6-C-glucosylnaringenin from flowers of Acacia retinoide

From the flowers of Acacia retinoide 6-C-glucosylnaringenin has been identified.     

Temperature dependence of intracellular pH in higher plant cells

The recent introduction of ³¹P nuclear magnetic resonance spectroscopy offers a new approach to the problem of obtaining a simultaneous and direct evaluation of both the cytoplasmic and vacuolar pH in higher plant cells (J. K. M. Roberts, P.M. Ray, N. Waderlardetzky and O. Sardetzky, 1980, Nature 283, 870–872; 1981, Planta 152, 74–78). Using this method we have been able to detect a selective pH decrease of about 0.5 units at the level of the cytoplasmic compartment of maize root tips when the temperature was increased from 4 to 28°C. This effect was completely reversible with temperature. No pH variation could be detected at the level of the vacuolar compartment.     

Determination of secondary structure of normal fibrin from human peripheral blood

The secondary structure of human fibrin from normal donors and from bovine and suilline plasma was studied by Fourier transform ir spectroscopy and a quantitative analysis of its secondary structure was suggested. For this purpose, a previously experimented spectrum deconvolution procedure based on the use of the Conjugate Gradient Minimisation Algorithm with the addition of suitable constraints was applied to the analysis of conformation-sensitive amide bands. This procedure was applied to amide I and III analysis of bovine and suilline fibrin, obtained industrially, and to amide III analysis of human fibrin clots. The analysis of both amide I and III in the first case was useful in order to test the reliability of the method. We found bovine, suilline, and human fibrin to contain about 30% α-helix (amide I and III components at 1653 cm⁻¹, and 1312 and 1284 cm⁻¹, respectively), 40% β-sheets (amide I and III components at 1625 and 1231 cm⁻¹, respectively) and 30% turns (amide I and III components at 1696, 1680, 1675 cm⁻¹, and 1249 cm⁻¹, respectively). The precision of the quantitative determination depends on the amount of these structures in the protein. Particularly, the coefficient of variation is < 10% for percentage values of amide I and III components > 15 and 5%, respectively. The good agreement of our quantitative data, obtained separately by amide I and amide III analysis, and consistent with a previous fibrinogen (from commercial sources) study that reports only information about fibrin β-sheet content obtained by factor analysis, leads us to believe that the amounts of secondary structures found (α-helix, β-sheets, and turns) are accurate. © 1997 John Wiley & Sons, Inc. Biopoly 41: 545–553, 1997.     

C-ferroptosis is an iron-dependent form of regulated cell death in cyanobacteria

Ferroptosis is an oxidative and iron-dependent form of regulated cell death (RCD) recently described in eukaryotic organisms like animals, plants, and parasites. Here, we report that a similar process takes place in the photosynthetic prokaryote Synechocystis sp. PCC 6803 in response to heat stress. After a heat shock, Synechocystis sp. PCC 6803 cells undergo a cell death pathway that can be suppressed by the canonical ferroptosis inhibitors, CPX, vitamin E, Fer-1, liproxstatin-1, glutathione (GSH), or ascorbic acid (AsA). Moreover, as described for eukaryotic ferroptosis, this pathway is characterized by an early depletion of the antioxidants GSH and AsA, and by lipid peroxidation. These results indicate that all of the hallmarks described for eukaryotic ferroptosis are conserved in photosynthetic prokaryotes and suggest that ferroptosis might be an ancient cell death program.     

Effectiveness of a WHO self‐help psychological intervention for preventing mental disorders among Syrian refugees in Turkey: a randomized controlled trial

Refugees are at high risk of developing mental disorders. There is no evidence from randomized controlled trials (RCTs) that psychological interventions can prevent the onset of mental disorders in this group. We assessed the effectiveness of a self‐help psychological intervention developed by the World Health Organization, called Self‐Help Plus, in preventing the development of mental disorders among Syrian refugees experiencing psychological distress in Turkey. A two‐arm, assessor‐masked RCT was conducted in two Turkish areas. Eligible participants were adult Syrian refugees experiencing psychological distress (General Health Questionnaire ≥3), but without a diagnosis of mental disorder. They were randomly assigned either to the Self‐Help Plus arm (consisting of Self‐Help Plus combined with Enhanced Care as Usual, ECAU) or to ECAU only in a 1:1 ratio. Self‐Help Plus was delivered in a group format by two facilitators over five sessions. The primary outcome measure was the presence of any mental disorder assessed by the Mini International Neuropsychiatric Interview at six‐month follow‐up. Secondary outcome measures were the presence of mental disorders at post‐intervention, and psychological distress, symptoms of post‐traumatic stress disorder and depression, personally identified psychological outcomes, functional impairment, subjective well‐being, and quality of life at post‐intervention and six‐month follow‐up. Between October 1, 2018 and November 30, 2019, 1,186 refugees were assessed for inclusion. Five hundred forty‐four people were ineligible, and 642 participants were enrolled and randomly assigned to either Self‐Help Plus (N=322) or ECAU (N=320). Self‐Help Plus participants were significantly less likely to have any mental disorders at six‐month follow‐up compared to the ECAU group (21.69% vs. 40.73%; Cramer''s V = 0.205, p<0.001, risk ratio: 0.533, 95% CI: 0.408‐0.696). Analysis of secondary outcomes suggested that Self‐Help Plus was not effective immediately post‐intervention, but was associated with beneficial effects at six‐month follow‐up in terms of symptoms of depression, personally identified psychological outcomes, and quality of life. This is the first prevention RCT ever conducted among refugees experiencing psychological distress but without a mental disorder. Self‐Help Plus was found to be an effective strategy for preventing the onset of mental disorders. Based on these findings, this low‐intensity self‐help psychological intervention could be scaled up as a public health strategy to prevent mental disorders in refugee populations exposed to ongoing adversities.     

Liver albumin synthesis increases in free ribosomes during the acute-phase reaction

Albumin concentration in the blood, and its synthesis by the liver, decrease in the rat during the acute-phase response to inflammation. In this paper we show that 24 hours after turpentine treatment free ribosomes from rat liver double their albumin synthesis and release preproalbumin in the cytosol. albumin mRNA from free polysomes, tested in reconstructed systems in vitro, directs the synthesis of preproalbumin which is correctly processed in the presence of microsomal membranes. Albumin mRNA in the free ribosomal fraction decreases in amount, but it is mainly associated with the heavier polysomal fraction. These data favor the hypothesis of a more, efficient utilization of the reduced amount of albumin mRNA, concurrent with failure of translational arrest of the nascent chain and with the release of unprocessed product in the cytosol.     

Plant amine oxidases “on the move”: An update

Amine oxidases (AOs) catalyse the oxidative de-amination of polyamines, ubiquitous polycationic compounds involved in important events of cell life. They include the copper-containing amine oxidases (CuAOs; EC 1.4.3.6) and the flavin-containing polyamine oxidases (PAOs; EC 1.5.3.11). The main physiological role of these moonlighting proteins has been linked to compartment-specific H₂O₂ synthesis in different phases of development and differentiation as well as in the course of defence mechanisms against pathogens and abiotic stress. Moreover, several studies evidenced a correlation of AO expression levels with physiological stages characterized by intense metabolism, such as cell division or organ formation, thus leaving open the hypothesis that AOs may have also a role in the regulation of cell cycle through the modulation of polyamine cellular content. This update will deal with recent reports on the involvement of CuAOs and PAOs in abiotic (salt) stress, wound-healing and host–pathogen interactions.     

Streptococcus pneumoniae Invades Endothelial Host Cells via Multiple Pathways and Is Killed in a Lysosome Dependent Manner

Streptococcus pneumoniae is one of the major causative agents of pneumonia, sepsis, meningitis and other morbidities. In spite of its heavy disease burden, surprisingly little is known about the mechanisms involved in the switch of life style, from commensal colonizer of the nasopharynx to invasive pathogen. In vitro experiments, and mouse models have shown that S. pneumoniae can be internalized by host cells, which coupled with intracellular vesicle transport through the cells, i.e. transcytosis, is suggested to be the first step of invasive disease. To further dissect the process of S. pneumoniae internalization, we chemically inhibited discrete parts of the cellular uptake system. We show that this invasion of the host cells was facilitated via both clathrin- and caveolae-mediated endocytosis. After internalization we demonstrated that the bulk of the internalized S. pneumoniae was killed in the lysosome. Interestingly, inhibition of the lysosome altered transcytosis dynamics as it resulted in an increase in the transport of the internalized bacteria out of the cells via the basal side. These results show that uptake of S. pneumoniae into host cells occurs via multiple pathways, as opposed to the often proposed view of invasion being dependent on specific, and singular receptor-mediated endocytosis. This indicates that the endothelium not only has a critical role as a physical barrier against S. pneumoniae in the blood stream, but also in degrading S. pneumonia cells that have adhered to, and invaded the endothelial cells.     

Systematic discovery of new recognition peptides mediating protein interaction networks

Many aspects of cell signalling, trafficking, and targeting are governed by interactions between globular protein domains and short peptide segments. These domains often bind multiple peptides that share a common sequence pattern, or “linear motif” (e.g., SH3 binding to PxxP). Many domains are known, though comparatively few linear motifs have been discovered. Their short length (three to eight residues), and the fact that they often reside in disordered regions in proteins makes them difficult to detect through sequence comparison or experiment. Nevertheless, each new motif provides critical molecular details of how interaction networks are constructed, and can explain how one protein is able to bind to very different partners. Here we show that binding motifs can be detected using data from genome-scale interaction studies, and thus avoid the normally slow discovery process. Our approach based on motif over-representation in non-homologous sequences, rediscovers known motifs and predicts dozens of others. Direct binding experiments reveal that two predicted motifs are indeed protein-binding modules: a DxxDxxxD protein phosphatase 1 binding motif with a K_D of 22 μM and a VxxxRxYS motif that binds Translin with a K_D of 43 μM. We estimate that there are dozens or even hundreds of linear motifs yet to be discovered that will give molecular insight into protein networks and greatly illuminate cellular processes.     

Concerted regulation of nuclear and cytoplasmic activities of SR proteins by AKT

Serine/arginine-rich (SR) proteins are important regulators of mRNA splicing. Several postsplicing activities have been described for a subset of shuttling SR proteins, including regulation of mRNA export and translation. Using the fibronectin gene to study the links between signal-transduction pathways and SR protein activity, we show that growth factors not only modify the alternative splicing pattern of the fibronectin gene but also alter translation of reporter messenger RNAs in an SR protein-dependent fashion, providing two coregulated levels of isoform-specific amplification. These effects are inhibited by specific small interfering RNAs against SR proteins and are mediated by the AKT kinase, which elicits opposite effects to those evoked by overexpressing SR protein kinases Clk and SRPK. These results show how SR protein activity is modified in response to extracellular stimulation, leading to a concerted regulation of splicing and translation.