A colorimetric method for the enzymatic analysis of gases: the determination of ethanol and formaldehyde vapors using solid alcohol oxidase

A novel enzymatic approach to the direct determination of ethanol vapors in the gas phase is described. The system is composed of alcohol oxidase, peroxidase, and the color indicator 2,6-dichloroindophenol dispersed on microcrystalline cellulose (avicel). Simple devices are developed for the semiquantitative determination of ethanol in the breath. The devices are optimized to produce a sharp color change at a set time of 1 min for ethanol concentrations above the legal limit for driving (kinetic method) or a stable final color after 5 min (equilibrium method). Such color changes are detectable by simple visual observation. Using TLC plastic sheets and a transmittance densitometer, the system can also be used as a quantitative method for the determination of ethanol or formaldehyde vapors. Dehydrated enzymes may be useful for the analysis of hazardous gases.     

Geographic differentiation of cortical monoterpenoids of Pseudotsuga macrocarpa

Cortical essential oil from Pseudotsuga macrocarpa was analyzed for monoterpenoid compounds. Only minor differences were apparent between samples collected in different locations. Pseudotsuga macrocarpa and P. menziesii appeared to be quite distinct chemically. No evidence was obtained of any gene exchange between the two species in the southern California coastal region, where they grow a short distance from each other.     

Ecological predictors of reduced avian reproductive investment in the southern hemisphere

Despite intensive research, the factors driving spatial patterns in life‐history traits remain poorly understood. One of the most frequently documented, and paradoxically, least understood patterns, is the latitudinal gradient of increasing avian clutch size at higher latitudes. These gradients are less marked in the southern hemisphere, thus clutch sizes tend to be smaller at southern latitudes than at equivalent northern ones. We exploited a natural experiment provided by the introduction of European passerines to New Zealand (NZ) to test three widely proposed ecological drivers of this pattern, i.e. the nest predation, Ashmole’s seasonality, and the breeding density hypotheses. We focus on the blackbird Turdus merula and the song thrush T. philomelos as founder effects do not have a major influence on the reproductive traits of their introduced populations. Both species laid smaller clutches in NZ than in Europe. These reductions had stabilised within one hundred years and were not associated with a compensatory increase in investment in individual offspring by laying larger eggs. In contrast to the nest predation hypothesis, daily nest predation rates were lower in NZ than in Europe. Smaller southern hemisphere clutches were associated with higher conspecific population densities and a relaxation of seasonal clutch size trends. These findings thus provide some support for both Ashmole’s seasonality and the breeding density hypotheses. Analyses across 11 European passerines introduced to NZ suggest, however, that neither of these hypotheses provide general explanations of smaller clutches in the southern hemisphere. We suggest that reduced seasonality and lower nest predation promote increased breeding densities and adult survival in the southern hemisphere. The later may drive smaller southern clutch sizes by generating spatial variation in the outcome of the trade‐off between reproductive investment and longevity.     

Pretreatment of Cells of Klebsiella pneumoniae with 50% (v/v) Dimethylsulfoxide Yields Purified Deoxyribonucleic Acid of Low Polysaccharide Content

The flow behavior and dynamic viscoelasticity of welan gum solutions were measured with a rheogoniometer. The welan gum showed shear-thinning behavior at a concentration of 0.1%, but plastic behavior above 0.3% at 25°C. The dynamic viscoelasticity increased with increasing concentration, and was scarcely changeable with increasing temperature even at 80°C. Gelation did not occur even in a polysaccharide concentration of 1.0% at low temperature (0°C). An increase of the dynamic modulus was not observed on the addition of CaCl₂ (6.8 mm). The dynamic viscoelasticity of welan gum solution was scarcely changeable in a wide range of pH from 2 to 12. The dynamic modulus was also scarcely changeable on addition of urea (4.0 m). Possible mode of intramolecular associations between the OH-4 of the d-glucosyl residue and the adjacent hemiacetal oxygen atom of the l-rhamnosyl residue, and between the methyl group of the l-rhamnosyl residue and the adjacent hemiacetal oxygen atom of the d-glucosyl residue were proposed.     

Cyclic chalcone analogue KRP6 as a potent modulator of cell proliferation: an in vitro study in HUVECs

In the present investigation a novel series of chalcone analogues were synthesized and evaluated for their anti-proliferative activity in human umbilical vein endothelial cells (HUVECs). Among 14 tested compounds, chalcone analogue (E)-3-(2′-methoxybenzylidene)-4-chromanone (KRP6) exhibited the most potent activity with IC₅₀ 19 μM. Moreover, HUVECs exhibited divergent, even opposing concentration-dependent responses to KRP6. This compound was the most potent inhibitor of cell proliferation and extracellular matrix formation (fibronectin and type IV collagen) at higher concentrations (20–50 μM). In contrast, KRP6 stimulated the compensatory increase in proliferative activity including extracellular matrix formation at low concentrations (1, 10 μM). KRP6 concentration-dependently modulated phosphorylation of Akt and mitogen-activated protein kinases such as extracellular signal-regulated kinase-1/-2 and p38 kinase, suggesting that these pathways play a role in the effect mediated by this compound. In addition, we found a selective effect on activated endothelial cells, in particular with resting endothelial cells. In conclusion, KRP6 is a potent modulator of selected steps of the angiogenic process in vitro. Accordingly, further in vivo research should be performed to facilitate its use in clinical practice.     

Antioxidant and phenolic acid profiles of tissue cultured and acclimatized Merwilla plumbea plantlets in relation to the applied cytokinins

Merwilla plumbea (Lindl.) Speta is an important medicinal plant widely used in traditional medicine. We evaluated the effect of five cytokinins [benzyladenine (BA), 2-isopentenyladenine (2iP), meta-topolin (mT), meta-topolin riboside (mTR), and meta-methoxy-9-tetrahydropyran-2-yl-topolin (MemTTHP)] on the level of phenolic acids and antioxidant activity of M. plumbea during the tissue culture and acclimatization stages. Two cytokinins (mT and mTR) significantly improved the antioxidant activity of tissue culture plantlets while the control plantlets were better after acclimatization. Using UPLC–MS/MS, the levels of hydroxybenzoic and hydroxycinnamic acid derivatives (phenolic acids) varied significantly during tissue culture and acclimatization, depending on the cytokinin and plant part analyzed. Vanillic acid (24.9 μg g⁻¹) detected in underground parts of tissue culture plants supplemented with BA was the most abundant phenolic acid detected. The current findings indicate that the phytochemicals together with the bioactivity during in vitro propagation of M. plumbea is influenced by the cytokinin type used and the stage of plant material collection.     

The Diversity of the Limnohabitans Genus,an Important Group of Freshwater Bacterioplankton,by Characterization of 35 Isolated Strains

Bacteria of the genus Limnohabitans, more precisely the R-BT lineage, have a prominent role in freshwater bacterioplankton communities due to their high rates of substrate uptake and growth, growth on algal-derived substrates and high mortality rates from bacterivory. Moreover, due to their generally larger mean cell volume, compared to typical bacterioplankton cells, they contribute over-proportionally to total bacterioplankton biomass. Here we present genetic, morphological and ecophysiological properties of 35 bacterial strains affiliated with the Limnohabitans genus newly isolated from 11 non-acidic European freshwater habitats. The low genetic diversity indicated by the previous studies using the ribosomal SSU gene highly contrasted with the surprisingly rich morphologies and different patterns in substrate utilization of isolated strains. Therefore, the intergenic spacer between 16S and 23S rRNA genes was successfully tested as a fine-scale marker to delineate individual lineages and even genotypes. For further studies, we propose the division of the Limnohabitans genus into five lineages (provisionally named as LimA, LimB, LimC, LimD and LimE) and also additional sublineages within the most diversified lineage LimC. Such a delineation is supported by the morphology of isolated strains which predetermine large differences in their ecology.     

Neurotrophins and Neurotrophin Receptors in Proliferative Diabetic Retinopathy

Neurotrophins (NTs) are emerging as important mediators of angiogenesis and fibrosis. We investigated the expression of the NTs nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) and their receptors TrkA, TrkB, and TrkC in proliferative diabetic retinopathy (PDR). As a comparison, we examined the expression of NTs and their receptors in the retinas of diabetic rats. Vitreous samples from 16 PDR and 15 nondiabetic patients were studied by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Epiretinal membranes from 17 patients with PDR were studied by immunohistochemistry. Rats were made diabetic with a single high dose of streptozotocin and retinas of rats were examined by Western blot analysis. Western blot analysis revealed a significant increase in the expression of NT-3 and NT-4 and the shedding of receptors TrkA and TrkB in vitreous samples from PDR patients compared to nondiabetic controls, whereas NGF and BDNF and the receptor TrkC were not detected with the use of Western blot analysis and ELISA. In epiretinal membranes, vascular endothelial cells and myofibroblasts expressed NT-3 and the receptors TrkA, TrkB and TrkC in situ, whereas NT-4 was not detected. The expression levels of NT-3 and NT-4 and the receptors TrkA and TrkB, both in intact and solubilized forms, were upregulated in the retinas of diabetic rats, whereas the receptor TrkC was not detected. Co-immunoprecipitation studies revealed binding between NT-3 and the receptors TrkA and TrkB in the retinas of diabetic rats. Our findings in diabetic eyes from humans and rats suggest that the increased expression levels within the NT-3 and NT-4/Trk axis are associated with the progression of PDR.     

Large‐Scale Restoration of Dry Grasslands on Ex‐Arable Land Using a Regional Seed Mixture: Establishment of Target Species

Large‐scale (circa 500 ha) restoration of species‐rich dry grasslands was conducted using a high‐diversity regional seed mixture in the White Carpathians Protected Landscape Area and Biosphere Reserve, Czech Republic, Central Europe. After sowing, the restored grasslands were regularly mown. Vegetation was analyzed at sites restored 1–12 years ago and compared with that of ancient, extremely species‐rich grasslands nearby. Nearly all (98%) sown target species successfully established and nearly half of unsown target species established spontaneously, partly dependent on distance to the ancient grasslands. Early mowing in the first half of June appeared to support species diversity and broad‐leaved forbs at the expense of competitive grasses. Using a regional seed mixture appeared to be an effective way of restoring dry grasslands and is especially recommended in the proximity of still existing ancient grasslands where spontaneous establishment of unsown target species may reinforce the success of restoration more easily.