Circulating SARS-CoV-2 spike N439K variants maintain fitness while evading antibody-mediated immunity

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Kinetics of Insoluble Cellulose Fermentation by Continuous Cultures of Ruminococcus albus

Data from analyses of continuous culture fermentation of insoluble cellulose by Ruminococcus albus 7 were used to derive constants for the rate of cellulose hydrolysis and fermentation, growth yield, and maintenance. Cellulose concentration was 1% in the nutrient reservoir, and hydraulic retention times of 0.5, 1.0, 1.5, 1.75, and 2.0 days were used. Concentrations of reducing sugars in the cultures were negligible (less than 1%) compared with the amount of hydrolyzed cellulose, indicating that cellulose hydrolysis was the rate-limiting step of the fermentation. The rate of utilization of cellulose depended on the steady-state concentration of cellulose and was first order with a rate constant (k) of 1.18 day⁻¹. The true microbial growth yield (Y) was 0.11 g g⁻¹, the maintenance coefficient (m) was 0.10 g g⁻¹ h⁻¹, and the maximum Y_ATP was 7.7 g of biomass (dry weight) mol of ATP⁻¹.     

Syntaxonomic typology of Greek habitats

A review of the vegetation of Greece, following the hierarchical system of four main syntaxonomic levels (association, alliance, order, class) is presented and the correspondence of the high-ranked syntaxa with the Habitat Types included in Annex I of the Directive 92/43/EEC has been prepared. The syntaxonomic list of the vegetation units of Greece (up to alliance level) is composed of 41 classes, 56 orders, and 91 alliances. Of the 226 Habitat Types listed in Annex I of Directive 92/43/EEC, 111 different Habitat Types are present in Greece, of which 26 are Priority Types. The establishment of a syntaxonomic typology for the Habitat Types recorded in Greece is essential for the sake of vegetation mapping and nature conservation. A habitat coding system, as applied in Spain, is proposed for Greece for mapping purposes. *** DIRECT SUPPORT *** A02DO015 00007     

Metal complexes of 1-methyl-3,4-diphenylpyrazole,a ligand formed by the reaction between benzil and N,N,-dimethylhydrazine

New complexes of the general formulae MnX₂L₂ (X = Cl,Br), MnBr₂L₃, CoX₂L₂ (X = Cl, Br, I, NCS, NO₃), NiX₂L₂ (X = Cl, NO₃), NiBr₂L₃·H₂O, NiL₂L₄·H₂O, CuCl₂L, CuBr₂L₂·H₂O, Cu(NO₃)₂L₂, ZnX₂L₂ (X = Cl, Br, NO₃, Zn(NCS)₂L₂·H₂O, CdX₂L₂ (X = I, NO₃) and HgCl₂L, where L is 1-methyl-3,4-diphenylpyrazole, have been prepared and characterized by elemental analysis, conductivity measurements, magnetic moments and spectral (¹H-NMR, IR and electronic) studies. The ligands is formed by the reaction between benzil and N,N-dimethylhydrazine. The nitrogen of the >CN bond is the donor atom to the metal ions. The bis-ligand halide complexes are pseudotetrahedral, while the nitrate complexes contain octahedrally coordinated metal ions. The IR spectra of MCl₂L (M = Cu, Hg) are indicative of the presence of both terminal and bridging metal-halogen bonds supporting polymeric structures. The stereochemistry and the nature of the nickel(II) complexes are markedly dependent upon the anions; the chloride complex is pseudotetrahedral, the iodide square planar, the nitrate polymeric octahedral, while the proposed structural formula for NiBr₂L₃·H₂O comprises Nickel(II) atoms present in both square planar and octahedral coordination environments.     

Competition for shelter occupancy between a native freshwater crab and an invasive crayfish

Aquatic Ecology - Potamon potamios populations have decreased significantly due to the degradation of its habitat caused by human activities, mainly the use of insecticides. Today, P. potamios is...     

The greatly increased amounts of accumulated versican and decorin with specific post-translational modifications may be closely associated with the malignant phenotype of pancreatic cancer

Pancreatic carcinoma (PC) is a cancer type with highly malignant growth and dissemination pattern of which the mechanisms are poorly understood. However, the malignant phenotype is closely linked to extracellular matrix (ECM) of which proteoglycans (PGs) and hyaluronan (HA) play a crucial role in the control of tumor progression and metastasis. In this study, we demonstrated that versican and decorin, two different PGs with contradictory roles and functions in the pathobiology of cancer, were the main matrix PGs in PC presenting a great increase 27- and 7-fold, respectively, in comparison to normal pancreas (NP). PC was characterized by the disproportional increase of versican compared to decorin, about 4 to 1, with a concurrent increase of HA, which may be closely associated with the growth and aggressiveness of this carcinoma. Significant specific post-translational modifications were also observed in both versican and decorin regarding the type, hydrodynamic size, sulfation pattern and extent of uronate epimerization of their glycosaminoglycan chains (GAGs). In particular, chondroitin sulphate (CS) was the predominant GAG type in both PC-associated versican and decorin. The CS of PC-decorin was increased 11-fold, compared to NP in which dermatan sulfate (DS) was the predominant GAG type in both PGs. The sulfation pattern of GAG chains was significantly altered in PC, since 6-sulfated disaccharides predominated in both versican and decorin with a marked presence of non-sulfated disaccharides accompanied by lower hydrodynamic sizes of both CS and DS chains compared to NP. In conclusion, all these findings agree with the highly malignant phenotype of this cancer and, thus, more studies need to be addressed on the roles of the post-translational modifications of versican and decorin in the biology of cancer.     

Glucose-based spiro-isoxazolines: A new family of potent glycogen phosphorylase inhibitors

A series of glucopyranosylidene-spiro-isoxazolines was prepared through regio- and stereoselective [3+2]-cycloaddition between the methylene acetylated exo-glucal and aromatic nitrile oxides. The deprotected cycloadducts were evaluated as inhibitors of muscle glycogen phosphorylase b. The carbohydrate-based family of five inhibitors displays K_i values ranging from 0.63 to 92.5 μM. The X-ray structures of the enzyme–ligand complexes show that the inhibitors bind preferentially at the catalytic site of the enzyme retaining the less active T-state conformation. Docking calculations with GLIDE in extra-precision (XP) mode yielded excellent agreement with experiment, as judged by comparison of the predicted binding modes of the five ligands with the crystallographic conformations and the good correlation between the docking scores and the experimental free binding energies. Use of docking constraints on the well-defined positions of the glucopyranose moiety in the catalytic site and redocking of GLIDE-XP poses using electrostatic potential fit-determined ligand partial charges in quantum polarized ligand docking (QPLD) produced the best results in this regard.     

The binding of β-d-glucopyranosyl-thiosemicarbazone derivatives to glycogen phosphorylase: A new class of inhibitors

Glycogen phosphorylase (GP) is a promising target for the treatment of type 2 diabetes. In the process of structure based drug design for GP, a group of 15 aromatic aldehyde 4-(β-d-glucopyranosyl)thiosemicarbazones have been synthesized and evaluated as inhibitors of rabbit muscle glycogen phosphorylase b (GPb) by kinetic studies. These compounds are competitive inhibitors of GPb with respect to α-d-glucose-1-phosphate with IC₅₀ values ranging from 5.7 to 524.3 μM. In order to elucidate the structural basis of their inhibition, the crystal structures of these compounds in complex with GPb at 1.95–2.23 Å resolution were determined. The complex structures reveal that the inhibitors are accommodated at the catalytic site with the glucopyranosyl moiety at approximately the same position as α-d-glucose and stabilize the T conformation of the 280s loop. The thiosemicarbazone part of the studied glucosyl thiosemicarbazones possess a moiety derived from substituted benzaldehydes with NO₂, F, Cl, Br, OH, OMe, CF₃, or Me at the ortho-, meta- or para-position of the aromatic ring as well as a moiety derived from 4-pyridinecarboxaldehyde. These fit tightly into the β-pocket, a side channel from the catalytic site with no access to the bulk solvent. The differences in their inhibitory potency can be interpreted in terms of variations in the interactions of the aldehyde-derived moiety with protein residues in the β-pocket. In addition, 14 out of the 15 studied inhibitors were found bound at the new allosteric site of the enzyme.