Tacrine derivatives-acetylcholinesterase interaction: 1H NMR relaxation study

Two acetylcholinesterase (AChE) inhibitors structurally related to Tacrine, 6-methoxytacrine (1a) and 9-heptylamino-6-methoxytacrine (1b), and their interaction with Electrophorus Electricus AChE were investigated. The complete assignment of the 1H and 13C NMR spectra of 1a and 1b was performed by mono-dimensional and homo- and hetero-correlated two-dimensional NMR experiments. This study was undertaken to elucidate the interaction modes between AChE and 1a and 1b in solution, using NMR. The interaction between the two inhibitors and AChE was studied by the analysis of the motional parameters non-selective and selective spin-lattice relaxation times, thereby allowing the motional state of 1a and 1b, both free and bound with AChE, to be defined. The relaxation data pointed out the ligands molecular moiety most involved in the binding with AChE. The relevant ligand/enzyme interaction constants were also evaluated for both compounds and resulted to be 859 and 5412M(-1) for 1a and1b, respectively.     

Characterization of a broad range antibacterial substance from a new <Emphasis Type="Italic">Bacillus</Emphasis> species isolated from Amazon basin

A Bacillus sp. strain producing a bacteriocin-like substance was characterized by biochemical profiling and 16S rDNA sequencing. The phylogenetic analysis indicated that this strain has low sequence similarity with most Bacillus spp., suggesting a new species was isolated. The antimicrobial activity was detected starting at the exponential growth phase, and maximum activity was observed at stationary phase. The substance was inhibitory to a broad range of indicator strains, incluing pathogenic and food spoilage bacteria such as Listeria monocytogenes, B. cereus, Aeromonas hydrophila, Erwinia carotovora, Pasteurella haemolytica, Salmonella Gallinarum, among other. The antibacterial substance was stable over a wide pH range, but it was sensitive to pronase E and lipase. The antibacterial substance was bactericidal and bacteriolytic to L. monocytogenes and B. cereus at 160 AU ml⁻¹. The identification of a broad range bacteriocin-like inhibitory substance active against L. monocytogenes addresses an important aspect of food protection against pathogens and spoilage microorganisms.     

Synthesis, isomer characterization, and anti-inflammatory properties of nitroarachidonate

Nitrated fatty acids (nitroalkenes) have been recently detected and quantified in cell membranes and human plasma. However, nitration of arachidonate (AA), that could redirect AA-dependent cell signaling pathways, has not been studied in detail. Herein, we synthesized and determined for the first time the isomer distribution of nitroarachidonate (AANO2) and demonstrate its ability to modulate inflammation. Synthesis of AANO2 was achieved by AA treatment with sodium nitrite in acidic conditions following HPLC separation. Mass spectrometry (MS) analysis showed the characteristic MS/MS transition of AANO2 (m/z 348/301). Moreover, the IR signal at 1378.3 cm(-1) and NMR studies confirmed the presence of mononitrated nitroalkenes. Positional isomer distribution was determined by NMR and MS fragmentation with lithium; four major isomers (9-, 12-, 14-, and 15-AANO2) were identified, which exhibited key anti-inflammatory properties. These include their ability to release biologically relevant amounts of nitric oxide, induce cGMP-dependent vasorelaxation, and down-regulate inducible nitric oxide synthase (NOS2) expression during macrophage activation, providing unique structural evidence and novel regulatory signaling properties of AANO2.     

Modelling the distribution of stygobionts in the Jura Mountains (eastern France). Implications for the protection of ground waters

Ground waters have exceptional conservation value due to the high endemism of their biota, the high occurrence of species relicts and because they are the second most important reservoir of freshwater after the glaciers. We used habitat-based models to predict the distribution of obligate groundwater species (stygobionts) in the Jura Mountains, eastern France. Current and historical environmental variables were selected to predict the occurrence of 19 stygobionts collected in different groundwater habitats. Species occurrence was weakly correlated with most of the physico-chemical variables and better correlated to habitat type, elevation gradient, hydraulic conductivity and the distance of the last glacial event. We identified two main groups of species, those whose distributions correlated with the last glacial event and those that did not. Our findings suggested that abilities for migrate and opportunities for dispersal using connections among habitats may explain part of these distributions and that specific spatial components should be incorporated in future modelling. We propose the identification of rich-species areas and protection of the complete spectrum of GW habitats as pertinent measures to achieve the stygobitoic persistence.     

The SAUR gene family in coffee: genome-wide identification and gene expression analysis during somatic embryogenesis

Molecular Biology Reports - Small auxin-up RNA (SAUR) genes form a wide family supposedly involved in different physiological and developmental processes in plants such as leaf senescence, auxin...