نشریه زیست شناسی کاربردی
سال سی و هفتم شماره 2 (تابستان 1403)

Antibacterial peptides have been widely investigated as potential bio-antibiotics against bacteria. However, the proteolytic degradation and structural changes may lead to a decrease in their antibacterial activity. Encapsulating peptides in liposomes may be a suitable method to solve such problems.

This study used the recombinant CAP18 (rCAP18) as an antibacterial peptide. After production and purification, encapsulation was done inside the liposomes constructed by phosphatidylcholine. The main characteristics of liposomes, such as size, morphology, type of functional groups, and encapsulation efficiency, were investigated. Antibacterial activity of free and encapsulated rCAP18 in the liposomes (Lipo@rCAP18) against Escherichia coli, Pseudomonas aeruginosa, Xanthomonas citri subsp. citri, and Staphylococcus aureus was evaluated and compared based on the MIC and MBC values.

The obtained findings showed that the lowest inhibitory concentration of free rCAP18 for E. coli, P. aeruginosa, X. citri, and S. aureus strains was determined to be 135, 101, 80, and > 320 µg/ml. MIC value of rCAP18 enclosed in liposomes was >320, 135, 180, and 320 µg/ml, for the strains mentioned above, respectively. The comparison of MIC results showed that free and encapsulated forms of rCAP18 have a more growth-inhibitory effect against P. aeruginosa, X. citri strains. Consequently, vesicles containing antibacterial peptides can be used as a powerful method to preserve their function and maintain the active peptides over time.

Many proteins can be converted into amyloid in the laboratory. These fields are of interest from various points of view, including as a substrate for enzyme stabilization. In this research, cellulase enzyme was immobilized on amyloid nano–biofibrils obtained from bovine serum albumin and its kinetic properties were compared with the free form.

The production of amyloid fibers was optimized by Congored absorbance and ThT fluorescence assay methods and was confirmed by transmission electron microscopy. Cellulase enzyme was immobilized via glutaraldehyde cross–linking bridges on amyloid nano–biofibrils.

The results of Congored absorbance and ThT fluorescence emission showed that the maximum amyloid fibers at 4 mg/ml of protein concentration, 60 ºC and a pH 3. Electron microscopy images confirmed the presence of amyloid fibers. Immobilizing the enzyme decreased the activity, specific activity and Vm and increased the Km of the enzyme. The optimum temperature of the enzyme increased from 40 to 50 ºC.

Amyloid nano–biofibrils can be used as a new nano–biomaterial for cellulase immobilization which introduce a useful product in cellulase–related industries.

Breast cancer is the most common type of cancer among women in the world. Research is ongoing to find new and less risky ways to treat breast cancer. Recent studies on the effect of Alpha-ketoglutarate (AKG) on various cancers have shown its inhibitory effect on some cancers. Here, the effect of AKG on the proliferation and migration of 4T1 breast cancer cells was investigated.

4T1 cells were treated with different concentrations of AKG, the cell viability was calculated using the MTT test, and 160 μM of AKG was selected. 4T1 cells were cultured in the presence and absence 160 μM AKG, and the growth of 4T1 cells, population doubling time, colony forming potential, cell cycle profile and cell migration rate were investigated.

The results showed that AKG reduces the growth of 4T1 cells and increases the population doubling time in the treatment group compared to the control group. Also, AKG decreased the colony forming potential of 4T1 cells (in terms of colony number and size). AKG caused changes in the cell cycle profile in the treatment group, and the results of the scratch repair test also showed the effects of AKG in reducing the ability of cell migration in the treatment group compared to the control. The results of this study showed that AKG can reduce the survival and proliferation of breast cancer cells. It seems that the use of AKG along with other available treatments can help to control and treat breast cancer.

Considering the effect of physical and chemical factors of soil and climatic factors of temperature and precipitation on the quantity and quality of plant essential oils, a study was conducted with the aim of evaluating the effect of climatic and soil factors on the phytochemistry of the medicinal species of Stachys lavandulifolia in Kalakuh of Amol rangeland and comparing it in two northern and southern aspects.

First, random sampling was done in three selected spots with three repetitions from two aspects. Soil samples were taken from a depth of 0-30 cm and transferred to the laboratory. The essential oils of plants were also extracted by water distillation and their composition was identified by GC/MS. In the statistical section, independent t-test was used to compare compounds in the two northern and southern aspects, and Pearson's correlation analysis was used to analyze the relationships between the data.

The results showed that among the extracted compounds, the compound α-Pinene, β-phellandrene, Thymol, Limonene, α-fenchene, γ-cadinene, cis-sabinene hydrate, 1-8-Cineole and Sabinene accounted for the largest percentage. Also, the comparison of the average yield of essential oil in the two aspects showed that the southern aspect has significantly higher average than the northern aspect. The correlation results also indicated that the index factors of soil grain stability, acidity and silt have a very strong correlation at the five percent level.

In general, the present results indicate that the compounds extracted from essential oil of Stachys lavandulifolia plant are strongly influenced by the habitat conditions of the region.

The appropriate management of fish waste is crucial in the fishing and processing industry, necessitating effective waste management strategies. Composting, which is rich in nutrients, is a well-regarded method. This study aimed to assess the impact of fish waste compost, an eco-friendly fertilizer, on the growth and performance of red radish plants, as well as its influence on heavy metal interactions and catalase enzyme activity. Under greenhouse and pot conditions, two studies with three treatments and three replications were carried out. In the first experiment, the effects of 20% and 50% compost on the morphological traits of radish plants were examined. In the second experiment, 50% compost was chosen based on the plant's morphological traits, and the characteristics of heavy metal removal and catalase enzyme activity were assessed. Results demonstrated that the use of 50% compost led to notable improvements in the fresh and dry weights of leaves and tubers, alongside increased proline content (5g, 0.05g, 6.6g, 1.91 µmol g-1 DW) in the plants. Furthermore, the 50% compost reduced cadmium activity (0.21 mg/kg) and enhanced catalase enzyme activity (34 µmol hydrogen peroxide/g-hour). Employing fish waste compost has the potential to enhance soil quality and decrease the impact of heavy metals in agricultural settings, ultimately facilitating an optimal environment for plant growth.

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The present study was conducted with the aim of nanoemulsifying Thymus vulgaris essential oil to increase its stability and investigate its antibacterial effects on E. coli DH5α bacteria.

First, the initial microemulsion was prepared in the oil phase and then it was transformed into a nanoemulsion by ultrasound. The amount of surface charge, viscosity, particle size and morphology of essential oil nanoemulsion was investigated by zeta potential device, DLS and TEM electron microscope.

The results showed that the zeta potential of nanoemulsion containing 10 and 30% essential oil was -11.5 and -11.1 mV, respectively. The morphology of the nanoparticles of both samples was spherical and the average size of the nanoemulsion nanoparticles with 10% and 30% essential oil was 43 and 30 nm, respectively. The results of the antibacterial effects of nanoemulsions showed that the nanoemulsion containing 10% essential oil (v/v), with a volume of 30 µl, and the nanoemulsion containing 30% essential oil (v/v), with a volume of 20 µl, had approximately 50% inhibitory effect (IC50) on the growth of E. coli DH5α. Also, the primary essential oil showed approximately 50% inhibition (IC50) on bacterial growth in 20 µl.

According to the stability of the produced thyme essential oil nanoemulsions, it can be concluded that the antibacterial effects of this compound have increased compared to the original essence.

Early blight is one of the most significant tomato diseases and fungicide application is the most common measure used to control its damage. Exploitation of generally regarded as safe (GRAS) and defense inducers have been focused on as alternative strategies to avoid environmental impacts of fungicides. Defense inducers enhance plant defense system against stresses through inducing specific changes in plant physiological characteristics. In the present study the effect of potassium sorbate (KS) on physiological, biochemical and defense response of Alternaria solani-infected tomato plants was investigated.

This research was conducted as split plot-factorial with three factors, presence or absence of a pathogen, the use of either KS or distilled water (control) for foliar spraying, and three time courses for sampling (24, 72, and 168 hours).

The results showed that the fresh and dry weights in inoculated plants were lower than that of non-inoculated plants. The pathogen caused damage to the plant cell membrane and significantly reduced photosynthetic pigments. Additionally, the amount of MDA and chla in inoculated plants was significantly decreased compared to non-inoculated plants. The activity of POD and CAT enzymes significantly increased in plants treated with KS compared to the control. Chitinase enzyme in plants treated with KS showed a significant increase in the inoculated plants 168 hours, which can be a sign of immune system stimulation. The results revealed that the KS inducer was effective on the weight and growth of plants and reduced biotic stress damages through increased activity of antioxidant and defense enzyme