Effect of iron on siderophore production and on outer membrane proteins ofRhizobium leguminosarum IARI 102

Rhizobium leguminosarum IARI 102 produced a phenolate type siderophore (a derivative of 2,3-DHBA) under iron-limited conditions. Addition of Fe³⁺ to the culture medium increased the growth yield significantly, but repressed the production of the iron-chelating compound. Iron level of culture medium also had a significant role in the composition of outer membrane proteins ofR. leguminosarum IARI 102. Maximum iron uptake was observed only in the presence of its own siderophore.     

Geomicrobiology of the carbon,nitrogen and sulphur cycles in Powell Lake: a permanently stratified water column containing ancient seawater

We present the first geomicrobiological characterization of the meromictic water column of Powell Lake (British Columbia, Canada), a former fjord, which has been stably stratified since the last glacial period. Its deepest layers (300–350 m) retain isolated, relict seawater from that period. Fine-scale vertical profiling of the water chemistry and microbial communities allowed subdivision of the water column into distinct geomicrobiological zones. These zones were further characterized by phylogenetic and functional marker genes from amplicon and shotgun metagenome sequencing. Binning of metagenomic reads allowed the linkage of function to specific taxonomic groups. Statistical analyses (analysis of similarities, Bray–Curtis similarity) confirmed that the microbial community structure followed closely the geochemical zonation. Yet, our characterization of the genetic potential relevant to carbon, nitrogen and sulphur cycling of each zone revealed unexpected features, including potential for facultative anaerobic methylotrophy, nitrogen fixation despite high ammonium concentrations and potential micro-aerobic nitrifiers within the chemocline. At the oxic–suboxic interface, facultative anaerobic potential was found in the widespread freshwater lineage acI (Actinobacteria), suggesting intriguing ecophysiological similarities to the marine SAR11. Evolutionary divergent lineages among diverse phyla were identified in the ancient seawater zone and may indicate novel adaptations to this unusual environment.     

Do People Take Stimulus Correlations into Account in Visual Search?

In laboratory visual search experiments, distractors are often statistically independent of each other. However, stimuli in more naturalistic settings are often correlated and rarely independent. Here, we examine whether human observers take stimulus correlations into account in orientation target detection. We find that they do, although probably not optimally. In particular, it seems that low distractor correlations are overestimated. Our results might contribute to bridging the gap between artificial and natural visual search tasks.     

Naphthalene-triazolopyrimidine hybrid compounds as potential multifunctional anti-Alzheimer’s agents

In an attempt to construct potential anti-Alzheimer’s agents Naphthalene-triazolopyrimidine hybrids were synthesized and screened in vitro against the two cholinesterases (ChE)s, amyloid β aggregation and for antioxidation activity. Single-crystal X-ray crystallography was utilized for crystal structure determination of one of the compounds. In vitro study of compounds revealed that most of the compounds are capable of inhibiting acetylcholinesterase and Butyrylcholinesterase activity. Particularly, the compounds 4e and 4d exhibited IC₅₀ values ranging from 8.6 to 14 nM against AChE lower than the standard drug Donepezil (IC₅₀ 49 nM). Best result was found for compound 4e with IC₅₀ of 8.6 nM (for AChE) and 150 nM (for BuChE). Selectivity upto that of Donepezil and even more was observed for 4a, 4c and 4h. Investigation by electron microscopy, transmission electron microscopy and ThT fluorescence assay unveils the fact that synthesized hybrids exhibit amyloid β self-aggregation inhibition. The compounds 4i and 4j revealed highest inhibitory potential, 85.46% and 72.77% at 50 μM respectively; above the standard Aβ disaggregating agent, Curcumin. Their antioxidation profile was also analyzed. Studies from DPPH free radical scavenging assay and ORAC assay depicts molecules to possess low antioxidation profile. Results suggest that triazolopyrimidines are potential candidate for Acetylcholinesterase (AChE), Butyrylcholinesterase (BuChE), and amyloid β aggregation inhibition. In silico ADMET profiling indicates drug-like properties with a very low toxic influence. Such synthesized compounds provide a strong vision for further development of potential anti-Alzheimer’s agents.     

RANBP2 is an allosteric activator of the conventional kinesin‐1 motor protein,KIF5B,in a minimal cell‐free system

The association of cargoes to kinesins is thought to promote kinesin activation, yet the validation of such a model with native cargoes is lacking because none is known to activate kinesins directly in an in vitro system of purified components. The RAN‐binding protein 2 (RANBP2), through its kinesin‐binding domain (KBD), associates in vivo with kinesin‐1, KIF5B/KIF5C. Here, we show that KBD and its flanking domains, RAN GTPase‐binding domains 2 and 3 (RBD2/RBD3), activate the ATPase activity of KIF5B approximately 30‐fold in the presence of microtubules and ATP. The activation kinetics of KIF5B by RANBP2 is biphasic and highly cooperative. Deletion of one of its RBDs lowers the activation of KIF5B threefold and abolishes cooperativity. Remarkably, RBD2–KBD–RBD3 induces unfolding and modest activation of KIF5B in the absence of microtubules. Hence, RANBP2 is the first native and positive allosteric activator known to jump‐start and boost directly the activity of a kinesin.     

Preformed enzyme profiling of Helicobacter pylori and Helicobacter mustelae from human and animal sources

A total of 126 strains of Helicobacter pylori from human and animal (monkey, baboon and pig) gastric mucosa, and four strains of H. mustelae were biotyped using preformed enzyme profiles (API Zym). The strains were from 10 countries and they were predominantly biotype II (85%). The other three biotypes, which were less frequently encountered, were detected with similar frequency (4–6%). There was no evidence of geographical or host-associated biotype differences. Reference strains for each of the biotypes are available from the NCTC for inclusion in future studies.     

Common precursors of human blood group MN specificities

Human blood group MM and NN specific structures have the same precursors. Complete sialic acid removal produced the Thomsen-Friedenreich T antigen which was transformed into Tn antigen by $\text{E. coli}\text{β-}\text{D}$-galactosidase on red cells as well as on isolated T antigen. MN antigens and their precursors are most clearly defined by isologous human antisera.     

The effects of nitrogen addition on the growth of two exotic and two native forest understory plants

Many studies have linked the spread of exotic, invasive species to high nitrogen supply, but most of this work does not distinguish between various inorganic forms and different concentrations of available nitrogen. Previous research has suggested that exotic, invasive species common in eastern deciduous forests may preferentially utilize nitrate in contrast to native species that preferentially make use of ammonium. We tested this hypothesis by comparing the growth response of two common forest invaders, Berberis thunbergii and Microstegium vimineum, and two co-occurring native species (Vaccinium pallidum and Hamamelis virginiana) to different forms of nitrogen under varying concentrations in a greenhouse experiment. Two forms of nitrogen (nitrate or ammonium) were added at different concentrations (22, 106, and 212 mg N l⁻¹) to all species. Growth response variables included survival, stem length, stem diameter, above and belowground biomass, and estimated seed production (Microstegium only). Unexpectedly the exotic species did not respond preferentially to nitrate addition. Microstegium responded most strongly to both nitrogen forms depending on the response variable. Berberis and Hamamelis surprisingly reacted similarly to nitrogen additions. As expected, Vaccinium fared poorly under most treatment conditions, but did show some growth in NH₄ ⁺ treatments. Our findings suggest species response to nitrogen addition is complex, and that exotic species do not all respond similarly to nitrogen inputs. In this study, the response of exotic and native species to available nutrients does not provide a general mechanism of invasion success.     

Design and Evaluation of Self-Nanoemulsifying Pellets of Repaglinide

The aim of study was to develop self-nanoemulsifying pellets (SNEP) for oral delivery of poorly water soluble drug, repaglinide (RPG). Solubility of RPG in oily phases and surfactants was determined to identify components of self-nanoemulsifying drug delivery system (SNEDDS). The surfactants and cosurfactants were screened for their ability to emulsify oily phase. Ternary phase diagrams were constructed to identify nanoemulsification area for the selected systems. SNEDDS formulations with globule size less than 100 nm were evaluated for in vivo anti-hyperglycemic activity in neonatal streptozotocin rat model. A significant reduction in glucose levels was produced by optimized SNEDDS formulation in comparison to the control group. The optimized SNEDDS formulations were pelletized via extrusion/spheronization technique using microcrystalline cellulose and lactose. SNEP were characterized by X-ray powder diffraction and scanning electron microscopy. X-ray diffraction study indicated loss of crystallinity of RPG in SNEP. The SNEP exhibited good flow properties, mechanical strength and formed nanoemulsion with globule size less than 200 nm. SNEP showed in vitro release of more than 80% RPG in 10 min which was significantly higher than RPG containing reference pellets. In conclusion, our studies illustrated that RPG, a poorly water soluble drug can be successfully formulated into SNEP which can serve as a promising system for the delivery of poorly water soluble drugs.