Investigating neural differentiation of mouse P19 embryonic stem cells in a time-dependent manner by bioinformatic, microscopic and transcriptional analyses

BACKGROUND

As an available cell line, mouse pluripotent P19 has been widely employed for neuronal differentiation studies. In this research, by applying the in vitro differentiation of this cell line into neuron-like cells through retinoic acid (RA) treatment, the roles of some genes including DNMT3B, ICAM1, IRX3, JAK2, LHX1, SOX9, TBX3 and THY1 in neural differentiation was investigated.

METHODS AND RESULTS

Bioinformatics, microscopic, and transcriptional studies were conducted in a time-dependent manner after RA-induced neural differentiation. According to bioinformatics studies, we determined the engagement of the metabolic and developmental super-pathways and pathways in neural cell differentiation, particularly focusing on the considered genes. According to our qRT-PCR analyses, JAK2, SOX9, TBX3, LHX1 and IRX3 genes were found to be significantly overexpressed in a time-dependent manner (p < 0.05). In addition, the significant downregulation of THY1, DNMT3B and ICAM1 genes was observed during the experiment (p < 0.05). The optical microscopic investigation showed that the specialized extensions of the neuron-like cells were revealed on day 8 after RA treatment.

CONCLUSION

Accordingly, the neural differentiation of P19 cell line and the role of the considered genes during the differentiation were proved. However, our results warrant further in vivo studies.

The impact of training chemotherapy safety standards with a smartphone application on the knowledge, attitude, and performance of nurses

BACKGROUND

Nurses who play the leading role in caring for patients, especially nurses in the chemotherapy department who are constantly exposed to high-risk drugs and their side effects, should pay more attention to occupational safety. This study was performed to determine the effect of training chemotherapy safety standards using a smartphone application on nurses' knowledge, attitude, and performance.

METHODS

The whole enumeration of fifty oncology nurses was recruited who they worked in 3 hospitals affiliated with Lorestan University of Medical Sciences (west of Iran). The study was conducted from June to November 2021. The training was done for four weeks with a smartphone application, including six main courses of familiarity with hazardous drugs, Personal Protective Equipment, preparation, storage and transfer, spilling, and wastes disposal of hazardous drudges . The nurses' knowledge, attitude, and performance questionnaire were completed before, immediately after, and one month after the intervention. Data analysis was performed using SPSS version 26, descriptive and inferential statistical tests of independent t-test, one-way analysis of variance, Spearman's rank correlation coefficient, repeated measures analysis of variance, and the Generalized Estimating Equation (GEE) model.

RESULTS

Mean knowledge score of participants before, immediately after, and one month after the intervention was (47.18 ± 8.19), (60.08 ± 3.82), and (61.88 ± 3.45), respectively. The mean attitude score of participants before, immediately after, and one month after the intervention was (30.34 ± 3.94), (34.32 ± 3.25), and (34.98 ± 2.88), in order, and the mean performance score of participants before, immediately after, and one month after the intervention was (43.60 ± 5.11), (51.78 ± 3.15) and (52.88 ± 3.06), respectively. The mean nurses' knowledge, attitude, and performance score increased significantly over time (P < 0.001).

CONCLUSIONS

Teaching chemotherapy safety standards using the application improved oncology nurses' knowledge, attitude, and performance. Appropriate educational programs, especially by new methods such as E-learning, are recommended for providing safety for nurses.

A progeroid syndrome caused by a deep intronic variant in TAPT1 is revealed by RNA/SI-NET sequencing

Exome sequencing has introduced a paradigm shift for the identification of germline variations responsible for Mendelian diseases. However, non-coding regions, which make up 98% of the genome, cannot be captured. The lack of functional annotation for intronic and intergenic variants makes RNA-seq a powerful companion diagnostic. Here, we illustrate this point by identifying six patients with a recessive Osteogenesis Imperfecta (OI) and neonatal progeria syndrome. By integrating homozygosity mapping and RNA-seq, we delineated a deep intronic TAPT1 mutation (c.1237-52 G>A) that segregated with the disease. Using SI-NET-seq, we document that TAPT1's nascent transcription was not affected in patients' fibroblasts, indicating instead that this variant leads to an alteration of pre-mRNA processing. Predicted to serve as an alternative splicing branchpoint, this mutation enhances TAPT1 exon 12 skipping, creating a protein-null allele. Additionally, our study reveals dysregulation of pathways involved in collagen and extracellular matrix biology in disease-relevant cells. Overall, our work highlights the power of transcriptomic approaches in deciphering the repercussions of non-coding variants, as well as in illuminating the molecular mechanisms of human diseases.

The Effect of Education and Telephone Follow-up on the Burden of Family Caregivers of Patients With Cancer

Introduction

Family caregivers of patients with cancer face a care burden due to the responsibilities and problems of providing care to the patients. Applying appropriate strategies to reduce the burden is essential.

Objective

The study aimed to determine the effect of education and telephone follow-up on family caregivers' burden on patients with cancer.

Methods

In this quasi-experimental study, 69 family caregivers of patients with cancer referred to only one chemotherapy center of a hospital in Lorestan province in Iran were recruited by convenience sampling method. They were randomly assigned to intervention (n  =  33) and control (n  =  36) groups. For the intervention group, two face-to-face training sessions and six telephone counseling sessions were held related to the care of the patients and self-care. The control group received only routine care. The family caregiver burden was measured by Novak and Gast Caregiver Burden Inventory (1989) completed before, immediately, and 6 weeks after the study. Data were analyzed by SPSS21 using independent t-tests, paired t-tests, and repeated measures.

Results

Both groups were homogeneous regarding demographic characteristics and the baseline care burden. The caregiver burden decreased significantly in the intervention group, so its score was 77.33  ±  8.49, 58.93  ±  8.03, and 52.78  ±  6.86 before the study, immediately after and 6 weeks later, respectively (p < .001). In the control group, there were no significant changes.

Conclusion

Education and telephone counseling reduced the burden on family caregivers. Therefore, this type of support is beneficial for providing holistic care and preserving the health of family caregivers.

A precise review on NAATs-based diagnostic assays for COVID-19: A motion in fast POC molecular tests

BACKGROUND

Diagnosis is one of the main strategies to deal with infectious and deadly diseases such as coronavirus disease 2019 (COVID-19). The global pandemic of COVID-19 has led to an immediate need to expand rapid diagnostic techniques. New isothermal-based methods are being developed for COVID-19 detection aiming to resolve the limitations related to the reverse transcription-quantitative polymerase chain reaction (RT-qPCR) method through immediate samples processing and minimizing false-negative or ambiguous results. Advances in nucleic acid amplification techniques (NAATs) can provide affordable and easy-to-use diagnostic platforms with high sensitivity and specificity in order to be available to the public as approved commercial kits.

AIMS

The development of point-of-care (POC) testing can assist in rapid clinical decision-making and mitigate burdens on health care facilities. Finally, we discussed the different diagnostic methods based on NAATs for COVID-19 in detail. Comparative parameters are addressed for all assays and Emergency Use Authorizations (EUA)-approved commercial tests are cited.

CONCLUSIONS

Isothermal-coupled methods and LAMP-based molecular methods have been suggested as suitable portable tests with high diagnostic speed for use in POC testing.

Improvement of Heart Function After Transplantation of Encapsulated Stem Cells Induced with miR-1/Myocd in Myocardial Infarction Model of Rat

Cardiovascular disease is one of the most common causes of death worldwide. Mesenchymal stem cells (MSCs) are one of the most common sources in cell-based therapies in heart regeneration. There are several methods to differentiate MSCs into cardiac-like cells, such as gene induction. Moreover, using a three-dimensional (3D) culture, such as hydrogels increases efficiency of differentiation. In the current study, mouse adipose-derived MSCs were co-transduced with lentiviruses containing microRNA-1 (miR-1) and Myocardin (Myocd). Then, expression of cardiac markers, such as NK2 homeobox 5(Nkx2-5), GATA binding protein 4 (Gata4), and troponin T type 2 (Tnnt2) was investigated, at both gene and protein levels in two-dimensional (2D) culture and chitosan/collagen hydrogel (CS/CO) as a 3D culture. Additionally, after induction of myocardial infarction (MI) in rats, a patch containing the encapsulated induced cardiomyocytes (iCM/P) was implanted to MI zone. Subsequently, 30 days after MI induction, echocardiography, immunohistochemistry staining, and histological examination were performed to evaluate cardiac function. The results of quantitative real -time polymerase chain reaction (qRT-PCR) and immunocytochemistry showed that co-induction of miR-1 and Myocd in MSCs followed by 3D culture of transduced cells increased expression of cardiac markers. Besides, results of in vivo study implicated that heart function was improved in MI model of rats in iCM/P-treated group. The results suggested that miR-1/Myocd induction combined with encapsulation of transduced cells in CS/CO hydrogel increased efficiency of MSCs differentiation into iCMs and could improve heart function in MI model of rats after implantation.

Identification of Circulating hsa-miR-324-3p and hsa-miR-331-3p Exchanges in The Serum of Alzheimer's Patients and Insights into The Pathophysiological Pathways

Objective

Alzheimer's disease (AD) is a type of dementia. Currently, there are not any existing and reliable methods for the prognosis or diagnosis of AD. Hence, finding a diagnostic/prognostic biomarker for AD helps physicians to prescribe the treatments and methods preventing disease progression. Circulating microRNAs (miRNAs) are the most promising biomarkers due to their non-invasive and easily accessible for diagnosis and prognosis of AD. The aim of current study is to evaluate expression levels of two unwell-known circulating miRNAs including hsa-miR-324-3p and hsa-miR-331-3p in serums of AD patients and to understand their roles in AD physiopathogenesis by in silico analysis.

Materials and Methods

In this case and control study, to get the gene targets related to these two miRNAs, TargetScan, miRTargetLink Human and mirDIP web servers were applied. In addition, gene networks and gene ontology enrichment analysis were performed by STRING 10.5, KEGG and ShinyGO v0.41. Experimentally, expression levels of these two miRNAs in the serum of 21 patients with AD and 23 healthy individuals were compared using the quantitative reverse transcription polymerase chain reaction (qRT-PCR) method.

Results

The pathophysiological pathways associated with these two miRNAs were nucleotide metabolism and cellular response to stress pathway. Furthermore, the upregulated expression levels of hsa-miR-324-3p and hsa-miR-331-3p in comparison with the healthy control serums were not statistically significant (P>0.05).

Conclusion

Non-significant results were obtained from the expression levels of AD patients and two significant pathways were obtained by networks and gene enrichment analysis.

A Novel CAR Expressing NK Cell Targeting CD25 With the Prospect of Overcoming Immune Escape Mechanism in Cancers

For many years, high-affinity subunit of IL-2 receptor (CD25) has been considered as a promising therapeutic target for different pathologic conditions like allograft rejection, autoimmunity, and cancers. Although CD25 is transiently expressed by newly-activated T cells, it is the hallmark of regulatory T (Treg) cells which are the most important immunosuppressive elements in tumor microenvironment. Thus, Tregs can be considered as a potential target for chimeric antigen receptor (CAR)-based therapeutic approaches. On the other hand, due to some profound adverse effects pertaining to the use of CAR T cells, CAR NK cells have caught researchers’ attention as a safer choice. Based on these, the aim of this study was to design and develop a CAR NK cell against CD25 as the most prominent biomarker of Tregs with the prospect of overcoming immune escape mechanism in solid and liquid cancers. In the current study, an anti-CD25 CAR was designed and evaluated by comprehensive in silico analyses. Then, using lentiviral transduction system, NK-92 cell line was engineered to express this anti-CD25 CAR construct. In vitro functional analyses of anti-CD25 CAR for its reactivity against CD25 antigen as well as for cytotoxicity and cytokine production assays against CD25 bearing Jurkat cell line were done. In silico analyses demonstrated that the anti-CD25 CAR transcript and scFv protein structures were stable and had proper interaction with the target. Also, in vitro analyses showed that the anti-CD25 CAR-engineered NK-92 cells were able to specifically detect and lyse target cells with an appropriate cytokine production and cytotoxic activity. To conclude, the results showed that this novel CAR NK cell is functional and warrant further investigations.

Bioenergetic analysis of aged-phenotype skin in a rare syndromic cutis laxa

BACKGROUND

Skin aging is an inevitable phenomenon characterized by wrinkled skin and loss of elasticity. To date, several studies have been performed on skin aging to discover the underlying mechanisms and improve efficient preventive strategies and anti-aging therapeutics.

AIMS

Here, we aimed to investigate the modifications of oxidative phosphorylation and glycolysis which are the critical determinants of aging in aged-phenotype skin.

METHODS

Due to the complexity of the skin aging process, we performed bioenergetic measurements on aged-phenotype fibroblasts from an inherited cutis laxa syndrome which remarkably presents clinical features of normal aged skin. Bioenergetic analysis was performed on cutis laxa samples (n = 3) and healthy samples (n = 3) using Seahorse XFe24 Analyzer. We also compared the sensitivity of cultured aged-phenotype fibroblasts to normal cells in glucose withdrawal.

RESULTS

Our results show a significant increase in oxidative phosphorylation parameters but not glycolysis in the patient fibroblast cells implying increased energy demand and preferential dependence on mitochondrial respiration in those cells. Interestingly, we found the patient cells demonstrate hypersensitivity to glucose starvation, supporting their enhanced energy consumption.

CONCLUSIONS

In summary, our work suggested increased energy demand and higher oxidative phosphorylation in aged-phenotype cells which can be considered in anti-skin aging therapeutic design.

CRISPR/Cas9-mediated knockout of clinically relevant alloantigenes in human primary T cells

Background

The ability of CRISPR/Cas9 to mutate any desired genomic locus is being increasingly explored in the emerging area of cancer immunotherapy. In this respect, current efforts are mostly focused on the use of autologous (i.e. patient-derived) T cells. The autologous approach, however, has drawbacks in terms of manufacturing time, cost, feasibility and scalability that can affect therapeutic outcome or wider clinical application. The use of allogeneic T cells from healthy donors may overcome these limitations. For this strategy to work, the endogenous T cell receptor (TCR) needs to be knocked out in order to reduce off-tumor, graft-versus-host-disease (GvHD). Furthermore, CD52 may be knocked out in the donor T cells, since this leaves them resistant to the commonly used anti-CD52 monoclonal antibody lymphodepletion regimen aiming to suppress rejection of the infused T cells by the recipient. Despite the great prospect, genetic manipulation of human T cells remains challenging, in particular how to deliver the engineering reagents: virus-mediated delivery entails the inherent risk of altering cancer gene expression by the genomically integrated CRISPR/Cas9. This is avoided by delivery of CRISPR/Cas9 as ribonucleoproteins, which, however, are fragile and technically demanding to produce. Electroporation of CRISPR/Cas9 expression plasmids would bypass the above issues, as this approach is simple, the reagents are robust and easily produced and delivery is transient.

Results

Here, we tested knockout of either TCR or CD52 in human primary T cells, using electroporation of CRISPR/Cas9 plasmids. After validating the CRISPR/Cas9 constructs in human 293 T cells by Tracking of Indels by Decomposition (TIDE) and Indel Detection by Amplicon Analysis (IDAA) on-target genomic analysis, we evaluated their efficacy in primary T cells. Four days after electroporation with the constructs, genomic analysis revealed a knockout rate of 12–14% for the two genes, which translated into 7–8% of cells showing complete loss of surface expression of TCR and CD52 proteins, as determined by flow cytometry analysis.

Conclusion

Our results demonstrate that genomic knockout by electroporation of plasmids encoding CRISPR/Cas9 is technically feasible in human primary T cells, albeit at low efficiency.

Computational study for suppression of CD25/IL-2 interaction

Cancer recurrence presents a huge challenge in cancer patient management. Immune escape is a key mechanism of cancer progression and metastatic dissemination. CD25 is expressed in regulatory T (Treg) cells including tumor-infiltrating Treg cells (TI-Tregs). These cells specially activate and reinforce immune escape mechanism of cancers. The suppression of CD25/IL-2 interaction would be useful against Treg cells activation and ultimately immune escape of cancer. Here, software, web servers and databases were used, at which in silico designed small interfering RNAs (siRNAs), de novo designed peptides and virtual screened small molecules against CD25 were introduced for the prospect of eliminating cancer immune escape and obtaining successful treatment. We obtained siRNAs with low off-target effects. Further, small molecules based on the binding homology search in ligand and receptor similarity were introduced. Finally, the critical amino acids on CD25 were targeted by a de novo designed peptide with disulfide bond. Hence we introduced computational-based antagonists to lay a foundation for further in vitro and in vivo studies.

The Highlighted Roles of Metabolic and Cellular Response to Stress Pathways Engaged in Circulating hsa-miR-494-3p and hsa-miR-661 in Alzheimer's Disease

Background:

Among different roles of miRNAs in AD pathogenesis, hsa-miR-494-3p and hsa-miR-661 functions are poorly understood.

Methods:

To obtain the gene targets, gene networks, gene ontology, and enrichment analysis of the two miRNAs, some web servers were utilized. Furthermore, the expressions of these miRNAs were analyzed by qRT-PCR in 36 blood sera, including 18 Alzheimer’s patients and 18 healthy individuals.

Results:

The in silico analysis demonstrated the highlighted roles of metabolic and cellular response to stress pathways engaged in circulating hsa-miR-494-3p and hsa-miR-661 in AD. The qRT-PCR analysis showed that the downregulated expression level of hsa-miR-661 was statistically significant (p < 0.05). Also, the ROC curve of hsa-miR-661 displayed the significant AUC (p = 0.01).

Conclusion:

Based on our findings, the metabolic and cellular responses to stress pathways are closely connected to these two miRNAs functions. Besides, the qRT-PCR and Roc curve determined hsa-miR-661 could be as a biomarker for diagnosis or prognosis of AD patients.

HER2 Testing in Invasive Breast Cancer: A Comparison Between Immunohistochemistry and Fluorescence In Situ Hybridization Assays

Background: HER2 status testing in breast cancer is crucial for the detection of eligible patients for trastuzumab therapy. In this study, the relative copy number of HER2 gene, in patients with breast cancer, was determined by fluorescence in situ hybridization (FISH) and the results were compared with those of immunohistochemistry (IHC) to obtain the concordance rate between these two methods. Material and Methods: HER2 status of 31 invasive breast cancer samples was compared using IHC and FISH techniques. The ratio of HER2/CEP17 was used to determine the amplification of the HER2 gene. If the ratio of HER2/CEP17 is greater than 2.2, HER2 gene amplification has occurred in the cancer cells. Then, a comparative analysis is performed to estimate the concordance rate between FISH and IHC results. Results: The gene amplification of HER2 was observed in 26% of cases by FISH. The IHC and FISH results showed 100%, 36.36%, and 85.71% concordance rates for cases with IHC scores of 3+, 2+, and 0/+1, respectively. The overall concordance between the two methods was 80%. Based on statistical analysis, HER2 status showed a considerable correlation with tumor grade (P= 0.02). No correlation was observed between HER2 gene status and the size and type of tumor, characteristics of lymph node, and patients’ age. Conclusion: The data suggested that IHC results are reliable for HER2 status testing in cases with IHC scores 0/+1 and 3+. However, in patients with an IHC score of +2, it is necessary to perform a complimentary test to evaluate HER2 status to avoid haphazard treatment with trastuzumab in negative cases and identifying positive cases for suitable treatment.

The Effects of Self-cleavage Intein-ELK16 Tag in the Transcript Steric Hindrance of IFN

Intervening proteins (Inteins) are identified as protein domains in a precursor protein structure. Inteins can excise itself from precursor protein and join the remaining portions which result in forming an active protein. In this study, the transcript expression level of recombinant human Interferon beta (rhIFNβ) connected to the self-cleavage Intein-ELK16 (LELELKLKLELELKLK) tag was measured by real-time PCR in HEK293T cell line. First, the sequence of Mycobacterium tuberculosis RecA (Mtu recA) was obtained from the InBase database to do appropriate changes including adding the restriction sites, kozak sequence, signal peptide and ELK16 sequence by SnapGene software. The RNA secondary structure were also examined using the online RNA Fold 2.2 web server. Next, the construct was inserted into pUC19 plasmid. The sequence of rhIFNβ was also cloned into pBudCE4.1 vector. In the next step, the rhIFNβ was ligated into the construct (self-cleavage tag of ELK16) using T4 DNA ligase and the recombinant construct was transfected into HEK293T cell line. Finally, expression of the cassette was evaluated by real-time PCR. The analysis of secondary RNA structure indicates a minimum free energy of MEF - 261.10 kcal/mol. Our results indicate that IFNβ was upregulated (37.8-fold, p < 0.0001) in cells which transfected by rhIFNβ-ELK16 compared to the mock and un-transfected conditions. Altogether, our results show that the presence of mini self-cleavage Intein-ELK16 tag along with the rhIFNβ had no interference in transcription of rhIFNβ in the HEK293T cell line.

The Comparison Between the Mutated HuIFN-β 27-101 and the Wild Type Interferon β: the Comprehensive In Silico Study to Evaluate the Effect of Mutations on IFN-β

Purpose: Interferon beta (IFN-β) is used to combat multiple sclerosis (MS) disease. Creating R27T and V101F mutations (mHuIFN-β-27 and mHuIFN-β-101) is one of the tasks performed to improve human interferon beta (HuIFN-β) half-life, function and expression. In this work, the impact of R27T and V101F mutations in recombinant IFN-β on its binding to interferon receptors were studied by molecular docking.

Methods: This work was performed through in silico study. The simulation of mutation was performed using the online Rosetta Backrub software and checked using server verify3D. Comparison of access to the solvent of the amino acids in the structures created was performed using the asaview online server. Also, the effect of mutations on the fold of the protein was reviewed by the online HOPE server. The molecular docking was performed between HuIFN-β and the external region of IFNAR receptor using the online ClusPro2 protein-protein docking server.

Results: The comparison of the values of the negative binding energy (ΔGbind) obtained from protein-protein molecular docking between IFNAR receptor and HuIFN-β, mHuIFN-β-27, mHuIFN-β-101 and mHuIFN-β-27-101 ligands did not show a significant difference, and these differences do not see any meaningful relationship between them (P > 0.9999).

Conclusion: Regarding these results, it can be concluded that these mutations do not have a negative effect on the composition of the complex rHuIFN-β/IFNAR. So, they do not interfere with the binding of the IFN-β to the receptor. It is concluded that the quality of the rHuIFN-β is improved by introducing these two mutations.

Integral membrane protein expression of human CD25 on the cell surface of HEK293 cell line: the available cellular model of CD25 positive to facilitate in vitro developing assays

Typically, CD25 is expressed on the cellular surface of regulatory T (Treg) cells. These cells are significant in regulating the self-tolerance and also preventing the immune system from attacking a person's own tissues and cells. They promote the cancer progression by playing an important role in evading the immune system. Thus, the experimental procedures was aimed to clone and express human CD25 in HEK293 cell line, as the available cellular model, for the purpose of developing assays to facilitate and enhance the studies on an available CD25 positive cell. The secondary RNA structure of CD25 was evaluated by in silico analysis. Then, cDNA of human CD25 were synthesized from isolated total mRNA of cultured and stimulated PBMCs from blood donors. After cloning the cDNA of CD25 into a pcDNA3.1(+) plasmid, using the effective transfection of the recombinant pcDNA3.1(+) in HEK293, qRT-PCR and flow cytometry methods were used to quantitatively evaluate CD25 transcripts and protein level. There was a 4.8 fold increase in transcripts and a 76.2% increase in protein levels of CD25 when comparing the transfected and control cell lines. The genetically engineered HEK293 cell line expressing Treg cell surface marker of CD25 was introduced in this study for the first time. This cell line can be used to overcome the problematic issues for studying Treg cells including low population of Tregs in peripheral blood, low recovery methods for Treg isolation, time-consuming and non-cost benefit methods in the conditions of in vitro cell culture experiments for the studies focused on the binding of IL-2 to CD25.

Evaluation of Silencing Effect of miR-133a-5p Mimic on TIM-3 Expression in AML (HL-60) Cell Line

Acute myelogenous leukemia (AML) is a complex blood malignancy leading to immature leukemic stem cells (LSCs) proliferation. T cell immunoglobulin mucin-3 (TIM-3) is known as a biomarker of AML LSCs. Several microRNAs (miRNAs) can affect gene expression in AML. In this study, the silencing effect of miR-133a-5p on TIM-3 expression in AML cell lineage (HL-60) was investigated. It's been hypothesized that miR-133a-5p may suppress the TIM-3 expression in AML cell line. Initially, miRNA-TIM-3 prediction, enrichment, and network analysis were done. Then, miR-133a-5p mimic was transfected into HL-60 cells. The TIM-3 protein and gene expression were measured by flow cytometry analysis and real-time PCR, respectively. MTT assay was also carried out. Based on the Bioinformatics predictions, miR-133a-5p was able to silence TIM-3 expression. Also, significant pathways pertained to miR-133a-5p were obtained using enrichment analysis. According to this, miR-133a-5p was mainly engaged in the MAPK signaling pathway and Nicotine addiction pathway using the KEGG database. The TIM-3 protein expression of the transfected cells was measured as 17.15 ± 8.87% (p = 0.001). A 52.48% significant gene silencing in mRNA level was obtained in comparison to the negative control. Despite of down regulation of TIM-3, HL-60 cell viability has not been significantly changed. It has been finally confirmed that miR-133a-5p could strongly suppress TIM-3 expression in AML cell line. Presumably, down regulation of TIM-3 could affect MAPK and Nicotine addiction signaling pathways.

Identification of Two Novel Mutations in KDM3A Regulatory Gene in Iranian Infertile Males

BACKGROUND

KDM3A is a key epigenetic regulator expressed in the testis and is required for packaging and condensation of sperm chromatin. To this point, the association of the KDM3A gene with infertility has not been studied in human. The aim of this study was to screen any new mutation in KDM3A gene to explore more details of human male infertility.

METHODS

In this work, 150 infertile men (oligozoospermia and azoospermia) and 150 normal healthy fathers were studied. Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequencing were used to screen any mutation in exons 12, 22, and 24 of KDM3A.

RESULTS

The infertile men showed various SSCP patterns for the exons 12 and 24, but not for exon 22. A transversion point mutation in exon 12 and a single nucleotide deletion in exon 24 were detected using sequencing analysis. The transversion mutation was located in the preceding exon of lysine-specific demethylase1 and Jumonji (Jmj)-C domain and the later one (deletion) in the cupin-like motif of KDM3A protein. Neither Y chromosome microdeletions nor partial azoospermia factor deletion was found in these patients.

CONCLUSION

The mutations found in infertile men with otherwise unexplained severe spermatogenic failure could be considered as the origin of their abnormalities.

Genetic Variation in Intergenic and Exonic miRNA Sequence and Risk of Multiple Sclerosis in the Isfahan Patients

MicroRNAs (miRNAs), have been documented to perform a key role in the pathogenesis of multiple sclerosis (MS), a chronic inflammatory and autoimmune disease. Recent studies have shown that single nucleotide polymorphism in the sequence of the miRNA may change their production and expression which can lead to miRNA dysfunction and pathogenicity. Some studies have reported the relationship between miRNA polymorphism and the increased risk of autoimmune disease. This study was conducted to investigate the association between mir155 rs767649, mir196a2 rs11614913 and mir23a rs3745453 polymorphism and the risk of multiple sclerosis in the Iranian MS patients in Isfahan. A population of 80 patients and the same number control were selected. After DNA extraction, genotyping was performed through tetra amplification refractory mutation system-PCR method (T ARMS PCR). The frequencies of TT, TC and CC genotypes of mir23a were 46, 35 and 20% in MS patients and 42, 14 and 24 in healthy subjects respectively. These results showed that individuals carrying the genotypes of rs3745453 TC had a 2.3-fold increased risk of MS (OR=2.3, p=0.048). There was no significant difference between genotypes and allele frequency of mir155 and mir196a2 in patients and healthy controls (p>0.05). Our findings specified that CT heterozygosity in mir23a gene significantly related with risk of MS. Unlike mir155 and mir196a2, mir23a rs3745453 may have contributed to the etiology of MS in Isfahan patients. However, extensive studies are required to gain more reliable and authentic results.

Reconstruction of the genome-scale co-expression network for the Hippo signaling pathway in colorectal cancer

The Hippo signaling pathway (HSP) has been identified as an essential and complex signaling pathway for tumor suppression that coordinates proliferation, differentiation, cell death, cell growth and stemness. In the present study, we conducted a genome-scale co-expression analysis to reconstruct the HSP in colorectal cancer (CRC). Five key modules were detected through network clustering, and a detailed discussion of two modules containing respectively 18 and 13 over and down-regulated members of HSP was provided. Our results suggest new potential regulatory factors in the HSP. The detected modules also suggest novel genes contributing to CRC. Moreover, differential expression analysis confirmed the differential expression pattern of HSP members and new suggested regulatory factors between tumor and normal samples. These findings can further reveal the importance of HSP in CRC.

Network-based expression analyses and experimental validations revealed high co-expression between Yap1 and stem cell markers compared to differentiated cells

The Hippo signaling pathway is identified as a potential regulatory pathway which plays critical roles in differentiation and stem cell self-renewal. Yap1 is a primary transcriptional effector of this pathway. The importance of Yap1 in embryonic stem cells (ESCs) and differentiation procedure remains a challenging question, since two different observations have been reported. To answer this question we used co-expression network and differential co-expression analyses followed by experimental validations. Our results indicate that Yap1 is highly co-expressed with stem cell markers in ESCs but not in differentiated cells (DCs). The significant Yap1 down-regulation and also translocation of Yap1 into the cytoplasm during P19 differentiation was also detected. Moreover, our results suggest the E2f7, Lin28a and Dppa4 genes as possible regulatory nuclear factors of Hippo pathway in stem cells. The present findings are actively consistent with studies that suggested Yap1 as an essential factor for stem cell self-renewal.

Screening of Two Neighboring CFTR Mutations in Iranian Infertile Men with Non-Obstructive Azoospermia

The genetic association between cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and male infertility due to congenital bilateral absence of vas deferens (CBAVD) is well established. Mutant CFTR, however may also be involved in the etiology of male infertility in non-CBAVD cases. The present study was conducted to estimate the frequency of ∆I507 and ∆F508 CFTR gene mutations in Iranian infertile males. We undertook the first study of association between these CFTR mutations and non-obstructive azoospermia in Iran. In this case-control study, 100 fertile healthy fathers and 100 non-obstructive azoospermia’s men were recruited from Isfahan Infertility Center (IIC) and Sari Saint Mary’s Infertility Center, between 2008 and 2009. Screening of F508del and I507del mutations was carried out by the multiplex-ARMS-PCR. Significance of differences in mutation frequencies between the patient and control groups was assessed by Fisher’s exact test. The ΔF508 was detected in three patients. However there are no significant association was found between the presence of this mutated allele and infertility [OR=9.2 (allele-based) and 7.2 (individual-based), P=0.179]. None of the samples carried the ΔI507 mutation. Altogether, we show that neither ΔI507 nor ΔF508 is involved in this population of Iranian infertile males with non-obstructive azoospermia.

Association between polymorphisms of exon 12 and exon 24 of JHDM2A gene and male infertility

BACKGROUND

Some dynamic changes occurs during spermatogenesis such as histone removal and its replacement with transition nuclear protein and protamine. These proteins are required for packing and condensation of sperm chromatin. JHDM2A is a histone demethylase that directly binds to promoter regions of Tnp1 and Prm1 genes and controls their expression by removing H3K9 at their promoters.

OBJECTIVE

The association between polymorphisms of exon 12 and exon 24 in JHDM2A gene and male infertility were evaluated for the first time.

MATERIALS AND METHODS

In this experimental study, 400 infertile men (oligospermia and azoospermia) and normal healthy fathers were evaluated (n=200). Single Strand Conformation Polymorphism (SSCP-PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods were used for screening any polymorphisms that are exist in exon 12 and exon 24.

RESULTS

Exon 24 PCR products were analyzed by RFLP but no polymorphism was found in this exon at the restriction site of EcoRV enzyme. Our monitoring along the whole nucleotides of exon 12 and exon 24 were continued using SSCP method, but we found no change along these exons.

CONCLUSION

Generally, this study evaluated the association between polymorphisms in exon 12 and exon 24 of JHDM2A gene and male infertility which suggests that polymorphisms of these exons may not be associated with the risk of male infertility.

Effects of disruption of the nucleotide pattern in CRID element and Kozak sequence of interferon β on mRNA stability and protein production

Interferon β (IFNβ) is the most important drug that has been used frequently for multiple sclerosis treatment. This study has tried to improve the IFNβ production by introducing mutations in the coding region of IFNβ, while its amino acid sequence is intact. Two recombinant vectors IFNβ(K) and IFNβ(K+CRID )were designed by site-directed mutagenesis. The IFNβ(K) and IFNβ(K+CRID) have two substitutions in Kozak sequence and four substitutions in CRID sequence, respectively. The Chinese hamster ovary (CHO) cell codon usage optimization was also performed for both of them. They were transiently transfected to CHO-dhfr(-) cell line using Lipofectamine kit (Invitrogen, Grand Island, NY). The amount of mRNA and protein was determined by real time PCR and ELISA. The results of this study indicate that the amount of IFNβ protein produced by CHO cells containing IFNβ(K) has been elevated up to 3.5-fold. On the other hand, enormous amounts of IFNβ mRNA and protein were produced by cells containing IFNβ(K+CRID) construct; more than 4.6-fold and 6-fold, respectively. It could be concluded that disruption of AT pattern in CRID element increase RNA and protein production, improve IFNβ mRNA stability and, may also enhance mRNA half-life. In a similar way, more proteins are produced by modification of Kozak sequence.

The FimH Gene in Uropathogenic Escherichia coli Strains Isolated From Patients With Urinary Tract Infection

Background:

Urinary tract infections (UTIs) are one of main health problems caused by many microorganisms, including uropathogenic Escherichia coli (UPEC). UPEC strains are the most frequent pathogens responsible for 85% and 50% of community and hospital acquired UTIs, respectively. UPEC strains have special virulence factors, including type 1 fimbriae, which can result in worsening of UTIs.

Objectives:

This study was performed to detect type 1 fimbriae (the FimH gene) among UPEC strains by molecular method.

Materials and Methods:

A total of 140 isolated E. coli strains from patients with UTI were identified using biochemical tests and then evaluated for the FimH gene by polymerase chain reaction (PCR) analysis.

Results:

The UPEC isolates were identified using biochemical tests and were screened by PCR. The fimH gene was amplified using specific primers and showed a band about 164 bp. The FimH gene was found in 130 isolates (92.8%) of the UPEC strains. Of 130 isolates positive for the FimH gene, 62 (47.7%) and 68 (52.3%) belonged to hospitalized patients and outpatients, respectively.

Conclusions:

The results of this study indicated that more than 90% of E. coli isolates harbored the FimH gene. The high binding ability of FimH could result in the increased pathogenicity of E. coli; thus, FimH could be used as a possible diagnostic marker and/or vaccine candidate.

New Insights into VEGF-A Alternative Splicing: Key Regulatory Switching in the Pathological Process

Vascular endothelial growth factor (VEGF-A) is one of the most important regulatory factors in pathological and physiological angiogenesis. Alternative splicing is a complicated molecular process in VEGF-A gene expression which adds complexity to VEGF-A biology. Among all VEGF-A exons, alternative splicing of exon 8 is the key determinant of isoform switching from pro-angio-genic VEGF-xxx to anti-angiogenic VEGF-xxxb. This is known as a key molecular switching in many pathological situations. In fact, the balance between VEGF-xxx and VEGF-xxxb isoforms is a critical controlling switch in both conditions of health and disease. Here, the properties of VEGF-xxx and VEGF-xxxb isoforms were discussed and their regulatory mechanism and their roles in certain pathological processes were evaluated. In summary, it was suggested that C-terminal VEGF-A alternative splicing can provide a new treatment opportunity in angiogenic diseases.

Assessment of HER-2 gene overexpression in Isfahan province breast cancer patients using Real Time RT-PCR and immunohistochemistry

PURPOSE

Overexpression of proto-oncogene HER-2 is one of the main molecular markers of breast cancer involved in prognosis and diagnosis and also in trastuzumab therapy. Thus, a request for the evaluation of HER-2 status in breast cancer has been increasing. The aim of our study was assessment of HER-2 overexpression in malignant and benign breast cancer specimens by Real Time RT-PCR technique and comparison of its results with IHC outcomes.

METHODS

Twenty benign and sixty malignant breast cancers in addition to fifteen normal breast tissue specimens were analyzed by Real Time RT-PCR method. Fresh tissue samples were disrupted by mortar and pestle. A syringe and a needle were used for complete homogenization of the tissues. The RNA was then isolated from the samples and converted to cDNA. A standard curve was initially plotted using BioEasy SYBR Green I and then all 95 specimens were studied by Real Time RT-PCR using 2(-ΔΔCt) method.

RESULTS

23.3% of 60 malignant specimens showed HER-2 overexpression, while all of the benign samples represented the normal expression level of HER-2 gene. The concordance rate between the results of Real Time RT-PCR and IHC was 86.6%.

CONCLUSION

Real Time RT-PCR method is an almost reliable technique and at least can be used as a complementary method for confirming IHC results. This is emanated from relatively high rate of concordance between outcomes of IHC test, as a routine method of detecting the HER-2 gene expression status, and Real Time RT-PCR technique.

The molecular study of IFNβ pleiotropic roles in MS treatment

Multiple sclerosis (MS) is one of the most important autoimmune diseases recognized by demyelination and axonal lesion. It is the most common cause of disability in the young population. Various immunomodulatory and immunosuppressive therapies, including different formulations of interferon beta (IFNβ), glatiramer acetate (GA), mitoxantrone, and natalizumab are available for this disease. However, interferon has been the best prescribed. Although the precise mechanism of IFNβ is unclear, many studies indicate some potential mechanism including blocking T cells activation, controlling pro- and anti-inflammatory cytokine secretion, preventing activated immune cell migration through BBB, and inducing repair activity of damaged nerve cells by differentiating neural stem cells into oligodendrocytes. These molecular mechanisms have significant roles in IFNβ therapy. More researches are required in order for us to comprehend the mechanism of action of IFNβ, and improve and develop drugs for more efficient MS treatment.

Determination of ctxAB expression in Vibrio cholerae Classical and El Tor strains using Real-Time PCR

Cholera is an infection of the small intestines caused by the bacterium V. cholerae. It is a major cause of health threat and also a major cause of death worldwide and especially in developing countries. The major virulence factor produced by V. cholerae during infection is the cholera toxin. Total mRNA extraction and reverse transcription was performed for making ctxAB cDNA. Relative Real-Time PCR analysis showed unequal enterotoxin production in V. cholerae strains. The results showed that, classical strain produces cholera toxin more than El Tor strain.

The stromelysin-1 5A/5A genotype enhances colorectal cancer cell invasion in Iranian population

BACKGROUND

Matrix metalloproteinases comprise a family of enzyme degrade components of extra cellular matrix. There are single nucleotide polymorphisms in the promoter regions of several genes with ability to influence cancer susceptibility. The aim of this study was to analyze association between MMP3 promoter polymorphisms and colorectal cancer occurrence and progression.

MATERIALS AND METHODS

In this case-control study 120 colorectal cancer patients and 100 controls were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on the genomic deoxyribonucleic acid (DNA). The patients group was divided into different subgroups: a subgroup without metastatic activity (M(-)) and a subgroup that had developed metastasis (M(+)).

RESULTS

There was a significant difference in frequency of the MMP-3 genotype between cases and controls (χ΂ = 16.17; P = 0.0003). The 5A homozygote in patients and controls was significantly different. The frequency of the 5A allele among affected patients (67.91%) was significantly higher than among the healthy controls (49%; χ(2) = 16.17, P = 0.00005). At the time of diagnosis, individual who was carrying the 5A allele was more represented in the M(+) subgroup than in M(-) subgroup (χ² = 7.49; P = 0.006, OR = 3.86; 95% CI, 1.43-10.33). The difference between M(-) and controls did not observe statistically significant (χ² = 0.009; P = 0.92).

CONCLUSIONS

Our results suggest that the presence of 5A polymorphism at the MMP-3 promoter region may favor the growth and the metastasis process in colorectal cancer patients and could be looked at as a risk factor for a worse prognosis.

Exon 10 CFTR gene mutation in male infertility

BACKGROUND

About 10% of infertilities with obstructive azoospermia are congenital and caused by CF gene mutations. M469I mutation was observed for the first time in Taiwanese patients. This mutation not only causes CF, but also may be the origin of infertility too.

OBJECTIVE

In this study, we aimed in designing a rapid, reliable RFLP-PCR procedure for detection of M469I mutation. The correlation and association between M469I mutation with infertility was investigated in this study.

MATERIALS AND METHODS

one hundred ten patients (90 non obstructive and 20 obstructive) and 60 normal individuals were considered in this study. M469I mutation was detected using RFLP-PCR. This technique was completely designed for M469I genotyping, for the first time in our study. Amplification of the region surrounding the mutation in exon 10 of CFTR gene was then performed. RFLP analysis was carried out using the NdeI restriction enzyme.

RESULTS

All genomic DNA samples were genotyped successfully. M469I mutation was observed only in patients group. Therefore, genotype containing mutant allele (GT) has been detected only in the patients group. There was no significant correlation between GT and TT genotypes with infertility (p=0.437).

CONCLUSION

The M469I mutation has only been observed in Exon 10 CFTR gene of infertile patients, not in the control group. This mutation causes congenital bilateral absence of vaz deferens and finally infertility. This indicates a strong association between the M469I mutation and male infertility. Therefore, this is a CF-causing CFTR mutation that could be considered as a cause of infertility.

Amplification of GC-rich Putative Mouse PeP Promoter using Betaine and DMSO in Ammonium Sulfate Polymerase Chain Reaction Buffer

BACKGROUND

Recently, we have shown that peroxisomal protein expression was induced upon retinoic acid treatment in mouse embryonic stem cells during the process of neurogenesis. Thus, characterization of the respective promoter could elucidate the molecular aspects of transcriptional regulation of this gene.

METHODS

Using the conventional software programs for promoter prediction, a putative promoter region was identified approximately 561 bp upstream of the peroxisomal protein coding sequence. In order to clone this region with a GC-content of 71.01%, a cocktail of ammonium sulfate buffer supplied with two additive components, betaine and dimethyl sulfoxide, and a high concentration of MgCl(2) was used.

RESULTS

The modulated polymerase chain reaction composition significantly improved the amplification of GC-rich DNA target sequences. Improved amplification of this region was due to reduction in the formation of secondary structures by the GC-rich region.

CONCLUSION

Therefore, this polymerase chain reaction composition could be generally used to facilitate the amplification of other GC-rich DNA sequences as verified by amplification of different GC rich regions.

Molecular Analysis of the Clavulanic Acid Regulatory Gene Isolated from an Iranian Strain of Streptomyces Clavuligerus , PTCC 1709

OBJECTIVE

The clavulanic acid regulatory gene (claR) is in the clavulanic acid biosynthetic gene cluster that encodes ClaR. This protein is a putative regulator of the late steps of clavulanic acid biosynthesis. The aim of this research is the molecular cloning of claR, isolated from the Iranian strain of Streptomyces clavuligerus (S. clavuligerus).

MATERIALS AND METHODS

In this experimental study, two different strains of S. clavuligerus were used (PTCC 1705 and DSM 738), of which there is no claR sequence record for strain PTCC 1705 in all three main gene banks. The specific designed primers were subjected to a few base modifications for introduction of the recognition sites of BamHI and ClaI. The claR gene was amplified by polymerase chain reaction (PCR) using DNA isolated from S. clavuligerus PTCC 1705. Nested-PCR, restriction fragment length polymorphism (PCR-RFLP), and sequencing were used for molecular analysis of the claR gene. The confirmed claR was subjected to double digestion with BamHI and ClaI. The cut claR was ligated into a pBluescript (pBs) vector and transformed into E. coli.

RESULTS

The entire sequence of the isolated claR (Iranian strain) was identified. The presence of the recombinant vector in the transformed colonies was confirmed by the colony-PCR procedure. The correct structure of the recombinant vector, isolated from the transformed E. coli, was confirmed using gel electrophoresis, PCR, and double digestion with restriction enzymes.

CONCLUSION

The constructed recombinant cassette, named pZSclaR, can be regarded as an appropriate tool for site directed mutagenesis and sub-cloning. At this time, claR has been cloned accompanied with its precisely selected promoter so it could be used in expression vectors. Hence the ClaR is known as a putative regulatory protein. The overproduced protein could also be used for other related investigations, such as a mobility shift assay.

Characterization of D6S2806 and D6S2879 short tandem repeat loci in HLA-DRB1 region in Iranian population

Genomewide screen analysis has shown the close association of the human leukocyte antigen (HLA)-DRB1 region with susceptibility to multiple sclerosis and a number of autoimmune diseases. Using bioinformatics software, several potential short tandem repeat (STR) markers have been introduced in this region in the major histocompatibility complex data base (dbMHC). In this study, the identity and characteristics of two putative STR markers, D6S2879 and D6S2806, in this region were examined in Iranian population. The loci were genotyped in 85 individuals using polymerase chain reaction followed by polyacrylamide gel electrophoresis and sequencing. Analysis of the allelic frequency showed the presence of six and four alleles for D6S2806 and D6S2879, respectively. Analysis of deviations from Hardy-Weinberg equilibrium (HWE) showed that D6S2806 was in equilibrium (P > 0.05). However, the D6S2879 locus showed a significant deviation from HWE (P < 0.05). Therefore, the D6S2806 locus could be suggested as a marker for linkage analysis and disease-susceptibility investigations in the MHC-DRB1 gene region.

Overproduction of Clavulanic Acid by UV Mutagenesis of Streptomyces clavuligerus

Clavulanic acid is produced industrially by fermentation of Streptomyces clavuligerus and researches have increased its production by strain improvement, recombinant DNA technology, and media composition and growth condition optimization. The main objective of this study was to increase the level of clavulanic acid production from Streptomyces clavuligerus (DSM 738), using UV irradiation. After incubation, the spores and aerial mycelia were scraped off the agar plate by a sterile loop. After passing through a cotton wool, the serially diluted spore suspension was spread on GYM- agar containing caffeine. The plates were irradiated with UV light, wrapped in aluminum foil and incubated. The colonies were sub-cultured again to express the mutations. An aliquot of the spore suspension prepared from the resulted culture was poured in GYM agar plates and incubated. The plates were overlaid with nutrient-agar containing penicillin G and Klebsiela pneumoniae, and incubated. The inhibition zone diameter was measured and compared with the wild type colony. Repeating this procedure, the overproducer mutants were selected. Concentration of clavulanic acid was determined by HPLC analysis. It was concluded that secondary metabolites, mainly antibiotics containing clavulanic acid, were produced about 6-7 days after the growth, and concentration of clavulanic acid was increased up to two-folds after UV mutagenesis.

Detection of cloned strR, an antibiotic regulatory gene, using RFLP and nested PCR

The genetics of streptomycin production is well characterized in Streptomyces griseus. More than 25 clustered genes encode proteins involved in biosynthesis, regulation and transport functions. StrR, the pathway specific transcriptional activator or regulator that located in this cluster, then induces transcription of other streptomycin production genes by binding multiple sites in the gene cluster. We aim to put strR gene in to different multicopy and integrated expression vector specifically designed for Streptomyces. To start with, the isolated strR gene was ligated into pBluescript (pBs) vector and transformed into different strains of Escherichia coli. The correct structure of the recombinant plasmid, isolated from transformed E. coli, was confirmed using gel electrophoresis, PCR and double digested with restriction enzymes BamHI and EcoRI. Finally the plasmid map, named pFDstrR. This unique vector has a much expanded Multiple Cloning Site (MCS), which makes it suitable for different purposes of gene cloning and also site directed mutagenesis or gene targeting. This gene will be lifted up and transfer into different varieties of Streptomyces specific vectors in order to make different transgenic or genetically manipulated Streptomyces.

The influence of interstitial collagenase-1 genotype polymorphism on colorectal cancer risk in Iranian population

Interstitial collagenase-1 degrades a variety of extracellular matrix components. A single guanine insertion polymorphism in the promoter has been found that influences on the transcription and expression level of the gene. It is suggested that this polymorphism may enhance susceptibility to some types of cancer. Therefore, this case-control study evaluated the association of this genotype polymorphism with susceptibility to initiation and invasion of colorectal cancer. For this reason, whole blood samples were obtained from 150 CRC patients and 100 control subjects in Tehran. Genomic DNA was extracted and genotyped by PCR-RFLP method. We showed that 2G allele and 2G/2G genotype had higher frequencies in patients (60% and 39%, respectively) than in controls (47% and 23%, respectively). The CRC patients were divided into two groups: with metastasis (M+) and without metastasis (M-) groups. The 2G allele was more frequent in M+ group compared with control group. However, no significantly difference was observed between M-group and control (chi(2) = 0.48, P = 0.78 for 2G/2G genotype). Further stratification analyses showed that only gender (OR = 2.58, 95% CI = 0.89-7.52 for women and OR = 4.12, 95% CI = 1.62-10.42 for men) and smoking (OR = 3.03, 95% CI = 1.28-7.16 for non-smokers and OR = 4.09, 95% CI = 1.18-4.15 for smoker) may modify the risk of colorectal invasion related to 2G/2G genotype. Furthermore, individual with 2G/2G genotype seems to spread metastasis, 3 years earlier than those who were 1G/1G and 1G/2G. In conclusion, to our knowledge, the present epidemiological study for the first time indicates the relationship of 2G/2G genotype polymorphism with invasion risk of colorectal cancer in subgroups of gender and smoking, especially in smoker men.

Unequal sister chromatid exchange in the rDNA array of Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae the nucleolar organiser region (NOR) is located on chromosome XII. It contains 100-200 copies of rDNA--a minimum of 20 rDNA genes in tandem--and is termed the RDN locus. Yeast cells may exist in either haploid or diploid form. There are two forms of life cycle: haploid and diploid cells double by mitosis, and diploid cells are reduced to the haploid state by meiosis. Diploid cells have two homologous chromosomes for each of the 16 chromosomes. They are usually of the same size. However, in this study it is shown that homologous chromosomes XII can become different in size due to unequal sister chromatid exchange during mitosis in 'old' cells.