The influence of organic and inorganic chelators on the toxicity of bulk and nanoparticles of zinc oxide during germination and seedling growth of Nicotiana tabacum L.

Nano and bulk-forms of zinc oxide (ZnO) are used extensively in industry and consequently may accumulate in the environment. However, there is little information available on the comparative effects of these forms during the critical early stages of plant life. Furthermore, the role of chelating agents, which affect the bioavailability of metals, in ameliorating plant stress due to exposure to nano and bulk-forms of ZnO is not well characterised. In this study, the effects of different concentrations (0.5, 2.5, 5, 10, 50 and 100 ppm) of nano ZnO (22 nm) and bulk ZnO (natural form, 1000 nm) with and without organic (citrate) and inorganic (EDTA) chelators on germination and seedling growth, and oxidative stress markers of Nicotiana tabacum L. were compared. Chelators (without ZnO) enhanced root growth, whilst ZnO negatively affected seedling growth. ZnO toxicity was often mitigated by adding chelators, especially citrate, although at the highest levels (50 and 100?ppm) of ZnO, toxicity was more pronounced when chelated with EDTA, but was decreased with citrate. Collectively, our findings provide important information regarding the different morpho-physiological and biochemical effects of bulk and nano ZnO and organic and inorganic chelators (citrate and EDTA), which are all prevalent in the environment.     

Prefrontal cortex lesions impair object-spatial integration

How and where object and spatial information are perceptually integrated in the brain is a central question in visual cognition. Single-unit physiology, scalp EEG, and fMRI research suggests that the prefrontal cortex (PFC) is a critical locus for object-spatial integration. To test the causal participation of the PFC in an object-spatial integration network, we studied ten patients with unilateral PFC damage performing a lateralized object-spatial integration task. Consistent with single-unit and neuroimaging studies, we found that PFC lesions result in a significant behavioral impairment in object-spatial integration. Furthermore, by manipulating inter-hemispheric transfer of object-spatial information, we found that masking of visual transfer impairs performance in the contralesional visual field in the PFC patients. Our results provide the first evidence that the PFC plays a key, causal role in an object-spatial integration network. Patient performance is also discussed within the context of compensation by the non-lesioned PFC.     

Molecular mechanisms underlying thalassemia intermedia in Iran

To improve the differentiation of thalassemia intermedia from other hemoglobinopathies in Iran, four known genetic mechanisms-XmnI (G)gamma polymorphism, inheritance of mild and silent beta-thalassemia alleles, delta beta deletion, and coinheritance of alpha- and beta-thalassemia-were investigated in 52 Iranian individuals suspected to have thalassemia intermedia based on clinical and hematological characteristics. Beta-globin mutations were studied using a reverse-hybridization assay and sequencing of the total beta-globin gene. The XmnI (G)gamma polymorphism, the Sicilian delta beta deletion, and four alpha-globin mutations (-a(3.7), -a(4.2), -(MED), aaa(anti-3.7)) were studied using PCR-based techniques. The inheritance of the XmnI (G)gamma polymorphism with severe beta-thalassemia alleles in the homozygous or compound heterozygous state was the predominant mechanism observed in 27 individuals (55.3%). In five cases, this status overlapped with the -a(3.7)/aa genotype. The second most frequent cause for thalassemia intermedia (14.8%) was the inheritance of mild beta-thalassemia alleles, including IVS-I-6 (T > C), -88 (C > A), and + 113 (A > G). In three subjects (4.3%) the Sicilian delta beta deletion was identified. HbS in association with beta-zero-thalassemia was found in three patients with thalassemia intermedia phenotype. In 11 cases (21.3%) no causative genetic alteration could be identified. Our results reflect the diversity underlying thalassemia intermedia, and the limitations of the applied clinical, hematological, and molecular approaches for correct diagnosis. Some of the unresolved cases will offer an opportunity to discover additional molecular mechanisms leading to thalassemia intermedia.     

Radiative Peristaltic Flow of Jeffrey Nanofluid with Slip Conditions and Joule Heating

Mixed convection peristaltic flow of Jeffrey nanofluid in a channel with compliant walls is addressed here. The present investigation includes the viscous dissipation, thermal radiation and Joule heating. Whole analysis is performed for velocity, thermal and concentration slip conditions. Related problems through long wavelength and low Reynolds number are examined for stream function, temperature and concentration. Impacts of thermal radiation, Hartman number, Brownian motion parameter, thermophoresis, Joule heating and slip parameters are explored in detail. Clearly temperature is a decreasing function of Hartman number and radiation parameter.     

Development of α4 integrin DNA aptamer as a potential therapeutic tool for multiple sclerosis

One of the most important molecules for multiple sclerosis pathogenesis is α4 integrin, which is responsible for autoreactive leukocytes migration into the brain. The monoclonal antibody, natalizumab, was introduced to market for blocking the extravasation of autoreactive leukocytes via inhibition of α4 integrin. However, the disadvantages of antibodies provided a suitable background for other agents to be replaced with antibodies. Considering the profound advantages of aptamers over antibodies, aptamer isolation against α4 integrin was intended in the current study. The α4 integrin-specific aptamers were selected using cell-systematic evolution of ligands by exponential enrichment (SELEX) method with human embryonic kidney (HEK)-293T overexpressing α4 integrin and HEK-293T as target and control cells, respectively. Evaluation of selected aptamer was performed through flow cytometric analysis. The selected clones were then sequenced and analyzed for any possible secondary structure and affinity. The results of this study led to isolation of 13 different single-stranded DNA clones in 11 rounds of selection which were categorized to three clusters based on common structural motifs and the equilibrium dissociation constant (K _d) of the most stable structure was calculated. The evaluation of SELEX progress showed growth in aptamer affinity with increasing of the number of cycles. Taken together, the findings of this study demonstrated the isolation of α4-specific single-stranded DNA aptamers with suitable affinity for ligand, which can further be replaced with natalizumab.     

Variation of Chemical Constituents and Antiradical Capacity of Nine Ferulago angulata Populations from Iran

The present study was designed to assess the influence of geographical factors on essential oil (EO) composition, along with antiradical potential and phytochemical contents of Ferulago angulata (Schltdl .) Boiss (Apiaceae) extracts for the first time. The aerial parts were hydrodistilled by Clevenger apparatus and subjected to gas chromatography coupled with flame ionization detector (GC/FID) and mass spectroscopy (GC/MS). The EO yields were significantly different from populations ‘Mongar’ (south‐slope, 3000 m) with 1.34±0.06 % and ‘Male‐Amiri’ (north slope, 2600 m) with 0.18±0.05 % of total oil. Thirty‐nine compounds were identified from the EOs of nine populations. α‐Pinene was the predominant component ranging from 20.84 to 49.06 % in ‘Gandomkar’ (north‐slope, 2500 m) and ‘Mongar’ (3000 m), respectively. The methanolic extract of ‘Mongar’ (north‐slope at 2500 m) possessed the highest total phenolic contents. Also, this population logically exhibited potent antiradical activity using both 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays with EC₅₀ of 42.07±4.12 μg/mL and 8.34±0.21 mmol Trolox® equivalents/g, respectively. Due to its moderate free‐radical scavenging potential and high α‐pinene content, the population ‘Mongar’ might be considered as a perspective raw material in food and phytopharmaceutical industries.     

A computational study of atomic oxygen-doped silicon carbide nanotubes

We investigated the properties of atomic oxygen-doped (O-doped) models of representative (6,0) and (4,4) silicon carbide nanotubes (SiCNTs) by density functional theory (DFT) calculations of isotropic and anisotropic chemical shielding (CS) parameters of Si-29, O-17 and C-13 atoms for the optimized structures. The calculated parameters indicated the effects of O-doping on the electronic environments of the first neighboring atoms of the doped sites. Comparing the results of the zigzag and armchair models also indicated that the latter model detects more effects of the O-doping than the former one.     

Molecular study of two distinct phytoplasma species associated with streak yellows of date palm in Iran

A disease with symptoms similar to palm lethal yellowing was noticed in the early 2013 in Khuzestan Province (Iran) in date palm (Phoenix dactylifera). Infected trees displaying symptoms of streak yellows and varied in the incidence and severity of yellowing. A study was initiated to determine whether phytoplasma was the causal agent. Polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) methods using universal phytoplasma primers pairs R16mF1/mR1 and M1/M2 were employed to detect putative phytoplasma(s) associated with date palm trees. Nested PCR using universal primers revealed that 40 out of 53 trees were positive for phytoplasma while asymptomatic date palms from another location (controls) tested negative. RFLP analyses and DNA sequencing of 16S rDNA indicated that the presence of two different phytoplasmas most closely related to clover proliferation (CP) phytoplasma (group 16SrVI) and ash yellows (AY) phytoplasma (group 16SrVII). Sequence analysis confirmed that palm streak yellows phytoplasmas in each group were uniform and to be phylogenetically closest to “CandidatusP. fraxini” (MF374755) and “Ca. P. trifolii” isolate Rus‐CP361Fc1 (KX773529). Result of RFLP analysis of secA gene of positive samples using TruI and TaqI endonuclease is in agreement with rDNA analysis. On this basis, both strains were classified as members of subgroups 16SrVI‐A and 16SrVII‐A. This is the first report of a phytoplasma related to CP and AY phytoplasma causing date palm yellows disease symptoms.