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Qing-Lai Dang Jacob Marfo Fengguo Du Rongzhou Man Sahari Inoue 《Journal of Plant Ecology》2021,14(2):291
北方针叶树CO2 的刺激和响应机制随光强而变化
黑云杉(Picea mariana [Mill.] B.S.P.)和白云杉(Picea glauca [Moench] Voss.)是同属物种,两者都是适度耐阴,并且在北美北方针叶林中广泛分布。为了了解光照对CO2 浓度升高的生理生态反应的影响,在三种光照条件下(温室中光照设置为100%、50%和30%)将一年生的两种幼苗暴露在360和720 µmol mol–1 浓度的CO2环境中,测定了其中后期叶面气体交换量。研究结果表明,CO2的浓度升高提高了净光合速率 (Pn)和光合水分利用效率,但降低了气孔导度和蒸腾作用。CO2对光合作用的刺激在50%光照下最大, 在100%光照下最小。光合作用、最大羧化速率(Vcmax)和光饱和电子传递速率(Jmax)均随光照强度的 降低而降低。升高的CO2在所有光照处理中显著降低了Vcmax,在生长季节中期,两种云杉的Vcmax均显著 降低,但在生长季节后期,当光照达到30%时,这一影响变得不明显,而且黑云杉的响应大于白云杉。CO2 浓度升高也降低了白云杉的Jmax,但在生长季后期30%光照时,这种影响变得不显著。但CO2 浓度升高对 黑云杉的影响随时间而变化。在所有光照处理中,CO2 浓度升高降低了黑云杉生长中期的Jmax,且在生长后 期30%光照时影响不显著,但在100%和50%光照时,Jmax升高。这些研究结果表明,两个树种植物都受益于CO2 浓度的升高,但它们的响应机制随着光照的增加而变化:即在100%和50%光照下,它们的响应主要是生理上的,而在30%光照下,它们的响应主要是形态上的。 相似文献
2.
Jemima L. Whyte Andrew A. Smith Bo Liu Wilfred R. Manzano Nick D. Evans Girija R. Dhamdhere Mark Y. Fang Howard Y. Chang Anthony E. Oro Jill A. Helms 《PloS one》2013,8(10)
Wnt signaling is required for both the development and homeostasis of the skin, yet its contribution to skin wound repair remains controversial. By employing Axin2LacZ/+ reporter mice we evaluated the spatial and temporal distribution patterns of Wnt responsive cells, and found that the pattern of Wnt responsiveness varies with the hair cycle, and correlates with wound healing potential. Using Axin2LacZ/LacZ mice and an ear wound model, we demonstrate that amplified Wnt signaling leads to improved healing. Utilizing a biochemical approach that mimics the amplified Wnt response of Axin2LacZ/LacZ mice, we show that topical application of liposomal Wnt3a to a non-healing wound enhances endogenous Wnt signaling, and results in better skin wound healing. Given the importance of Wnt signaling in the maintenance and repair of skin, liposomal Wnt3a may have widespread application in clinical practice. 相似文献
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Erin P. Price Derek S. Sarovich Elizabeth Nosworthy Jemima Beissbarth Robyn L. Marsh Janessa Pickering Lea-Ann S. Kirkham Anthony D. Keil Anne B. Chang Heidi C. Smith-Vaughan 《BMC genomics》2015,16(1)
Background
Haemophilus influenzae is an opportunistic bacterial pathogen that exclusively colonises humans and is associated with both acute and chronic disease. Despite its clinical significance, accurate identification of H. influenzae is a non-trivial endeavour. H. haemolyticus can be misidentified as H. influenzae from clinical specimens using selective culturing methods, reflecting both the shared environmental niche and phenotypic similarities of these species. On the molecular level, frequent genetic exchange amongst Haemophilus spp. has confounded accurate identification of H. influenzae, leading to both false-positive and false-negative results with existing speciation assays.Results
Whole-genome single-nucleotide polymorphism data from 246 closely related global Haemophilus isolates, including 107 Australian isolate genomes generated in this study, were used to construct a whole-genome phylogeny. Based on this phylogeny, H. influenzae could be differentiated from closely related species. Next, a H. influenzae-specific locus, fucP, was identified, and a novel TaqMan real-time PCR assay targeting fucP was designed. PCR specificity screening across a panel of clinically relevant species, coupled with in silico analysis of all species within the order Pasteurellales, demonstrated that the fucP assay was 100 % specific for H. influenzae; all other examined species failed to amplify.Conclusions
This study is the first of its kind to use large-scale comparative genomic analysis of Haemophilus spp. to accurately delineate H. influenzae and to identify a species-specific molecular signature for this species. The fucP assay outperforms existing H. influenzae targets, most of which were identified prior to the next-generation genomics era and thus lack validation across a large number of Haemophilus spp. We recommend use of the fucP assay in clinical and research laboratories for the most accurate detection and diagnosis of H. influenzae infection and colonisation.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1857-x) contains supplementary material, which is available to authorized users. 相似文献5.
Mechanisms underlying the vascular differentiation of human bone marrow stromal cells (HBMSCs) and their contribution to neovascularisation are poorly understood. We report the essential role of cell density-induced signals in directing HBMSCs along endothelial or smooth muscle lineages. Plating HBMSCs at high density rapidly induced Notch signaling, which initiated HBMSC commitment to a vascular progenitor cell population expressing markers for both vascular lineages. Notch also induced VEGF-A, which inhibited vascular smooth muscle commitment while consolidating differentiation to endothelial cells with cobblestone morphology and characteristic endothelial markers and functions. These mechanisms can be exploited therapeutically to regulate HBMSCs during neovascularisation. 相似文献
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Swan GE Cuthbert R Quevedo M Green RE Pain DJ Bartels P Cunningham AA Duncan N Meharg AA Oaks JL Parry-Jones J Shultz S Taggart MA Verdoorn G Wolter K 《Biology letters》2006,2(2):279-282
Three endemic vulture species Gyps bengalensis, Gyps indicus and Gyps tenuirostris are critically endangered following dramatic declines in South Asia resulting from exposure to diclofenac, a veterinary drug present in the livestock carcasses that they scavenge. Diclofenac is widely used globally and could present a risk to Gyps species from other regions. In this study, we test the toxicity of diclofenac to a Eurasian (Gyps fulvus) and an African (Gyps africanus) species, neither of which is threatened. A dose of 0.8 mg kg(-1) of diclofenac was highly toxic to both species, indicating that they are at least as sensitive to diclofenac as G. bengalensis, for which we estimate an LD50 of 0.1-0.2 mg kg(-1). We suggest that diclofenac is likely to be toxic to all eight Gyps species, and that G. africanus, which is phylogenetically close to G. bengalensis, would be a suitable surrogate for the safety testing of alternative drugs to diclofenac. 相似文献
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Localization of the delta-like-1-binding site in human Notch-1 and its modulation by calcium affinity 总被引:1,自引:0,他引:1
Cordle J Redfieldz C Stacey M van der Merwe PA Willis AC Champion BR Hambleton S Handford PA 《The Journal of biological chemistry》2008,283(17):11785-11793
The Notch signaling pathway plays a key role in a myriad of cellular processes, including cell fate determination. Despite extensive study of the downstream consequences of receptor activation, very little molecular data are available for the initial binding event between the Notch receptor and its ligands. In this study, we have expressed and purified a natively folded wild-type epidermal growth factor-like domain (EGF) 11-14 construct from human Notch-1 and have used flow cytometry and surface plasmon resonance analysis to demonstrate a calcium-dependent interaction with the human ligand Delta-like-1. Site-directed mutagenesis of three of the calcium-binding sites within the Notch-(11-14) fragment indicated that only loss of calcium binding to EGF12, and not EGF11 or EGF13, abrogates ligand binding. Further mapping of the ligand-binding site within this region by limited proteolysis of Notch wild-type and mutant fragments suggested that EGF12 rather than EGF11 contains the major Delta-like-1-binding site. Analysis of an extended fragment EGF-(10-14), where EGF11 is placed in a native context, surprisingly demonstrated a reduction in ligand binding, suggesting that EGF10 modulates binding by limiting access of ligand. This inhibition could be overcome by the introduction of a calcium binding mutation in EGF11, which decouples the EGF-(10-11) module interface. This study therefore demonstrates that long range calcium-dependent structural perturbations can influence the affinity of Notch for its ligand, in the absence of any post-translational modifications. 相似文献
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Laura Senyonjo James Addy Diana L. Martin David Agyemang Dorothy Yeboah-Manu Sarah Gwyn Benjamin Marfo Adwoa Asante-Poku Agatha Aboe Ernest Mensah Anthony W. Solomon Robin L. Bailey 《PLoS neglected tropical diseases》2021,15(9)
IntroductionTo date, eleven countries have been validated as having eliminated trachoma as a public health problem, including Ghana in 2018. Surveillance for recrudescence is needed both pre- and post-validation but evidence-based guidance on appropriate strategies is lacking. We explored two potential surveillance strategies in Ghana.Methodology/principal findingsAmongst randomly-selected communities enrolled in pre-validation on-going surveillance between 2011 and 2015, eight were identified as having had trachomatous-inflammation follicular (TF) prevalence ≥5% in children aged 1–9 years between 2012 and 2014. These eight were re-visited in 2015 and 2016 and neighbouring communities were also added (“TF trigger” investigations). Resident children aged 1–9 years were then examined for trachoma and had a conjunctival swab to test for Chlamydia trachomatis (Ct) and a dried blood spot (DBS) taken to test for anti-Pgp3 antibodies. These investigations identified at least one community with evidence of probable recent Ct ocular transmission. However, the approach likely lacks sufficient spatio-temporal power to be reliable.A post-validation surveillance strategy was also evaluated, this reviewed the ocular Ct infection and anti-Pgp3 seroprevalence data from the TF trigger investigations and from the pre-validation surveillance surveys in 2015 and 2016. Three communities identified as having ocular Ct infection >0% and anti-Pgp3 seroprevalence ≥15.0% were identified, and along with three linked communities, were followed-up as part of the surveillance strategy. An additional three communities with a seroprevalence ≥25.0% but no Ct infection were also followed up (“antibody and infection trigger” investigations). DBS were taken from all residents aged ≥1 year and ocular swabs from all children aged 1–9 years. There was evidence of transmission in the group of communities visited in one district (Zabzugu-Tatale). There was no or little evidence of continued transmission in other districts, suggesting previous infection identified was transient or potentially not true ocular Ct infection.Conclusions/significanceThere is evidence of heterogeneity in Ct transmission dynamics in northern Ghana, even 10 years after wide-scale MDA has stopped. There is added value in monitoring Ct infection and anti-Ct antibodies, using these indicators to interrogate past or present surveillance strategies. This can result in a deeper understanding of transmission dynamics and inform new post-validation surveillance strategies. Opportunities should be explored for integrating PCR and serological-based markers into surveys conducted in trachoma elimination settings. 相似文献
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