Characterization of class I integrons among Salmonella enterica serovar Enteritidis isolated from humans and poultry

A total of 84 Salmonella enterica serovar Enteritidis (S. Enteritidis) isolates, 42 of human and 42 of poultry origin, were characterized for antimicrobial resistance patterns and class I integrons. Among them, 58 (69%) S. Enteritidis were multidrug-resistant (MDR) and showed resistance to two or more antibiotic classes. By PCR assays and DNA sequencing, 50 (59.5%) S. Enteritidis isolates were found to carry class I integrons. Amplification of internal variable regions of class I integrons revealed five different arrays (0.75 kb only, 1 kb only, 1.3 kb only, both 1 and 1.2 kb, and both 1 and 1.3 kb). The integrons were further sequenced and the dfrA25 (0.75 kb), aadA1 (1 kb), aadA2 (1 kb), bla(PSE1) (1.2 kb) aadA6-orfD (1.3 kb) gene cassette arrays were identified. Ciprofloxacin minimum inhibitory concentration (MIC) values for the three isolates that showed resistance or reduced susceptibility via the disc diffusion method were 0.5-4 μg mL(-1), although only three isolates exhibited resistance to cefteriaxone (MIC: 128-256 μg mL(-1)) and four isolates were resistant to florfenicol (MIC: 32-128 μg mL(-1)). In conclusion, the high rates of multidrug-resistance and class I integrons found among S. Enteritidis isolates in humans and poultry in Tehran suggest that efforts are needed to confine the prevalence of MDR Salmonella isolates.     

A novel single step double positive double negative selection strategy for beta-globin gene replacement

beta-Thalassemias are a heterogeneous group of autosomal recessive disorders, characterized by reduced or absence of the beta-globin chain production by the affected alleles. Transplantation of genetically corrected autologous hematopoietic stem cell (HSC) is an attractive approach for treatment of these disorders. Gene targeting (homologous recombination) has many desirable features for gene therapy due to its ability to target the mutant genes and restore their normal expression. In the present study, a specific gene construct for beta-globin gene replacement was constructed consisting of: two homologous stems including, upstream and downstream regions of beta-globin gene, beta-globin gene lying between hygromycin and neomycin resistant genes as positive selection markers and thymidine kinase expression cassettes at both termini as negative selection marker. All segments were subcloned into pBGGT vector. The final plasmid was checked by sequencing and named as pFBGGT. Mammalian cell line COS-7 was transfected with linear plasmid by lipofection followed by positive and negative selection. DNA of the selected cells was analyzed by PCR and sequencing to confirm the occurrence of homologous recombination. In this novel strategy gene replacement was achieved in one step and by a single construct.     

A new, efficient, and simple method for the one-pot synthesis of alpha-acetoxyphosphonates from aldehydes under solvent-free conditions

A simple, efficient, and new method has been developed for the synthesis of alpha-acetoxyphosphonates from aldehydes through a one-pot reaction of aldehydes with diethylphosphite in the presence of acetic anhydride under solvent-free conditions using magnesium oxide. This method is easy, rapid, and high yielding for the one-pot synthesis of alpha-acetoxyphosphonates from aldehydes.     

The role of endogenous opioids in the protective effects of local sublethal hyperthermia against the progression of burn injury

The aim of the present study was to evaluate the role of endogenous opioids in local sublethal hyperthermia-induced protection against burn injury.Second-degree burn wounds were induced on the back of Balb/c mice. Progression of burn injury and expression of heat shock protein (HSP)-70 were evaluated after 24 h.Both inhibition of HSP synthesis and blocking opioid receptors before applying local sublethal hyperthermia decreased the protective effects of sublethal hyperthermia against the progression of burn injury. Blocking opioid receptors attenuated induction of HSP-70 by sublethal hyperthermia.     

Genetic relationships among Pistacia species using AFLP markers

This study addresses the phylogenetic relationship between Pistacia species by amplified fragment length polymorphism (AFLP). The plant materials of this study consisted of a total of 44 accessions belonging to P. vera, P. eurycarpa, P. khinjuk, all subspecies of P. atlantica (atlantica, mutica, kurdica and cabulica), three unknown genotypes and three accessions, proposed to be hybrid from P. eurycarpa × P. atlantica. The accessions were from Iran, Turkey, USA and Syria. Six AFLP primer combinations produced a total of 475 fragments, with average of 79.16 fragments per primer pair, of which, 336 bands were polymorphic. Unweighted pair group method based on arithmetic average (UPGMA) analysis was performed on jaccard’s similarity coefficient matrix and also average similarity of each species. According to the results, two main clusters were developed and P. vera, P. eurycarpa, P. atlantica (subsp. atlantica, kurdica, mutica, cabulica) and the hybrid genotypes located in the first main cluster. P. khinjuk accessions from Iran and USA localized in second main cluster. The hybrid accessions located between eurycarpa and atlantica species and their hybrid nature between these two species were confirmed. One of the unknown accessions clustered with the hybrid ones and the two other were grouped closely with P. Khinjuk. According to this study, the closest species to P. vera was Eurycarpa group, followed by P. atlantica. UPGMA analysis separated P. atlantica subsp. mutica and cabulica from P. atlantica and P. eurycarpa. Subspecies mutica and cabulica were two closest genotypes; hence, P. atlantica subsp. mutica could be classified as a distinct species as P. mutica and the cabulica as a subspecies of P. mutica. This study revealed that P. eurycarpa is synonym for P. atlantica subsp. kurdica and should be considered distinct from P. atlantica; however, P. atlantica showed a closer genetic similarity to P. eurycarpa than the other species.     

Analysis of HLA DR2&;DQ6 (DRB1*1501, DQA1*0102, DQB1*0602) Haplotypes in Iranian Patients with Multiple Sclerosis

Multiple sclerosis (MS) is prototype of inflammatory demyelinating disease of the central nervous system .The etiology of MS remains unclear, but according to current data the disease develops in genetically susceptible individuals and may require additional environmental triggers. The human leukocyte antigen (HLA) class II alleles (DRB1*1501, DQA1*0102, DQB1*0602) may have the strongest genetic effect in MS. In this study, the role of these alleles were investigated in 183 Iranian patients with multiple sclerosis and compared with 100 healthy individuals. HLA typing for DRB1*1501, DQA1*0102, DQB1*0602 was performed by polymerase chain reaction (PCR) amplification with sequence-specific primers (PCR-SSP) method. The results show that, HLA DR B1*1501 was significantly more frequent among MS patients (46% vs. 20%, PV = 0.0006) but DQA1*0102 haplotype was negatively associated with MS (30% vs. 50%, PV = 0.0049) and no significant association was found with DQB1*0602 and MS patients in comparison with control group (24% and 30%, PV = 0.43). No significant correlation was observed among these alleles with sex, type of disease; initial symptoms, expanded disability status scale (EDSS), as well as age at onset and familial MS. This study therefore indicates that there is no association of above HLA haplotypes with clinical presentation, disease duration, and disability in Iranian patients with MS which is in line with other previous studies in different ethnic groups.     

Fast biodegradation of long chain n-alkanes and crude oil at high concentrations with Rhodococcus sp. Moj-3449

Biodegradation of long chain n-alkanes and crude oil with fast rate and high concentration are desirable for bioremediation, especially in heavily oil-polluted areas, and enhanced oil recovery. We discovered Rhodococcus sp. Moj-3449 with such unique abilities by screening microorganisms for the growth on n-hexadecane at 30 mg/mL. The new strain grew very fast on 120 mg/mL of n-hexadecane giving a cell density of 14.7 g cdw/L after only 2 days’ incubation. During the growth with this strain, the oil–water phases were rapidly emulsified, giving rise to tolerance to high alkane concentration (250 mg/mL) and fast growth rate of 0.10–0.20 h^?1 for alkane concentration of 1–180 mg/mL. The degraded concentration of n-hexadecane increased linearly with the initial alkane concentration (1–250 mg/mL). Incubation on n-hexadecane at 250 mg/mL for 7 days gave a cell density of 13.5 g cdw/L and degraded 124 mg/mL of n-hexadecane. The strain grew also fast on n-dodecane (C12), n-tetradecane (C14), and n-octadecane (C18), with degradation preference of C14 (=C16) > C12 > C18. Different from many alkane-degrading strains, Rhodococcus sp. Moj-3449 was found to have subterminal oxidation pathway. Rhodococcus sp. Moj-3449 degraded also crude oil fast at 60–250 mg/mL, with a wide range of n-alkanes (C10–C35) as substrates in which C14–C19 are preferred. The degradation ability increased with initial oil concentration from 60 to 150 mg/mL and slightly decreased afterwards. Incubation on 150 mg/mL of crude oil for 7 days degraded 37% of n-alkanes. The outstanding ability of rapidly degrading long chain n-alkanes and crude oil at high concentration makes Rhodococcus sp. Moj-3449 potentially useful for bioremediation and microbial enhanced oil recovery.     

Ribosome release factor RF4 and termination factor RF3 are involved in dissociation of peptidyl-tRNA from the ribosome.

Peptidyl-tRNA dissociation from ribosomes is an energetically costly but apparently inevitable process that accompanies normal protein synthesis. The drop-off products of these events are hydrolysed by peptidyl-tRNA hydrolase. Mutant selections have been made to identify genes involved in the drop-off of peptidyl-tRNA, using a thermosensitive peptidyl-tRNA hydrolase mutant in Escherichia coli. Transposon insertions upstream of the frr gene, which encodes RF4 (ribosome release or recycling factor), restored growth to this mutant. The insertions impaired expression of the frr gene. Mutations inactivating prfC, encoding RF3 (release factor 3), displayed a similar phenotype. Conversely, production of RF4 from a plasmid increased the thermosensitivity of the peptidyl-tRNA hydrolase mutant. In vitro measurements of peptidyl-tRNA release from ribosomes paused at stop signals or sense codons confirmed that RF3 and RF4 were able to stimulate peptidyl-tRNA release from ribosomes, and showed that this action of RF4 required the presence of translocation factor EF2, known to be needed for the function of RF4 in ribosome recycling. When present together, the three factors were able to stimulate release up to 12-fold. It is suggested that RF4 may displace peptidyl-tRNA from the ribosome in a manner related to its proposed function in removing deacylated tRNA during ribosome recycling.