Phytoremediation Effect and Growth Responses of Cynodon spp. and Agropyron desertorum in a Petroleum-Contaminated Soil

In order to compare the petroleum tolerance and phytoremediation ability of a native grass, Agropyron desertorum (desert Wheatgrass) with Cynodon spp. (Bermuda grass) in a petroleum hydrocarbon-contaminated soil, a 7-month greenhouse experiment was performed. There were 4 soil treatments with 0% (uncontaminated soil), 2%, 4%, and 12% (w_oil/w_soil) petroleum concentration. Parameters including shoot and root fresh weight and dry weight, root penetration depth and root density depth, soil respiration, and total petroleum hydrocarbons (TPH) degradation were measured during and after experiments. The results showed an increase in shoot fresh weight of A. desertorum in soil polluted with 2% petroleum sludge compared to the uncontaminated soil, whereas the growth of Bermuda grass significantly decreased in corresponding treatment. Root growth of A. desertorum was decreased in 2% and 4% petroleum sludge, whereas it was increased in Bermuda grass species. Overall, root fresh weight of Bermuda grass was higher than that of A. desertorum in all treatments. Significant increase in microorganisms' activity was observed in the presence of petroleum sludge and plants in soil compared with uncontaminated soil without plants, and the highest soil respiration (37.6 mg C-CO₂/kg soil day) has been observed in the rhizosphere of Bermuda grass in treatment with 12% petroleum sludge. Plants had a significant role in the degradation of soil contaminants as TPH degradation in planted soils was significantly higher than that in unplanted soil (TPH degradation (%) was 30.4 and 38.9 in A. desertorum and Bermuda grass, respectively, whereas it was just 13.3 in unplanted soil). The rhizosphere of Bermuda grass had significantly less residual TPHs compared to A. desertorum. The results indicated that both Cynodon spp. and A. desertorum had a peculiar tolerance to petroleum pollution. Therefore, as Bermuda grass has already been suggested to be a typical and efficient species for phytoremediating petroleum-contaminated sites, A. desertorum may also prove to be a suitable native alternative.     

In silico analysis of squalene synthase in Fabaceae family using bioinformatics tools

Triterpenoid saponins are a diverse group of bioactive compounds, which are used for possessing of many biomedical and pharmaceutical products. Generally, squalene synthase (SQS) is defined as an emerging and essential branch point enzyme far from the major pathway of isoprenoids biosynthetic and a latent adjusting point, which manages carbon flux into triterpenes biosynthesis and sterols. The present study deals with the detailed characterization of SQS by bioinformatics approaches to evaluate physicochemical properties, structural characteristics including secondary and 3D structure prediction and functional analysis from eight plants related to Fabaceae family and Arabidopsis thaliana. Bioinformatics analysis revealed that SQS proteins have two transmembrane regions in the C-terminal. The predicted motifs were used to design universal degenerate primers for PCR analysis and other molecular applications. Phylogenetic analysis showed conserved regions at different stretches with maximum homology in amino acid residues within all SQSs. The secondary structure prediction results showed that the amino acid sequence of all squalene synthases had α helix and random coil as the main components. The reliability of the received model was confirmed using the ProSA and RAMPAGE programs. Determining of active site by CASTp proposes the possibility of using this protein as probable medication target. The findings of the present study may be useful for further assessments on characterization and cloning of squalene synthase.     

How Methylammonium Cations and Chlorine Dopants Heal Defects in Lead Iodide Perovskites

Lead tri‐iodide methylammonium (MAPbI₃) perovskite polycrystalline materials show complex optoelectronic behavior, largely because their 3D semiconducting inorganic framework is strongly perturbed by the organic cations and ubiquitous structural or chemical inhomogeneities. Here, a newly developed time‐dependent density functional theory‐based theoretical formalism is taken advantage of. It treats electron–hole and electron–nuclei interactions on the same footing to assess the many‐body excited states of MAPbI₃ perovskites in their pristine state and in the presence of point chemical defects. It is shown that lead and iodine vacancies yield deep trap states that can be healed by dynamic effects, namely rotation of the methylammonium cations in response to point charges, or through slight changes in chemical composition, namely by introducing a tiny amount of chlorine dopants in the defective MAPbI₃. The theoretical results are supported by photoluminescence experiments on MAPbI_3?mCl_m and pave the way toward the design of defect‐free perovskite materials with optoelectronic performance approaching the theoretical limits.     

Identification and Characterization of Novel Antimicrobial Peptide from <Emphasis Type="Italic">Hippocampus comes</Emphasis> by In Silico and Experimental Studies

Antimicrobial peptides (AMPs) have attracted attentions as a novel antimicrobial agent because of their unique activity against microbes. In the present study, we described a new, previously unreported AMP, moronecidin-like peptide, from Hippocampus comes and compared its antimicrobial activity with moronecidin from hybrid striped bass. Antibacterial assay indicated that gram-positive bacteria were more sensitive to moronecidin and moronecidin-like compared with gram-negative bacteria. Furthermore, both AMPs were found to exhibit effective antifungal activity. Comparative analysis of the antimicrobial activity revealed that moronecidin-like peptide has higher activity against Acinetobacter baumannii and Staphylococcus epidermidis relative to moronecidin. Both moronecidin-like and moronecidin peptides retained their antibacterial activity in physiological pH and salt concentration. The time-killing assay showed that the AMPs completely killed A. baumannii and S. epidermidis isolates after 1 and 5 h at five- and tenfold above their corresponding MICs, respectively. Anti-biofilm assay demonstrated that peptides were able to inhibit 50% of biofilm formation at sub-MIC of 1/8 MIC. Furthermore, moronecidin-like significantly inhibited biofilm formation more than moronecidin at 1/16 MIC. Collectively, our results revealed that antimicrobial and anti-biofilm activities of moronecidin-like are comparable to moronecidin. In addition, the hemolytic and cytotoxic activities of moronecidin-like were lower than those of moronecidin, suggesting it as a potential novel therapeutic agent, and a template to design new therapeutic AMPs.     

Time‐lapse microscopy of oxidative stress demonstrates metabolic sensitivity of retinal pericytes under high glucose condition

Hyperglycemia affects retinal vascular cell function, promotes the development and progression of diabetic retinopathy and ultimately causes vision loss. Oxidative stress, reactive oxygen species (ROS) in excess, is a key biomarker for diabetic retinopathy. Using time‐lapse fluorescence microscopy, ROS dynamics was monitored and the metabolic resistivity of retinal endothelial cells (REC) and pericytes (RPC) was compared under metabolic stress conditions including high glucose (HG). In the presence of a mitochondrial stressor, REC exhibited a significant increase in the rate of ROS production compared with RPC. Thus, under normal glucose (NG), REC may utilize oxidative metabolism as the bioenergetic source, while RPC metabolic activity is independent of mitochondrial respiration. In HG condition, the rate of ROS production in RPC was significantly higher, whereas this rate remained unchanged in REC. Thus, under HG condition RPC may preferentially utilize oxidative metabolism, which results in increased rate of ROS production. In contrast, REC use glycolysis as their major bioenergetic source for ATP production, and consequently HG minimally affects their ROS levels. These observations are consistent with our previous studies where we showed HG condition has minimal effect on apoptosis of REC, but results in increased rate of apoptosis in RPC. Collectively, our results suggest that REC and RPC exhibit different metabolic activity preferences under different glucose conditions. Thus, protection of RPC from oxidative stress may provide an early point of intervention in development and progression of diabetic retinopathy.      

Defects formation and spiral waves in a network of neurons in presence of electromagnetic induction

Complex anatomical and physiological structure of an excitable tissue (e.g., cardiac tissue) in the body can represent different electrical activities through normal or abnormal behavior. Abnormalities of the excitable tissue coming from different biological reasons can lead to formation of some defects. Such defects can cause some successive waves that may end up to some additional reorganizing beating behaviors like spiral waves or target waves. In this study, formation of defects and the resulting emitted waves in an excitable tissue are investigated. We have considered a square array network of neurons with nearest-neighbor connections to describe the excitable tissue. Fundamentally, electrophysiological properties of ion currents in the body are responsible for exhibition of electrical spatiotemporal patterns. More precisely, fluctuation of accumulated ions inside and outside of cell causes variable electrical and magnetic field. Considering undeniable mutual effects of electrical field and magnetic field, we have proposed the new Hindmarsh–Rose (HR) neuronal model for the local dynamics of each individual neuron in the network. In this new neuronal model, the influence of magnetic flow on membrane potential is defined. This improved model holds more bifurcation parameters. Moreover, the dynamical behavior of the tissue is investigated in different states of quiescent, spiking, bursting and even chaotic state. The resulting spatiotemporal patterns are represented and the time series of some sampled neurons are displayed, as well.