Metabolic Engineering of Cofactor F420 Production in Mycobacterium smegmatis

Cofactor F420 is a unique electron carrier in a number of microorganisms including Archaea and Mycobacteria. It has been shown that F420 has a direct and important role in archaeal energy metabolism whereas the role of F420 in mycobacterial metabolism has only begun to be uncovered in the last few years. It has been suggested that cofactor F420 has a role in the pathogenesis of M. tuberculosis, the causative agent of tuberculosis. In the absence of a commercial source for F420, M. smegmatis has previously been used to provide this cofactor for studies of the F420-dependent proteins from mycobacterial species. Three proteins have been shown to be involved in the F420 biosynthesis in Mycobacteria and three other proteins have been demonstrated to be involved in F420 metabolism. Here we report the over-expression of all of these proteins in M. smegmatis and testing of their importance for F420 production. The results indicate that co–expression of the F420 biosynthetic proteins can give rise to a much higher F420 production level. This was achieved by designing and preparing a new T7 promoter–based co-expression shuttle vector. A combination of co–expression of the F420 biosynthetic proteins and fine-tuning of the culture media has enabled us to achieve F420 production levels of up to 10 times higher compared with the wild type M. smegmatis strain. The high levels of the F420 produced in this study provide a suitable source of this cofactor for studies of F420-dependent proteins from other microorganisms and for possible biotechnological applications

Impacts of inorganic nitrogen fertiliser on soil fertility and groundwater quality of Touba orchards (western Iran)

Input of nitrogen (N) fertiliser in agricultural systems is important for their sustainability. However, when N inputs are very high, the excess can contribute to environmental problems such as loss of soil fertility and groundwater pollution. Based on this hypothesis, a field trial was carried out in Touba orchards of the Kurdistan province (Western Iran) in 2009, which aimed at evaluation of soil and groundwater quality of the mentioned orchards. Soil samples were analysed to measure quality parameters including soil organic carbon (SOC), total nitrogen (TN), available phosphorous (P-av) and available potassium (K-av). Moreover, nitrate (NO3) concentration was measured in water samples and compared with WHO standards of drinking water (50 mg l(-1)). The obtained results of soil analysis showed that SOC is significantly higher (1.55 g kg(-1)) and lower (0.71) in the orchards of the Sanandaj and Qorveh counties, respectively. In addition, the results of hydrochemical analysis showed that NO3 concentration was in the range of 21-95 mg l(-1). Moreover, 90% of groundwater samples collected from the orchards of the Qorveh county, exceeded WHO standard level which is a reflection of N-fertiliser application at high rate (340 kg ha(-1))

Study on the size dependent effective Young modulus by EPI method based on modified couple stress theory

\u3cp\u3eVarious experimental and theoretical researches have been shown the size-dependence behavior of the effective Young modulus (EYM) in the micron and sub-micron scales. One of the most accurate methods is the electrostatic pull-in instability (EPI) method that is based on the bending of the classical beam under the electrostatic force. In this paper, the modified couple stress theory (MCST) is employed to calculate the EYM of silicon nanocantilevers. The MCST compensates the inability of the classical continuum mechanic to predicting the size-dependent behavior of the nano-scale structures. Next, as a case study the EYM of silicon nanocantilevers have been calculated and results compared with classical EPI. The governing equation is solved by the Galerkin method and obtained results show significant size-dependent behavior in the EYM. From the other hand, a new value for the material length scale parameter is introduced based on the dimension of the crystal or grain size of the material.\u3c/p\u3

Z-scan method to measure the nonlinear optical behavior of cells for evaluating the cytotoxic effects of chemotherapy and hyperthermia treatments

The effects of new treatments must be investigated in vitro before using clinically or in vivo. The aim of this study was to introduce the Z-scan technique as a fast, accurate, inexpensive, and safe in vitro method to distinguish the cytotoxic effects of various treatments. C6 and OLN-93 cell lines were prepared and treated with Temozolomide (TMZ), radiofrequency hyperthermia (HT), and chemo-hyperthermia (HT+TMZ). The cytotoxic effects of different treatments on both cell lines were evaluated using colony formation assay and Z-scan method. The results of colony assay showed that the surviving fraction (SF) of C6 cells treated with TMZ, HT, and HT + TMZ were significantly decreased compared to the control group. Whereas, hyperthermia treatment had no significant effect on the SF of OLN-93 cells. The results of Z-scan technique indicated that the control group of C6 cells had the negative nonlinear refractive index (n2). Whereas, the C6 cells treated with HT, TMZ, and HT + TMZ had the positive n2 index. The sign of n2 index in the control and HT groups of OLN-93 cells was positive but treatment of cells with TMZ and HT + TMZ changed the sign of it. Moreover, with increasing the cytotoxic effects of different treatments, the SF value of both cell lines decreased and the magnitude of n2 index increased. The results of Z-scan technique were completely in line with the results of colony assay. Therefore, Z-scan method could distinguish the cytotoxic effects of various treatments by examining the nonlinear optical properties of the samples. © 2020, Springer-Verlag London Ltd., part of Springer Nature

Magneto-plasmonic nanoparticle mediated thermo-radiotherapy significantly affects the nonlinear optical properties of treated cancer cells

In order to determine the level of cell damage in cancerous cells, current cytogenetic tests have limitations such as time consumption and high cost. The aim of this study was to demonstrate the ability of nonlinear refractive (NLR) index as a predictor of breast cell damage caused by magneto-plasmonic nanoparticle based thermo-radiotherapy treatments. MCF-7 breast cancer cells were subjected individually to the treatment of radiation, radio-frequency (RF) hyperthermia, and radiation + RF hyperthermia. These treatments were repeated in the presence of magneto-plasmonic nanoparticle (Au@IONP). The MTT and nonlinear optical assays were used to evaluate the damage induced by different treatment modalities. The results of MTT were correlated with Z-scan, as the magnitude of nonlinear refraction increased with higher intensity of induced cell damages. In this regard, the lowest cell viability (38 ,) and highest magnitude of NLR index (+28.12) were obtained from combination of radiation (at 4 Gy dose) and hyperthermia treatment in the presence of nanoparticles. The proposed optical index (NLR) indicated high capability and can be used as an auxiliary tool to monitor induced cell damage during different treatment strategies. This technique is fast, noninvasive, does not impose cost, and finally does not waste materials. © 2020 Elsevier B.V

Evaluation of nonlinear optical differences between breast cancer cell lines SK-BR-3 and MCF-7; an in vitro study

Background: This study aimed to explore the potential of the Z-scan technique to improve accuracy in identifying SK-BR-3 and MCF-7 breast cancer cell lines. Methods: Three in vitro samples were prepared for each breast cancer cell line. A closed-aperture Z-scan technique was used to measure the sign and magnitude of the nonlinear refractive index of each sample. Prior to the Z-scan, all samples were fixed with 1 mL of 5 paraformaldehyde. Results: The sign of the nonlinear refractive indices of MCF-7 and SK-BR-3 breast cancer cell lines were negative and positive, respectively. The repeated Z-scan measurements for all samples of each cell line were similar. Conclusion: The results indicated that the proposed bio-optical method is a reliable method for characterizing differences in various breast cancer cell types. It is suggested that the nonlinear refractive index of cells be considered as an indicator for differentiating various breast cell lines from each other. © 2018 Elsevier B.V