Dynamics of neural fields with exponential temporal kernel

Various experimental methods of recording the activity of brain tissue in vitro and in vivo demonstrate the existence of traveling waves. Neural field theory offers a theoretical framework within which such phenomena can be studied. The question then is to identify the structural assumptions and the parameter regimes for the emergence of traveling waves in neural fields. In this paper, we consider the standard neural field equation with an exponential temporal kernel. We analyze the time-independent (static) and time-dependent (dynamic) bifurcations of the equilibrium solution and the emerging Spatio-temporal wave patterns. We show that an exponential temporal kernel does not allow static bifurcations such as saddle-node, pitchfork, and in particular, static Turing bifurcations, in contrast to the Green's function used by Atay and Hutt (SIAM J. Appl. Math. 65: 644-666, 2004). However, the exponential temporal kernel possesses the important property that it takes into account the finite memory of past activities of neurons, which the Green's function does not. Through a dynamic bifurcation analysis, we give explicit Hopf (temporally non-constant, but spatially constant solutions) and Turing-Hopf (spatially and temporally non-constant solutions, in particular traveling waves) bifurcation conditions on the parameter space which consists of the coefficient of the exponential temporal kernel, the transmission speed of neural signals, the time delay rate of synapses, and the ratio of excitatory to inhibitory synaptic weights.Comment: 25 pages, 8 Figures, 44 Reference

Comparative study of methods for extraction and purification of environmental DNA from high-strength wastewater sludge

DNA extraction from wastewater sludge (COD 50000 and BOD 25000 mg/l) was conducted using nine different methods normally used for environmental samples including a procedure used in this study and the results obtained were compared. The quality of the differently extracted DNAs was subsequently assessed by measuring humic acid concentration, cell lysis efficiency, polymerase chain reaction (PCR) amplification of methanogenic and eubacterial 16S rDNA. The protocol developed in this study was further evaluated by extracting DNA from various high-strength wastewater sludge samples, denaturing gradient gel electrophoresis (DGGE) and fluorescent in situ hybridization (FISH) analyses. The results revealed that great differences existed among the nine procedures and only a few produced satisfactory results when applied to high-strength wastewater sludge. Thermal shock alone was shown inefficient to disrupt the methanogenic cell wall to release the DNA. The method presented in this study (Procedure 9) is generally recommended because of the low concentration of contaminants and its high efficiency despite its simplicity.Key words: High-strength wastewater sludge, DNA extraction, environmental samples, humic acids, denaturing gradient gel electrophoresis, fluorescent in situ hybridizatio

Genetically modified mice- Methods, applications and outlook

Background & Aim: Transgenic mice, of tengenerated by random integration of foreign genes into the mouse genome or by targeted mutation in a particular gene, have demonstrated to be a very effective tool for studying gene function in living things. In this review article, we discussed on the current methods of generating genetically-modified mice and their related problems and then investigated the new methods developed to overcome these problems. Finally, we discussed future prospects on the gene targeting. Methods & Materials: This is a review article, which has been written after searching Pubmed, Scopus, Google Scholar, Springer, Elsevier and Magiran databases by using keywords of transgenic mice, functional genetics, genetargeting, and homologous recombination. Results: This study dealt with genetic variations in a wide range, differential processing and inactivation of gene-specific isoforms, local and induced genetic changes, Cre/loxP system and some future perspectives. Conclusion: Success rate in genetic modification of mouse genome has increased dramatically, and use of knockout mice has resulted in increased knowledge of human biology and diseases

Improved efficiency of genome editing by constitutive expression of Cas9 endonuclease in genetically-modified mice

Despite its convenience and precision, CRISPR-based gene editing approaches still suffer from off-target effects and low efficiencies, which are partially rooted in Cas9, the nuclease component of the CRISPR/Cas9 system. In this study, we showed how mouse genome editing efficiency can be improved by constitutive and inheritable expression of Cas9 nuclease. For this goal, a transgenic mouse line expressing the Cas9 protein (Cas9-mouse) was generated. For in vitro assessment of gene editing efficiency, the Cas9-mice were crossed with the EGFP-mice to obtain mouse embryonic fibroblasts (MEF) expressing both EGFP and Cas9 (MEFCas9-EGFP). Transfection of these cells with in vitro transcribed (IVT) EGFP sgRNA or phU6-EGFPsgRNA plasmid led to robust decrease of Mean Fluorescent Intensity (MFI) to 8500 ± 1025 a.u. and 13,200 ± 1006 a.u. respectively. However, in the control group, in which the MEFEGFP cells were transfected with a pX330-EGFPsgRNA plasmid, the measured MFI was 16,800 ± 2254 a.u. For in vivo assessment, the Cas9-zygotes at two pronuclei stage (2PN) were microinjected with a phU6-HhexsgRNA vector and the gene mutation efficiency was compared with the wild-type (WT) zygotes microinjected with a pX330-HhexsgRNA plasmid. The analysis of born mice showed that while the injection of Cas9-zygotes resulted in 43.75 Hhex gene mutated mice, it was just 15.79 for the WT zygotes. In conclusion, the inheritable and constitutive expression of Cas9 in mice provides an efficient platform for gene editing, which can facilitate the production of genetically-modified cells and animals. © 2021, King Abdulaziz City for Science and Technology

Pipeline for the generation of gene knockout mice using dual sgRNA CRISPR/Cas9-mediated gene editing

Animal models possess undeniable utility for progress on biomedical research projects and developmental and disease studies. Transgenic mouse models recreating specific disease phenotypes associated with β-hemoglobinopathies have been developed previously. However, traditional methods for gene targeting in mouse using embryonic stem cells (ESCs) are laborious and time consuming. Recently, CRISPR has been developed to facilitate and improve genomic modifications in mouse or isogenic cell lines. Applying CRISPR to gene modification eliminates the time consuming steps of traditional approach including selection of targeted ESC clones and production of chimeric mouse. This study shows that microinjection of a plasmid DNA encoding Cas9 protein along with dual sgRNAs specific to Hbb-bs gene (hemoglobin, beta adult s chain) enables breaking target sequences at exons 2 and 3 positions. The injections led to a knockout allele with efficiency around 10 for deletion of exons 2 and 3 and 20 for indel mutation. © 2018 Elsevier Inc

Effect of valproic acid on Expression of Bim gene and viability of ovarian cancer cell line A2780

Background and Objective: Ovarian cancer is the fifth common cancer among women and the number of new cases is increasing. Valproic acid is a histone deacetylase inhibitor effectively used to treat epilepsy and bipolar disease. Recently, this compound has attracted attention as an anti-cancer agent. Bim is one of the most important genes of mitochondrial pathway of apoptosis, and it plays an important role in the biology of cancer. Expression of this gene is greatly reduced in ovarian cancer. This study was done to evaluate the effect of valproic acid on the viability of ovarian cancer cells, apoptosis and Bim gene expression in A2780 line. Methods: In this experimental study, the human ovarian cancer cells (A2780) were grown in RPMI-1640 medium in appropriate culture conditions. The cells were treated by various concentrations valproic acid (1-30 mM) and were incubated for 24, 48 and 72 hours. After the incubation of period, cell viability was investigated using MTT. Apoptosis was analyzed by flow-cytometry method in the cells were treated by valproic acid. The Real time PCR test was used to assess the effect of this drug on the expression of Bim gene. Results: The results of MTT assay showed that valproic acid reduced the viability of A2780 cells, and this effect was time and dose-dependent. The reduction of cell viability at 30 mM concentration and 72 hours after treatment, was maximum and statistically significant (P<0.05). Exposure to valproic acid significantly increased the percentage of apoptotic cells (P<0.05). Also, Valproic acid significantly increased the expression of Bim (P<0.05). Conclusion: Valproic acid reduced viability in ovarian cancer cell line A2780. Valproic acid increased cell death by altering the expression of genes involved in apoptosis in ovarian cancer cell line A2780

Efficient generation of dopaminergic-like neurons by overexpression of Nurr1 and Pitx3 in mouse induced Pluripotent Stem Cells

Parkinson's disease (PD) is a neurodegenerative disorder, in which the nigro-striatal Dopaminergic (DAergic) neurons are selectively lost. Treatment of neurodegenerative diseases with Pluripotent Stem Cells (PSCs) is a big interest in cell therapy. Here, we used induced Pluripotent Stem Cells (iPSCs) expressing two master Dopaminergic (DAergic) transcription factors, i.e. Nurr1 and Pitx3, to generate functional in vitro DAergic-like neurons. After establishment and characterization of Doxycycline-inducible iPSCs from mouse fibroblasts, the cells were transduced by NURR1- and PITX3-harboring lentiviruses. The Nurr1/Pitx3 -iPSCs were differentiated through a five-stage protocol to generate DAergic-like neurons. The results confirmed the efficient expression of DAergic neuron markers in the end of protocol. Beside, the generated cells could exclusively synthesize and secrete Dopamine in response to secretagogues. In conclusion, overexpression of Nurr1 and Pitx3 in iPSCs could efficiently program iPSCs into functional DAergic-like neurons. This finding may have an impact on future stem cell therapy of PD. © 2016 Elsevier Ireland Ltd

The relationship between brain volume, brain weight and IQ in children in primary schools in the south of Iran

Background: Anthropometry is a branch of anatomy. One of the important parts of anthropometry is cephalometry, which is characterized by anatomical dimensions of the head area. The aim of this study was to investigate the relationship between brain volume, weight, and IQ in children. Methods: This descriptive-analytical study was performed on 300 students. Conventional measuring instruments were used for anthropometric measurements. Body weight and skull dimensions were measured. Then, using the appropriate formulas, the volume and weight of the brain and the brain index were measured. Results: The Pearson correlation coefficient confirmed a weak correlation between the amounts of IQ and anthropometric dimension in female samples. The mean head circumference of males was 2 cm above the mean head circumference of females. Compared to the central index and the dispersion, anthropometric dimensions were significant between boys and girls. According to the analysis of neural network, the anthropometric dimensions of head height, brain weight, head width, and brain index in boys and anthropometric dimensions around the head volume of head width and head height in girls were the most important in relation to IQ. Conclusion: The results of this study showed that there was a significant statistical difference between the central index and the distribution of anthropometric dimensions in boys and girls. Moreover, there was not a signfficantrelationship between IQ and anthropometric dimensions of the body. In girls, there was a weak correlation between IQ and head width, head height, brain volume, and brain weight. © 2020, Kerman University of Medical Sciences. All rights reserved