Interactions between Glutathione-S-Transferase M1, T1 and P1 polymorphisms and smoking,and increased susceptibility to esophageal squamous cell carcinoma

Background: A complex of genetic and environmental factors is involved in carcinogenesis of the esophageal squamous cell carcinoma (ESCC). Glutathione-S-Transferases (GSTs) are phase-II enzymes playing role in detoxification of carcinogen electrophiles. Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 in association with some environmental factors and their impact on esophageal cancer susceptibility were assessed in the Iranian population. Methods: Genomic DNA of peripheral blood leukocytes from 148 confirmed esophageal cancer cases and 137 healthy individuals as control group was assayed for restriction fragment length polymorphisms in the GSTP1 loci by PCR amplification followed by digestion with Alw26I. Deletion of the GSTM1 and GSTT1 genes was detected by multiplex PCR. A data-mining method based on decision trees was applied to produce a predictive model of interactions between genotypes. Results: Smoking was independently associated with ESCC (p < 0.05, OR: 2.286, 95% CI = 1.311–3.983). Smoking along with GSTP1 Val/Val genotype was associated to ESCC (p < 0.001, OR: 3.886, 95% CI = 1.830–8.251), while non-smokers with GSTP1 Val/Val were significantly more frequent in non-cancerous group. (p = 0.007, OR: 0.507, 95% CI = 0.309–0.830). Conclusions: Data-mining methods are useful tools to map out a scheme for predicting complex relations and combinations of different genotypes. Genotyping analysis of GSTP1 together with assessment of smoking seems to be important in determining the risk of ESCC in the Iranian population.     

A refined method for ovule culture in sugar beet (Beta vulgaris L.)

Induction of gynogenesis through ovule culture is a valuable tool to produce haploid and doubled haploid plants in sugar beet (Beta vulgaris L.). However, there is still large room for refining the method. In this study we investigated the gynogenic response of cultured ovules of three sugar beet genotypes, the effect of the application to inflorescences of different pretreatments with mannitol at 4ºC and with 5-azacytidine and 2,4-D, and the effect of the use of different basal culture media and sucrose concentrations. The response was evaluated in terms of percentages of induction of gynogenesis, embryogenesis and callogenesis, as well as of regenerated plants. We showed that a pretreatment with 0.5 M mannitol at 4 °C for 4 days, and with 50 µM 5-AzaC for 1 h, notably improved the percentage of embryogenesis and plant regeneration. Besides, the use of MS basal medium and 60 g/L sucrose was also found beneficial. This study provides new ways to improve the efficiency of haploid induction and plant regeneration through ovule culture in sugar beet, and is potentially applicable to ovule culture in other crops.

     

High frequency production of rapeseed transgenic plants via combination of microprojectile bombardment and secondary embryogenesis of microspore-derived embryos

Transgenic doubled haploid rapeseed (Brassica napus L. cvs. Global and PF₇₀₄) plants were obtained from microspore-derived embryo (MDE) hypocotyls using the microprojectile bombardment. The binary vector pCAMBIA3301 containing the gus and bar genes under control of CaMV 35S promoter was used for bombardment experiments. Transformed plantlets were selected and continuously maintained on selective medium containing 10 mg l⁻¹ phosphinothricin (PPT) and transgenic plants were obtained by selecting transformed secondary embryos. The presence, copy numbers and expression of the transgenes were confirmed by PCR, Southern blot, RT-PCR and histochemical GUS analyses. In progeny test, three out of four primary transformants for bar gene produced homozygous lines. The ploidy level of transformed plants was confirmed by flow cytometery analysis before colchicine treatment. All of the regenerated plants were haploid except one that was spontaneous diploid. High frequency of transgenic doubled haploid rapeseeds (about 15.55% for bar gene and 11.11% for gus gene) were considerably produced after colchicines treatment of the haploid plantlets. This result show a remarkable increase in production of transgenic doubled haploid rapeseed plants compared to previous studies.     

A cross-linked anti-TNF-α aptamer for neutralization of TNF-α-induced cutaneous Shwartzman phenomenon: A simple and novel approach for improving aptamers' affinity and efficiency

To increase the efficiency of aptamers to their targets, a simple and novel method has been developed based on aptamer oligomerization. To this purpose, previously anti-human TNF-α aptamer named T1–T4 was trimerized through a trimethyl aconitate core for neutralization of in vitro and in vivo of TNF-α. At first, 54 mer T1–T4 aptamers with 5′-NH₂ groups were covalently coupled to three ester residues in the trimethyl aconitate. In vitro activity of novel anti-TNF-α aptamer and its dissociation constant (K_d) was done using the L929 cell cytotoxicity assay. In vivo anti-TNF-α activity of new oligomerized aptamer was assessed in a mouse model of cutaneous Shwartzman. Anchoring of three T1–T4 aptamers to trimethyl aconitate substituent results in formation of the 162 mer fragment, which was well revealed by gel electrophoresis. In vitro study indicated that the trimerization of T1–T4 aptamer significantly improved its anti-TNF-α activity compared to non-modified aptamers (P < 0.0001) from 40% to 60%. The determination of K_d showed that trimerization could effectively enhance K_d of aptamer from 67 nM to 36 nM. In vivo study showed that trimer aptamer markedly reduced mean scar size from 15.2 ± 1.2 mm to 1.6 ± 0.1 mm (P < 0.0001), which prevent the formation of skin lesions. In vitro and in vivo studies indicate that trimerization of anti-TNF-α aptamer with a novel approach could improve the anti-TNF-α activity and therapeutic efficacy. According to our findings, a new anti-TNF-α aptamer described here could be considered an appropriate therapeutic agent in treating several inflammatory diseases.     

Analysis of Genetic Diversity of Chukar Partridge (Alectoris chukar) Populations in Khorasan-e-Razavi Province of Iran by RAPD-PCR

RAPD markers were used to investigate population genetic parameters of an endangered partridge, Alectoris chukar, in four areas of Iran, as a part of a genetic conservation program. The aim of this study was to analyze the genetic similarity among these populations. Blood samples from 75 birds were used for DNA extraction and RAPD-PCR analysis of 67 loci, with 28 polymorphic bands (41.79%). The populations of Kalat-e-Nader and Mashhad were found to be closely related, as were the Torbat-e-Jaam and the Quchan populations. Mean heterozygosity for all populations was 0.4405 ± 0.0755. The results indicate that chukar partridge genetic diversity in Khorasan-e-Razavi province is sufficient and the amount of gene flow among populations is acceptable.     

Retrotransposon insertional polymorphism in sunflower (Helianthus annuus L.) lines revealed by IRAP and REMAP markers

Retrotransposons are ubiquitous components of plants genomes, making them useful molecular markers for genetic diversity studies. We used inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) markers to assess genetic diversity and survey activity of LTR retrotransposon elements in 106 sunflower (Helianthus annuus L.) genotypes from different research centers. We found 118 (out of 128) and 113 (out of 120) polymorphic loci using 14 IRAP and 14 REMAP primers, respectively. The Mantel test between IRAP and REMAP cophenetic matrices revealed low correlation (r = 0.55) between them. Dice similarities based on combined (IRAP + REMAP) data ranged from 0.34 to 0.93 among (“11 × 12” and “F1250/03”) and (“HA335B” and “TMB51”) genotypes, respectively. Classification of genotypes using the Dice similarity matrix derived from IRAP+REMAP data based on the un-weighted pair-group method using the arithmetic average algorithm resulted in nine distinct groups. The studied genotypes were divided into seven groups considering their origins (research centers). Classification of genotypes can be useful to assess the genetic variation and gene flow between and within research centers. Analysis of molecular variance based on IRAP+REMAP data revealed a higher level of genetic variation within (94%) than between (6%) research centers. A high amount of gene flow was detected among USDA, ASGROW, and ENSAT groups. Because environmental factors have no influence on molecular markers, the construction of heterotic groups based on retrotransposon markers will be useful for the selecting of parents with a high probability of producing superior hybrids.     

Siderophore-Mediated Iron Acquisition Influences Motility and Is Required for Full Virulence of the Xylem-Dwelling Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart''s wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen.     

GRM7 polymorphisms are not associated with ischemic stroke in Iranian population

Abstract

Objectives: Ischemic stroke is the main neurological cause of acquired incapability in adults and a prominent cause of mortality. Several association studies have been conducted to explore the role of candidate genes in this neurological condition.

Methods: In the present study, we aimed at identification of association between Glutamate Metabotropic Receptor 7 (GRM7) and risk of ischemic stroke in Iranian population. Two intronic variants within this gene (rs6782011 and rs779867) were genotyped in 318 sporadic ischemic stroke cases and 300 unrelated, healthy controls individuals.

Results: No significant difference was found in allele, genotype or haplotype frequencies of these SNPs between cases and controls after correction for multiple comparisons.

Conclusion: Consequently, the assessed GRM7 variants are not implicated in risk of ischemic stroke in Iranian population.     

Gain-Assisted Propagation and Angular Response of Surface Plasmon Resonance in Nonlinear Kretschmann Configuration

The present study investigates the optical characteristics and angular response of gain-assisted surface plasmon resonance incorporating a nonlinear Kretschmann configuration. Nonlinear susceptibility of two-level atoms is used to describe the gain and nonlinear characteristics of amplifying medium. The structure is investigated and compared in both linear and nonlinear regimes. Our theory presents surface plasmon polaritons (SPPs) amplification accounting for saturation of linear gain by nonlinear losses. Reflectivity curve of the Kretschamnn configuration, attenuation constant, propagation length, and magnetic field intensity of plasmonic wave at the interface provide direct proofs of saturated gain induced by nonlinear absorption loss. Linear analysis predicts enhanced total reflection (ETR) in the presence of gain while in nonlinear regime, no ETR phenomenon occurs due to nonlinear loss absorption. Our analysis verifies that in the presence of nonlinear absorption loss, a saturation tendency of propagation length and plasmonic intensity is inevitable which is coincident with the practical observations.