MAPK phosphatase AP2C3 induces ectopic proliferation of epidermal cells leading to stomata development in Arabidopsis

In plant post-embryonic epidermis mitogen-activated protein kinase (MAPK) signaling promotes differentiation of pavement cells and inhibits initiation of stomata. Stomata are cells specialized to modulate gas exchange and water loss. Arabidopsis MAPKs MPK3 and MPK6 are at the core of the signaling cascade; however, it is not well understood how the activity of these pleiotropic MAPKs is constrained spatially so that pavement cell differentiation is promoted only outside the stomata lineage. Here we identified a PP2C-type phosphatase termed AP2C3 (Arabidopsis protein phosphatase 2C) that is expressed distinctively during stomata development as well as interacts and inactivates MPK3, MPK4 and MPK6. AP2C3 co-localizes with MAPKs within the nucleus and this localization depends on its N-terminal extension. We show that other closely related phosphatases AP2C2 and AP2C4 are also MAPK phosphatases acting on MPK6, but have a distinct expression pattern from AP2C3. In accordance with this, only AP2C3 ectopic expression is able to stimulate cell proliferation leading to excess stomata development. This function of AP2C3 relies on the domains required for MAPK docking and intracellular localization. Concomitantly, the constitutive and inducible AP2C3 expression deregulates E2F-RB pathway, promotes the abundance and activity of CDKA, as well as changes of CDKB1;1 forms. We suggest that AP2C3 downregulates the MAPK signaling activity to help maintain the balance between differentiation of stomata and pavement cells.     

Simultaneous application of cisplatin and static magnetic field enhances oxidative stress in HeLa cell line

In this study, we reported the effects of simultaneous application of static magnetic field (SMF) and cisplatin as an anticancer drug on the oxidative stress in human cervical cancer (HeLa) cell line and normal skin fibroblast cells (Hu02). The cells were exposed to different SMF intensities (7, 10, and 15 mT) for 24 and 48 h. IC₅₀ concentrations of cisplatin were obtained by MTT assay. The cytotoxic effects of combined treatment were studied by measuring the intracellular reactive oxygen species content using flow cytometric method and estimation of membrane lipid peroxidation by spectrophotometry. Statistical analysis was assessed using one-way repeated measures analysis of variance (ANOVA) followed by Tukey’s test. Based on the obtained results, the highest and lowest death rate, respectively, in HeLa and Hu02 cell lines was observed at the intensity of 10 mT. Also, we found that membrane lipid peroxidation in cancer cells is higher than that of normal counterparts. SMF potently sensitized human cervical cancer cells to cisplatin through reactive oxygen species (ROS) accumulation while it had small effects on normal cells. The combination of both treatments for 48 h led to a marked decrease in the viability percentage of HeLa cells by about 89% compared to untreated cells. This study suggests that conjugation of both physical and chemical treatments could increase the oxidative stress in HeLa cell line and among three optional intensities of SMF, the intensity of 10 mT led to the higher damage to cancer cells in lower doses of drug.     

Analysis of B-genome chromosome introgression in interspecific hybrids of Brassica napus × B. carinata

Brassica carinata, an allotetraploid with B and C genomes, has a number of traits that would be valuable to introgress into B. napus. Interspecific hybrids were created between B. carinata (BBCC) and B. napus (AACC), using an advanced backcross approach to identify and introgress traits of agronomic interest from the B. carinata genome and to study the genetic changes that occur during the introgression process. We mapped the B and C genomes of B. carinata with SSR markers and observed their introgression into B. napus through a number of backcross generations, focusing on a BC(3) and BC(3)S(1) sibling family. There was close colinearity between the C genomes of B. carinata and B. napus and we provide evidence that B. carinata C chromosomes pair and recombine normally with those of B. napus, suggesting that similar to other Brassica allotetraploids no major chromosomal rearrangements have taken place since the formation of B. carinata. There was no evidence of introgression of the B chromosomes into the A or C chromosomes of B. napus; instead they were inherited as whole linkage groups with the occasional loss of terminal segments and several of the B-genome chromosomes were retained across generations. Several BC(3)S(1) families were analyzed using SSR markers, genomic in situ hybridization (GISH) assays, and chromosome counts to study the inheritance of the B-genome chromosome(s) and their association with morphological traits. Our work provides an analysis of the behavior of chromosomes in an interspecific cross and reinforces the challenges of introgressing novel traits into crop plants.     

Isolation, structural characterization and antioxidant activity of a new water-soluble polysaccharide from Acanthophyllum bracteatum roots

ABPS-1, a new water-soluble polysaccharide with molecular weight of 26 kDa and a specific optical rotation of +170° (c 1.0, H₂O), was extracted from the roots of Acanthophyllum bracteatum by warm water and further successively purified through DEAE-cellulose A52 and Sephadex G-100 columns. Monosaccharide analysis revealed that the ABPS-1 was composed of Glc, Gal and Ara with a relative molar ratio of 1.4:5.2:1.0. Its structural features were elucidated by a combination of FT-IR, methylation and GC-MS analysis, periodate oxidation and Smith degradation, partial acid hydrolysis and ¹³C and ¹H NMR spectroscopy. The data obtained indicate that ABPS-1 possessed a backbone of α-(1 → 6)-linked Gal with branches attached to O-2 by α-1 → linked Glc and at O-3 by α-1 → linked Gal and by α-(1 → 3)-linked Ara. The in vitro antioxidant activity showed that ABPS-1 possesses DPPH radical-scavenging activity in a concentration-dependent manner with an EC₅₀ value of 2.6 mg/ml.     

RANTES gene mRNA expression and its -403 G/A promoter polymorphism in coronary artery disease

Objective

Increased RANTES expression has been described to have a role in atherosclerosis plaque formation. Functional polymorphisms within RANTES promoter region have shown association with increased risk of coronary atherosclerosis (CAD). The aim of this study was to examine the RANTES mRNA expression in patients with CAD compared to patients without CAD and its association with RANTES − 403 G/A polymorphism in an Iranian population.

Methods

The study was performed on 319 patients who underwent coronary artery angiography and patients with > 50% stenosis in vessels considered as case groups (CAD+) N = 191 and normal vessels group as control (CAD−) N = 128. In each group 20 patients were examined for RANTES mRNA expression.RANTES mRNA expression was examined using quantitative real-time PCR. Genotyping of − 403 polymorphism was performed using PCR-RFLP technique.

Results

We found that RANTES mRNA expression was increased to 1.37 fold in CAD patients compared to the controls but the difference was not statistically significant. Also comparing the RANTES mRNA expression in patients with different RANTES − 403 G/A polymorphism showed that in patients carrying AA genotype RANTES mRNA expression was increased to 1.74 fold compared to patients carrying GG genotype and to 1.51 fold compared to patients carrying GA genotype. No significant difference for allele and genotype frequencies of RANTES − 403 polymorphism was found between cases and controls.

Conclusion

More studies on larger number of samples are required to further evaluate role of RANTES in pathogenesis of CAD.     

Homology modeling, docking, molecular dynamics simulation, and structural analyses of coxsakievirus B3 2A protease: an enzyme involved in the pathogenesis of inflammatory myocarditis

2A protease of the pathogenic coxsackievirus B3 is key to the pathogenesis of inflammatory myocarditis and, therefore, an attractive drug target. However lack of a crystal structure impedes design of inhibitors. Here we predict 3D structure of CVB3 2A^pro based on sequence comparison and homology modeling with human rhinovirus 2A^pro. The two enzymes are remarkably similar in their core regions. However they have different conformations at the N-terminal. A large number of N-terminal hydrophobic residues reduce the thermal stability of CVB3 2A^pro, as we confirmed by fluorescence, western blot and turbidity measurement. Molecular dynamic simulation revealed that elevated temperature induces protein motion that results in frequent movement of the N-terminal coil. This may therefore induce successive active site changes and thus play an important role in destabilization of CVB3 2A^pro structure.     

Bioavailability and Concentration of Heavy Metals in the Sediments and Leaves of Grey Mangrove, <Emphasis Type="BoldItalic">Avicennia marina</Emphasis> (Forsk.) Vierh,in Sirik Azini Creek,Iran

The concentration and bioavailability of Ni, Cu, Cd, Zn, and Pb in the sediments and leaves of grey mangrove, Avicennia marina, were studied throughout Sirik Azini creek (Iran) with a view to determine heavy metals bioavailability, and two methods were used. Results show that Zn and Ni had the highest concentrations in the sediments, while Cd and Cu were found to have the lowest concentrations in the sediments. Compared to the mean concentrations of heavy metals in sedimentary rock (shales), Zn and Cu showed lower concentration, possibly indicating that the origin of these heavy metals is natural. A geo-accumulation index (I _geo) was used to determine the degree of contamination in the sediments. I _geo values for Zn, Cu, Pb, and Ni showed that there is no pollution from these metals in the study area. As heavy metal concentrations in leaves were higher than the bioavailable fraction of metals in sediments, it follows that bioconcentration factors (leaf/bioavailable sediment) for some metals were higher than 1.     

Induced in vitro differentiation of neural-like cells from human exfoliated deciduous teeth-derived stem cells

Stem cells from human exfoliated deciduous teeth (SHED) are highly proliferative, clonogenic and multipotent stem cells with a neural crest cell origin. Additionally, they can be collected with minimal invasiveness in comparison with other sources of mesenchymal stem cells (MSCs). Therefore, SHED could be a desirable option for potential therapeutic applications. In this study, SHEDs were established from enzyme-disaggregated deciduous dental pulp obtained from 6 to 9 year-old children. The cells had typical fibroblastoid morphology and expressed antigens characteristic of MSCs, STRO1, CD146, CD45, CD90, CD106 and CD166, but not the hematopoietic and endothelial markers, CD34 and CD31, as assessed by FACS analysis. Differentiation assessment revealed a strong osteogenic and adipogenic potential of SHEDs. In order to further evaluate the in vitro differentiation potential of SHED into neural cells, a simple short time growth factor-mediated induction was used. Immunofluorescence staining and flow cytometric analysis revealed that SHED rapidly expressed nestin and b-III tubulin, and later expressed intermediate neural markers. In addition, the intensity and percentages of nestin and b-III tubulin and mature neural markers (PSA-NCAM, NeuN, Tau, TH, or GFAP) increased significantly following treatment. Moreover, RT-PCR and Western blot analyses showed that the neural markers were strongly up-regulated after induction. In conclusion, these results provide evidence that SHED can differentiate into neural cells by the expression of a comprehensive set of genes and proteins that define neural-like cells in vitro. SHED cells might be considered as new candidates for the autologous transplantation of a wide variety of neurological diseases and neurotraumatic injuries.     

The influence of salinity on cell ultrastructures and photosynthetic apparatus of barley genotypes differing in salt stress tolerance

A hydroponic experiment was conducted to elucidate the difference in growth and cell ultrastructure between Tibetan wild and cultivated barley genotypes under moderate (150 mM NaCl) and high (300 mM NaCl) salt stress. The growth of three barley genotypes was reduced significantly under salt stress, but the wild barley XZ16 (tolerant) was less affected relative to cultivated barley Yerong (moderate tolerant) and Gairdner (sensitive). Meanwhile, XZ16 had lower Na⁺ and higher K⁺ concentrations in leaves than other two genotypes. In terms of photosynthetic and chlorophyll fluorescence parameters, salt stress reduced maximal photochemical efficiency (F _v/F _m), net photosynthetic rate (Pn), stomatal conductance (Gs), and intracellular CO₂ concentration (Ci). XZ16 showed relatively smaller reduction in comparison with the two cultivated barley genotypes. The observation of transmission electron microscopy found that fundamental cell ultrastructure changes happened in both leaves and roots of all barley genotypes under salt NaCl stress, with chloroplasts being most changed. Moreover, obvious difference could be detected among the three genotypes in the damage of cell ultrastructure under salt stress, with XZ16 and Gairdner being least and most affected, respectively. It may be concluded that high salt tolerance in XZ16 is attributed to less Na⁺ accumulation and K⁺ reduction in leaves, more slight damage in cell ultrastructure, which in turn caused less influence on chloroplast function and photosynthesis.     

Herbivore-induced indirect defense across bean cultivars is independent of their degree of direct resistance

We tested the extent to which resistance of common bean (Phaseolus vulgaris) cultivars to the spider mite Tetranychus urticae parallels the extent to which these plants display indirect defenses via the induced attraction of the predatory mite Phytoseiulus persimilis. First, via field and greenhouse trials on 19 commercial bean cultivars, we selected two spider mite-resistant (Naz and Ks41128) and two susceptible (Akthar and G11867) cultivars and measured the spider mite-induced volatiles and the subsequently induced attraction of predatory mites via olfactory choice assays. The two major volatiles, 4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT) and (Z)-3-hexenyl-acetate, were induced in the resistant but not in the susceptible cultivars. However, uninfested susceptible cultivars emitted these volatiles at levels similar to those of mite-infested resistant cultivars. Significant induction of several minor components was observed for all four cultivars except for the infested-susceptible cultivar G11867. Both, the spider mite-resistant cultivar Naz and the susceptible cultivar G11867, attracted more predatory mites when they were infested. In contrast, spider mites induced increased emission of two major and five minor volatiles in Ks41128, but predatory mites did not discriminate between infested and uninfested plants. Overall, the attraction of predatory mites appeared to correlate positively with the presence of TMTT and (Z)-3-hexenyl acetate and negatively with β-caryophyllene and α-pinene in the bean headspace. Taken together, our data suggest that resistance and attraction of natural enemies via induced volatiles are independent traits. We argue that it should be possible to cross predator-attraction promoting traits into resistant cultivars that lack sufficiently inducible indirect defenses.