Efficient hydrogen production from the lignocellulosic energy crop Miscanthus by the extreme thermophilic bacteria Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana

Background  

The production of hydrogen from biomass by fermentation is one of the routes that can contribute to a future sustainable hydrogen economy. Lignocellulosic biomass is an attractive feedstock because of its abundance, low production costs and high polysaccharide content.     

ESCRT‐II functions by linking to ESCRT‐I in human immunodeficiency virus‐1 budding

Human immunodeficiency virus (HIV) uses the ESCRT (endosomal sorting complexes required for transport) protein pathway to bud from infected cells. Despite the roles of ESCRT‐I and ‐III in HIV budding being firmly established, participation of ESCRT‐II in this process has been controversial. EAP45 is a critical component of ESCRT‐II. Previously, we utilised a CRISPR‐Cas9 EAP45 knockout cell line to assess the involvement of ESCRT‐II in HIV replication. We demonstrated that the absence of ESCRT‐II impairs HIV budding. Here, we show that virus spread is also defective in physiologically relevant CRISPR/Cas9 EAP45 knockout T cells. We further show reappearance of efficient budding by re‐introduction of EAP45 expression into EAP45 knockout cells. Using expression of selected mutants of EAP45, we dissect the domain requirement responsible for this function. Our data show at the steady state that rescue of budding is only observed in the context of a Gag/Pol, but not a Gag expressor, indicating that the size of cargo determines the usage of ESCRT‐II. EAP45 acts through the YPXL‐ALIX pathway as partial rescue is achieved in a PTAP but not a YPXL mutant virus. Our study clarifies the role of ESCRT‐II in the late stages of HIV replication and reinforces the notion that ESCRT‐II plays an integral part during this process as it does in sorting ubiquitinated cargos and in cytokinesis.     

Plasma oxysterols and angiographically determined coronary atherosclerosis: a case control study

Several in vitro and in vivo experiments have implicated oxysterols in the aetiology and progression of atherosclerosis. Oxysterols may be formed endogenously by oxidation of cholesterol and thus may form a marker of LDL oxidation. They may also be obtained exogenously through dietary intake. We investigated the association of oxysterols with the degree of coronary stenosis in patients undergoing coronary angiography. Cases with severe coronary atherosclerosis 80 stenosis in one of the major coronary vessels, n =80 were compared with controls with no or minor stenosis 50 stenosis in all three major coronary vessels, n =79 . Cases and controls were prestratified on age, gender and smoking habits. Evaluated were plasma levels of unesterified 7 hydroxycholesterol, 7 hydroxycholesterol, 25 hydroxycholesterol, 7 ketocholesterol, cholestane triol and 5,6 epoxycholestanol. 7 Hydroxycholesterol made up 67 of the total amount of plasma oxysterol concentration and was the only one significantly higher in cases 1.53 mu g per 100 ml vs 1.27 mu g per 100 ml, p 0.05 . Further, cases had somewhat higher LDL cholesterol levels and significantly lower HDL cholesterol levels than controls. After multivariate adjustment to account for this difference in lipid levels and for the prestratification factors the mean difference between cases and controls for 7 hydroxycholesterol 0.14 mu g per 100 ml was no longer significant. Also the other oxysterols showed no significant association with the degree of coronary stenosis. Multiple logistic regression analyses showed an adjusted odds ratio of 1.07 95 CI, 0.45-2.59 in the highest tertile of total plasma oxysterol level. We conclude, that this study does not support the hypothesis that plasma oxysterols form an additional risk factor for coronary atherosclerosis.     

Synthesis of cyclic α-MSH peptides

Summary Cyclic lactam analogs of α-melanocyte stimulating hormone (α-MSH) have been shown to be potent agonists in the frog skin bioassay [Al-Obeidi, F. et al., J. Med. Chem., 32 (1989) 2555], demonstrating melanocortin-1 (MC1) receptor activity. We synthesized cyclic α-MSH(1–13) and α-MSH(4–10) lactam analogs. The peptides were synthesized using Fmoc chemistry. We improved the cyclization procedure: side chains of Asp⁵ and Lys¹⁰ from the deprotected peptide were coupled in DMF to form a cyclic lactam, using an excess of PyBOP reagent and DIEA as a base. The cyclization reaction was completed within 1 h and was almost quantitative. We also synthesized an α-MSH analog cyclized via a disulphide bridge. The peptides were tested for their selectivity for the rat MC4 receptor. Cyclization and substitutions at position 7 dramatically influenced the selectivity for the rMC4 receptor.     

Neuron‐specific translational control shift ensures proteostatic resilience during ER stress

Proteostasis is essential for cellular survival and particularly important for highly specialised post‐mitotic cells such as neurons. Transient reduction in protein synthesis by protein kinase R‐like endoplasmic reticulum (ER) kinase (PERK)‐mediated phosphorylation of eukaryotic translation initiation factor 2α (p‐eIF2α) is a major proteostatic survival response during ER stress. Paradoxically, neurons are remarkably tolerant to PERK dysfunction, which suggests the existence of cell type‐specific mechanisms that secure proteostatic stress resilience. Here, we demonstrate that PERK‐deficient neurons, unlike other cell types, fully retain the capacity to control translation during ER stress. We observe rescaling of the ATF4 response, while the reduction in protein synthesis is fully retained. We identify two molecular pathways that jointly drive translational control in PERK‐deficient neurons. Haem‐regulated inhibitor (HRI) mediates p‐eIF2α and the ATF4 response and is complemented by the tRNA cleaving RNase angiogenin (ANG) to reduce protein synthesis. Overall, our study elucidates an intricate back‐up mechanism to ascertain translational control during ER stress in neurons that provides a mechanistic explanation for the thus far unresolved observation of neuronal resilience to proteostatic stress.     

Antifungal activity of synthetic peptides derived from Impatiens balsamina antimicrobial peptides Ib-AMP1 and Ib-AMP4

Seeds of Impatiens balsamina contain a set of related antimicrobial peptides (Ib-AMPs). We have produced a synthetic variant of Ib-AMP1, oxidized to the bicyclic native conformation, which was fully active on yeast and fungal strains; and four linear 20-mer Ib-AMP variants, including two all-D forms. We show that the all-D variants are as active on yeast and fungal strains as native peptides. In addition, fungal growth inhibition nor salt-dependency of Ib-AMP4 could be improved by more than two-fold via replacement of amino acid residues by arginine or tryptophan. Native Ib-AMPs showed no hemolytic nor toxic activity up to a concentration of 100 microM. All these data demonstrate the potential of the native Ib-AMPs to combat fungal infections.     

Structure and thermal stability of pyruvated carrageenans from the red alga Coccotylus truncatus

The composition, structure, and thermal stability of carrageenans from unattached Coccotylus truncatus (the Baltic Sea, Estonia) were investigated. The complex polysaccharide was characterized by ¹³C NMR and FTIR spectroscopy, ICP-OES and gel permeation chromatography methods. The main components of C. truncatus galactan are 3,6-anhydro-α-d-galactose-2-sulfate (30 ± 1.5%) and β-d-galactose-4-sulfate (45.3%), indicating a ι-carrageenan backbone. As the minor components, α-d-galactose-2,6-disulfate (12 ± 2%) from ν-carrageenan and 4′,6′-pyruvated β-d-galactopyranosyl residues (1.4%) from pyruvated α-carrageenan are found to be present, latter being responsible for the undersulfated nature of the galactan. The native polysaccharide with the average molecular weight of about 1500 kDa is highly susceptible to thermal degradation. The high-temperature treatment of this galactan gives products with 3,6-anhydro-α-d-galactose units predominantly at the reducing end. The carrageenan extraction from C. truncatus gives characteristically low yields (12-17%); weak gelling ability of the polysaccharides from this seaweed species (gel strength 30-40 g/cm²) does not depend significantly on extraction conditions.