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排序方式: 共有9466条查询结果,搜索用时 11 毫秒
891.
S. Krause P. M. van Bodegom W. K. Cornwell P. L. E. Bodelier 《Journal of evolutionary biology》2014,27(6):1240-1247
The presence of phylogenetic signal is assumed to be ubiquitous. However, for microorganisms, this may not be true given that they display high physiological flexibility and have fast regeneration. This may result in fundamentally different patterns of resemblance, that is, in variable strength of phylogenetic signal. However, in microbiological inferences, trait similarities and therewith microbial interactions with its environment are mostly assumed to follow evolutionary relatedness. Here, we tested whether indeed a straightforward relationship between relatedness and physiological traits exists for aerobic methane‐oxidizing bacteria (MOB). We generated a comprehensive data set that included 30 MOB strains with quantitative physiological trait information. Phylogenetic trees were built from the 16S rRNA gene, a common phylogenetic marker, and the pmoA gene which encodes a subunit of the key enzyme involved in the first step of methane oxidation. We used a Blomberg's K from comparative biology to quantify the strength of phylogenetic signal of physiological traits. Phylogenetic signal was strongest for physiological traits associated with optimal growth pH and temperature indicating that adaptations to habitat are very strongly conserved in MOB. However, those physiological traits that are associated with kinetics of methane oxidation had only weak phylogenetic signals and were more pronounced with the pmoA than with the 16S rRNA gene phylogeny. In conclusion, our results give evidence that approaches based solely on taxonomical information will not yield further advancement on microbial eco‐evolutionary interactions with its environment. This is a novel insight on the connection between function and phylogeny within microbes and adds new understanding on the evolution of physiological traits across microbes, plants and animals. 相似文献
892.
Absorbance changes induced by 25-ps laser flashes were measured in membranes of Heliobacterium chlorum at 15 K. Absorbance difference spectra, measured at various times after the flash showed negative bands in the Qy region at 812, 793 and 665 nm. The first of these bands was attributed to the formation of excited singlet states of a long-wavelength form of antenna bacteriochlorophyll g (BChl g 808). Absorbance changes of shorter wavelength absorbing antenna BChls g were at least an order of magnitude smaller, indicating rapid excitation energy transfer (i.e. within the time resolution of the apparatus) from these BChls to BChl g 808. Excited BChl g 808 showed a bi-exponential decay with time constants of 50 and 200 ps. The bands at 793 and 665 nm may be attributed to the primary charge separation and reflect the photooxidation of the primary electron donor P-798 and photoreduction of a primary electron acceptor absorbing near 670 nm, presumably a BChl c or Chl a-like pigment. The bleaching of this pigment reversed with a time constant of 300 ps at 15 K and of 800 ps at 300 K. This indicates that electron transfer from the primary to the secondary electron acceptor is approximately 2.5 times faster at 15 K than at room temperature.Abbreviations BChl
bacteriochlorophyll
- FWHM
full width at half maximum
- P-798
primary electron donor
- Tris
tris(hydroxymethyl)amino methane 相似文献
893.
Azhar Fakharuddin Lukas Schmidt‐Mende Germà Garcia‐Belmonte Rajan Jose Ivan Mora‐Sero 《Liver Transplantation》2017,7(22)
Rapid improvement in photoconversion efficiency (PCE) of solution processable organometallic hybrid halide based perovskite solar cells (PSCs) have taken the photovoltaic (PV) community with a surprise and has extended their application in other electronic devices such as light emitting diodes, photo detectors and batteries. Together with efforts to push the PCE of PSCs to record values >22% – now at par with that of crystalline silicon solar cells – origin of their PV action and underlying physical processes are also deeply investigated worldwide in diverse device configurations. A typical PSC consists of a perovskite film sandwiched between an electron and a hole selective contact thereby creating ESC/perovskite and perovskite/HSC interfaces, respectively. The selective contacts and their interfaces determine properties of perovskite layer and also control the performance, origin of PV action, open circuit voltage, device stability, and hysteresis in PSCs. Herein, we define ideal charge selective contacts, and provide an overview on how the choice of interfacing materials impacts charge accumulation, transport, transfer/recombination, band‐alignment, and electrical stability in PSCs. We then discuss device related considerations such as morphology of the selective contacts (planar or mesoporous), energetics and electrical properties (insulating and conducting), and its chemical properties (organic vs inorganic). Finally, the outlook highlights key challenges and future directions for a commercially viable perovskite based PV technology. 相似文献
894.
895.
Ethan Newman Bruce Anderson 《Evolution; international journal of organic evolution》2020,74(2):283-296
Interactions between plant community members are an underexplored driver of angiosperm floral variation. We investigate character displacement as a potential contributor to floral variation in Pelargonium communities. Pelargoniums all place pollen on the ventral sides of their pollinators, potentially leading to interspecific pollen transfer (IPT) in sympatry. We show that the positions of pollen placement and receipt are determined by anther and style exsertion lengths. Using field experiments, we demonstrate that heterospecific species experience higher IPT if they have similar style lengths than when they have greater style length differences. Using crosses, we show that IPT has negative consequences on seed set. In combination, these results suggest that character displacement in style length is likely to reduce IPT and increase female fitness in sympatry. Patterns of style length variation across 29 different Pelargonium communities suggest that character displacement has occurred in multiple communities. Furthermore, analyses using a wide-ranging species pair show that style lengths are more different between sympatric populations than they are between allopatric populations. In addition to pollinators as agents of floral divergence, this study suggests that variation in Pelargonium community structure has driven style length variation through character displacement. 相似文献
896.
基于电子捕获裂解/电子转运裂解串联质谱技术的蛋白质组学研究 总被引:1,自引:0,他引:1
蛋白质组学的兴起带动了质谱技术的快速发展,而质谱技术的进步则拓宽了蛋白质组学研究问题的广度.最近10年内,肽段或完整蛋白质在质谱仪中的裂解技术——电子捕获裂解(electron capture dissociation,ECD)与电子转运裂解(electron transfer dissociation,ETD)逐渐发展起来.ECD和ETD在蛋白质组学中的应用,特别是在蛋白质的翻译后修饰鉴定和自顶而下(Top-down)的完整蛋白质裂解研究中已经展示出了诱人的前景.对ECD和ETD的基本原理、质谱特点、仪器实现、数据解析算法与软件开发,以及在蛋白质组学中的应用进展等方面进行了比较系统全面的阐述,并对当前的研究问题、面临的技术挑战与未来的发展趋势等方面作了深入剖析. 相似文献
897.
Production of Transgenic-clone Pigs by the Combination of ICSI-mediated Gene Transfer with Somatic Cell Nuclear Transfer 总被引:5,自引:0,他引:5
The objective of this study was to examine whether the ICSI-mediated gene transfer method using in vitro matured oocytes and frozen sperm head could actually produce transgenic pigs. We also aimed at examining whether transgenic
pigs can be cloned from somatic cells of a transgenic pig generated by the ICSI-mediated method. A bicistronic gene constituted
of the human albumin (hALB) and enhanced green fluorescent protein (EGFP) genes was introduced into pig oocytes by the ICSI-mediated
method. Transfer of 702 embryos produced by the ICSI-mediated method into five gilts resulted in 4 pregnancies. When three
of the recipients, which had received total 312 of the embryos were autopsied, 32 including 1 transgenic fetuses were obtained.
One of the recipients gave birth to three live piglets including one transgenic pig, showing a strong green fluorescence in
the eyeballs, oral mucous membrane and subcutaneous tissues. Fluorescent microscopy revealed uniform GFP expression in all
cell lines established from kidney, lung and muscle of the founder transgenic pig obtained. Nuclear transfer of these cells
resulted in stable in vitro development of cloned embryos into the blastocyst stage, ranging from 12.9 to 19.8%. When 767 of the nuclear transfer embryos
were transferred to 5 recipients, all became pregnant and gave birth to a total of six live transgenic-clones. The transgene
copy number and integrity in the founder pig were maintained in the primary culture cells established from the founder as
well as in the clones produced from these cells. Our study demonstrates that the ICSI-mediated gene transfer is an efficient
and practical method to produce transgenic pigs, using frozen sperm heads and in vitro matured oocytes. It was also shown that combination of ICSI-mediated transgenesis and nuclear transfer is a feasible technology
of great potential in transgenic pig production. 相似文献
898.
Nanoparticles: A Light Harvesting Antenna Using Natural Extract Graminoids Coupled with Plasmonic Metal Nanoparticles for Bio‐Photovoltaic Cells (Adv. Energy Mater. 18/2014) 下载免费PDF全文
899.
Similar or Totally Different: the Adjustment of the Twist Conformation Through Minor Structural Modification,and Dramatically Improved Performance for Dye‐Sensitized Solar Cell 下载免费PDF全文
Zhaofei Chai Mei Wu Manman Fang Sushu Wan Ting Xu Runli Tang Yujun Xie Anyi Mei Hongwei Han Qianqian Li Zhen Li 《Liver Transplantation》2015,5(18)
A novel approach for enhancing the performance of dye‐sensitized solar cells is presented. It is based on the analysis of five sensitizers by utilizing triarylamine as donor, thiophene benzothiadiazole as chromophore and substituted thienyl linked with cyanoacrylic acid as the anchoring group (LI‐80‐LI‐84). Accompanied with the increasing steric hindrance of the substituents on the thienyl isolation group, the conformation of the dyes, in particular the angle between the chromophore and the anchoring group, becomes more and more twisted. Surprisingly, sensitizers with poorer conjugation effects (the higher twisted conformation) achieve better photovoltaic performances, showing a contrary trend to the traditional donor‐(π‐spacer)‐acceptor dyes with a better co‐planarity. On the basis of the preceding fundamental comprehensions, an empirical method is successfully applied to a new phenyl‐based system (LI‐85 and LI‐86) to improve their performances. The systematical investigation indicates that the twisted structures can contribute to the ECB of the TiO2 film, electron lifetime and resistance at the TiO2/dye/electrolyte interface. Thereby, the efficiency of the initial LI‐80‐based cell has been dramatically improved to 2.45 times higher for LI‐86‐based cell, paving a new way for the design of better sensitizers with higher device performances. 相似文献
900.