis of a novel male sterile type resulting from spontaneous floral organ homeotic conversion in marigold (<Emphasis Type="Italic">Tagetes erecta</Emphasis> L.)

A male sterile line was isolated in marigold (Tagetes erecta L.) and cytological analysis determined this to be a novel genic male sterility trait (Tems). Through the use of amplified fragment length polymorphisms (AFLPs) and bulked segregant analysis (BSA), tightly linked markers of Tems were identified with a view towards a map-based cloning strategy. It was found that spontaneous homeotic conversion of floral organs was the underlying cause of the male sterility in this marigold line. Thus, petals of male sterile plants resembled sepal-like structures and the stamens were partially converted to styles, although without the full characteristics or function of the true style organs. We have constructed a fine marker-based map for the Tems gene. This is intended to provide a tool for marker assisted selection (MAS) strategies in hybrid breeding and map-based cloning strategies for the male sterility locus. We discuss the significance of this spontaneously derived genic male sterility trait relating to the homeotic conversion of floral organs in marigold.     

大壁虎的染色体及减数分裂联会复合体的研究

大壁虎(Gekko gecko)的染色体数目为2n=38,核型由2对中着丝粒(Nos.1.4.)、3对亚中着丝粒(Nos.2.3.5)及14对端着丝粒和亚端着丝粒(Nos.6—19)染色体组成。一对核仁组织者(NOR_s),位于第7对端着丝粒染色体的末端。同时,本文还对大壁虎的减数分裂以及联会复合体(S.C)的结构和组型,进行了详细的观察和分析。     

松辽盆地阿尔必期微体浮游植物新属种

该文描述了松辽盆地中白垩世阿尔必期泉头组三段的微体浮游植物化石1新属7新种,隶属于微咸水沟鞭藻类2属5新种(含4新亚种),淡水绿藻1属1种和疑源类1新属1新种。并对沟鞭藻 Ngktericysta Bint,1986进行了修订。     

大果木姜子的甘油三酯组成

采用光谱法和胰酯酶分解法对大果木姜子油酯中分得的结晶C—I组成进行了分析,结果表明C—I是由11种甘油三酯组成。其中2-位为月硅酸的甘油三酯占91.80％,1,3-位脂肪酸主要为癸酸和月桂酸,甘油三酯的组成中,CLC占62.24％,LLC占24.50％。     

模拟酸雨对主要酸性土壤中铝的溶出及形态的影响

本文研究了模拟酸雨对主要酸性土壤中铝的溶出及形态变化的影响。结果表明,模拟酸雨对土壤酸化的影响较小,但对土壤铝的溶出却影响明显,尤其在pH<4.0时;模拟酸雨对不同类型土壤的影响是不同的,其中以高度风化的酸性土壤较为敏感。模拟酸雨对土壤游离铝形态的影响是重要的,酸处理后,交换性铝略有增加,无定形活性铝增加较多,而有机络合态铝有减少的趋势。这表明在酸雨的长期作用下,铝终将转化为交换性铝和水溶性铝而进入环境并危害生态系统。