جستجوی مقالات مرتبط با کلیدواژه « mutation » در نشریات گروه « زیست شناسی »

Wellness requires the proper functioning of the immune system in all of the body systems. The immune system active by the cooperation of several immune sections. The immune cells and substances can identify and destroy foreign viral and microbial agents that worn out cells and cancer cells in the body. The aim of this study was to investigate the effect of high-speed sports activity on the anti-inflammatory factors lysozyme, LL-37 and HDB-2 in the saliva of obese adolescent boys.

32 male students voluntarily participated in the present study and were randomly assigned to four groups: 1) obese aerobic exercise, 2) normal weight aerobic exercise, 3) obese control without exercise, and 4) normal weight control without exercise. Anthropometric indices of height, weight and body mass index were measured. Before and after eight weeks of practice, Shatell-Run standard test was performed. Salivary samples of lysozyme, lactoferrin, lactate and C-reactive protein concentrations were taken after eight weeks of training with a frequency of three sessions per week with an intensity of 30 to 90% of maximum aerobic power. Using analysis of covariance, variables with a significance level of less than (p≥0.05) were included in the analysis.

The results showed that the salivary levels of lysozyme (p=0.001), LL-37 (p=0.002), and HDB2 (p=0.001) increased significantly, and the amount of increase in obese students was higher than in people with normal weight.

The increased response of some salivary anti-inflammatory proteins following eight weeks of high-speed exercise training after increased activity may be due to the short-term responses of the immune system against the pressures caused by intense activity.

It has been more than two years since the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan, China. The SARS-CoV-2 has created an unprecedented pandemic (COVID-19) in the modern era and challenged all the scientific, economic, and social structures of the world. Extensive worldwide research has been conducted to study the structure and function of the SARS-CoV-2 spike protein since the beginning of the pandemic. The role and importance of spike protein in the introduction of SARS-CoV-2 into human cells has been proven. Among the important and effective factors in controlling the Covid-19 pandemic is understanding the structural changes of spike protein in different variants of the virus and the effectiveness of drugs and vaccines against new SARS-CoV-2 variants. Due to the great importance of spike protein SARS-CoV-2, it was tried to study its structure and interaction with cellular receptors using bioinformatics tools in this study. Furthermore, the effects of different SARS-CoV-2 variants on existing drugs and vaccines were reviewed.

The bioinformatics methods and molecular docking was used to study the binding function of spike protein to its various cellular receptors in the human body. HDOCK web server was used to perform the molecular docking process and in the next step, the PDBsum web server was used for post-docking checks and to ensure the accuracy of the obtained data. PyMOL software was also used to study and visualize replacement and deletion mutations in the spike protein.

Extensive mutations in the spike protein in the omicron variant indicate a redesign in the spike protein. These massive mutations cause extensive changes in the structure and function of the spike protein. The data obtained from molecular docking and comparing the energy level (docking score) of spike protein binding of different variants of the virus with different cellular receptors indicate a high tendency of the spike protein to bind, with lower energy levels and more stable, to KREMEN1 receptor than the main ACE2 receptor.  The level of spike protein binding energy levels of different virus variants was almost similar to other receptors (except the KREMEN1 receptor) or slightly different from the spike protein binding energy levels with the main ACE2 receptor.

There is not much difference in the tendency of spike protein binding of emerging and important variants of the virus (main, alpha, delta, and omicron) to ACE2 receptor, but the tendency to bind to KREMEN1 receptor is increasing and has reached its peak in the delta variant. The energy level of the spike protein binding to the KREMEN1 receptor is significantly negative compared to other receptors, indicating greater binding and stability. Also, considering the level of energy received from the HDOCK web server, it can be concluded that although the ACE2 receptor is the main receptor for the spike protein, other receptors can still bind to the spike protein with good stability. Based on the available information, so far there have been no reports of docking between spike protein and other non-main spike protein receptors (AXL, ASGR1, KREMEN1). Therefore, more comprehensive research is needed to confirm or refute these findings.

Mutation in microbial strains to increase coenzyme Q10 production is one of the successful strategies for strain development. Therefore, in this study, the production of coenzyme Q10 by Gluconobacter oxydans H621 was investigated through chemical mutation with nitrosoguanidine using the response surface methodology. Nitrosoguanidine was used to induce mutations at different concentrations (2.79 - 4.21 mg/mL) and treatment times (11.89 – 33.12 minutes), which was designed by a central composite design. The detection of mutant strains was investigated through their ability to grow in medium containing 160 μg/mL of menadione. The mutant strains were then examined for coenzyme Q10 and dry cell weight production. The results showed that no mutant strains were obtained at a concentration of 4 mg/ml and above. The highest number of mutant colonies was obtained at a concentration of 2.79 mg/mL of nitrosoguanidine and treatment time of 22.5 minutes. It was also found that the concentration of nitrosoguanidine was effective on mutagenesis but the treatment time had a little effect. The mutant strain that was able to produce the highest amount of coenzyme Q10 produced 5.2 mg/L, which was twice as much as the parent strain. According to the results of this study, it is concluded that by inducing mutation using nitrosoguanidine, mutant strains can be generated in Gluconobacter oxydans H621 that are able to produce more coenzyme Q10 than the parent strain.

Tolerance to ethanol is a key characteristic of the yeast Saccharomyces cerevisiae. Any increase in ethanol tolerance in the industrial strains could lead to faster and more complete fermentations, and may also allow the production of more alcohol. Due to the complex nature of ethanol tolerance, it appears that a large increase in ethanol tolerance requires several changes in the yeast’s genome. Several approaches that rely on the effect of (random) variation generated by evolutionary engineering or mutagenesis have successfully yielded strains with increased ethanol tolerance.

In the present study, to improve the ethanol tolerance phenotype in the industrial Ethanol Red strain, the parent strain was mutated physically and chemically. The mutants were screened using 1-butanol containing medium. The primary parent and the mutants were evolved within 144 days with evolutionary engineering strategy, while ethanol production of the selected strains was investigated

According to the increase in the maximum growth rate, 8 strains were selected including parental strain and mutants, and the amounts of ethanol production of these strains were evaluated after evolutionary adaptation tests. Ethanol production of ER 103 and ER 106 which were mutated with EMS before the adaptive evolution test and then evolved at 11 and 9% v/v ethanol was improved from 103.44 ± 0.5 g/L to 112.45 ± 1 and 112.3 ± 0.9 g/L, respectively.

Due to the extensive capabilities of the evolutionary engineering method in creating capable strains in order to increase ethanol tolerance in industrial strains, the evolutionary engineering strategy was used. To increase the genetic diversity of the primary population, before starting the adaptive evolution experiments, mutation with ethyl methane sulfonate was used, which was more efficient than ultraviolet radiation in accelerating the evolution process to achieve the desired phenotype.

Nowadays, aromatic componds are widely used in food, pharmaceutical, cosmetic and chemical industries. Due to the growing tendency of consumers to use natural products, biotransformation by microorganisms is an interesting method for the production of aromatic compounds. Gamma-decalactone is a cyclic aroma with a peach-like flavor. The non-conventional yeast Yarrowia lipolytica can bioconversion the inexpensive castor oil substrate into the valuable gamma-decalactone. The process begins with the hydrolysis of castor oil by the lipase to ricinoleic acid, then continues by shortening the chain by beta-oxidation, and finally ends by lactonization. In this study, gamma-decalactone production was optimized via Response surface methodology (RSM) by a mutant strain of this yeast with the ability to produce high amounts of lipase. For this purpose, castor oil, yeast extract, peptone and pH were studied as factors at five levels. Based on statistical analysis of the relationships between the experimental variables, a mathematical model was obtained for the governing relationships between the experimental variables. Based on the results, the best values were obtained for castor oil 35 ml/l, yeast extract 6 g/l, peptone 8.5 g/l and pH 4. To validate the mathematical model, the proposed values were tested and 126 mg/L of gamma-decalactone was produced by the yeast strain, which shows a 46% increase compared to non-optimal conditions. The results of this study can be used to make cost-effective production of gamma-decalactone from castor oil by microbial biotransformation process.

Phytoremediation as a cost-effective and environmental friendly technique used to polluted soils with heavy metals contamination. The present study was aimed to evaluate the resistance and remediation of Tamarix aphylla calli affected by in vitro mutagenesis with. In the first step, optimization of callus induction and mutation in media with different concentrations of -2,4 was performed. The third experiments involved the evaluating of resistance and remeditaion rate of callus to cadmium at the concentrations of 0-40 mg L-1 in both treated and untreated explants with Ethyl methanesulfonate in medium. The highest survival and induction of callus was induced by the concentration of 1 mg L-1 2,4-D during the short time. Ethyl methanesulfonate at concentration of 0.2 percentage and 30 minutes made the maximum survival and minimum blacking phenomenon of explants. The highest accumulation of cadmium was obtained 1053.56 mg kg-1 dry weight in callus treated by 40 mg L-1 cadmium.

Aspergillus niger were isolated from the soil and surface of corn seeds purified and identified according to morphological characteristics. The irradiation rate was calculated based on the duration of UV radiation received in Jules per square meter. The specific method of Marier and Boulet was used to quantitatively measure the production of citric acid. Radiation with 1200 seconds showed the greatest effect on the increase in the production of citric acid. The mean production of citric acid in the preferable mutated isolates and parents were 51.01 and 37.87 mg/l respectively, which increased by 14.14 g/l. In the study of the stability of mutated genotypes, the mean production of citric acid in 1200 seconds of radiation in the fourth consecutive culture of the first culture was not statistically significant. The performance and efficacy of mutated isolates (5uv) showed an increase in the production of citric acid by about 3 times compared to parent isolates. In isolation of 5uv and its parents, the kinetic parameters of product formation (citric acid) were twice as high and the kinetic parameters of the substrate (glucose consumption) were approximately equal, while the dry weight of the cell mass in the isolate 5uv increased relative to the parental isolate 5 with the same gradient. In this study, it was found that random mutations with UV radiation have improved the kinetic parameters of the production of citric acid versus glucose consumption as a substrate.

The CD80 protein, a member of the super-family of immunoglobulin, is a transmembrane protein expressed on the surface of the antigen-presenting cells (APC). This protein has two receptors on the surface of T cells (CTLA-4 and CD28), due to the binding of this protein to these receptors, the inhibitory and stimulatory pathway in the T cells begin, respectively. Naturally, CD80 proteins tend to have more binding affinity to CTLA-4 than CD28, and this is a factor in the extinction of T cells in the immune system in order to prevent autoimmunity. The aim of the present study is to create a variant of the CD80 protein that has an increased binding affinity to CD28 to bind to this receptor more strongly and induce more simulate pathways than the wild type of this protein (primary CD80 protein) in T cells. To identify this variant, first, the ancestral sequence was mutated by R software at positions 31 and 92 with amino acids that play an important role in the formation of hydrogen bonds. The R software output sequences were modeled with the SWISS-MODEL server. Then, each output model was docked with the HADDOCK server, and finally, the electrostatic and van der Waals energies between the receptors and the ligands were calculated. Among all the built-in models, the mutated K31Y, R92F has the best electrostatic and van der Waals energies and has the ability to have a much better connection to its CD28 receptor compared to the ancestral type of CD80.