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51.
This study aims to assess the photoprotective potential of desiccation-induced curling in the light-susceptible old forest
lichen Lobaria pulmonaria by using chlorophyll fluorescence imaging. Naturally curled thalli showed less photoinhibition-induced limitations in primary
processes of photosynthesis than artificially flattened specimens during exposures to 450 μmol m−2 s−1 in the laboratory after both 12- (medium dose treatment) and 62-h duration (high dose treatment). Thallus areas shaded by
curled lobes during light exposure showed unchanged values of measured chlorophyll fluorescence parameters (F
V/F
M, ΦPS II), whereas non-shaded parts of curled thalli, as well as the mean for the entire flattened thalli, showed photoinhibitory
limitation after light treatments. Furthermore, the chlorophyll fluorescence imaging showed that the typical small-scale reticulated
ridges on the upper side of L. pulmonaria caused a spatial, small-scale reduction in damage due to minor shading. Severe dry-state photoinhibition readily occurred
in flattened and light-treated L. pulmonaria, although the mechanisms for such damage in a desiccated and inactive stage are not well known. Natural curling is one strategy
to reduce the chance for serious photoinhibition in desiccated L. pulmonaria thalli during high light exposures. 相似文献
52.
53.
Hansen T Arnfors L Ladenstein R Schönheit P 《Extremophiles : life under extreme conditions》2007,11(1):105-114
Recently, unusual non-regulated ATP-dependent 6-phosphofructokinases (PFK) that belong to the PFK-B family have been described
for the hyperthermophilic archaea Desulfurococcus amylolyticus and Aeropyrum pernix. Putative homologues were found in genomes of several archaea including the hyperthermophilic archaeon Methanocaldococcus jannaschii. In this organism, open reading frame MJ0406 had been annotated as a PFK-B sugar kinase. The gene encoding MJ0406 was cloned
and functionally expressed in Escherichia coli. The purified recombinant enzyme is a homodimer with an apparent molecular mass of 68 kDa composed of 34 kDa subunits. With
a temperature optimum of 85°C and a melting temperature of 90°C, the M. jannaschii nucleotide kinase represents one of the most thermoactive and thermostable members of the PFK-B family described so far.
The recombinant enzyme was characterized as a functional nucleoside kinase rather than a 6-PFK. Inosine, guanosine, and cytidine
were the most effective phosphoryl acceptors. Besides, adenosine, thymidine, uridin and xanthosine were less efficient. Extremely
low activity was found with fructose-6-phosphate. Further, the substrate specificity of closely related PFK-Bs from D. amylolyticus and A. pernix were reanalysed. 相似文献
54.
55.
《Process Biochemistry》2014,49(12):2207-2213
Enhanced biological phosphorus removal (EBPR) technology has been widely considered as a key strategy in preventing eutrophication and recognized as the advancing front of research in wastewater treatment. The key to keep its high efficiency in biological phosphorus removal is to optimize the operation and management of the system. Previous research in this field has undoubtedly improved understanding of the factors hindered overall efficiency of EBPR. However, it is obvious that much remains to be learnt. This paper attempts to review the fundamental understanding in factors inhibiting the stability and reliability of the EBPR systems in the state-of-the-art research. In view of modeling the EBPR systems, an appropriate extension of the current mechanistic models with these inhibitory factors is recommended in order to better simulate and predict the behavior of full-scale and lab-scale EBPR plants. From the perspectives of the further mechanistic and multi-factors study, the direction of denitrifying dephosphatation and granules/biofilms are also discussed. This comprehensive overview will not only help us to understand the overall mechanism of the EBPR process, but also benefit the researchers and engineers to consider all the possible factors affecting the process in the urban sewage treatment plants. 相似文献
56.
Kosuke Minamihata Masamichi Tokunaga Noriho Kamiya Shiro Kiyoyama Haruhiko Sakuraba Toshihisa Ohshima Masahiro Goto 《Biotechnology letters》2009,31(7):1037-1041
Peptide tags containing tyrosines (Y-tag) were introduced at the C-terminus of a hyperthermophilic enzyme, alkaline phosphatase from Pyrococcus furiosus (PfuAP). Immobilization of the recombinant PfuAPs onto water-in-oil-in-water (W/O/W) type microcapsules was performed by
an in situ polymerization method. All the recombinant PfuAPs prepared in this study were quantitatively immobilized onto microcapsules.
The PfuAP-immobilized microcapsules showed no significant loss of enzymatic activity until the 5th round of assays. This result
implies that the recombinant PfuAPs were covalently immobilized onto microcapsules. Immobilized PfuAP tagged with a Y-tag
having the sequence GGYYY exhibited approximately a twofold higher catalytic activity compared with the wild-type PfuAP.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
57.
58.
Lead sulfide (PbS) nanoparticles were synthesized in aqueous solution and used as oligonucleotide labels for electrochemical detection of the 35 S promoter from cauliflower mosaic virus (CaMV) sequence. The PbS nanoparticles were modified with mercaptoacetic acid and could easily be linked with CaMV 35 S oligonucleotide probe. Target DNA sequences were covalently linked on a mercaptoacetic acid self-assembled gold electrode, and DNA hybridization of target DNA with probe DNA was completed on the electrode surface. PbS nanoparticles anchored on the hybrids were dissolved in the solution by oxidation of HNO3 and detected using a sensitive differential pulse anodic stripping voltammetric method. The detection results can be used to monitor the hybridization reaction. The CaMV 35 S target sequence was satisfactorily detected with the detection limit as 4.38 × 10−12 mol/L (3σ). The established method extends nanoparticle-labeled electrochemical DNA analysis to specific sequences from genetically modified organisms with higher sensitivity and selectivity. 相似文献
59.
60.
Rates of root and organism growth, soil conditions, and temporal and spatial development of the rhizosphere 总被引:5,自引:0,他引:5
BACKGROUND: Roots growing in soil encounter physical, chemical and biological environments that influence their rhizospheres and affect plant growth. Exudates from roots can stimulate or inhibit soil organisms that may release nutrients, infect the root, or modify plant growth via signals. These rhizosphere processes are poorly understood in field conditions. SCOPE AND AIMS: We characterize roots and their rhizospheres and rates of growth in units of distance and time so that interactions with soil organisms can be better understood in field conditions. We review: (1) distances between components of the soil, including dead roots remnant from previous plants, and the distances between new roots, their rhizospheres and soil components; (2) characteristic times (distance(2)/diffusivity) for solutes to travel distances between roots and responsive soil organisms; (3) rates of movement and growth of soil organisms; (4) rates of extension of roots, and how these relate to the rates of anatomical and biochemical ageing of root tissues and the development of the rhizosphere within the soil profile; and (5) numbers of micro-organisms in the rhizosphere and the dependence on the site of attachment to the growing tip. We consider temporal and spatial variation within the rhizosphere to understand the distribution of bacteria and fungi on roots in hard, unploughed soil, and the activities of organisms in the overlapping rhizospheres of living and dead roots clustered in gaps in most field soils. CONCLUSIONS: Rhizosphere distances, characteristic times for solute diffusion, and rates of root and organism growth must be considered to understand rhizosphere development. Many values used in our analysis were estimates. The paucity of reliable data underlines the rudimentary state of our knowledge of root-organism interactions in the field. 相似文献