Frontiers in Biology
Cover Story   2013, Volume 8 Issue 3
New neurons are generated throughout life in distinct areas of the mammalian brain. This process, called adult neurogenesis, has challenged previously held concepts about adult brain plasticity and opened novel therapeutic avenues to treat certain neuropsychiatric diseases. In the adult mammalian hippocampus, neural stem cells (NSCs) give rise to g [Detail] ...
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, Volume 8 Issue 3

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REVIEW
A review of factors affecting the success of membrane protein crystallization using bicelles
Ann C. KIMBLE-HILL
Front Biol. 2013, 8 (3): 261-272.  
https://doi.org/10.1007/s11515-012-1208-0

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Several reports have been published detailing various platforms for obtaining crystals of membrane proteins to determine their structure including those that use disk shaped bilayers called bicelles. While these crystals have been readily grown and used for X-ray diffraction, the general understanding as to why bicelles are adequate for such a procedure or how to rationally choose conditions remains unknown. This review intends to discuss issues of protein stabilization and precipitation in the presence of lipids that may influence crystal formation.

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ROS-mediated regulation of CXCR4 in cancer
Mahandranauth A. CHETRAM, Cimona V. HINTON
Front Biol. 2013, 8 (3): 273-278.  
https://doi.org/10.1007/s11515-012-1204-4

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Oxidative stress and the accumulation of reactive oxygen specie (ROS) play a role in cancer cells developing an advanced, phenotypic signature that associates with metastasis and progression. Increased ROS concentrations are involved in promoting cancer development and metastasis by inducing expression of oncogenes, suppressing activity of anti-survival molecules and by activating various cell survival and proliferation signaling pathways. Oxidative stress is higher in the epithelium of cancer patients than patients without the disease, and antioxidant trials are currently being explored as a therapeutic option. However, studies have shown that ROS increases expression of CXCR4 in cancer and immune cells. CXCR4 expression in tumors strongly correlates to metastasis and poor prognosis. Herein, we discuss an emerging relationship between ROS and CXCR4 in cancer cells.

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Notch signaling and its emerging role in autoimmunity
Tanapat PALAGA, Lisa M. MINTER
Front Biol. 2013, 8 (3): 279-294.  
https://doi.org/10.1007/s11515-012-1209-z

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Studies of notch signaling in immune cells have uncovered critical roles for this pathway both during the differentiation and effector function phases of immune responses. Cells of the myeloid lineage, including macrophages and dendritic cells, function as key components of innate immune defense against infection and, by acting as antigen presenting cells, can instruct cells of the adaptive immune response, specifically CD4 and CD8 T cells. Tight regulation of this functional interaction is needed to ensure a well-balanced immune response and its dysregulation may indirectly or directly cause the tissue damage characteristic of autoimmune diseases. In this review, the focus will be placed on those recent findings which support a role for notch signaling in inflammatory responses mediated by macrophages and other myeloid lineage cells, as well as peripheral T cells, and their relevance to inflammatory and autoimmne diseases.

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Adult neurogenesis in the mammalian brain
Simon M.G. BRAUN, Sebastian JESSBERGER
Front Biol. 2013, 8 (3): 295-304.  
https://doi.org/10.1007/s11515-013-1263-1

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New neurons are generated throughout life in distinct areas of the mammalian brain. This process, called adult neurogenesis, has challenged previously held concepts about adult brain plasticity and opened novel therapeutic avenues to treat certain neuro-psychiatric diseases. Here, we review the current knowledge regarding the fate and potency of neural stem cells (NSCs), as well as the mechanisms underlying neuronal differentiation and subsequent integration. Furthermore, we discuss the functional significance of adult neurogenesis in health and disease, and offer brief insight into the future directions of the adult neurogenesis field.

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Ischemic and hypoxic preconditioning protect cardiac muscles via intracellular ROS signaling
Li ZUO, William J. ROBERTS, Rosa C. TOLOMELLO, Adam T. GOINS
Front Biol. 2013, 8 (3): 305-311.  
https://doi.org/10.1007/s11515-012-1225-z

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Oxidative stress can cause extensive damage to cardiac tissue under reperfusion conditions. However, preconditioning the myocardium may diminish these negative effects and alleviate reperfusion injury. There are a variety of preconditioning therapies, such as ischemic preconditioning (IPC) and hypoxic preconditioning (HPC), each targeting specific channels, receptors, and/or intracellular molecules. Ischemic preconditioning involves brief periods of ischemia followed by brief periods of reperfusion, thus strengthening the cardiac resistance for a longer period of ischemia. IPC involves complex mechanisms, some of which are still not completely understood today. Nevertheless, many studies have already established models of IPC. In addition, similar to IPC, HPC has also been recognized as preventing reperfusion injury. Reactive oxygen species (ROS) are known mediators of IPC and HPC. Particularly, mitochondria-generated ROS initiate activity of several beneficial preconditioning pathways. The role of ROS is paradoxical; low levels of ROS are key factors in signaling IPC/HPC, but high levels of ROS can contribute to increased oxidative stress on cardiomyocytes. Therefore, it is important to determine the molecular mechanism of IPC and HPC to avoid excessive accumulation of ROS to prevent cardiac injury. In this review, we will outline IPC and HPC, explaining the putative role of ROS in both pathways. We will also discuss preconditioning efficacy in certain conditions such as exercise and how the aging myocardium responds to preconditioning therapies.

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Roles of manganese in photosystem II dynamics to irradiations and temperatures
Xuejing HOU, Harvey J. M. HOU
Front Biol. 2013, 8 (3): 312-322.  
https://doi.org/10.1007/s11515-012-1214-2

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The most amazing chemistry is the light-driven water splitting reaction occurred in the oxygen-evolving complex of phototsystem II in higher plants, green algae, and cyanobacteria. Mn, in the form of Mn4CaO5 cluster in photosystem II, is responsible for the catalytic water splitting reaction as well as plays roles in photosystem II dynamics to irradiation and temperatures. Manganese hypothesis of UV-initiated photoinhibition as a direct target is established, and thermal inactivation of photosystem II involves the valence and structural changes of manganese. Recent progresses in understanding the roles of manganese in photoinhibition especially under UV light and in thermal inactivation including elevated temperatures using synthetic models and native PS II complexes are summarized and evaluated. Potential problems and possible solutions are discussed and presented.

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Engineering industrial fatty acids in oilseeds
Anna R. SNAPP, Chaofu LU
Front Biol. 2013, 8 (3): 323-332.  
https://doi.org/10.1007/s11515-012-1228-9

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More than 300 types of modified fatty acids (mFA) are produced in triacylglycerols (TAG) by various plant species, with many of these unusual structures rendering unique physical and chemical properties that are desirable for a variety of bio-based industrial uses. Attempts to produce these mFA in crop species have thus far failed to reach the desired levels of production and highlighted the need to better understand how fatty acids are synthesized and accumulated in seed oils. In this review we discuss how some of the progress made in recent years, such as the improved TAG synthesis model to include acyl editing and new enzymes such as PDCT, may be utilized to achieve the goal of effectively modifying plant oils for industrial uses. Co-expressing several key enzymes may circumvent the bottlenecks for the accumulation of mFA in TAG through efficient removal of mFA from phosphatidylcholine. Other approaches include the prevention of feedback inhibition of fatty acid synthesis and improving primary enzyme activity in host transgenic plants. In addition, genomic approaches are providing unprecedented power to discover more factors that may facilitate engineering mFA in oilseeds. Based on the results of the last 20 years, creating a high mFA accumulating plant will not be done by simply inserting one or two genes; it is necessary to stack genes encoding enzymes with favorable kinetic activity or specificity along with additional complementary transgenes in optimized plant backgrounds to produce industrial fatty acids at desirable levels. Finally, we discuss the potential of Camelina as an industrial oilseed platform.

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A review on the spot-billed pelican Pelecanus philippensis literature
Vaithianathan KANNAN, Jeganathan PANDIYAN
Front Biol. 2013, 8 (3): 333-352.  
https://doi.org/10.1007/s11515-013-1252-4

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Literature on spot-billed pelican has not been reviewed lately which could provide a critique of the emerging data. We have now chosen it as a key species through which we suggest a conservation action plan which will benefit several waterbird species. The information provided here is scholastic in nature and is meant to focus on aspects that require attention and help plan future work for applied conservation. All known information on this species is brought together in this review which will also provide an update of its biology. Notes on the breeding biology of the species first published in the Journal of the Bombay Natural History Society. So far, 380 works have appeared on the species; of these, 36 contain material reported in earlier works or appeared as papers subsequently. Most appeared as articles in journals, both national and regional, a few international journals, newsletters/bulletins (48.2%), 4 dissertations, 76 reports and 6 popular science articles in magazines. This review on the species will provide an insight into different factors that can be weighed and combined while making a decision in investing resources in species conservation, i.e. importance of the species, level of threat and the time frame over which results are to be achieved.

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RESEARCH ARTICLE
Accurate prediction of protein dihedral angles through conditional random field
Shesheng ZHANG, Shengping JIN, Bin XUE
Front Biol. 2013, 8 (3): 353-361.  
https://doi.org/10.1007/s11515-013-1261-3

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Identifying local conformational changes induced by subtle differences on amino acid sequences is critical in exploring the functional variations of the proteins. In this study, we designed a computational scheme to predict the dihedral angle variations for different amino acid sequences by using conditional random field. This computational tool achieved an accuracy of 87% and 84% in 10-fold cross validation in a large data set for ? and ψ, respectively. The prediction accuracies of ? and ψ are positively correlated to each other for most of the 20 types of amino acids. Helical amino acids can achieve higher prediction accuracy in general, while amino acids in beet sheet have higher accuracy at specific angular regions. The prediction accuracy of ? is negatively correlated with amino acid flexibility represented by Vihinen Index. The prediction accuracy of ? can also be negatively correlated with angle distribution dispersion.

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9 articles