Coating polypropylene surfaces with protease weakens the adhesion and increases the dispersion of <Emphasis Type="Italic">Candida albicans</Emphasis> cells

Objectives

To investigate the ability of the proteases, subtilisin and α-chymotrypsin (aCT), to inhibit the adhesion of Candida albicans biofilm to a polypropylene surface.

Results

The proteases were immobilized on plasma-treated polypropylene by covalently linking them with either glutaraldehyde (GA) or N′-diisopropylcarbodiimide (DIC) and N-hydroxysuccinimide (NHS). The immobilization did not negatively affect the enzyme activity and in the case of subtilisin, the activity was up to 640% higher than that of the free enzyme when using N-acetyl phenylalanine ethyl ester as the substrate. The efficacies against biofilm dispersal for the GA-linked SubC and aCT coatings were 41 and 55% higher than the control (polypropylene coated with only GA), respectively, whereas no effect was observed with enzymes immobilized with DIC and NHS. The higher dispersion efficacy observed for the proteases immobilized with GA could be both steric (proper orientation of the active site) and dynamic (higher protein mobility/flexibility).

Conclusions

Proteases immobilized on a polypropylene surface reduced the adhesion of C. albicans biofilms and therefore may be useful in developing anti-biofilm surfaces based on non-toxic molecules and sustainable strategies.

     

Reduction of indole‐3‐acetic acid methyltransferase activity compensates for high‐temperature male sterility in Arabidopsis

High temperature is a general stress factor that causes a decrease in crop yield. It has been shown that auxin application reduces the male sterility caused by exposure to higher temperatures. However, widespread application of a hormone with vast effects on plant physiology may be discouraged in many cases. Therefore, the generation of new plant varieties that locally enhance auxin in reproductive organs may represent an alternative strategy. We have explored the possibility of increasing indole‐3‐acetic acid (IAA) in ovaries by reducing IAA methyltransferase1 (IAMT1) activity in Arabidopsis thaliana. The iamt1 mutant showed increased auxin signalling in funiculi, which correlated with a higher growth rate of wild‐type pollen in contact with mutant ovaries and premature ovule fertilization. While the production of seeds per fruit was similar in the wild type and the mutant at 20 °C, exposure to 29 °C caused a more severe decrease in fertility in the wild type than in the mutant. Loss of IAMT1 activity was also associated with the production of more nodes after flowering and higher tolerance of the shoot apical meristem to higher temperatures. As a consequence, the productivity of the iamt1 mutant under higher temperatures was more than double of that of the wild type, with almost no apparent trade‐off.     

Uric Acid Metabolism in Patients with Primary Gout and the Metabolic Syndrome

Forty-four patients (40 males) with a mean age of 58 years were included in this pilot study. Mean serum urate concentration in patients with and without the metabolic syndrome (MS) was 8.8 mg/dL and 8.1 mg/dL, respectively. Urinary uric acid excretion was 543 mg/day/1.73m² in the former and 609 mg/day/1.73m² in the latter. Uric acid to creatinine ratio was 0.37 mg/mg in patients with the MS and 0.42 mg/mg in those without the MS. Mean serum urate increased from 8.6 mg/dL in subjects with three or more MS components to 10.3 mg/dL in those with five MS components. Serum urate was markedly lower in patients with mild MS (9 patients, 8.6 mg/dL) as compared to severe MS (10 patients, 9.2 mg/dL). In contrast, urinary uric acid to creatinine ratio was 0.42 mg/mg in patients with gout and mild MS and 0.33 mg/mg in gout patients with severe MS. Uric acid underexcretion appears to be more severe in gout patients with the MS. This disturbance appears to be related to the severity of the MS.     

1,2-Disubstituted Carbocyclic Analogues of Thymine Nucleosides

Abstract

A series of o ne t wo c arbonucleoside (OTC) analogues of thymine was synthetized and their conformation was studied by AM1 theoretical calculations. The low-energy conformations of Compound 1 and 2′,3′-dideoxythymidine, showed a degree of steric congruity.     

Endocytosis optimizes the dynamic localization of membrane proteins that regulate cortical polarity

Diverse cell types require the ability to maintain dynamically polarized membrane-protein distributions through balancing transport and diffusion. However, design principles underlying dynamically maintained cortical polarity are not well understood. Here we constructed a mathematical model for characterizing the morphology of dynamically polarized protein distributions. We developed analytical approaches for measuring all model parameters from single-cell experiments. We applied our methods to a well-characterized system for studying polarized membrane proteins: budding yeast cells expressing activated Cdc42. We found that a balance of diffusion, directed transport, and endocytosis was sufficient for accurately describing polarization morphologies. Surprisingly, the model predicts that polarized regions are defined with a precision that is nearly optimal for measured endocytosis rates and that polarity can be dynamically stabilized through positive feedback with directed transport. Our approach provides a step toward understanding how biological systems shape spatially precise, unambiguous cortical polarity domains using dynamic processes.     

Innovative metal oxide-based substrates for DNA microarrays

In the present report, we propose a novel approach to synthesize DNA microarrays that employs immobilization of the nucleic acid molecules onto zinc and iron oxide surfaces through their phosphate backbone. Oxide films were prepared by the sol–gel technique and the resulting surfaces were characterized especially with respect to surface chemistry and morphological features by both X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). ZnO films annealed at T ? 300 °C show the most promising surface features to be employed for DNA microarray preparation, i.e. high density of binding sites (hydroxyl groups), smooth and homogeneous surfaces, high optical transmittance in the visible spectral range suitable for detection using fluorescence, and easy handling during preparation procedures. The analysis of nucleic acid retention on the oxide layers was performed by the scanning of dye-labelled DNA previously printed on the substrate using the DNA microarray robotic arm. Clearly visible spots with regular shape were revealed above the background noise indicating that anchoring of the DNA on the treated surface is efficient and does not interfere with hybridization processes. The use of suitably engineered zinc oxide film makes the immobilization strategy ideal for facile, efficient, and cost-effective manufacturing of DNA microarrays.     

Low temperature optical spectroscopy of cobalt-substituted hemocyanin from Carcinus maenas

In this work we report the optical absorption spectra of three cobalt-substituted derivatives of hemocyanin (He) from Carcinus maenas, in the temperature range 300–20 K. The derivatives studied are the mononuclear (Co²⁺)-He with a single cobalt ion in the Cu_A site, the binuclear (Co²⁺)₂-He and the binuclear mixed metal (Co²⁺-Cu¹⁺)-He. At low temperature three main bands are clearly resolved; the temperature dependence of their zeroth, first and second moments sheds light on the stereodynamic properties in the surroundings of the chromophore. Within the limits of the reported analysis, in the binuclear derivatives the motions coupled to the chromophore appear to be essentially harmonic in the whole temperature range investigated; moreover the data are consistent with the presence of an exogenous ligand strongly bound to the two metal ions. For the mononuclear derivative an essentially harmonic behavior is evident only up to 200 K where the data are consistent with the presence of an exogenous ligand much less strongly bound, while at higher temperatures the behavior of the spectra indicates the onset of very large anharmonic contributions to motions, that plausibly involve the above exogenous ligand and, quite likely, the entire active site.Abbreviations He Hemocyanin - M₀ zeroth moment - M₁ first moment - M₂ second moment - (Co^2–)₂-He binuclear bicobalt hemocyanin derivative - (Co²⁺)-He mononuclear monocobalt hemocyanin derivative - (Co²⁺-Cu¹⁺)-He binuclear mixed metals hemocyanin derivative - LFT ligand field theory - CT charge transfer - EPR electronic paramagnetic resonance - XANES X-ray absorption near edge structure Correspondence to: L. Cordone     

Biliverdin reductase-A protein levels and activity in the brains of subjects with Alzheimer disease and mild cognitive impairment

Biliverdin reductase-A is a pleiotropic enzyme involved not only in the reduction of biliverdin-IX-alpha into bilirubin-IX-alpha, but also in the regulation of glucose metabolism and cell growth secondary to its serine/threonine/tyrosine kinase activity. Together with heme oxygenase, whose metabolic role is to degrade heme into biliverdin-IX-alpha, it forms a powerful system involved in the cell stress response during neurodegenerative disorders. In this paper, an up-regulation of the biliverdin reductase-A protein levels was found in the hippocampus of the subjects with Alzheimer disease and arguably its earliest form, mild cognitive impairment. Moreover a significant reduction in the phosphorylation of serine, threonine and tyrosine residues of biliverdin reductase-A was found, and this was paralleled by a marked reduction in its reductase activity. Interestingly, the levels of both total and phosphorylated biliverdin reductase-A were unchanged as well as its enzymatic activity in the cerebella. These results demonstrated a dichotomy between biliverdin reductase-A protein levels and activity in the hippocampus of subjects affected by Alzheimer disease and mild cognitive impairment, and this effect likely is attributable to a reduction in the phosphorylation of serine, threonine and tyrosine residues of biliverdin reductase-A. Consequently, not just the increased levels of biliverdin reductase-A, but also its changed activity and phosphorylation state, should be taken into account when considering potential biomarkers for Alzheimer disease and mild cognitive impairment.