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991.
Irene Friligou Evangelia Papadimitriou Dimitrios Gatos John Matsoukas Theodore Tselios 《Amino acids》2011,40(5):1431-1440
A fast and efficient microwave-assisted solid phase peptide synthesis (MW-SPPS) of a 51mer peptide, the main heparin-binding
site (60–110) of human pleiotrophin (hPTN), using 2-chlorotrityl chloride resin (CLTR-Cl) following the 9-fluorenylmethyloxycarbonyl/tert-butyl (Fmoc/tBu) methodology and with the standard N,N′-diisopropylcarbodiimide/1-hydroxybenzotriazole (DIC/HOBt) coupling reagents, is described. An MW-SPPS protocol was for the
first time successfully applied to the acid labile CLTR-Cl for the faster synthesis of long peptides (51mer peptide) and with
an enhanced purity in comparison to conventional SPPS protocols. The synthesis of such long peptides is not trivial and it
is generally achieved by recombinant techniques. The desired linear peptide was obtained in only 30 h of total processing
time and in 51% crude yield, in which 60% was the purified product obtained with 99.4% purity. The synthesized peptide was
purified by reversed phase high performance liquid chromatography (RP-HPLC) and identified by electrospray ionization mass
spectrometry (ESI-MS). Then, the regioselective formation of the two disulfide bridges of hPTN 60–110 was successfully achieved
by a two-step procedure, involving an oxidative folding step in dimethylsulfoxide (DMSO) to form the Cys77–Cys109 bond, followed by iodine oxidation to form the Cys67–Cys99 bond. 相似文献
992.
993.
Intensified wind pollination mediated by pollen dimorphism after range expansion in an ambophilous biennial Aconitum gymnandrum 下载免费PDF全文
Lin‐Lin Wang Chan Zhang Ming‐Liu Yang Guo‐Peng Zhang Zhi‐Qiang Zhang Yong‐Ping Yang Yuan‐Wen Duan 《Ecology and evolution》2017,7(2):541-549
Pollination systems and associated floral traits generally differ between core and marginal populations of a species. However, such differences are rarely examined in plants with a mixed wind‐ and bumblebee‐pollination system, and the role of wind pollination during range expansion in ambophilous plants remains unclear. We compared floral traits and the contributions of bumblebee and wind pollination in refugium and marginal populations of the ambophilous plant Aconitum gymnandrum. We found that most floral traits differed between the two populations, and those traits associated with the shift to wind pollination were pronounced in the marginal population. Bumblebee visitation rates varied significantly, but were generally low in the marginal population. Wind pollination occurred in both populations, and the efficiency was lower than that of bumblebee pollination. Two types of pollen grains, namely round and fusiform pollen, were transported to a stigma by bumblebees and wind, but fusiform pollen contributed to wind pollination to a larger degree, especially in the marginal population. Our results suggest that wind pollination was enhanced by pollen dimorphism in the marginal population of A. gymnandrum, and wind pollination may provide reproductive assurance when bumblebee activity is unpredictable during range expansion, indicating that ambophily is stable in this species and shift in pollination system could be common when plants colonize new habitats. 相似文献
994.
Jun Zhang Zanchao Liu Yuanyuan Pei Wen Yang Chicu Xie Shiqi Long 《Neurochemical research》2018,43(3):736-744
Brain-derived neurotrophic factor (BDNF) is a crucial regulator to support synaptic plasticity and neuronal survival, its significant decrease is a pathophysiological hallmark in Alzheimer’s disease (AD) brains and accounts for poor prognosis. MicroRNAs (miRNAs) interfere with the translation of target mRNAs and control a variety of physiological and pathological processes. MiR-322 is the rodent homologue of human miR-424, it is involved in the modulation of cell differentiation, proliferation, apoptosis and metabolic activities in diverse tissues and organs. However, the roles and potential mechanisms of miR-322 remain elusive in AD pathogenesis. Here we observed miR-322 is significantly increased along with BDNF decrease in AD mouse brain. Bioinformatics prediction implicated that BDNF 3′-untranslated region (3′-UTR) possesses the putative target sequence of miR-322. Luciferase reporter assay identified that miR-322 can directly conjugate to BDNF 3′-UTR. The functional research showed that MiR-322 input deregulates BDNF expression at either mRNA or protein levels, whereas miR-322 silence restores BDNF expression in vitro. Furthermore, we found miR-322 promotes Tau phosphorylation via negatively controlling BDNF–TrkB receptor activation, otherwise MiR-322 silence restores TrkB activation and attenuates tau phosphorylation. Collectively, this study demonstrated a novel miRNA-dependent manner of BDNF degradation in AD pathogenesis, it may drive a miRNAs- or BDNF based therapeutic strategies against Alzheimer’s disease. 相似文献
995.
996.
Michael D Kennedy Mark J Haykowsky Carol A Boliek Ben TA Esch Jessica M Scott Darren ER Warburton 《Dynamic medicine : DM》2006,5(1):8
Background
Near infrared spectroscopy (NIRS) is used to assess muscle oxygenation (MO) within skeletal muscle at rest and during aerobic exercise. Previous investigations have used a single probe placement to measure MO during various forms of exercise. However, regional MO differences have been shown to exist within the same muscle which suggests that different areas of the same muscle may have divergent MO. Thus, the aim of this study was to examine whether regional differences in MO exist within the same muscle during different types of incremental (rest, 25, 50, 75, 100 % of maximum) exercise (1 leg knee extension (KE), 2 leg KE, or cycling).Methods
Nineteen healthy active males (Mean ± SD: Age 27 ± 4 yrs; VO2max: 55 ± 11 mL/kg/min) performed incremental exercise to fatigue using each mode of exercise. NIRS probes were placed on the distal and proximal portion of right leg vastus lateralis (VL). Results were analyzed with a 3-way mixed model ANOVA (probe × intensity × mode).Results
Differences in MO exist within the VL for each mode of exercise, however these differences were not consistent for each level of intensity. Comparison of MO revealed that the distal region of VL was significantly lower throughout KE exercise (1 leg KE proximal MO – distal MO = 9.9 %; 2 leg KE proximal MO – distal MO = 13 %). In contrast, the difference in MO between proximal and distal regions of VL was smaller in cycling and was not significantly different at heavy workloads (75 and 100 % of maximum).Conclusion
MO is different within the same muscle and the pattern of the difference will change depending on the mode and intensity of exercise. Future investigations should limit conclusions on MO to the area under assessment as well as the type and intensity of exercise employed.997.
Quillaguamán J Doan-Van T Guzmán H Guzmán D Martín J Everest A Hatti-Kaul R 《Applied microbiology and biotechnology》2008,78(2):227-232
High poly(3-hydroxybutyrate) (PHB) content and volumetric productivity were achieved by fed-batch culture of Halomonas boliviensis using a defined medium. Initial shake flask cultivations in a minimal medium revealed that the growth of H. boliviensis was supported only when the medium was supplemented with aspartic acid, glycine, or glutamine. Addition of 0.1% (w/v) glutamine in the medium resulted in the highest cell dry weight (CDW; 3.9 g l−1). Glutamine was replaced by the less expensive monosodium glutamate (MSG) in the medium without any notable change in the
final cell density. Effect of initial concentrations of NH4Cl and K2HPO4 on cell growth and PHB accumulation by H. boliviensis was then analyzed using a fed-batch fermentation system. The best conditions for PHB production by H. boliviensis were attained using 0.4% (w/v) NH4Cl and 0.22% (w/v) K2HPO4 and adding MSG intermittently to the fermentor. Poly(3-hydroxybutyrate) content and CDW reached 90 wt.% and 23 g l−1, respectively, after 18 h of cultivation. In order to increase CDW and PHB content, MSG, NH4Cl, and K2HPO4 were initially fed to the fermentor to maintain their concentrations at 2%, 0.4%, and 0.22% (w/v), respectively, and subsequently their feed was suppressed. This resulted in a CDW of 44 g l−1, PHB content of 81 wt.%, and PHB volumetric productivity of 1.1 g l−1 h−1. 相似文献
998.
Cuicai Zhang Huimian Yang Xiuwen Li Zhiqiang Cao Haijian Zhou Linzi Zeng Jianmin Xu Yinghua Xu Yung-Fu Chang Xiaokui Guo Yongzhang Zhu Xiugao Jiang 《PLoS neglected tropical diseases》2015,9(5)
Background
Leptospirosis is one of the most important neglected tropical infectious diseases worldwide. Icterohaemorrhagiae has been throughout recent history, and still is, the predominant serogroup of this pathogen in China. However, very little in detail is known about the serovars or genotypes of this serogroup.Methodology/Principal Findings
In this study, 120 epidemic strains from five geographically diverse regions in China collected over a 50 year period (1958~2008), and 8 international reference strains characterized by 16S rRNA sequencing and MLST analysis. 115, 11 and 2 strains were identified as L. interrogans, L. borgpetersenii, and L. kirschneri, respectively. 17 different STs were identified including 69 ST1 strains, 18 ST17, 18 ST128, 9 ST143 and 2 ST209. The remaining 12 strains belonged to 12 different STs. eBURST analysis demonstrated that, among the clonal complexes isolated (CCs), CC1 accounted for 73.3% (88/120) strains representing three STs: ST1, ST128 and ST98. ST1 was the most likely ancestral strain of this CC, followed by singleton CC17 (17/120) and CC143 (11/120). Further analysis of adding 116 serogroup Icterohaemorrhagiae strains in the MLST database and studies previously described using global eBURST analysis and MST dendrogram revealed relatively similar ST clustering patterns with five main CCs and 8 singletons among these 244 strains. CC17 was found to be the most prevalent clone of pathogenic Leptospira circulating worldwide. This is the first time, to our knowledge, that ST1 and ST17 strains were distributed among 4 distinct serovars, indicating a highly complicated relationship between serovars and STs.Conclusions/Significance
Our studies demonstrated a high level of genetic diversity in the serogroup Icterohaemorrhagiae strains. Distinct from ST17 or ST37 circulating elsewhere, ST1 included in CC1, has over the past 50 years or so, proven to be the most prevalent ST of pathogenic leptospires isolated in China. Moreover, the complicated relationship between STs and serovars indicates an urgent need to develop an improved scheme for Leptospira serotyping. 相似文献999.
The formation of colonies and the evolution of coloniality have been suggested to be a by-product of the use of public information
to select breeding habitats. In this study we performed an experimental test to investigate whether the Lesser Kestrel (Falco naumanni) uses breeding success of conspecifics as a source of public information to select a breeding colony. We considered four
potential cues based on reproductive performance of conspecifics in each colony: mean and variance of breeding success measured
in both all pairs (TRS, total reproductive success), and only successful pairs (PRS, partial reproductive success). Both mean
PRS and mean TRS could be predictive cues of the future reproductive output at a given site, because they varied among colonies
and were autocorrelated from one year to the next. To dissociate any relationship between habitat quality and reproductive
success we manipulated the mean brood sizes by transferring chicks among ten colonies. In five colonies, all the broods with
at least two nestlings were reduced in one chick and in other five colonies all broods were enlarged by one chick. In the
following year, we found that the number of adult immigrant kestrels settled at a colony was only explained by mean PRS in
the previous year. We also examined the settlement of yearlings, which lack of information on breeding success in previous
years. Unlike adult immigrant kestrels, yearlings tended to settle more frequently in those colonies with low mean PRS in
the previous year, probably because of the lower pressure for occupation in those colonies. A multiple regression analysis
showed that the growth of colonies was positively dependent on the mean PRS in the experimental year, and negatively on the
number of predated nests. This study provides a solid support to the hypothesis that colonial species can use mean breeding
success of successful pairs as a source of public information to make settlement decisions. 相似文献
1000.