Trehalose 6-phosphate (Tre6P), the intermediate of trehalose biosynthesis, is an essential signal metabolite in plants, linking growth and development to carbon status. The Suc-Tre6P nexus model ...postulates that Tre6P is both a signal and negative feedback regulator of Suc levels, forming part of a mechanism to maintain Suc levels within an optimal range and functionally comparable to the insulin-glucagon system for regulating blood Glc levels in animals. The target range and sensitivity of the Tre6P-Suc feedback control circuit can be adjusted according to the cell type, developmental stage, and environmental conditions. In source leaves, Tre6P modulates Suc levels by affecting Suc synthesis, whereas in sink organs it regulates Suc consumption. In illuminated leaves, Tre6P influences the partitioning of photoassimilates between Suc, organic acids, and amino acids via posttranslational regulation of phosphoenolpyruvate carboxylase and nitrate reductase. At night, Tre6P regulates the remobilization of leaf starch reserves to Suc, potentially linking starch turnover in source leaves to carbon demand from developing sink organs. Use of Suc for growth in developing tissues is strongly influenced by the antagonistic activities of two protein kinases: SUC-NON-FERMENTING-1-RELATED KINASE1 (SnRK1) and TARGET OF RAPAMYCIN (TOR). The relationship between Tre6P and SnRK1 in developing tissues is complex and not yet fully resolved, involving both direct and indirect mechanisms, and positive and negative effects. No direct connection between Tre6P and TOR has yet been described. The roles of Tre6P in abiotic stress tolerance and stomatal regulation are also discussed.
Jasmonates (JAs) are signalling molecules involved in stress responses, development and secondary metabolism biosynthesis, although their roles in fleshy-fruit development and ripening processes are ...not well known. In strawberry fruit, it has been proposed that JAs could regulate the early development through the activation of the JAs biosynthesis. Moreover, it has been reported that JA treatment increases anthocyanin content in strawberry fruit involving the bioactive jasmonate biosynthesis. Nevertheless, JA signalling pathway, of which main components are the COI1-JAZ co-receptor and the MYC transcription factors (TFs), has not been characterized in strawberry until now. Here we identified and characterized the woodland strawberry (Fragaria vesca) JAZ and MYC genes as well as studied their expression during development and ripening stages in commercial strawberry (Fragaria × ananassa) fruit. We described twelve putative JAZ proteins and two MYC TFs, which showed high conservation with respect to their orthologs in Arabidopsis thaliana and in other fleshy-fruit species such as Malus × domestica, Vitis vinifera and Solanum lycopersicum as revealed by gene synteny and phylogenetic analyses. Noteworthy, their expression levels exhibited a significant decrease from fruit development to ripening stages in F. × ananassa, along with others of the JA signalling-related genes such as FaNINJA and FaJAMs, encoding for negative regulators of JA responses. Moreover, we found that main JA signalling-related genes such as FaMYC2, and FaJAZ1 are promptly induced by JA treatment at early times in F. × ananassa fruit. These results suggest the conservation of the canonical JA signalling pathway in strawberry and a possible role of this pathway in early strawberry fruit development, which also correlates negatively with the beginning of the ripening process.
Titanium dioxide (TiO2) possesses high photocatalytic activity, which can be utilized to power the autonomous motion of microscale objects. This paper presents the first examples of TiO2 micromotors ...and micropumps. UV‐induced TiO2 reversible microfireworks phenomenon was observed and diffusiophoresis has been proposed as a possible mechanism.
Titanium dioxide (TiO2), which possesses high photocatalytic activity, can be utilized to power the autonomous motion of microscale objects. This paper presents the first examples of TiO2 micromotors and micropumps. UV‐induced TiO2 reversible microfireworks phenomenon is observed, and diffusiophoresis is proposed as a possible mechanism.
Active biocompatible systems are of great current interest for their possible applications in drug or antidote delivery at specific locations. Herein, we report the synthesis and study of ...self-propelled microparticles powered by enzymatic reactions and their directed movement in substrate concentration gradient. Polystyrene microparticles were functionalized with the enzymes urease and catalase using a biotin-streptavidin linkage procedure. The motion of the enzyme-coated particles was studied in the presence of the respective substrates, using optical microscopy and dynamic light scattering analysis. The diffusion of the particles was found to increase in a substrate concentration dependent manner. The directed chemotactic movement of these enzyme-powered motors up the substrate gradient was studied using three-inlet microfluidic channel architecture.
The Nearest Young Moving Groups López-Santiago, J; Montes, D; Crespo-Chacón, I ...
Astrophysical journal/The Astrophysical journal,
06/2006, Letnik:
643, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The latest results in the research of forming planetary systems have led several authors to compile a sample of candidates for searching for planets in the vicinity of the Sun. Young stellar ...associations are indeed excellent laboratories for this study, but some of them are not close enough to allow the detection of planets through adaptive optics techniques. However, the existence of very close young moving groups can solve this problem. Here we have compiled the members of the nearest young moving groups, as well as a list of new candidates from our catalog of late-type stars that are possible members of young stellar kinematic groups, studying their membership through spectroscopic and photometric criteria.
•We investigate Cu tolerance and accumulation in Vitis vinifera ssp. sylvestris.•Effective concentration was higher in wild grapevine than in 41B rootstock.•Wild grapevine can be considered a ...Cu-tolerant subspecies of Vitis vinifera.•Plants from the contaminated site are more efficient in controlling root Cu content.
We evaluate copper tolerance and accumulation in Vitis vinifera ssp. sylvestris in populations from a copper contaminated site and an uncontaminated site, and in the grapevine rootstock “41B”, investigating the effects of copper (0–23mM) on growth, photosynthetic performance and mineral nutrient content. The highest Cu treatment induced nutrient imbalances and inhibited photosynthetic function, causing a drastic reduction in growth in the three study plants. Effective concentration was higher than 23mM Cu in the wild grapevines and around 9mM in the “41B” plants. The wild grapevine accessions studied controlled root Cu concentration more efficiently than is the case with the “41B” rootstock and must be considered Cu-tolerant. Wild grapevines from the Cu-contaminated site present certain physiological characteristics that make them relatively more suitable for exploitation in the genetic improvement of vines against conditions of excess Cu, compared to wild grapevine populations from uncontaminated sites.
Colloidal suspensions containing microscopic swimmers have been the focus of recent studies aimed at understanding the principles of energy transfer in fluidic media at low Reynolds number ...conditions. Going down in scale, active enzymes have been shown to be force-generating, nonequilibrium systems, thus offering opportunity to examine energy transfer at the ultralow Reynolds number regime. By monitoring the change of diffusion of inert tracers dispersed in active enzyme solutions, we demonstrate that the nature of energy transfer in these systems is similar to that reported for larger microscopic active systems, despite the large differences in scale, modes of energy transduction, and propulsion. Additionally, even an enzyme that catalyzes an endothermic reaction behaves analogously, suggesting that heat generation is not the primary factor for the observed enhanced tracer diffusion. Our results provide new insights into the mechanism of energy transfer at the molecular level.
Intrahepatic cholangiocarcinoma (iCCA) is rising in incidence, and at present, there are limited effective systemic therapies. iCCA tumours are infiltrated by stromal cells, with high prevalence of ...suppressive myeloid populations including tumour-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs). Here, we show that tumour-derived granulocyte-macrophage colony-stimulating factor (GM-CSF) and the host bone marrow is central for monopoiesis and potentiation of TAMs, and abrogation of this signalling axis facilitates antitumour immunity in a novel model of iCCA.
Blood and tumours were analysed from iCCA patients and controls. Treatment and correlative studies were performed in mice with autochthonous and established orthotopic iCCA tumours treated with anti-GM-CSF monoclonal antibody.
Systemic elevation in circulating myeloid cells correlates with poor prognosis in patients with iCCA, and patients who undergo resection have a worse overall survival if tumours are more infiltrated with CD68
TAMs. Mice with spontaneous iCCA demonstrate significant elevation of monocytic myeloid cells in the tumour microenvironment and immune compartments, and tumours overexpress GM-CSF. Blockade of GM-CSF with a monoclonal antibody decreased tumour growth and spread. Mice bearing orthotopic tumours treated with anti-GM-CSF demonstrate repolarisation of immunosuppressive TAMs and MDSCs, facilitating T cell response and tumour regression. GM-CSF blockade dampened inflammatory gene networks in tumours and TAMs. Human tumours with decreased GM-CSF expression exhibit improved overall survival after resection.
iCCA uses the GM-CSF-bone marrow axis to establish an immunosuppressive tumour microenvironment. Blockade of the GM-CSF axis promotes antitumour T cell immunity.
•Arginine enhances antimicrobial peptide activity compared to lysine.•Both permeabilizing and translocating peptides exhibit arginine effect.•Increasing arginine content is a potential strategy for ...antimicrobial peptide design.
Translocation of cell-penetrating peptides is often promoted by increased content of arginine or other guanidinium groups. However, relatively little research has considered the role of these functional groups on antimicrobial peptide activity. This study compared the activity of three histone-derived antimicrobial peptides—buforin II, DesHDAP1, and parasin—with variants that contain only lysine or arginine cationic residues. These peptides operate via different mechanisms as parasin causes membrane permeabilization while buforin II and DesHDAP1 translocate into bacteria. For all peptides, antibacterial activity increased with increased arginine content. Higher arginine content increased permeabilization for parasin while it improved translocation for buforin II and DesHDAP1. These observations provide insight into the relative importance of arginine and lysine in these antimicrobial peptides.
PDF
