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101.
Source-sink regulation of cotyledonary reserve mobilization during cashew (Anacardium occidentale) seedling establishment under NaCl salinity 总被引:1,自引:0,他引:1
Voigt EL Almeida TD Chagas RM Ponte LF Viégas RA Silveira JA 《Journal of plant physiology》2009,166(1):80-89
Seedling establishment is a critical process to crop productivity, especially under saline conditions. This work was carried out to investigate the hypothesis that reserve mobilization is coordinated with salt-induced inhibition of seedling growth due to changes in source-sink relations. To test this hypothesis, cashew nuts (Anacardium occidentale) were sown in vermiculite irrigated daily with distilled water (control) or 50mM NaCl and they were evaluated at discrete developmental stages from the seed germination until the whole seedling establishment. The salt treatment coordinately delayed the seedling growth and the cotyledonary reserve mobilization. However, these effects were more pronounced at late seedling establishment than in earlier stages. The storage protein mobilization was affected by salt stress before the lipid and starch breakdown. The globulin fraction represented the most important storage proteins of cashew cotyledons, and its mobilization was markedly delayed by NaCl along the seedling establishment. Free amino acids were mostly retained in the cotyledons of salt-treated seedlings when the mobilization of storage proteins, lipids and starch was strongly delayed. Proline was not considerably accumulated in the cotyledons of cashew seedlings as a response to NaCl salinity. According to these results it is noteworthy that the salt-induced inhibition of seedling growth is narrowly coordinated with the delay of reserve mobilization and the accumulation of hydrolysis products in cotyledons. Also, it was evidenced that free amino acids, especially those related to nitrogen transport, are potential signals involved in the regulation of storage protein hydrolysis during cashew seedling establishment under NaCl salinity. 相似文献
102.
Eugenol specialty chemical production in transgenic poplar (Populus tremula × P. alba) field trials 下载免费PDF全文
Joaquim V. Marques P. Pawan Chakravarthy Syed G. A. Moinuddin Randi Luchterhand Barri Herman Laurence B. Davin Norman G. Lewis 《Plant biotechnology journal》2017,15(8):970-981
A foundational study assessed effects of biochemical pathway introduction into poplar to produce eugenol, chavicol, p‐anol, isoeugenol and their sequestered storage products, from potentially available substrates, coniferyl and p‐coumaryl alcohols. At the onset, it was unknown whether significant carbon flux to monolignols vs. other phenylpropanoid (acetate) pathway metabolites would be kinetically favoured. Various transgenic poplar lines generated eugenol and chavicol glucosides in ca. 0.45% (~0.35 and ~0.1%, respectively) of dry weight foliage tissue in field trials, as well as their corresponding aglycones in trace amounts. There were only traces of any of these metabolites in branch tissues, even after ~4‐year field trials. Levels of bioproduct accumulation in foliage plateaued, even at the lowest introduced gene expression levels, suggesting limited monolignol substrate availability. Nevertheless, this level still allows foliage collection for platform chemical production, with the remaining (stem) biomass available for wood, pulp/paper and bioenergy product purposes. Several transformed lines displayed unexpected precocious flowering after 4‐year field trial growth. This necessitated terminating (felling) these particular plants, as USDA APHIS prohibits the possibility of their interacting (cross‐pollination, etc.) with wild‐type (native plant) lines. In future, additional biotechnological approaches can be employed (e.g. gene editing) to produce sterile plant lines, to avoid such complications. While increased gene expression did not increase target bioproduct accumulation, the exciting possibility now exists of significantly increasing their amounts (e.g. 10‐ to 40‐fold plus) in foliage and stems via systematic deployment of numerous ‘omics’, systems biology, synthetic biology and metabolic flux modelling approaches. 相似文献
103.
Alla Shvaleva Filipe Costa e Silva Joaquim Miguel Costa Alexandra Correia Margaret Anderson Raquel Lobo-do-Vale David Fangueiro Catarina Bicho João Santos Pereira Maria Manuela Chaves Ute Skiba Cristina Cruz 《Plant and Soil》2014,374(1-2):883-898
Background and aims
During the recent decades, cork oak (Q. suber) mortality has been increasing in Mediterranean oak woodland endangering the economical and environmental sustainability of the “montado” ecosystem. This fact in combination with climate change and conversion of forestland to pasture may significantly affect the soil-atmosphere greenhouse gases (GHGs) exchange. Our study evaluates the impact of oak trees as compared to pasture on net ecosystem GHG (CH4, N2O, and CO2) exchange as well as the main environmental factors influencing this exchange.Methods
We used field chamber measurements for the collection of GHGs under three different conditions: 1) open area (OA), 2) under tree canopy area (UC) and 3) improved pasture (IP). Experiments were done under typical Mediterranean climate at central Portugal in 2010 and 2011.Results
The UC had higher nitrification potential, soil C/N ratio, electrical conductivity, litter input and soil organic matter (SOM) than OA and IP. SOM positively correlated with soil CH4 and N2O fluxes but not with soil CO2 respiration rates. Soil water content (SWC) drives both CH4 and N2O fluxes. Under certain conditions, when SWC reached a threshold (7 % for CH4 and 3 % for N2O) the result was net uptake and that net uptake increased with SWC. This was the case for the UC and OA. Conversely, for the IP soil water content above 4 % promoted net CH4 release.Conclusions
Our results show that cork oak influences soil properties and consequently GHGs fluxes. In the UC the input of litter for SOM together with soil moisture, favoured microbiological activity and related GHGs fluxes. Soil temperature is a secondary factor in the studied conditions. Our results also emphasized the potential impact posed by decreased cork oak tree density in the functioning of the “montado” ecosystem. 相似文献104.
The enzymatic transesterification of oils with an alcohol, using recombinant cutinase of Fusarium solani pisi microencapsulated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reversed micelles, was performed in a membrane bioreactor (MBR). A tubular ceramic membrane with a nominal molecular weight cut off of 15,000 Da was used to retain the enzyme, and characterized in terms of rejection coefficients of the reaction components by transmission experiments. The performance of the MBR in a total recirculation-batch mode was compared with results obtained in a stirred batch tank reactor. The continuous operation of the MBR was also evaluated and the influence of the alcohol type and permeate flow rate on conversion degree and productivity (up to 500 g(product) /day/g(enzyme) was attained) were analyzed. Cutinase wild type and mutant T179C were tested for this process and the high long-term operational stability of the cutinase mutant demonstrated its potential as biocatalyst for the enzymatic continuous production of biodiesel. 相似文献
105.
Sousa AF Andrade PZ Pirzgalska RM Galhoz TM Azevedo AM da Silva CL Aires-Barros MR Cabral JM 《Biotechnology letters》2011,33(12):2373-2377
A novel cell separation process based on immunoaffinity aqueous two phase systems is presented to isolate and purify CD34+ stem/progenitor cells directly from the whole umbilical cord blood (UCB). A system, composed of polyethylene glycol and dextran,
was evaluated for the selective recovery of CD34+ cells from UCB. A monoclonal antibody against the CD34 surface antigen was used for the direct partitioning of CD34+ cells in UCB to the PEG-rich phase. The initial population of CD34+ cells (0.2% of the initial sample) was enriched to values up to 42% in a single partitioning step, while the majority of
contaminant cells were partitioned to the dextran-rich phase (1.37 × 10−2 < KP < 2.76 × 10−2). This novel selection method allowed a recovery yield of 95% of CD34+ cells with a purification factor of 245 and is expected to pave a new way to purify hematopoietic stem/progenitor cells for
use in a variety of clinical settings. 相似文献
106.
Fernández S Eritja R Aviñó A Jaumot J Gargallo R 《International journal of biological macromolecules》2011,49(4):729-736
The influence of pH, temperature and the cationic porphyrin TMPyP4 on the conformational equilibria of the cytosine-rich strand of the human telomeric sequence 5′-(C3TA2)4-3′, as well as those of the sequence 5′-(C3TT2)4-3′, was studied. The presence of adenine bases at the loops causes the formation of two different intramolecular i-motif structures with a pH-transition midpoint around 4.6, which stability is lower than the i-motif formed by the sequence 5′-(C3TT2)4-3′. The stoichiometries of the complexes formed by these i-motif structures with TMPyP4 are also influenced by the presence of adenine at the loops. 相似文献
107.
The human immunodeficiency virus has been shown to increase its infectivity throughout the course of infection. This virus selection property has been associated with genome mutations and recombinations among virus variants, causing amino acid residue alterations in important viral proteins. In order to explore the contribution of Env signal peptide (Env-sp) to Env glycoprotein expression and its possible relationship to increased virus infectivity observed at late stages of infection, we characterized Env-sp sequences derived from twelve patients at “early” and “late” stages of HIV infection without antiretroviral therapy use. In spite of the remarkable overall similarity between both stages, we observed the deletion of a sequence of neutral and basic residues at the Env-sp amino terminus in virus from early stage specimens and the insertion of basic residues in the hydrophobic region on late-stage viral isolates. The Env-sp sequence alterations may have viral adaptive functions during HIV infection. 相似文献
108.
Yamagishi S Hampel F Hata K Del Toro D Schwark M Kvachnina E Bastmeyer M Yamashita T Tarabykin V Klein R Egea J 《The EMBO journal》2011,30(14):2920-2933
Netrin-1 induces repulsive axon guidance by binding to the mammalian Unc5 receptor family (Unc5A-Unc5D). Mouse genetic analysis of selected members of the Unc5 family, however, revealed essential functions independent of Netrin-1, suggesting the presence of other ligands. Unc5B was recently shown to bind fibronectin and leucine-rich transmembrane protein-3 (FLRT3), although the relevance of this interaction for nervous system development remained unclear. Here, we show that the related Unc5D receptor binds specifically to another FLRT protein, FLRT2. During development, FLRT2/3 ectodomains (ECDs) are shed from neurons and act as repulsive guidance molecules for axons and somata of Unc5-positive neurons. In the developing mammalian neocortex, Unc5D is expressed by neurons in the subventricular zone (SVZ), which display delayed migration to the FLRT2-expressing cortical plate (CP). Deletion of either FLRT2 or Unc5D causes a subset of SVZ-derived neurons to prematurely migrate towards the CP, whereas overexpression of Unc5D has opposite effects. Hence, the shed FLRT2 and FLRT3 ECDs represent a novel family of chemorepellents for Unc5-positive neurons and FLRT2/Unc5D signalling modulates cortical neuron migration. 相似文献
109.