干旱胁迫对小麦幼苗抗氰呼吸和活性氧代谢的影响

研究了干旱胁迫对抗旱性强弱不同的两种小麦幼苗的抗氰呼吸和活性氧代谢的影响。干旱胁迫导致了两种小麦抗氰呼吸活性及基因转录水平的下降,但抗旱品种在轻度干旱胁迫下表现出一定的适应能力,其抗氰呼吸活性及基因转录水平均高于不抗旱品种。干旱胁迫下,对干旱敏感的小麦幼苗叶片中活性氧含量高于抗旱小麦;3种抗氧化酶的活性低于抗旱小麦的3种抗氧化酶的活性。据此认为,严重的干旱胁迫引起活性氧含量的增加扰动了活性氧与抗氰呼吸之间的应答平衡,但抗氰呼吸可能通过清除活性氧等机制而起了抗旱的作用。     

Formation of soluble microbial products (SMP) by activated sludge at various salinities

Soluble microbial products (SMP) present a significant component of effluent organic matter from biological wastewater treatment reactors, and can affect the membrane fouling and formation of disinfection by-products. Thus, SMP have attracted increasing concerns in wastewater treatment and reclamation. In this work, the formation of SMP by activated sludge at various NaCl concentrations is investigated by using fluorescence excitation–emission matrix (EEM) spectroscopy with parallel factor analysis (PARAFAC) and fluorescence regional integration (FRI). The results show that a high level of salinity decreases substrate removal efficiency and leads to an accumulation of SMP, especially proteins. Three components of SMP, one protein-like and two humic-acid-like components, are identified by PARAFAC, which exhibit different trends with the variation of NaCl concentration. FRI analysis reveals that the majority of protein fluorescence is attributed to tryptophan and tryptophan-like proteins, rather than tyrosine and tyrosine-like proteins. With an increase in NaCl concentration, the normalized volume percentages of tyrosine and tryptophan region increase, while those of humic- and fulvic-acid-like region decrease significantly. This work demonstrates that salinity affects the formation of SMP, and that EEM with PARAFAC in combination with FRI analysis is a useful tool to get insight into the formation of SMP by activated sludge.     

Surfactant-enhanced anaerobic acidogenesis of Canna indica L. by rumen cultures

Polyoxyethylene sorbitan monoolate (Tween 80) was used to enhance the anaerobic acidogenesis of Canna indica L. (canna) by rumen culture in this study. Dose of Tween 80 at 1 ml/l enhanced the volatile fatty acids (VFA) production from the acidogenesis of canna compared to the control. However, Tween 80 at higher dosages than 5 ml/l inhibited the rumen microbial activity and reduced the VFA yield. Response surface methodology was successfully used to optimize the VFA yield. A maximum of VFA yield of 0.147 g/g total solids (TS) added was obtained at canna and Tween 80 concentrations of 6.3g TS/l and 2.0 ml/l, respectively. Dosage of Tween 80 at 1-3.75 ml/l reduced the unproductive adsorption of microbes or enzymes on the lignin part in canna and increased microbial activity. A high VFA production was achieved from canna presoaked with Tween 80, suggesting that the structure of canna was disrupted by Tween 80.     

人红细胞膜上阴离子交换蛋白和葡萄糖运输蛋白的相互影响

用细胞松弛素Ｂ抑制红细胞膜上葡萄糖运输蛋白（ＧｌｕＴ－１）对葡萄糖的运输,观察到对阴离子运输有促进作用。当ＧｌｕＴ－１结合其底物分子－葡萄糖后同样加快了阴离子运输速率．另一方面,实验办给出了葡萄糖跨膜运输特性和Ｃｌ－离子浓度的关系,表明随着Ｃｌ－离子浓度的加大能使葡萄糖运输过程中Ｋｍ减小、Ｖ（ｍａｘ）增大。这些结果表明了在完整红细胞膜上阴离子交换蛋白Ｂａｎｄ３和ＧｌｕＴ－１之间存在着双向联系,即一种膜蛋白的构象改变能影响另一种膜蛋白的功能。     

交替呼吸途径对CuCl2胁迫下菜豆叶片光系统Ⅱ的保护作用

以“农普”12号菜豆幼苗为材料,采用1mmol·L^-1的水杨基氧肟酸（SHAM）抑制交替呼吸途径活性,探讨了在CuCl₂胁迫下交替呼吸途径对菜豆幼苗叶片光系统Ⅱ的保护作用。结果表明,随着CuCl₂胁迫浓度的增加,菜豆幼苗叶片潜在最大光化学效率F_v/F_m、光适应下叶片的最大光化学效率F_v'/F_m'、PSⅡ的实际光化学效率Y（Ⅱ）以及光化学猝灭系数qP、叶绿素含量均呈下降趋势,而非光学猝灭系数NPQ和交替呼吸途径的容量水平则呈上升趋势。较之在CuCl₂处理下的菜豆幼苗,用交替呼吸途径抑制剂预处理后的菜豆再置于CuCl₂的胁迫下,则会导致F_v/F_m、F_v'/F_m'、Y（Ⅱ）、qP以及叶绿素含量的进一步下降和NPQ的进一步上升。上述观察表明,在CuCl₂胁迫下交替呼吸途径可以缓解PSⅡ光化学效率的下降、维持PSⅡ反应中心的开放程度、减少天线色素的热耗散以及缓解叶绿素含量的降低,从而保护菜豆叶片光系统Ⅱ免受CuCl₂胁迫的伤害。     

Wolbachia prevalence patterns: horizontal transmission,recombination, and multiple infections in chestnut gall wasp-parasitoid communities

The Oriental chestnut gall wasp, Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), is a global invasive pest that causes serious damage to almost all chestnut species belonging to the Castanea genus (Fagaceae). Dryocosmus zhuili Liu et Zhu is a recently described sibling species of D. kuriphilus, which induces galls on Castanea henryi (Skan) Rehd. et Wils. There are many indigenous parasitoid species in China which play an important role in the natural regulation of their population dynamics. Wolbachia is a maternally inherited α-proteobacterium widely found in arthropods. This study screened for the presence of Wolbachia in the two chestnut gall wasps and in six parasitoid species from 12 populations, to investigate the prevalence patterns of Wolbachia in the chestnut gall wasp-parasitoid communities. We found that D. zhuili and four parasitoid species were infected with Wolbachia; among them, all individuals of the two populations of Megastigmus sp. had multiple Wolbachia infections. By using multilocus sequence types to characterize bacterial strains, three new sequence types were identified. The Wolbachia strains infecting D. zhuili (ST-507), Torymus sinensis Kamijo (ST-508), and Sycophila variegata (Curtis) (ST-508) belonged to supergroup A, whereas the Wolbachia strain infecting Megastigmus nipponicus Kamijo (ST-503) belonged to supergroup B. Our results also suggested that horizontal transmission of Wolbachia occurs between chestnut gall wasps and their parasitoids. Moreover, multiple Wolbachia infections of Megastigmus sp. may be due to gene recombination and horizontal transmission.     

水稻RNA结合蛋白C3H12与RNA结合位点的鉴定

CCH型锌指蛋白质C3H12是进化上保守的RNA结合蛋白质,它含有5个串联的CCCH锌指结构域ZnF1-5,形成2个紧密的锌指簇ZnF1-3和ZnF4-5。早期的研究发现,C3H12可能通过与mRNA结合的方式在转录后水平调控基因的表达。然而,与C3H12结合的mRNA类型和他们的结合模式,并未通过实验得到证明。本文表达纯化了一系列C3H12截短及全长蛋白质,并合成了一些潜在RNA底物ARE9、ARE19及对照Random21。通过等温滴定量热法 (isothermal titration calorimetry, ITC) 确定了C3H12与富含腺嘌呤尿嘧啶单元 (AU-rich element, ARE) mRNA底物的结合,并揭示了互作核心区域和热力学性质。通过荧光光谱分析和微型热泳动 (microscale thermophoresis, MST)技术对ITC的结果进一步佐证。结果表明：(1) C3H12与ARE底物的相互作用是焓驱动的能量有利的 (ΔG<0) 特异性结合,结合比为1:1。(2) C3H12与ARE19的亲和力较ARE9更高（约2倍）。(3) C3H12中ZnF1-3在与ARE类底物的结合活性中发挥主导作用。(4) C3H12结构中的141个氨基酸残基的接头不直接参与和ARE底物的相互作用。本研究揭示的CCCH型锌指蛋白质C3H12与ARE底物结合模式,将为进一步在分子结构水平阐明C3H12与ARE底物结合的机制奠定基础。     

An innovative miniature microbial fuel cell fabricated using photolithography

Recently microbial fuel cells (MFCs) have attracted increasing interests in both environmental and energy fields. Among the various MFC configurations, miniature microbial fuel cell (mini-MFC) has a great potential for the application in medical, communication and other areas because of its miniature volume and high output power density. In this work, a 25-μL single-chamber mini-MFC was fabricated using the photolithography technique. The plate-shaped gold anodic electrode in the mini-MFC showed a higher electrochemical activity than the stripe-shaped one. A biofilm of Shewanella oneidensis MR-1 was formed on the surface of gold electrode in this micro-liter-scale MFCs. As a result, a maximum power density of 29 mW/m(2) and a maximum current density of 2148 mA/m(2) were achieved by this single-chamber mini-MFC.     

Repurposing CRISPR RNA-guided integrases system for one-step,efficient genomic integration of ultra-long DNA sequences

Genomic integration techniques offer opportunities for generation of engineered microorganisms with improved or even entirely new functions but are currently limited by inability for efficient insertion of long genetic payloads due to multiplexing. Herein, using Shewanella oneidensis MR-1 as a model, we developed an optimized CRISPR-associated transposase from cyanobacteria Scytonema hofmanni (ShCAST system), which enables programmable, RNA-guided transposition of ultra-long DNA sequences (30 kb) onto bacterial chromosomes at ∼100% efficiency in a single orientation. In this system, a crRNA (CRISPR RNA) was used to target multicopy loci like insertion-sequence elements or combining I-SceI endonuclease, thereby allowing efficient single-step multiplexed or iterative DNA insertions. The engineered strain exhibited drastically improved substrate diversity and extracellular electron transfer ability, verifying the success of this system. Our work greatly expands the application range and flexibility of genetic engineering techniques and may be readily extended to other bacteria for better controlling various microbial processes.