中度嗜盐菌Martelella sp. AD-3 降解菲过程中水杨酸-5-羟化酶的酶学性质

[目的]研究中度嗜盐菌Martelella sp.AD-3在降解菲过程中水杨酸-5-羟化酶的活性与菲降解效率的关系及其酶学性质.[方法]通过HPLC分析菲的降解效率和AD-3菌粗酶液催化水杨酸的产物,根据NADH在340 nm处的吸光度变化计算水杨酸-5-羟化酶的活性.[结果]水杨酸-5-羟化酶是一种诱导酶,在AD-3菌的对数生长期和稳定初期时活性较高,酶活力大小与该菌对菲的降解速率基本一致.在菲浓度为200 mg/L、生长盐度为3％、pH为9.0的培养条件下,AD-3菌株表达的水杨酸-5-羟化酶的活力最高,为132.8 nmol/(min·mg).水杨酸-5-羟化酶催化水杨酸降解时的最适温度、pH和盐度分别为30℃、7.5和3％,酶的最大反应速率为200 nmol/(min· mg)、米氏常数Km为8.7μmol/L.[结论]AD-3菌在降解菲的过程中表达水杨酸-5-羟化酶,该酶的活性与菲降解速率具有相关性.     

Working Memory Cells' Behavior May Be Explained by Cross-Regional Networks with Synaptic Facilitation

Neurons in the cortex exhibit a number of patterns that correlate with working memory. Specifically, averaged across trials of working memory tasks, neurons exhibit different firing rate patterns during the delay of those tasks. These patterns include: 1) persistent fixed-frequency elevated rates above baseline, 2) elevated rates that decay throughout the tasks memory period, 3) rates that accelerate throughout the delay, and 4) patterns of inhibited firing (below baseline) analogous to each of the preceding excitatory patterns. Persistent elevated rate patterns are believed to be the neural correlate of working memory retention and preparation for execution of behavioral/motor responses as required in working memory tasks. Models have proposed that such activity corresponds to stable attractors in cortical neural networks with fixed synaptic weights. However, the variability in patterned behavior and the firing statistics of real neurons across the entire range of those behaviors across and within trials of working memory tasks are typical not reproduced. Here we examine the effect of dynamic synapses and network architectures with multiple cortical areas on the states and dynamics of working memory networks. The analysis indicates that the multiple pattern types exhibited by cells in working memory networks are inherent in networks with dynamic synapses, and that the variability and firing statistics in such networks with distributed architectures agree with that observed in the cortex.     

Ancient genomes reveal the genetic inheritance and recent introgression in Chinese indigenous pigs

Science China Life Sciences -     

野山参叶、园参叶和西洋参叶中氨基酸含量

报道了野山参叶中氨基酸的含量并与园参叶、国产西洋参中氨基酸含量进行了对比分析。     

新疆喀什下坂地墓地青铜时代人群颅骨的测量性状

下坂地墓地青铜时代居民是帕米尔高原区早期人群的代表。通过颅骨测量性状特征对该人群来源和流向问题的讨论,为建立欧亚大陆青铜时代人群的流动、变迁史提供了新的素材。与欧亚大陆青铜时代时空相关人群对比分析的结果表明,下坂地青铜组居民的祖先人群,可能是来自东欧南部草原地带的洞室墓文化居民。他们在安德罗诺沃文化的繁盛期,自东欧草原地带迁徙到帕米尔高原区,逐渐发展为安德罗诺沃文化的一个地方变体。     

Effects of glucose and phenol on soluble microbial products (SMP) in sequencing batch reactor systems

Soluble microbial products (SMP) are ubiquitously present in the effluents of biological wastewater treatment systems. In sequencing batch reactor (SBR) systems, effects of influent concentration and temperature on the amount and the molecular weight (MW) distribution of SMP were investigated for the two substrates, glucose and phenol. The values of effluent SMP/S₀ of phenol were higher than those of glucose at different influent concentrations and temperatures. It was found that the effluent SMP (S_e) was linearly correlated to the influent total organic carbon (TOC) (S₀) for both substrates. The slope and intercept of the equation were affected by the temperature. According to the analysis of the MW distribution, it was shown that there exists a bimodal pattern with the majority of SMP having a MW<1 kDa or >10 kDa. The low MW fraction (<1 kDa) amounts to 47.3–70.4% of the effluent SMP. The high MW fraction (>10 kDa) slightly fluctuates in the range of 21.2–32.8% of the effluent SMP.     

In situ bioremediation of petroleum hydrocarbon–contaminated soil: isolation and application of a Rhodococcus strain

International Microbiology - Due to low consumption and high efficiency, in situ microbial remediation of petroleum hydrocarbons (PHs)-contaminated sites in in-service petrochemical enterprises has...     

微生物净化电镀铬废水的研究

用厌氧技术从电镀铬淤泥中分离出SRⅠ高效菌株。对SRⅠ菌净化电镀铬废水的研究表明,电镀废水中的Zn~(2+)、UO_2~(2-)和Sr~(2+)对SRⅠ菌净化铬有促进作用,Ag~-、CA~(2+)和SiF_6~(2-)对其有抑制作用,SO_4~(2-)、CO_3~(2-)和Cl~-无影响。在铬(Ⅵ)浓度5—600μg·ml~(-1)、pH6—7,20—30℃,SRⅠ菌对铬(Ⅵ)的净化率达99.6％。