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

In daily life, stress in one of the important and potent modulators of behaviour. Inhibitory or faciliatory effects of acute and chronic stress exposure on memory performance (acquisition, consolidation and retrieval) have shown in previous researches. Under such circumstances, the levels of (nor) epinephrine (NE) rapidly increases in the memory related area including hippocampus and amygdala. Along with NE, the hypothalamic-pituitary-adrenocortical axis activates. Glocorticoids (GCs) hormones are the main end-products of the HPA axis activation. In different animal models have been shown that NE and glocorticoids mediate the modulatory effect of stress on memory. Microglia that originally form in the yolk sac are immune cells in the central nervous system and act as the brain's first line of cellular defense against various pathogens. These cells release inflammatory mediators and neurotrophic factors and also phagocytes cellular debris. In addition, are also shown to play a role in the development of brain. During embryonic development, microglia remove apoptotic cells and regulate synaptic pruning. These cells play an essential role in regulating of synapse regeneration, neurogenesis, synaptic function, angiogenesis and myelination. They are dynamic cells in the adult brain and have the ability to rapidly change their morphology to properly respond to the functional needs of the brain. Microglia is activated in M1 and M2 phenotype. M1 microglia activation is induced by gamma interferon and LPS and promotes inflammation via release of inflammatory mediators such as tumor necrosis factor alpha (αTNF) and interleukins. M2 activation mainly is related to secretion of glucocorticoids, extracellular matrix proteins and anti-inflammatory cytokines. It has been reported that microglia as a key regulator of neuronal function have NE and GCs receptors, suggesting a critical role of these brain cells in modulating stress effects. Several lines of studies indicates that microglia regulate learning and memory via the formation and stability of synapses. Microglia actively contribute in synaptic pruning via classical complement cascade mechanism. Apoptotic, immature or poorly growing synapses are labeled with complement components, C1q and C3. Microglia recognize these complement components through the complement receptor CR3 and eliminate C1q and C3-labeled synapses. Microglia also detect and remove inactive synapses by the triggering receptor expressed on myeloid cells 2 (TREM2) consequently regulate brain connectivity and activity. Moreover, microglia regulatory negative feedback mechanism prevents neuron hyperactivity. Microglia play an important role in the stability of long-term potentiation. In addition, microglial fractalkine signaling is potentially involved in LTD. The number and morphology of hippocampal microglia is altered in response to chronic stress exposure thus consequently becomes reactive phenotype. This effect is mediated via stress hormones. Evidence show that stress also affect expression of microglial genes (cytokines, TNF-α and interleukins) that have regulatory role in learning and memory. Microglial–neuronal crosstalk which is crucial for memory processing is another site for stress-induced memory changes. Moreover, stress exposure alters glutamate transmission through negative effect on kynurenine pathway. These effects support the involvement of microglia in destructive effect of stress on memory. In this review article, focusing on newly published articles, we examine the role of microglia in synaptic plasticity, learning and memory, and especially the role of activated microglia in the effects of stress on learning and memory. By examining these processes, our aim is to provide an overview of the role of microglia in synaptic plasticity and learning and memory, and the possibility of using microglia targeting as a therapeutic method to improve cognitive deficits associated with stressful conditions

Red blood cells and white blood cells are the main  cells of blood.These two types of cells have significant differences in number, nucleus, and other intracellular organelles such as mitochondria, ribosomes, and metabolic pathways. Enzymes are important proteins found in these cells . MAPKinase (Mitogen activated protein kinase) superfamily are protein kinases playing key role in phosphorylation of threonine , thyrosine and serine in the enzymes of the family and target proteins during kinase cascades  in metabolic pathways  of cells. They are found in nucleated cells from unicellular to multicellular. These enzymes have important roles in regulating various processes of eukaryotic cells, including cell proliferation, differentiation, survival , apoptosis  and  in various signaling pathways and gene expression as well. These enzymes are ubiquitously expressed and evolutionarily conserved in eukaryotes. In mammalian cells, there are three well-known MAPK   including  extracellular signal-regulated protein kinase (ERK) 1/2 , c-Jun N-terminal Kinase 1, 2, 3 (JNK1/2/3) and p38 MAPK α,β,δ,γERK, JNK and p38 isoforms are grouped according to their motif, structure and function.  ERK 1/2 is related to  the response to growth factors, hormones and inflammatory stimuli, while JNK1/2/3 and p38 MAPK α, β, δ, and γ are activated through environmental or cellular stress and inflammatory stimuli.JNK   enzyme is activated under stress. JNK pathway has role in apoptosis and cell survival. The presence of JNK is essential for stress-induced mitochondrial cytochrome c release. Cytochrome c together with Apaf activates the initiator caspase 9. If the defect in the release of cytochrome c from the mitochondrial membrane is likely to cause a defect in the release of pro-apoptotic molecules such Smac/DIABLO, AIF. The aim of the study is to investigate the JNK enzyme level in blood anucleated cell such as RBC compared to nucleated cell like WBC. 

RBCs were isolated from a fresh blood. WBCs (Mononuclear) were separated from blood using Ficoll solution.  Their suspensions were prepared in isotonic condition using 0.9 % NaCl. In next step, the number of cells counted by means of cell counter followed by lysis  RBCs by ultrasonic  homogenizer and  lysis of WBCs using  ultrasonic bath. Considering that, the presence of hemoglobin following the lysis of RBCs affects the assay of JNK level by ELISA immunoassay technique, hence 6 mM zinc sulfate used to remove the hemoglobin. Two kinds of lysates were centrifuged to separate the  lysed cells membranes before assay the level of JNK.  Then, the level of JNK in the RBC and WBC lysates were measured using ELISA technique.

Regarding that the number of RBCs in sample was 1000 times more than WBCs one per sample volume, but the JNK enzyme level showing  1.72 x10 -2  ng/ml per cell and 6.2 x 10 -6  ng/ml per cell in WBCs and RBCs  respectively. As a result, JNK enzyme level in each WBC   is 2770 fold   more than each RBC.

In comparison with WBCs having nuclei and high level of   JNK enzyme,  RBCs due to losing their nuclei during differentiation from stem cells in bone marrow show low level of JNK enzyme denoting blocking of pathways related to MAPK enzymes. This is an evidence that the absence of nucleus does not support of MAPK family enzyme and related pathways.

Potato (Solanum tuberosum L.) is a key crop within the Solanaceae family and ranks as the most significant non-cereal crop globally following major staples such as wheat, rice, and corn. Potatoes can reproduce sexually and asexually via tubers, and plant tissue culture is emerging as an effective method for vegetative propagation, addressing the increasing global demand for agricultural products. Ethylene, a critical plant growth regulator, influences various physiological processes including growth and development. During in vitro culture and due to the wounding of explants, ethylene accumulation can lead to abnormal biological responses, with potato seedlings being susceptible. Thus, investigating the effects of ethylene biosynthesis inhibitors such as pyrazinamide (PZA) and AgNO₃ on potato growth in vitro is essential.

In this study, potato seedlings were cultivated in Murashige and Skoog (MS) medium, with concentrations of PZA ranging from 0 to 6 mg L⁻¹ and AgNO₃ at 2 mg L⁻¹. After four weeks, the seedlings were harvested and stored at -70°C for later analysis. The growth parameters measured included fresh weight (FW), dry weight (DW), stem and root lengths, leaf area, and leaf and root number. In addition, biochemical parameters, such as photosynthetic pigment levels, total phenol content (TPC), total reactive oxygen species (ROS), and proline concentration were analyzed. Statistical evaluations were conducted using SPSS and PAST software

The results showed that the 2 mg L⁻¹ PZA treatment led to the highest FW and DW and increased leaf numbers; however, it was also correlated with a lower number of rooted plants. Conversely, treatments with 6 mg L⁻¹ PZA promoted longer stem growth, whereas control plants exhibited the largest leaf area, and AgNO3-treated plants produced the longest roots. The accumulation of H₂O₂ in plants treated with ethylene inhibitors was like controls, but total ROS levels soared by 36% in those treated with 6 mg L⁻¹ PZA compared to controls. This suggests a link between reduced ethylene production, oxidative stress mitigation, and enhanced potato growth. Additionally, total ROS was positively correlated with stem length, but negatively correlated with root length.Plants use several strategies to combat the damaging effects of ROS, such as the production of antioxidant compounds such as phenolics. Although PZA did not significantly alter TPC compared to controls, treatment with AgNO₃ caused a 61% reduction in TPC. Therefore, PZA did not appear to significantly affect phenolics production in the potato seedlings.Proline, another critical antioxidant in plants, was found to accumulate significantly in the leaves of plants treated with 6 mg L⁻¹ PZA, which was more than 2.3 times higher than that in controls. This accumulation correlated positively with ROS levels at higher PZA concentrations but showed an inverse relationship with photosynthetic pigment levels.The PCA revealed the relationships between the measured parameters and the applied elicitors. The samples were categorized into four distinct groups:Control group: This group primarily exhibited higher FW, DW, and longer roots compared to the treated plants.Low PZA dose group: These plants displayed elevated levels of photosynthetic pigments, TPC, and leaf area.Medium PZA dose group: Correlations were observed with an increased number of roots.6 mg L⁻¹ PZA and AgNO₃ group: These samples contained elevated levels of total ROS and proline.

The study concludes that low concentrations of PZA can stimulate growth while inhibiting ethylene production, resulting in fewer growth abnormalities compared to control plants. However, at elevated PZA concentrations, increased ROS levels may lead to oxidative stress, emphasizing the delicate balance in ethylene's role in plant growth and the necessity for further research to optimize conditions for potato cultivation in vitro. The findings contribute to a deeper understanding of how ethylene inhibitors can enhance potato propagation and possibly other crops in controlled agricultural environments.

Pheasant is a pleasant bird whose long and magnificent tail distinguishes it from other types of birds. The cerebellum is organized in the form of leaves that are located in a row in the rostrocaudal axis of the brain. Myelin is the twisting of the plasma membrane of the oligodendrocyte and Schwann cells around an axon, which insulates it and increases the speed of nerve current conduction. Due to the importance and fundamental role of the nervous system, many studies have been done on the nervous system of mammals and other birds, but no research has been done on the development of the pheasant's nervous system, therefore, this research is proposed.

In this study, sixty fertilized pheasant eggs were used. Healthy eggs were placed in the automatic incubator and head sampling was done on different days of the embryo from the 7th day and the one-day-old chick. The specimens were immediately fixed in 10% neutral buffered formalin solution for 24–48 hours and then submitted to the dehydration process by passing them through a series of ascending ethanol alcohol each for two hours (70, 80, 90 and 100%) and then specimens were cleared in xylene for one hour after that embedded in paraffin wax and then the blocks were sectioned by microtome at 5μm thickness. First, all tissue sections were stained with Hematoxylin and Eosin for histological structure, and then to identify myelin fibers and glial cells, sections were stained with special stain; Luxal Fast Blue Cresyl Etch Violet and Mallory's Phosphotungstic Acid-Hematoxylin dyes.

In the cerebellum of a 7-day-old pheasant fetus, myelin fibers were seen in the form of very thin short strands among the primary nerve cells in an irregular and scattered manner. With increasing fetal age, the density, and probably the length of myelin fibers and the size of nerve cells increased also, the spatial arrangement of myelin fibers was seen in the form of regular thickness and almost from the 17-day embryo of the pheasant onwards, the regular arrangement of these fibers led to the recognition of the white and gray matter of the cerebellum.In 19-day-old pheasant embryo onwards, the regular arrangement of these fibers caused a clear recognition of the white and gray matter of the cerebellum, which until now from this age, they were not distinguishable, but empty spaces between myelin fibers were observed.

The results showed that myelin and glial cells start to form in the pheasant cerebellum from the age of 7 and as the embryo ages, these cells become bigger and completely fill the space between the neurons. Also, myelin fibers were first observed in the form of very thin and scattered threads at the age of 7 embryos and As the embryo ages, these fibers become denser  and finally, in the white matter of the cerebellum of a day-old chick, they find a spatial arrangement in the form of very thick and regular bundles.

Alzheimer's is a neurological disorder characterized by cognitive decline, neuron loss, and eventually dementia. On the other hand, studies have shown that physical activity causes synaptic plasticity, improves cognitive performance, increases memory and learning, reduces anxiety and depression, and protects the brain against neuron-destroying diseases in humans and animals. In addition, sumac has a high antioxidant capacity and can be useful in relieving Alzheimer's disease. According to the studies conducted on the positive effect of exercise on cognitive functions and increasing the antioxidant capacity (including receiving sumac) in improving the process of Alzheimer's disease, the effect of these two factors together on the inflammatory factors of Alzheimer's patients has not been investigated. The purpose of the present study was to investigate the effect of a period of endurance training along with sumac supplementation on inflammatory and apoptotic indices in Alzheimer's male rats. 

The current research is experimental with a post-test and controlled design with a control group and a placebo. 35 rats (with an average age of 4 to 5 weeks and an average weight of 180 to 200 grams) were randomly divided into control group, Alzheimer's disease, Alzheimer's disease with sumac supplementation, Alzheimer's disease with endurance exercise, and Alzheimer's disease with endurance exercise and sumac supplementation. Alzheimer's induction was done by injecting 8 mg/kg of trimethyl tin chloride along with 200 microliters of normal saline. To feed the sumac (Rhus coriaria L)) to rats, the top branch of the sumac plant was ground. The powder obtained from it was mixed with the food of rats at a ratio of ten percent. Then, the mixture was made into a paste and molded into a plate and dried. Endurance training was done in the form of swimming in a special rat pool with dimensions of 80 x 50 x 50 cm, with a water wave maker and water with a temperature of 30 to 33 degrees. Endurance swimming exercises were performed for 12 weeks and 5 days a week. 48 hours after the end of the training program, the rats were anesthetized. 5 ml of blood sample was taken from the heart and transferred to gel tubes. Then the serum was separated by a centrifuge model 5804 manufactured by Eppendorf and transferred to a microtube and a negative twenty-degree freezer. The levels of IL-18, bax, bcl2 and cas3 were analyzed using ELISA method. Data were analyzed using one-way ANOVA test and Tukey's post hoc test (P<0.05).

We found that induction of Alzheimer's disease increases IL-18, bax, bcl2 and cas3 proteins (p=0.001). After 12 weeks of intervention, the level of IL-18, bax, bcl2 and cas3 proteins in the Alzheimer group + endurance exercise was significantly lower than the Alzheimer group (p=0.001). On the other hand, there was no significant difference between Alzheimer's + endurance training and Alzheimer's + endurance + sumac groups in terms of IL-18, bax, bcl2 and cas3 protein levels (p>0.05).

Epidemiological studies suggest the reduction of inflammation in the prevention and treatment of Alzheimer's. However, clinical evidence does not consider the use of anti-inflammatory drugs to be very successful. Both sumac and exercise are strong antioxidants and anti-inflammatory agents, which probably have double positive physiological effects when they are placed next to each other. Our findings suggest that endurance training improves the level of inflammatory indices in Alzheimer's rat, although adding sumac to the exercise program is not likely to improve apoptotic and inflammatory indices.