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Frontiers in Biology

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, Volume 12 Issue 4 Previous Issue   
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Illuminating the structure and dynamics of chromatin by fluorescence labeling
Shipeng Shao, Lei Chang, Yingping Hou, Yujie Sun
Front. Biol.. 2017, 12 (4): 241-257.   DOI: 10.1007/s11515-017-1454-2
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BACKGROUND: Visualization of chromosomal loci location and dynamics is crucial for understanding many fundamental intra-nuclear processes such as DNA transcription, replication, and repair.

OBJECTIVE: Here, we will describe the development of fluorescence labeling methods for chromatin imaging, including traditional as well as emerging chromatin labeling techniques in both fixed and live cells. We will also discuss current issues and provide a perspective on future developments and applications of the chromatin labeling technology.

METHODS: A systematic literature search was performed using the PubMed. Studies published over the past 50 years were considered for review. More than 100 articles were cited in this review.

RESULTS: Taking into account sensitivity, specificity, and spatiotemporal resolution, fluorescence labeling and imaging has been the most prevalent approach for chromatin visualization. Among all the fluorescent labeling tools, the adoption of genome editing tools, such as TALE and CRISPR, have great potential for the labeling and imaging of chromatin.

CONCLUSION: Although a number of chromatin labeling techniques are available for both fixed and live cells, much more effort is still clearly required to develop fluorescence labeling methods capable of targeting arbitrary sequences non-intrusively to allow long-term, multiplexing, and high-throughput imaging of genomic loci and chromatin structures. The emerging technological advances will outline a next-generation effort toward the comprehensive delineation of chromatin at single-cell level with single-molecule resolution.

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Salicylic acid-mediated plant defense: Recent developments, missing links, and future outlook
Ian Arthur Palmer, Zhenhua Shang, Zheng Qing Fu
Front. Biol.. 2017, 12 (4): 258-270.   DOI: 10.1007/s11515-017-1460-4
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BACKGROUND: Plant pathogens are responsible for many of history’s greatest famines. Understanding how plants defend themselves against pathogens is crucial to preventing future famines. Salicylic acid (SA)-mediated plant defense is a key defense pathway, which plants use to defend against biotrophic and hemi-biotrophic pathogens. As a master regulator of SA-mediated plant defense, NPR1 interacts with TGA and WRKY transcription factor families, individual members of which positively or negatively regulate plant defense.

OBJECTIVE:In this review we describe the recent developments and predict future directions of research on the involvement of circadian rhythm-, autophagy-, and viral RNA silencing-related genes in SA-mediated plant defense on SA, on plant defense, the induction effects of PR proteins, and the mechanisms by which NPR1 regulates defense-related genes.

METHODS:We performed an extensive search of current and past literature using the PubMed, Google Scholar, and Google search engines. Our search terms included: “SA-mediated plant defense,” and “NPR1 [AND] salicylic acid.” Other search terms, wildcards, and Boolean operators were paired with “NPR1” or “plant defense” as needed to research more detailed information related to specific topics covered within this review. We also used Google to search for, “economic impact citrus greening,” “aspirin,” “Irish potato famine,” and “rice blast,” among other terms, to gather background information on the history and impact of plant diseases, and the historical use of aspirin.

RESULTS:Of 148 sources found, 132 were directly related to plant defense. The remaining sources are related to the historical and economic impact of plant diseases and the historical use and mechanism of action of aspirin or salicylate. All reviewed sources have been documented in the references section.

CONCLUSION:The topic of salicylic acid-mediated plant defense is broad, and new research is expanding our understanding of this topic quickly. In this review, we give a basic overview of the historical economic impact of plant diseases, and how an understanding of SA-mediated plant defense can prevent future famines. We provide a basic overview of plant defense, then discuss how SA acts as a defense signaling molecule.We discuss how SA regulates NPR1, which goes on to activate expression of SA-related genes includingPRgenes. Later, we discuss current research topics, including the role of NPR1 and SA in autophagy, circadian rhythmicity, viral gene silencing, SA biosynthesis, and SAR. We also discuss the potential roles of PR proteins, other SA binding proteins, WRKY and TGA family transcription factors, Elongator, and ER transport proteins in plant defense. Finally, we discuss the potential future routes that research into this topic could take, in order to further our understanding of role SA plays in plant defense.

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Copper-induced liver fibrosis affects the behavior of bone marrow cells in primary culture
Anatoliy I. Bozhkov, Eugeniy G. Ivanov, Yuliya A. Kuznetsova, Svetlana L. Ohiienko, Anastasiya Yu. Bondar’
Front. Biol.. 2017, 12 (4): 271-279.   DOI: 10.1007/s11515-017-1458-y
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BACKGROUND:The present study investigated the effects of low-molecular-weight components of bovine colostrum (LMCC), which were administeredper os, on the differentiation, growth, and survival of cells obtained from the bone marrow of rats in primary culture.

METHODS: Bone marrow cells (BMCs) were obtained from both the rat femurs and were cultured in medium 199 supplemented with antibiotics (8% streptomycin and 8% gentamycin) and 20% inactivated fetal calf serum. In addition, the number of BMCs was counted and their morphotypes were determined.

RESULTS: Animals were treated with copper (Cu) sulfate to induce liver fibrosis. Subsequent treatment with LMCC eliminated growth inhibition and normalized the bodyweight and temperature of animals with Cu-induced liver fibrosis. The number of lymphocytes in the bone marrow of animals with Cu-induced liver fibrosis was significantly higher than that in the bone marrow of control animals. The number of neutrophils in untreated animals with liver fibrosis and LMCC-treated animals with liver fibrosis was lower than that in control animals. Neutrophils obtained from untreated animals with liver fibrosis and LMCC-treated animals with liver fibrosis underwent two-times faster degradationin vitro than neutrophils obtained from control animals.

CONCLUSIONS: Our results indicate that LMCC affects the distribution of different morphological types of BMCs but does not prevent their degradationin vitro, which was two-times faster than that of BMCs obtained from control animals.

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Bioactive compounds from marine Streptomycessp. VITPSA as therapeutics
S. Pooja, T. Aditi, S. Jemimah Naine, C. Subathra Devi
Front. Biol.. 2017, 12 (4): 280-289.   DOI: 10.1007/s11515-017-1459-x
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BACKGROUND: Marine actinomycetes are efficient producers of new secondary metabolites that show different biological activities, including antibacterial, antifungal, anticancer, insecticidal, and enzyme inhibition activities.

METHODS: The morphological, physiological, and biochemical properties of the strain Streptomyces sp. VITPSA were confirmed by conventional methods. Antibacterial, anti-oxidant, anti-inflammatory, anti-diabetic, and cytotoxic activities of Streptomyces sp. VITPSA extract were determined. The media were optimized for the production of secondary metabolites. Characterization and identification of secondary metabolites were conducted by high-performance liquid chromatography, gas chromatography-mass spectroscopy, and Fourier transform infrared spectroscopy analysis.

RESULTS: The strain showed significant antibacterial, anti-oxidant, and cytotoxic activities, moderate anti-inflammatory activity, and no satisfactory anti-diabetic activity. The ethyl acetate extract of Streptomyces sp. VITPSA showed maximum antibacterial activity against two gram-positive and gram-negative bacteria at 0.5 mg/mL. The antioxidant potential of the crude extract exhibited strong reducing power activity at 0.5 mg/mL with 95.1% inhibition. The cytotoxic effect was found to be an IC50 of 50 µg/mL on MCF-7 cell lines. Experimental design of optimization by one-factor analysis revealed the most favorable sucrose, yeast extract, pH (7.25), and temperature (28°C) conditions for the effective production of secondary metabolites.

CONCLUSION: This study revealed that Streptomycessp. VITPSA is an excellent source of secondary metabolites with various bioactivities.

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Thiamine deficiency perturbed energy metabolism enzymes in brain mitochondrial fraction of Swiss mice
Anupama Sharma, Renu Bist, Surender Singh
Front. Biol.. 2017, 12 (4): 290-297.   DOI: 10.1007/s11515-017-1457-z
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BACKGROUND: Thiamine is an essential cofactor associated with several enzymes in energy metabolism and its deficiency may lead to neurological deficits. Current research evaluated the biochemical and molecular changes in TCA cycle enzymes using the mitochondrial fraction of the brain following thiamine deficiency (TD) in mice.

METHODS: The investigation was carried out on Swiss mice (6-8 week old) allocated into three groups. First group was control; second and third group were made thiamine deficient for 8 and 10 days.

RESULTS: Current study showed that alpha-ketoglutarate dehydrogenase (KGDHC) (thiamine-dependent enzyme) level found to be significantly reduced in experimental groups as compared to control group. In comparison to control group, a significant decrease in the succinate dehydrogenase (SDH) activity was calculated in group II and group III (p<0.0001) mice. Diminished enzymatic activity of fumarase and MDH enzyme in thiamine deficient groups exposed for 8 and 10 days was calculated as compared to control group. The expression analysis of different genes governing TCA cycle enzymes in different experimental groups showed that there was a negotiable change in the expression of fumarase and DLD (dihydrolipoyl dehydrogenase- E3 subunit of KGDHC) whereas a declined in the expression of SDH and two subunits of KGDHC i.e. OGDH (2-oxoglutarate dehydrogenase- E1 subunit of KGDHC) and DLST (dihydrolipoyllysine-residue succinyltransferase- E2 subunit of KGDHC) was observed as compared to control group.

CONCLUSIONS: Hence, current findings strongly entail that TD promotes alteration in energy metabolism in brain mitochondria which will decline the neuronal progression which may lead to neurodegenerative diseases such as Alzheimer’s diseases.

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The role of dopamine D2 receptors in the amygdala in metabolic and behavioral responses to stress in male Swiss-Webster mice
Maryam Hassantash, Hedayat Sahraei, Zahra Bahari, Gholam Hossein Meftahi, Roshanak Vesali
Front. Biol.. 2017, 12 (4): 298-310.   DOI: 10.1007/s11515-017-1455-1
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OBJECTIVE: The D2 dopamine receptor is found in different parts of the amygdala. However, its contribution to stress is unknown. Thus, in the present study, we examined the effects of excitation and inhibition of D2 dopamine receptors in the amygdala on the metabolic and hormonal changes in response to stress.

METHODS: Bilateral amygdala cannulation was carried out in Swiss-Webster mice (n = 7). On recovery, different doses of the dopamine D2 receptor antagonist, sulpiride (1, 5 and 10 µg/mouse) or the dopamine D2 receptor agonist, bromocriptine (1, 5 and 10 µg/mouse) were injected into the amygdala. The animals were then placed in stress apparatus (communication box) where they received an electric shock (10 mV voltage, 10 Hz frequency and 60 s duration) after 30 min. The animal's activities were recorded for 10 min before and 10 min after the stress induction. Locomotion, rearing and freezing were investigated. Metabolic changes, such as food and water intake and anorexia, were studied.

RESULTS: The results show that stress increased the concentration of plasma corticosterone, which was followed by a decrease in locomotion and rearing and an increase in freezing behavior. Furthermore, both weight and water and food intake were reduced. Administration of bromocriptine led to a reduction of corticosterone at doses of 1 and 5 µg/mouse and an increase of corticosterone at 10 µg/mouse. Additionally, lower doses of bromocriptine (1 and 5 µg/mouse) caused an increase in locomotion and rearing and a decrease in freezing behavior. Similar results were observed with sulpiride injection.

CONCLUSION: D2 dopamine receptors can play a major role in the amygdala in stress. Both an agonist and an antagonist of the D2 receptor attenuate the metabolic and hormonal changes observed in response to stress

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Relationship between serum ferritin and hemoglobin levels determined by cardiac and hepatic T2 MRI in beta-thalassemia intermedia and major patients
Bijan Keikhaei, Pejman Slehi-fard, Seyed-Ali Nojoumi, Abbas Khosravi
Front. Biol.. 2017, 12 (4): 311-315.   DOI: 10.1007/s11515-017-1431-9
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BACKGROUND: Thalassemia major is one of the most common hereditary disorders, and it causes ineffective hematopoiesis in the body through disarrangement of the hemoglobin synthesis balance. Regular blood transfusions cause complications of iron overload in the body in these patients. Tissue iron status can be determined by measuring serum and liver biopsy ferritin levels and by T2* MRI. This study assessed the relationship between serum ferritin and hemoglobin by T2* MRI of the heart and liver.

METHOD: This cross-sectional descriptive study was carried out on patients with beta-thalassemia intermedia and major who visited the Center for Thalassemia and Hemoglobinopathies at Shafa Hospital, Ahwaz, between 2014 and 2015. All patients were receiving regular blood transfusions every 2?4 weeks. Pearson’s correlation test was used to assess serum ferritin and T2* values from heart and liver MRI.

RESULTS:A total of 260 patients (mean age is 23-year-old) were enrolled in the study. The incidence of iron overload in the liver and heart was 83% and 39%, respectively. Serum ferritin levels showed a very strong inverse correlation with T2* values on heart (r= -3.54, p<0.0001) and liver (r= -3.03, p<0.0001) MRI. Additionally, a meaningful interaction was observed between the T2* values from liver and heart MRI (r= 0.29, p<0.0001).

CONCLUSION:Serum ferritin is strongly and inversely correlated with T2* values of MRI of the liver and heart in patients with thalassemia. Therefore, T2* MRI can be used to assess tissue iron levels with very high accuracy.

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