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51.
Magnaporthe oryzae and Rhizoctonia solani, are among the most important pathogens of rice, severely limiting its productivity. Dm-AMP1, an antifungal plant defensin from Dahlia merckii, was expressed in rice (Oryza sativa L. sp. indica cv. Pusa basmati 1) using Agrobacterium tumefaciens-mediated transformation. Expression levels of Dm-AMP1 ranged from 0.43% to 0.57% of total soluble protein in transgenic plants. It was observed that constitutive expression of
Dm-AMP1 suppresses the growth of M. oryzae and R. solani by 84% and 72%, respectively. Transgenic expression of Dm-AMP1 was not accompanied by an induction of pathogenesis-related (PR) gene expression, indicating that the expression of DmAMP1
directly inhibits the pathogen. The results of in vitro, in planta and microscopic analyses suggest that Dm-AMP1 expression has the potential to provide broad-spectrum disease resistance in rice. 相似文献
52.
The vast majority of lakes examined worldwide emit CO2 to the overlying atmosphere, through a process by which catchment-derived subsidies of terrigenous C, often in the form of
dissolved organic carbon (DOC), augment within-lake CO2 production above the level consumed via photosynthesis. We show that shallow, macrophyte-rich lakes of the Mackenzie Delta,
western Canadian Arctic, do not follow this pattern. These lakes are strong summertime CO2 absorbers, despite DOC concentrations at or above levels commonly shown to produce CO2 emission. Paradoxically, CO2 levels were lowest where DOC was greatest, in lakes which appear to be annual net CO2 absorbers, and have poor hydrologic connection to the terrestrial landscape. CO2 in these lakes is depleted by high macrophyte productivity, and although catchment-derived C subsidies are low, within-lake
DOC generation appears to occur as a byproduct of macrophyte photosynthesis and evapoconcentration. Additionally, after accounting
for DOC and macrophytes, lakes that were least connected to the larger terrestrial landscape remained weaker CO2 absorbers, suggesting that CO2 balance may also be affected by DOC quality, foodweb structure, or inputs of pCO2-rich riverwater to connected lakes. In contrast, a small subset of Delta lakes that were strongly affected by permafrost
melting were CO2 emitters, suggesting future permafrost degradation could engender a change in the overall CO2 balance of these lakes from near-CO2 neutral over the ice-free season, to clear CO2 emission. Our work suggests that the current paradigm of lakewater CO2 regulation may need to specifically incorporate shallow, productive lakes, and those that are poorly connected to their surrounding
landscape.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
ST, LL, and RH designed the study, ST performed research, ST analyzed data, ST, LL, and RH wrote the paper. 相似文献
53.
54.
Soltis DE Smith SA Cellinese N Wurdack KJ Tank DC Brockington SF Refulio-Rodriguez NF Walker JB Moore MJ Carlsward BS Bell CD Latvis M Crawley S Black C Diouf D Xi Z Rushworth CA Gitzendanner MA Sytsma KJ Qiu YL Hilu KW Davis CC Sanderson MJ Beaman RS Olmstead RG Judd WS Donoghue MJ Soltis PS 《American journal of botany》2011,98(4):704-730
55.
Bhilocha S Amin R Pandya M Yuan H Tank M LoBello J Shytuhina A Wang W Wisniewski HG de la Motte C Cowman MK 《Analytical biochemistry》2011,417(1):41-49
Agarose and polyacrylamide gel electrophoresis systems for the molecular mass-dependent separation of hyaluronan (HA) in the size range of approximately 5–500 kDa were investigated. For agarose-based systems, the suitability of different agarose types, agarose concentrations, and buffer systems was determined. Using chemoenzymatically synthesized HA standards of low polydispersity, the molecular mass range was determined for each gel composition over which the relationship between HA mobility and logarithm of the molecular mass was linear. Excellent linear calibration was obtained for HA molecular mass as low as approximately 9 kDa in agarose gels. For higher resolution separation, and for extension to molecular masses as low as approximately 5 kDa, gradient polyacrylamide gels were superior. Densitometric scanning of stained gels allowed analysis of the range of molecular masses present in a sample as well as calculation of weight-average and number-average values. The methods were validated for polydisperse HA samples with viscosity-average molecular masses of 112, 59, 37, and 22 kDa at sample loads of 0.5 μg (for polyacrylamide) to 2.5 μg (for agarose). Use of the methods for electrophoretic mobility shift assays was demonstrated for binding of the HA-binding region of aggrecan (recombinant human aggrecan G1–IGD–G2 domains) to a 150-kDa HA standard. 相似文献
56.
Protein lifetime is of critical importance for most biological processes and plays a central role in cell signaling and embryonic development, where it impacts the absolute concentration of signaling molecules and, potentially, the shape of morphogen gradients. Early conceptual and mathematical models of gradient formation proposed that steady-state gradients are established by an equilibration between the lifetime of a morphogen and its rates of synthesis and diffusion, though whether gradients in fact reach steady state before being read out is a matter of controversy. In any case, this class of models predicts that protein lifetime is a key determinant of both the time to steady state and the spatial extent of a gradient. Using a method that employs repeated photoswitching of a fusion of the morphogen Bicoid (Bcd) and the photoconvertible fluorescent protein Dronpa, we measure and modify the lifetime of Dronpa-Bcd in living Drosophila embryos. We find that the lifetime of Bcd is dynamic, changing from 50 min before mitotic cycle 14 to 15 min during cellularization. Moreover, by measuring total quantities of Bcd over time, we find that the gradient does not reach steady state. Finally, using a nearly continuous low-level conversion to the dark state of Dronpa-Bcd to mimic the effect of increased degradation, we demonstrate that perturbation of protein lifetime changes the characteristic length of the gradient, providing direct support for a mechanism based on synthesis, diffusion, and degradation. 相似文献
57.
The chemical warfare nerve agent (CWNA) soman irreversibly inhibits acetylcholinesterase (AChE) causing seizure, neuropathology
and neurobehavioral deficits. Pyridostigmine bromide (PB), the currently approved pretreatment for soman, is a reversible
AChE inhibitor that does not cross the blood–brain barrier (BBB) to protect against central nervous system damage. [−]-Huperzine
A, a natural reversible AChE inhibitor, rapidly passes through the BBB and has numerous neuroprotective properties that are
beneficial for protection against soman. However, [−]-Huperzine A is toxic at higher doses due to potent AChE inhibition which
limits the utilization of its neuroprotective properties. [+]-Huperzine A, a synthetic stereoisomer of [−]-Huperzine A and
a weak inhibitor of AChE, is non-toxic. In this study, we evaluated the efficacy of [+]-Huperzine A for protection against
soman toxicity in guinea pigs. Pretreatments with [+]-Huperzine A, i.m., significantly increased the survival rate in a dose-dependent
manner against 1.2× LD50 soman exposures. Behavioral signs of soman toxicity were significantly reduced in 20 and 40 mg/kg [+]-Huperzine A treated
animals at 4 and 24 h compared to vehicle and PB controls. Electroencephalogram (EEG) power spectral analysis showed that
[+]-Huperzine A significantly reduces soman-induced seizure compared to PB. [+]-Huperzine A (40 mg/kg) preserved higher blood
and brain AChE activity compared to PB in soman exposed animals. These data suggest that [+]-Huperzine A protects against
soman toxicity stronger than PB and warrant further development as a potent medical countermeasure against CWNA poisoning. 相似文献
58.
59.
Rajendran V Saxena A Doctor BP Kozikowski AP 《Bioorganic & medicinal chemistry letters》2002,12(11):1521-1523
The synthesis and acetylcholinesterase inhibition activity of analogues of huperzine B are reported. These new racemic analogues show a better AChE inhibitory activity than the natural product huperzine B. 相似文献
60.