Decoding the Structure-Function Relationship of the Muramidase Domain in E. coli O157.H7 Bacteriophage Endolysin: A Potential Building Block for Chimeric Enzybiotics

Bacteriophage endolysins are potential alternatives to conventional antibiotics for treating multidrug-resistant gram-negative bacterial infections. However, their structure-function relationships are poorly understood, hindering their optimization and application. In this study, we focused on the individual functionality of the C-terminal muramidase domain of Gp127, a modular endolysin from E. coli O157:H7 bacteriophage PhaxI. This domain is responsible for the enzymatic activity, whereas the N-terminal domain binds to the bacterial cell wall. Through protein modeling, docking experiments, and molecular dynamics simulations, we investigated the activity, stability, and interactions of the isolated C-terminal domain with its ligand. We also assessed its expression, solubility, toxicity, and lytic activity using the experimental data. Our results revealed that the C-terminal domain exhibits high activity and toxicity when tested individually, and its expression is regulated in different hosts to prevent self-destruction. Furthermore, we validated the muralytic activity of the purified refolded protein by zymography and standardized assays. These findings challenge the need for the N-terminal binding domain to arrange the active site and adjust the gap between crucial residues for peptidoglycan cleavage. Our study shed light on the three-dimensional structure and functionality of muramidase endolysins, thereby enriching the existing knowledge pool and laying a foundation for accurate in silico modeling and the informed design of next-generation enzybiotic treatments.

Isolation, characterization, and genome analysis of a broad host range Salmonella phage vB_SenS_TUMS_E4: a candidate bacteriophage for biocontrol

Salmonella enteritidis is one of the most important foodborne pathogens that cause numerous outbreaks worldwide. Some strains of Salmonella have become progressively resistant to antibiotics, so they could represent a critical threat to public health and have led to the use of alternative therapeutic approaches like phage therapy. In this study, a lytic phage, vB_SenS_TUMS_E4 (E4), was isolated from poultry effluent and characterized to evaluate its potential and efficacy for bio-controlling S. enteritidis in foods. Transmission electron microscopy revealed that E4 has a siphovirus morphotype, with an isometric head and non-contractile tail. Determining the host range showed that this phage can effectively infect different motile as well as non-motile Salmonella enterica serovars. The biological characteristics of E4 showed that it has a short latent period of about 15 min and a large burst size of 287 PFU/cell, and is also significantly stable in a broad range of pHs and temperatures. The E4 whole genome contains 43,018 bp and encodes 60 coding sequences (CDSs) but no tRNA genes. Bioinformatics analysis revealed that the genome of E4 lacks any genes related to lysogeny behavior, antibiotic resistance, toxins, or virulence factors. The efficacy of phage E4 as a bio-control agent was assessed in various foodstuffs inoculated with S. enteritidis at 4°C and 25°C, and the resulting data indicated that it could eradicate S. enteritidis after a very short time of 15 min. The findings of the present study showed that E4 is a hopeful candidate as a bio-control agent against S. enteritidis and has the potential to be used in various foodstuffs.

Isolation, characterization, and genomic analysis of vB_PaeP_TUMS_P121, a new lytic bacteriophage infecting Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that can cause life-threatening nosocomial infections. The alarming increase in antibiotic resistance has led to an urgent need for alternative therapeutic approaches, such as phage therapy, which has shown promising results in many studies. In this study, P121, a new lytic Pseudomonas phage, was isolated and characterized. Whole-genome sequencing showed that it has a genome of 73,001 bp that contains 91 predicted coding sequences. No genes involved in virulence or lysogeny were found in the genome, thus making it potentially safe for therapeutic applications. Genomic and phylogenetic analysis indicated that P121 is a member of the genus Litunavirus, family Schitoviridae. The present study provides some basic information for further research on treatment of P. aeruginosa infections.

Comparison of Cytokine Expression in Human PBMCs Stimulated with Normal and Heat-Shocked Lactobacillus plantarum Cell Lysate

Regulation of immune responses is among the beneficial effects of probiotic bacteria on human health. In this study, we aim to investigate the effect of normal and heat-shocked Lactobacillus plantarum PTCC 1058 cell lysate on cytokine expression by human PBMCs. The mid-exponential phase L. plantarum (10⁸ CFU/mL) were used to prepare cell lysate. Isolated PBMCs were stimulated with 100 µg/mL of each normal and heat-shocked L. plantarum cell lysate for 72 h. Non-stimulated PBMCs were also evaluated as negative control. The mRNA expression of IL-6, IL-10, IFN-ɣ, TNF-α, and TGF-β genes was determined by quantitative RT-PCR amplification of total RNA extracted from PBMCs. Both types of cell lysate were able to increase pro-inflammatory cytokines and decrease anti-inflammatory cytokines. However, this effect was significantly stronger in heat-shocked cell lysate-treated PBMCs. Moreover, comparison of IFN-ɣ/IL-10, IFN-ɣ/TGF-β, IL-6/IL-10, IL-6/TGF-β, and TNF-α/IL-10 ratios in both conditions demonstrated that in the heat-shocked group, all of the above ratios were significantly higher than normal lysate treatment (p˂0.001), suggesting that heat-shocked probiotics are a potent inducer of the immune system in comparison to intact probiotics. Regarding these results, it may be possible to develop a new postbiotic product for the stimulation of immune responses of cancer patients or individuals who suffer from an immune defect.

Expression of recombinant G-CSF receptor domains and their inhibitory role on G-CSF function

Background and purpose:

Granulocyte colony-stimulating factor (G-CSF) is routinely used in combination with chemotherapy to battle neutropenia. However, studies suggest that this chemokine may increase the risk of metastasis and malignancy in many cancers. To counteract the adverse effects of G-CSF in cancer, antibodies have been used to block its action. However, antibodies are large and complex molecules which makes their production expensive. Thus in this study, we aim to construct different structure variants of the G-CSF receptor containing different domains and select the best variant that prevents the adverse actions of this chemokine. These novel structures are smaller than antibodies and easier to produce.

Experimental approach:

Different domains of the G-CSF receptor were designed and cloned into the pET28a expression vector. These recombinant receptor subunits were then expressed in Escherichia coli and purified using standard affinity chromatography techniques. Interaction of recombinant receptor subunits with G-CSF was assessed using enzyme-linked immunosorbent assay and NFS60 cells.

Findings / Results:

Two recombinant receptor subunits containing D1 + D2 + D3 domains and D2 domain showed the strongest inhibitory activity to G-CSF.

Conclusion and implications:

These novel recombinant receptor variants could be candidates for further studies in the development of novel therapeutics.

Nanobodies in Human Infections: Prevention, Detection, and Treatment

Despite the existence of vaccination, antibiotic therapy, and antibody therapies, infectious diseases still remain as one of the biggest challenges to human health all over the world. Among the different methods for treatment and prevention of infectious diseases, antibodies are well known but poorly developed. There is a new subclass of antibodies calledheavy-chain antibodies that belong to the IgG isotype. However, they are low in molecular weight and lost the first constant domain (CH1). Their single-domain antigen-binding fragments, identified as nanobodies, have unique characteristics, which make them superior in comparison with the conventional antibodies. Low molecular weight and small size, high stability and solubility, ease of expression, good tissue penetration, and low-cost production make nanobodies an appropriate alternative to use against infectious disease. In this research, we review the properties of nanobodies and their potential applications in controlling human infections and inflammations.

PerioVax3, a key antigenic determinant with immunoprotective potential against periodontal pathogen

Treponema (T.) denticola is one of the key etiological agents in the development of periodontitis. The major outer sheath protein (Msp) of T. denticola has been shown to mediate pathogenesis and to facilitate adhesion of T. denticola to mucosal surfaces. This study aimed to find short polypeptides in the amino acid sequence of Msp which may be immunogenic and might elicit protective antisera against T. denticola. The complete msp sequence was divided into six fragments and the corresponding genes were cloned and expressed. Antisera against the polypeptides were raised in rabbits and fragment 3 (F3), hereinafter called PerioVax3 was the most potent fragment of the Msp in terms of yielding high titer antiserum. An adhesion assay was done to examine the inhibitory effects of antisera on the attachment of T. denticola to human gingival fibroblasts (HGFs) and human fibronectin. Antiserum against PerioVax3 significantly inhibited attachment of T. denticola to the substratum. Also, antiserum against PerioVax3 inhibited detachment of HGFs upon T. denticola exposure. To begin examining the clinical relevance of this work, blood samples from 12 sever periodontitis patients were collected and the sera were used in western blotting against the recombinant polypeptides. Periodontitis patient antisera exclusively detected PerioVax3 in western blotting. The data suggest that PerioVax3 carries epitopes that may trigger humoral immunity against T. denticola, which may protect against its adhesion functions. The complexity of periodontitis suggests that PerioVax3 may be considered for testing as a component of an experimental multivalent periodontal vaccine in further preclinical and clinical studies.

Genetic polymorphism of Plasmodium vivax Duffy Binding Protein in malarious areas in southeastern of Iran

Plasmodium vivax parasite causes the largest number of malaria infection in some malarious areas of the world including Iran. Considering transfer and genetic dynamics of the parasite population in a specific area can help us to predict the spread of the infection either emergence of new cases or drug resistance in the context of elimination program in the malarious areas. Study on the genetic diversity of common alleles in a given geographical area, for vaccine and immune level studies can be important. The purpose of this study was to know the status of P. vivax Duffy Binding Protein (PvDBP) polymorphism in patients infected with the parasite in malaria endemic southeastern Iran. The fragment of gene corresponding to PvDBP of thirty P. vivax malaria infected individuals was amplified. A 1176 bp band related to this fragment was purified and PCR-RFLP method was employed using enzymatic digestion with PstI and RsaI restriction enzymes. Ten percent of samples were sent for sequencing. PCR-RFLP showed that 99.7% of the samples were cut as the same together, either the PstI enzyme or the enzyme of RsaI. In each case, only 2 isolates were unlike others. Findings revealed that there is at least 96% identity among isolates in the nucleotide level. Amino acid pattern of PvDBP in Iranian isolates showed little discrepancies with those PvDBP genes that have been recorded in GenBank. Sequencing of PvDBP isolates of Iranian P. vivax infected patients showed low level of genetic polymorphism among them. Results of this study can prepare valuable information for malaria policy makers to intend them in their malaria control program.

A minireview on the in vitro and in vivo experiments with anti-Escherichia coli O157:H7 phages as potential biocontrol and phage therapy agents

Phage therapy is an old method of combating bacterial pathogens that has recently been taken into consideration due to the alarming spread of antibiotic resistance. Escherichia coli O157:H7 is a foodborne pathogen that causes hemorrhagic colitis and life-threatening Hemolytic Uremic Syndrome (HUS). There are several studies on isolation of specific phages against E. coli O157:H7 and more than 60 specific phages have been published so far. Although in vitro experiments have been successful in elimination or reduction of E. coli O157:H7numbers, in vivo experiments have not been as promising. This may be due to escape of bacteria to locations where phages have difficulties to enter or due to the adverse conditions in the gastrointestinal tract that affect phage viability and proliferation. To get around the latter obstacle, an alternative phage delivery method such as polymer microencapsulation should be tried. While the present time results are not very encouraging the work should be continued as more efficient phage treatment regimens might be found in future.

Th1 Immune Response Induction by Biogenic Selenium Nanoparticles in Mice with Breast Cancer: Preliminary Vaccine Model

BACKGROUND

Tumor associated antigens can be viably used to enhance host immune response.

OBJECTIVES

The immunomodulatory effect of biogenic selenium nanoparticles (SeNPs) was compared between treated and untreated mice with crude antigens of 4T1 cells.

MATERIALS AND METHODS

Female inbred BALB/c mice (60) were injected by cancinogenic 4T1 cells causing breast cancer. After 10 days, all tumor bearing mice were divided into 4 groups. Group 1 was daily provided oral PBS and injected by the same buffer after tumor induction and was considered as control. Group 2 received only 100 μg/day SeNPs as an oral supplement for 30 days. Group 3 was only injected with 4T1 cells crude antigens with nil supplementation of SeNPs. Group 4 animals were supplemented 100 μg/day SeNPs for 30 days and simultaneously injected with crude antigens of 4T1 cells. All antigens or PBS injections were introduced at 7, 14 and 28 days following tumor induction. Oral PBS and SeNPs supplementation initiated from the first day of tumor induction and continued up to 30 days. During tumor growth, animal weights and survival rates were monitored and at the end of the study the concentrations of different cytokines and DTH responses were measured.

RESULTS

Data clearly showed that the levels of cellular immunomodulatory components (granzyme B, IL-12, IFN-γ, and IL-2) significantly increased (P < 0.05) in mice treated with both SeNPs and crude antigens of 4T1 cells in comparison to the other groups. In contrast, the levels of TGF-β in these mice decreased.

CONCLUSIONS

Although SeNPs showed a noticeable boosting effect for the immune response in mice bearing tumor exposed to crude antigens of 4T1 cells, further complementary studies seem to be inevitable.

Assessment of cytokine expression profile in acute myeloid leukemia patients before and after chemotherapy

OBJECTIVE

One of the major goals of cancer treatment is the monitoring of chemotherapeutic protocols. Quantitative and comparative cytokine expression profiling could be reliable to be used for biomarkers in deadly and fast-growing cancers such as acute myeloid leukemia (AML). The present study aims to assess and further validate cytokines with probable effects on proliferation and maturation of blood cells in AML.

MATERIALS AND METHODS

Gene expression levels of IL-1β, IL-10, IL-8, TNF-α, and IFN-γ were analyzed before and after chemotherapy and after granulocyte colony-stimulating factor (G-CSF) therapy in 46 AML patients by an in-house quantitative comparative RT-PCR method.

RESULTS

Our findings indicated that although the gene expression level of TNF-α was almost constant in all 3 samples, IL-1β, IL-8, and IL-10 expression levels showed a decrease after chemotherapy and an increase after G-CSF therapy. On the other hand, the expression level of IFN-γ had a different pattern with an increase after chemotherapy and a decrease after G-CSF therapy.

CONCLUSION

Taken together, the results of this study are in support of the idea that the analyzed cytokines could be useful biomarkers for AML treatment monitoring. However, further molecular epidemiological investigations are suggested to elaborate more cancer monitoring biomarkers.

Identification of novel genes involved in gastric carcinogenesis by suppression subtractive hybridization

Gastric cancer (GC) is one of the most common and life-threatening types of malignancies. Identification of the differentially expressed genes in GC is one of the best approaches for establishing new diagnostic and therapeutic targets. Furthermore, these investigations could advance our knowledge about molecular biology and the carcinogenesis of this cancer. To screen for the overexpressed genes in gastric adenocarcinoma, we performed suppression subtractive hybridization (SSH) on gastric adenocarcinoma tissue and the corresponding normal gastric tissue, and eight genes were found to be overexpressed in the tumor compared with those of the normal tissue. The genes were ribosomal protein L18A, RNase H2 subunit B, SEC13, eukaryotic translation initiation factor 4A1, tetraspanin 8, cytochrome c oxidase subunit 2, NADH dehydrogenase subunit 4, and mitochondrially encoded ATP synthase 6. The common functions among the identified genes include involvement in protein synthesis, involvement in genomic stability maintenance, metastasis, metabolic improvement, cell signaling pathways, and chemoresistance. Our results provide new insights into the molecular biology of GC and drug discovery: each of the identified genes could be further investigated as targets for prognosis evaluation, diagnosis, treatment, evaluation of the response to new anticancer drugs, and determination of the molecular pathogenesis of GC.

Enhancement of Immune Responses by Co-delivery of CCL19/MIP-3beta Chemokine Plasmid With HCV Core DNA/Protein Immunization

BACKGROUND

Using molecular adjuvants offers an attractive strategy to augment DNA vaccine-mediated immune responses. Several studies have revealed that an efficient HCV vaccine model should be able to induce both humoral and cell mediated immune responses targeting the conserved regions of the virus to circumvent the immune escape mutants. The beta chemokine Macrophage Inflammatory Protein 3-beta (MIP-3beta) is a key modulator of dendritic cells (DCs) and T-cells interaction, functions during immune response induction and is secreted specifically by cells in the lymphoid tissues.

OBJECTIVES

In the present study, we questioned whether co-administration of MIP-3beta gene could enhance the immune responses to HCV core in DNA vaccination.

MATERIALS AND METHODS

Expression and biological activity of MIP-3beta expressing plasmid were evaluated by ELISA and transwell migration assays, respectively. HCV core DNA vaccine ± plasmid expressing MIP-3beta were electroporated subcutaneously to the front foot pads of BALB/c mice on days 0 and 14, and HCV core protein booster was applied to all core-DNA-vaccine received mice on the day 28. Both cell mediated immunity (proliferation, IFN-γ and IL-4 cytokine release, IFN-γ ELISpot and cytotoxic Granzyme B release assays) and humoral immune responses (total IgG and IgG2a/IgG1 subtyping) were evaluated ten days after final immunization.

RESULTS

Mice covaccinated with MIP-3beta elicited an enhanced Th1 biased systemic immune response as evidenced by higher IFN-γ/IL-4 and anti-core IgG2a/IgG1 ratio, lymphoproliferation, strong cytolytic GrzB release and enhanced population of IFN-γ producing immunocytes. Likewise, the humoral immune response assumed as the total anti-core IgG level was augmented by MIP-3beta co-delivery.

CONCLUSIONS

These results exhibited the immuno potentiator effects of MIP-3beta plasmid when coadministrated with the HCV core DNA vaccine. Complimentary studies integrating MIP-3beta as a genetic adjuvant in HCV-core-DNA vaccination models are warranted.

Genome expression analysis by suppression subtractive hybridization identified overexpression of Humanin, a target gene in gastric cancer chemoresistance

BACKGROUND

In cancer cells, apoptosis is an important mechanism that influences the outcome of chemotherapy and the development of chemoresistance. To find the genes involved in chemoresistance and the development of gastric cancer, we used the suppression subtractive hybridization method to identify the genes that are overexpressed in gastric cancer tissues compared to normal gastric tissues.

RESULTS

In the suppression subtractive hybridization library we constructed, the most highly overexpressed genes were humanin isoforms. Humanin is a recently identified endogenous peptide that has anti-apoptotic activity and has been selected for further study due to its potential role in the chemoresistance of gastric cancer. Upregulation of humanin isoforms was also observed in clinical samples by using quantitative real-time PCR. Among the studied isoforms, humanin isoform 3, with an expression level of 4.166 ± 1.44 fold, was the most overexpressed isoform in GC.

CONCLUSIONS

The overexpression of humanin in gastric cancer suggests a role for chemoresistance and provides new insight into the biology of gastric cancer. We propose that humanin isoforms are novel targets for combating chemoresistance in gastric cancer.

Cloning, molecular characterization and expression of a DNA-ligase from a new bacteriophage: Phax1

DNA ligases join 3' hydroxyl and 5' phosphate ends in double stranded DNA and are necessary for maintaining the integrity of genome. The gene encoding a new Escherichia phage (Phax1) DNA ligase was cloned and sequenced. The gene contains an open reading frame with 1,428 base pairs, encoding 475 amino acid residues. Alignment of the entire amino acid sequence showed that Phax1 DNA ligase has a high degree of sequence homology with ligases from Escherichia (vB_EcoM_CBA120), Salmonella (PhiSH19 and SFP10), Shigella (phiSboM-AG3), and Deftia (phiW-14) phages. The Phax1 DNA ligase gene was expressed under the control of the T7lac promoter on the pET-16b (+) in Escherichia coli Rossetta gami. The enzyme was then homogeneously purified by a metal affinity column. Enzymatic activity of the recombinant DNA ligase was assayed by an in-house PCR-based method.

Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 : H7

Bacteriophages are considered as promising biological agents for the control of infectious diseases. Sequencing of their genomes can ascertain the absence of antibiotic resistance, toxin or virulence genes. The anti-O157 : H7 coliphage, PhaxI, was isolated from a sewage sample in Iran. Morphological studies by transmission electron microscopy showed that it has an icosahedral capsid of 85-86 nm and a contractile tail of 115×15 nm. PhaxI contains dsDNA composed of 156 628 nt with a G+C content of 44.5 mol% that encodes 209 putative proteins. In MS analysis of phage particles, 92 structural proteins were identified. PhaxI lyses Escherichia coli O157 : H7 in Luria-Bertani medium and milk, has an eclipse period of 20 min and a latent period of 40 min, and has a burst size of about 420 particles per cell. PhaxI is a member of the genus 'Viunalikevirus' of the family Myoviridae and is specific for E. coli O157 : H7.

Radioprotective effect of melatonin on the cervical spinal cord in irradiated rats

OBJECTIVE

It has been suggested that the vascular endothelial growth factor (VEGF) gene expression plays an important role in radiation-induced injury to the spinal cord. This study assesses the radioprotective effects of N-acetyl-5-methoxytryptamine (melatonin) through its modulation of VEGF expression after localized irradiation of the cervical spinal cord.

MATERIALS AND METHODS

In this experimental study, we divided 192 male rats into four groups: 1. control (n=48); 2. rats that received an intraperitoneal (IP) injection of melatonin (n=48); 3. rats that received an IP injection of melatonin 30 minutes prior to cervical spinal cord gamma irradiation [dose: 22 Gy; (n=48)]; and 4. rats that received an IP injection of vehicle prior to spinal cord irradiation (n=48). The changes in VEGF expression were assessed using real-time RT-PCR and enzyme-linked immunosorbent assays. Samples for light microscopy were stained with hematoxylin and eosin (H&E). The differences among the groups were analyzed using the analysis of variance (ANOVA) test followed by Tukey's multiple comparisons test.

RESULTS

Up-regulation of VEGF expression was observed from 8 to 22 weeks after irradiation (p<0.05). Paralysis and other radiation-induced myelopathy manifestations developed within 22 weeks after irradiation. VEGF expression in the melatonin pre-treatment group significantly down-regulated in the 20(th) and 22(nd) weeks after irradiation compared to the radiation-only group.

CONCLUSION

The results support the hypothesis that modulation of VEGF expression by melatonin administration may increase the survival rate of irradiated animals.

Human cytochrome b5 reductase: structure, function, and potential applications

Cytochrome b5 reductase is a flavoprotein that is produced as two different isoforms that have different localizations. The amphipathic microsomal isoform, found in all cell types with the exception of erythrocytes, consists of one hydrophobic membrane-anchoring domain and a larger hydrophilic flavin catalytic domain. The soluble cytochrome b5 reductase isoform, found in human erythrocytes, is a truncated protein that is encoded by an alternative transcript and consists of the larger domain only. Cytochrome b5 reductase is involved in the transfer of reducing equivalents from the physiological electron donor, NADH, via an FAD domain to the small molecules of cytochrome b5. This protein has received much attention from researchers due to its involvement in many oxidation and reduction reactions, such as the reduction of methemoglobin to hemoglobin. Autosomal cytochrome b5 reductase gene deficiency manifests with the accumulation of oxidized Fe+3 and recessive congenital methemoglobinemia in humans. In this article, we provide a comprehensive overview of the structure and function of cytochrome b5 reductase from different eukaryotic sources and its potential use in the food industry, biosensor, and diagnostic areas.

Prediction of the pho regulon in Streptomyces clavuligerus DSM 738

Negative control of clavulanic acid by phosphate in Streptomyces clavuligerus DSM 738 suggests that a pho regulon may exist in this bacterium. S. clavuligerus PhoP was expressed with a C-terminal His-tag in Escherichia coli and purified. Binding of PhoP-His 6 to promoter fragments of phoRP/phoU and pstS was demonstrated in gel retardation experiments. These fragments contained direct 11 bp repeats resembling PHO boxes. The tentative consensus sequence, GKTCRHBBNSV, was used to search other potential PhoP target genes in the genomic sequence of S. clavuligerus. In total, the putative PHO binding sequence was found in promoter regions of 31 S. clavuligerus genes. Binding of PhoP- His 6 to the PHO box present in the promoter region of the phosphate transporter gene SSCG_07547 of S. clavuligerus was demonstrated. Furthermore, it was shown by real time PCR that decreased concentrations of phosphate do affect increased expressions of genes to which PhoP binds. These findings confirm that a pho regulon exists in S. clavuligerus.

Melatonin may play a role in modulation of bax and bcl-2 expression levels to protect rat peripheral blood lymphocytes from gamma irradiation-induced apoptosis

The close relationship between free radicals effects and apoptosis process has been proved. Melatonin has been reported as a direct free radical scavenger. We investigated the capability of melatonin in the modification of radiation-induced apoptosis and apoptosis-associated upstream regulators expression in rat peripheral blood lymphocytes. Rats were irradiated with a single whole body Cobalt 60-gamma radiation dose of 8Gy at a dose rate of 101cGy/min with or without melatonin pretreatments at different concentrations of 10 and 100mg/kg body weight. The rats were divided into eight groups of control, irradiation-only, vehicle-only, vehicle plus irradiation, 10mg/kg melatonin alone, 10mg/kg melatonin plus irradiation, 100mg/kg melatonin alone and 100mg/kg melatonin plus irradiation. Rats were given an intraperitoneal (IP) injection of melatonin or the same volume of vehicle alone 1h prior to irradiation. Blood samples were taken 4, 24, 48 and 72h after irradiation for evaluation of flow cytometric analysis of apoptotic lymphocytes using Annexin V/PI assay and measurement of bax and bcl-2 expression using quantitative real-time PCR (RT(2)qPCR). Irradiation-only and vehicle plus irradiation showed an increase in the percentage of apoptotic lymphocytes significantly different from control group (P<0.01), while melatonin pretreatments in a dose-dependent manner reduced it as compared with the irradiation-only and vehicle plus irradiation groups (P<0.01) in all time points. This reduced apoptosis by melatonin was related to the downregulation of bax, upregulation of bcl-2, and therefore reduction of bax/bcl-2 ratio. Our results suggest that melatonin in these doses may provide modulation of bax and bcl-2 expression as well as bax/bcl-2 ratio to protect rat peripheral blood lymphocytes from gamma irradiation-induced apoptosis.

A suggested new bacteriophage genus: "Viunalikevirus"

We suggest a bacteriophage genus, “Viunalikevirus”, as a new genus within the family Myoviridae. To date, this genus includes seven sequenced members: Salmonella phages ViI, SFP10 and ΦSH19; Escherichia phages CBA120 and PhaxI; Shigella phage phiSboM-AG3; and Dickeya phage LIMEstone1. Their shared myovirus morphology, with comparable head sizes and tail dimensions, and genome organization are considered distinguishing features. They appear to have conserved regulatory sequences, a horizontally acquired tRNA set and the probable substitution of an alternate base for thymine in the DNA. A close examination of the tail spike region in the DNA revealed four distinct tail spike proteins, an arrangement which might lead to the umbrella-like structures of the tails visible on electron micrographs. These properties set the suggested genus apart from the recently ratified subfamily Tevenvirinae, although a significant evolutionary relationship can be observed.

A recombinant Plasmodium vivax apical membrane antigen-1 to detect human infection in Iran

In Iran, Plasmodium vivax is responsible for more than 80% of the infected cases of malaria per year. Control interventions for vivax malaria in humans rely mainly on developed diagnostic methods. Recombinant P. vivax apical membrane antigen-1 (rPvAMA-1) has been reported to achieve designing rapid, sensitive, and specific molecular diagnosis. This study aimed to perform isolation and expression of a rPvAMA-1, derived from Iranian patients residing in an endemic area. Then, the diagnostic efficiency of the characterized Iranian PvAMA-1 was assessed using an indirect ELISA method. For this purpose, a partial region of AMA-1 gene was amplified, cloned, and expressed in pET32a plasmid. The recombinant His-tagged protein was purified and used to coat the ELISA plate. Antibody detection was assessed by indirect ELISA using rPvAMA-1. The validity of the ELISA method for detection of anti-P. vivax antibodies in the field was compared to light microscopy on 84 confirmed P. vivax patients and compared to 84 non-P. vivax infected individuals. The ELISA cut-off value was calculated as the mean+2SD of OD values of the people living in malaria endemic areas from a south part of Iran. We found a cut-off point of OD=0.311 that showed the best correlation between the sera confirmed with P. vivax infection and healthy control sera. A sensitivity of 81.0% and specificity of 84.5% were found at this cut off titer. A good degree of statistical agreement was found between ELISA using rPvAMA-1 and light microscopy (0.827) by Kappa analysis.

Ligation Independent Cloning of Polycistronic, Genetically Modified, HuMAb4D5-8 F (ab') 2, in Bacterial Plasmid

In recent years, recombinant monoclonal antibodies and their derivatives have emerged as important targeted therapy agents. Monoclonal antibodies are extremely difficult to produce. So, the cost of production is very high and many people cannot afford these drugs. In this regard, choosing inexpensive and easy ways to manipulate production systems such as bacterial hosts to reduce the cost of manufacturing these critical components are considered as vital step for developmental issues in recombinant expression systems. We, therefore, attempted to generate a polycistronic construct of anti HER-2 F(ab')2 fragment antibody for insertion in an expression bacterial plasmid. Also some modifications were made in the hinge region to express antibody F(ab')2 fragment in its authentic form preventing from multiple varieties of disulfide bond formation. Finally, synthesized construct was cloned in pET-32 Ek/LIC vector without using restriction enzyme digestion or ligation reactions. The results of this study showed that modified F(ab')2 fragment was simply and successfully inserted in Escherichia coli (E.coli) using the Ligation Independent Cloning technology.

Sequence Analysis of Different Domains of Plasmodium vivax Apical Membrane Antigen (PvAMA-1 gene) Locus in Iran

BACKGROUND

Plasmodium vivax is responsible for approximately 80 million malaria cases in the world. Apical membrane antigen1 (AMA-1) is a type I integral membrane protein present in all Plasmodium species. AMA-1 interferes in critical steps of invasion of human hepatocytes by sporozoites and red blood cells by merozoites and is one of the most immunodominant antigens for eliciting a protective immune response in human. It is considered as a promising antigen for inclusion in a vaccine against P. vivax. Since more knowledge is needed to lighten the scope of such antigen we compared genetic variation in P. vivax AMA-1from an Iranian isolate with those reported from some of the other malarious countries so far.

METHODS

P. vivax genomic DNA was extracted from the whole blood of an Iranian patient with patent P. vivax infection. The nucleotide sequence for 446 amino acid (AA) residues (42-488 of PvAMA-1) was amplified by PCR and cloned in pUC19 vector for sequencing.

RESULTS

Sequence analysis of the antigen showed a high degree of identity (99%) with strong homology to the PvAMA-1 gene of P. vivax S3 and SKO814 isolates from India and Korea (Asian isolates) respectively, and 96% similarity with P. vivax Sal-1 AMA-1 gene from El Salvador.

CONCLUSIONS

We cloned and characterized three domains of PvAMA-1 gene from an Iranian patient. Predicted protein sequence of this gene showed some discrepancies in corresponding protein in comparing with similar genes reported from other malarious countries.

Diabetic thermal hyperalgesia: role of TRPV1 and CB1 receptors of periaqueductal gray

Hyperalgesia is one of the debilitating complications of diabetes. This condition might be caused by defects in central or peripheral processing of pain signals. In the present study we aim to see if diabetic hyperalgesia is related to changes in Transient Receptor Potential Vanilloid 1 (TRPV1) or Cannabinoid CB1 receptors of periaqueductal gray (PAG). Activation of glutamatergic projecting neurons in midbrain ventrolateral periaqueductal gray (VL-PAG) induces antinociception. Agonists of TRPV1 in VL-PAG increase firing of these glutamatergic neurons. CB1 receptor agonists also cause antinociception by decreasing Gamma Aminobutyric Acid (GABA) release in PAG and disinhibiting these glutamatergic neurons. In the present study antinociceptive effect of intra VL-PAG microinjections of CB1 and TRPV1 agonists [WIN55,212-2 (WIN) and capsaicin respectively] were compared in diabetic vs. non-diabetic rats, meanwhile mRNA expression of these receptors in PAG of diabetic and non-diabetic rats were evaluated by real time polymerase chain reaction (real time PCR) assay. Our results showed an attenuation of capsaicin antinociceptive effect (P<0.05) and TRPV1 receptor expression (P=0.023) but an increase in WIN antinociceptive effect (P<0.05) and CB1 receptor expression (P<0.001) in PAG of diabetic vs. non-diabetic rats. It is concluded that down-regulation of TRPV1 receptors in PAG is responsible for reduced antinociceptive effect of TRPV1 agonist. This finding may be an underlying cause of diabetic hyperalgesia. Up-regulation of CB1 receptors might be a compensatory mechanism but the precise elucidation of the effects of CB1 changes on disinhibition needs further studies.

Cloning, molecular characterization and expression of a cDNA encoding a functional NADH-cytochrome b5 reductase from Mucor racemosus PTCC 5305 in E. coli

The present work aims to study a new NADH-cytochrome b5 reductase (cb5r) from Mucor racemosus PTCC 5305. A cDNA coding for cb5r was isolated from a Mucor racemosus PTCC 5305 cDNA library. The nucleotide sequence of the cDNA including coding and sequences flanking regions was determined. The open reading frame starting from ATG and ending with TAG stop codon encoded 228 amino acids and displayed the closest similarity (73%) with Mortierella alpina cb5r. Lack of hydrophobic residues in the N-terminal sequence was apparent, suggesting that the enzyme is a soluble isoform. The coding sequence was then cloned in the pET16b transcription vector carrying an N-terminal-linked His-Tag sequence and expressed in Escherichia coli BL21 (DE3). The enzyme was then homogeneously purified by a metal affinity column. The recombinant Mucor enzyme was shown to have its optimal activity at pH and temperature of about 7.5 and 40 degrees C, respectively. The apparent K(m) value was calculated to be 13 microM for ferricyanide. To our knowledge, this is the first report on cloning and expression of a native fungal soluble isoform of NADH-cytochrome b5 reductase in E. coli.

Lithium chloride protects PC12 pheochromocytoma cell line from morphine-induced apoptosis

BACKGROUND

Opioid drugs are considered as important members of drugs of abuse. Opioid abusers are more likely to be infected which may be due to apoptotic effects of the drugs on immune cells. Furthermore, there are some reports on the apoptotic effect of morphine on neural cells. In the present study, the effect of morphine and lithium on apoptosis in PC12 cell line (as a model of neural cells) was examined.

METHODS

We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, annexin V-fluorescein isothiocyanate test and quantitative real time RT-polymerase chain reaction for detection of necrosis and apoptosis (programmed cell death).

RESULTS

PC12 cells were exposed to different concentrations of morphine for six, 12, 24, 48, and 96 hours. Quantitative real-time RT-polymerase chain reaction revealed that mRNA expression of BAX (proapoptotic element) increased while a decrement in the mRNA expression of BCL-2 (protective element) was observed after six hours (but not after 12 or 24 hours) exposure to morphine. Furthermore, the results of MTT assay and annexin V-fluorescein isothiocyanate test indicated that morphine exposure causes an increase in the percentage of apoptotic and necrotic cells, respectively. Interestingly, the results of MTT assay and annexin V-fluorescein isothiocyanate test were observed 12 and 24 hours after morphine exposure. Thus, it can be concluded that alteration in mRNA expression is an early event rather than as a consequence of apoptosis or necrosis. On the other hand, lower concentrations of lithium elicit protective effect against apoptosis in some of mammalian cells while the higher concentrations are toxic. Despite large body of evidences on the protective effect of lithium, elucidation of downstream events are still unknown. In the present study, 72-hour preincubation of PC12 cells with 1.2 mM lithium chloride reversed the effects of morphine on the mRNA expression of BAX and BCL-2. Furthermore, the results of real time RT-polymerase chain reaction were supported by annexin V-fluorescein isothiocyanate test and MTT assay.

CONCLUSION

The protective effect of lithium on the morphine-induced cytotoxicity is mediated via down-regulation of BAX and up-regulation of BCL-2 mRNA expression.

Morphine-induced behavioral sensitization increased the mRNA expression of NMDA receptor subunits in the rat amygdala

This study was designed to evaluate the effect of repeated morphine treatment on rat behavioral responses. In the genetic section, the mRNA expression of NMDA receptor subunits (NR1 and NR2A) was measured in certain areas of the male rat brain (striatum, prefrontal cortex, hippocampus, hypothalamus and amygdala). In the behavioral section, the effect of repeated morphine treatment on animal models such as locomotion, oral stereotypy, and state-dependent memory in a passive avoidance test was evaluated in the presence or absence of MK801 (NMDA receptor antagonist). Our results showed that chronic morphine treatment, followed by a 7-day (but not 24-hour) washout period, potentiated the effect of test doses of morphine, which is referred to as behavioral sensitization. Meanwhile, pretreatment of animals with MK801 (0.1 and 0.25 mg/kg), 30 min before a test dose of morphine (5 mg/kg), failed to attenuate the locomotion and oral stereotypy in the behavioral sensitization state. Interestingly, a higher dose of MK801 (0.25 mg/kg) decreased memory retrieval induced by morphine (2.5 mg/kg) in state-dependent memory. This effect may be due to the intrinsic motor enhancer property of higher doses of MK801, rather than the blockade of NMDA receptors. It can be concluded that MK801 does not affect morphine-induced behavioral sensitization in the expression phase. In the genetic section of the study, results of quantitative real-time RT-PCR clearly indicated that morphine sensitization increased the expression of NMDA receptor subunits mRNA in the amygdala (NR1 by 104% and NR2A by 85%), while the other areas of the brain were unaffected. Maenwhile, no change in the mRNA levels was observed in non-sensitized animals (chronic morphine treatment followed by a 24-hour washout period). In summary, the present study indicates that repeated morphine treatment followed by long-term (7-day washout) induces behavioral sensitization and causes a delayed increase in mRNA levels of NMDA receptor subunits in the rat amygdala. Meanwhile, it has previously been reported that the amygdala is involved in behavioral sensitization. Thus, it can be concluded that the increase in NMDA receptor expression is associated with morphine-induced behavioral sensitization.

Using universal degenerate primers for restriction digestion mapping by PCR

In this study, a polymerase chain reaction (PCR) is developed to determine the restriction map without using restriction endonucleases. A 937 bp fragment of pUC 19 which contained one cut site for EcoRI and two recognition sites for PvuII was used as a model. The PCR was carried out using designed degenerate primers and the products were analyzed on 1.5% agarose gel. The number of cut sites, length of fragments and the arrangement of the fragments from 3' or 5' end of desired sequence were determined.