Comparison of bacterial and plant genes participating in proline biosynthesis with Osmotin gene, with respect to enhancing salinity tolerance of transgenic tobacco plants

In an attempt to increase tolerance to salinity stress in tobacco plants, the genes encoding the mutant form of glutamyl kinase (proB), pyrroline-5-carboxylate synthetase, and osmotin were cloned into three different shuttle vectors and were separately introduced into the tobacco plants. The transgenic lines were compared for their ability to produce shoots and grow in MS medium containing 320 mM NaCl; it was shown that the transgenic lines containing genetically handled osmotin gene are more resistant to salinity. The amount of chlorophyll a was used to show continuing growth of plant lines. The results showed that only the tobacco lines transformed with the modified osmotin gene exhibited greater tolerance to salinity. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 122–127. The text was submitted by the authors in English.     

Terahertz Selective Emission Enhancement from a Metasurface-Coupled Photoconductive Emitter in Quasi-Near-Field Zone

We present a THz emission enhancement of 41 times at 0.92 THz from a metasurface made of T-shaped resonators excited in a quasi-near-field zone. Such a metasurface has an intrinsic transmission minimum with Q factor of 4 at 1.25 THz under far-field excitation. When this metasurface is coupled onto the backside of a 625-μm-thick photoconductive emitter, the metasurface is below the Fraunhofer distance to the excitation source. As such, one broad enhancement around 0.47 THz and another extremely narrow enhancement at 0.92 THz in the emission spectrum are observed owing to a quasi-near-field excitation. Theoretically, the Q factor of the latter is up to 307, which is limited by the spectral resolution in experiment. The numerical simulations indicate that the T-shaped resonators serve as an array of plasmonic antennas resulting in the aforementioned emission enhancement of THz radiation.

     

Large-scale purification of recombinant hepatitis B surface antigen from Pichia pastoris with non-affinity chromatographic methods as a substitute to immunoaffinity chromatography

Abstract

The costly media, inconsistent ligand density, ligand leakage, and possible destabilization of recombinant hepatitis B surface antigen (rHBsAg) particles are main drawbacks of using immunoaffinity chromatography (IAF) in the large-scale downstream processing. In this study, we aimed to use an efficient large-scale purification system as an alternative purification method for immunoaffinity chromatography. For this purpose, we suggested integrating non-affinity chromatographic methods of hydrophobic interaction chromatography (HIC) and size-exclusion chromatography (SEC) for cost-effective purification of rHBsAg expressed in P. pastoris. The optimization of such process is not trivial and straightforward since diverse molecular characteristics of expressed rHBsAg in each type of host cell cause different interactions in non-affinity chromatography processes. The working buffer composition and chromatography parameters are the most influential factors in hydrophobic interaction chromatography. The best result for lab-scale HIC was achieved by using ammonium sulfate buffer in 10% of saturation concentration in pH 7.0 with Butyl-S Sepharose 6 Fast Flow medium and with subsequent Tween-100 and urea elution. In this process, the recovery, purity, and total yield were about 84%, 82%, and 69%, respectively. By scaling-up the HIC and integrating it with Sephacryl S-400?SEC, we obtained highly pure, i.e.,?>?90%, rHBsAg virus-like particles (VLP).     

A novel bioactive nanoparticle synthesized by conjugation of 3-chloropropyl trimethoxy silane functionalized Fe3O4 and 1-((3-(4-chlorophenyl)-1-phenyl-1H-pyrazol-4-yl)methylene)-2-(4-phenylthiazol-2-yl) hydrazine: assessment on anti-cancer against gastric AGS cancer cells

Molecular Biology Reports - Gastric cancer is one of the common types of cancer around the world which has few therapeutic options. Nitrogen heterocyclic derivatives such as thiazoles are used as...     

Spermine as a possible endogenous allosteric activator of carboxypeptidase A: multispectroscopic and molecular simulation studies

Abstract

Carboxypeptidase A (EC.3.4.17.1) is a zinc-containing proteolytic enzyme that removes the C-terminal amino acid from a peptide chain with the free carboxylate-terminal. In this study, the effect of spermine interaction on the structure and thermal stability of Carboxypeptidase A was investigated by ultraviolet???visible spectroscopy, fluorescence spectroscopy, circular dichroism, Kinetic measurement, molecular docking and simulation studies have also been followed at the pH of 7.5. The transition temperature of Carboxypeptidase A, as a criterion of protein thermal stability, in the presence of spermine was enhanced by increasing the concentration of spermine. The results of fluorescence intensity changes, at two temperatures of 308 and 318?K, also suggested that spermine had a great ability to quench the fluorescence of Carboxypeptidase A through the static quenching procedure. The thermodynamic parameters changes, including standard Gibbs free-energy, entropy and enthalpy, showed that the binding of spermine to Carboxypeptidase A was spontaneous and the hydrogen bonding and van der Waals interactions played a major role in stabilizing the Carboxypeptidase A–spermine complex. The changes in the content of the α-helix and the β-sheet of the Carboxypeptidase A with binding to spermine were shown by the CD spectra method. Further, kinetic studies revealed that by increasing concentration of spermine, the activity of Carboxypeptidase A was enhanced. Also, the docking study revealed that the hydrogen bonding and van der Waals interactions played a major role in stabilizing the Carboxypeptidase A–spermine complex. As a result, spermine could be considered as an activator and a stabilizer for Carboxypeptidase A.

Communicated by Ramaswamy H. Sarma     

Efficient growth inhibition of EGFR over-expressing tumor cells by an anti-EGFR nanobody

Epidermal growth factor receptor (EGFR) is deemed to be one of the main molecular targets for diagnosis and treatment of cancer. It has been identified that EGFR involves in pathogenesis of some forms of human cancers. Monoclonal antibodies targeting EGFR could control the tumor cell growth, proliferation, and apoptosis by suppressing the signal transduction pathways. Nanobodies can be regarded as the smallest intact antigen binding fragments, derived from heavy chain-only antibodies existing in camelids. Here, we describe the identification of an EGFR-specific nanobody, referred to as OA-cb6, obtained from immunized camel with a cell line expressing high levels of EGFR. Utilizing flow cytometry (FACS) and blotting methods, we demonstrated that OA-cb6 nanobody binds specifically to EGFR expressing on the surface of A431 cells. In addition, OA-cb6 nanobody potently causes the inhibition of EGFR over expression, cell growth and proliferation. The antibody fragments can probably be regarded as worthwhile binding block for further rational design of anti-cancer therapy.     

Intraplaque Stretch in Carotid Atherosclerotic Plaque – an Effective Biomechanical Predictor for Subsequent Cerebrovascular Ischemic Events

Background

Stretch is a mechanical parameter, which has been proposed previously to affect the biological activities in different tissues. This study explored its utility in determining plaque vulnerability.

Methods

One hundred and six patients with mild to moderate carotid stenosis were recruited in this study (53 symptomatic and 53 asymptomatic). High resolution, multi-sequence magnetic resonance (MR) imaging was performed to delineate various plaque components. Finite element method was used to predict high stretch concentration within the plaque.

Results

During a two-year follow-up, 11 patients in symptomatic group and 3 in asymptomatic group experienced recurrent cerebrovascular events. Plaque stretch at systole and stretch variation during one cardiac cycle was greater in symptomatic group than those in the asymptomatic. Within the symptomatic group, a similar trend was observed in patients with recurrent events compared to those without.

Conclusion

Plaques with high stretch concentration and large stretch variation are associated with increased risk of future cerebrovascular events.     

Enhancement of production and activity of alkaline zinc metalloprotease from <Emphasis Type="Italic">Salinivibrio proteolyticus</Emphasis> using low intensity direct electric current and zinc nanoparticles

Objectives

To improve the production and activity of an alkaline zinc metalloprotease from Salinivibrio proteolyticus in response to ZnSO₄ (ionic and nanoparticle forms) and low intensity direct electric current (LIDC).

Results

A DC of 50 µA for 10 min increased enzyme production from 35 to 53 U ml^?1 when applied to the stationary phase bacterial cells. Zn²⁺ improved enzyme production better than zinc nanoparticles (52 vs. 43.5 U ml^?1). Zinc nanoparticles (0.5 mM) added to an enzyme reaction mixture containing casein (0.65 %) and 20 mM Tris/HCl buffer (pH 8) improved enzyme activity more than Zn²⁺ (42 vs. 36 U ml^?1).

Conclusion

LIDC exposure (50 µA, 10 min) to the stationary phase bacterial cells increases metalloprotease production in Salinivibrio. A low concentration of zinc nanoparticles (0.5 mM) increases maximum enzyme activity.

     

Investigating the Structural Stability of RADA16-I Peptide Conjugated to Gold Nanoparticles

International Journal of Peptide Research and Therapeutics - RADA 16-I is an amphiphilic peptide which can form macroscopic scaffolds through self-assembly and has found many applications in tissue...