Search results: Found 9

Listing 1 - 9 of 9
Sort by
The microbial nitrogen cycle

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194124 Year: Pages: 174 DOI: 10.3389/978-2-88919-412-4 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2015-12-10 11:59:06
License:

Loading...
Export citation

Choose an application

Abstract

Nitrogen is an essential element in biological systems, and one that often limits production in both aquatic and terrestrial systems. Due to its requirement in biological macromolecules, its acquisition and cycling have the potential to structure microbial communities, as well as to control productivity on the ecosystem scale. In addition, its versatile redox chemistry is the basis of complex biogeochemical transformations that control the inventory of fixed nitrogen, both in local environments and over geological time. Although many of the pathways in the microbial nitrogen cycle were described more than a century ago, additional fundamental pathways have been discovered only recently. These findings imply that we still have much to learn about the microbial nitrogen cycle, the organisms responsible for it, and their interactions in natural and human environments. Progress in nitrogen cycle research has been facilitated by recent rapid technological advances, especially in genomics and isotopic approaches. In this Research Topic, we reviewed the leading edge of nitrogen cycle research based on these approaches, as well as by exploring microbial processes in modern ecosystems.

From Sex Differences in Neuroscience to a Neuroscience of Sex Differences: New Directions and Perspectives

Author:
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196890 Year: Pages: 199 DOI: 10.3389/978-2-88919-689-0 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Medicine (General) --- Neurology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
License:

Loading...
Export citation

Choose an application

Abstract

This research topic aims to integrate scattered findings on sex differences in neuroscience into a broader theory of how the human brain is shaped by sex and sex hormones in order to cause the great variety of sex differences that are commonly observed. It can be assumed that these differences didn’t occur arbitrarily, but that they rather determined and still determine evolutionary success of individuals and were shaped by the processes of natural and in particular sexual selection. Therefore, sex differences are not negligible and sex difference research cannot be discriminating against one sex or the other. In fact a better understanding of the underlying causes of sex differences has great advantages for both men and women and society as a whole, not only in terms of health care, but in every aspect of life. Gender equality can only work out if it is equally well understood for men and women what their individual resources and needs are. Therefore, it is of great importance to pave the way for identifying the underlying principles of structural and functional brain organization that cause men and women to act, think and feel differently. To this end it is of particular interest to identify possible similarities and interrelations between sex differences that did so far stand separately, in order to investigate whether they share a common source. To understand, where a specific sex difference comes from and whether or not it is caused by the same principle as other sex differences, it is necessary to explicitly link sex differences in behavior to their neuronal correlates and vice versa link sex differences in brain structure and function to their behavioral outcomes. In particular a new understanding of male and female brain functioning may arise from findings on how sex hormones interact with various neurotransmitter systems. In the past few years several findings demonstrated that women’s behavior is influenced by the sex hormone fluctuations they experience naturally during their menstrual cycle to the extent that sex differences may only be detectable in one cycle phase but not another. The study of menstrual cycle dependent effects gives important hints about which sex differences are activational and which are organizational. Additionally it only recently came to attention, that hormonal contraception may alter a women’s mood, cognition and behavior as a consequence of changes in brain structure and function. The underlying mechanisms are so poorly understood that it is even hard to predict, whether hormonal contraception will mask or amplify sex differences in a given task. Since the oral hormonal contraceptive pill is meanwhile used by 100 million women worldwide and even by teenagers whose brains are not yet fully developed, the question of how the synthetic steroids contained in hormonal contraceptives act on the brain is to be studied hand in hand with naturally occurring sex differences. This topic summarizes the current state of the art in sex difference research and gives new perspectives in terms of hypothesis generation an methodology. Both are necessary to gain a complete picture of what it is that makes a brain male or female and move towards a neuroscience of sex differences.

Transcriptional Regulation in Cancers and Metabolic Diseases

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197125 Year: Pages: 98 DOI: 10.3389/978-2-88919-712-5 Language: English
Publisher: Frontiers Media SA
Subject: Oncology --- Medicine (General) --- Internal medicine
Added to DOAB on : 2016-04-07 11:22:02
License:

Loading...
Export citation

Choose an application

Abstract

The transcription factor (TF) mediated regulation of gene expression is a process fundamental to all biological and physiological processes. Genetic changes and epigenetic modifications of TFs affect target gene expression during the formation of malignant cells. Extensive work has been done on the critical TFs in various disease models. Despite the success of numerous TF-targeted therapies, there remain significant hurdles understanding the mechanisms, transcriptional targets and networks of physiologic pathways that govern TF action. This effort is now beginning to produce exciting new avenues of research. A clinically relevant topic for genetic change of TF is the mutant isoforms of p53, the most famous tumor suppressor. The p53 mutations either results in loss of function, or acting as dominant negative for wild-type protein, or ‘gain of function’ specifically promoting cancer survival. The gain of function is achieved by shifting p53 binding partner proteins, or changed genomic binding landscape leading to a cancer-promoting transcriptome. Another example of genetic change of TF causing malignancy is the AML-ETO fusion protein in the human t(8;21)-leukemia. The fusion protein is an active TF, and more interestingly, new studies link the disease causing role of AML-ETO to the unique transcriptome in the hematopoietic stem cells. Nuclear receptors (NR) are a group of ligand-dependent TFs governing the expression of genes involved in a broad range of reproductive, developmental and metabolic programs. Genetic changes and epigenetic modifications of NRs lead to cancers and metabolic diseases. Androgen receptor (AR), estrogen receptor (ER) and progesterone receptor (PR) are well studied NRs in prostate, breast and endometrial cancers. The development in sequencing technology and computational genomics enable us to investigate the transcription programs of these master TFs in an unprecedented level. This Research Topic aims to present the most up-to-date progress in the field of transcription regulation in cancers and metabolic diseases.

The Origin of the Plasma Cell Heterogeneity

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197347 Year: Pages: 80 DOI: 10.3389/978-2-88919-734-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2016-04-07 11:22:02
License:

Loading...
Export citation

Choose an application

Abstract

Plasma cells (PCs) are terminally differentiated B-cells producing large amounts of immunoglobulins (Ig). In humans, most of circulating Ig are produced by bone marrow plasma cells. PCs differentiate from activated naïve or memory B-cells usually activated by specific antigens. It is still controversial whether the regulation of PCs numbers and the “active” in vivo Ig diversity depend or not on non-specific reactivation of B-cells during infections. Depending on the stimulus (T-independent/T-dependent antigen, cytokines, partner cells) and B-cell types (naïve or memory, circulating or germinal center, lymph nodes or spleen, B1 or B2...), both the phenotype and isotype of PCs differ suggesting that PC diversity is either linked to B-cell diversity or to the type of stimulus or to both. Knowledge of the mechanisms supporting PC diversity has important consequences for the management of i) plasma cell neoplasia such as Multiple Myeloma and Waldenström's Macroglobulinemia, ii) vaccine protection against pathogens and iii) auto-immune diseases.

Keywords

Plasma cell --- B-cell --- differentiation --- Cell Cycle --- IL21 --- Autophagy --- B1 --- Autoimmunity --- Myeloma

The metabolic challenges of immune cells in health and disease

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196227 Year: Pages: 80 DOI: 10.3389/978-2-88919-622-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2016-08-16 10:34:25
License:

Loading...
Export citation

Choose an application

Abstract

Obesity and its co-morbidities, including atherosclerosis, insulin resistance and diabetes, are a world-wide epidemic. Inflammatory immune responses in metabolic tissues have emerged as a universal feature of these metabolic disorders. While initial work highlighted the contribution of macrophages to tissue inflammation and insulin resistance, recent studies demonstrate that cells of the adaptive immune compartment, including T and B lymphocytes and dendritic cells also participate in obesity-induced pathogenesis of these conditions. However, the molecular and cellular pathways by which the innate and adaptive branches of immunity control tissue and systemic metabolism remain poorly understood. To engage in growth and activation, cells need to increase their biomass and replicate their genome. This process presents a substantial bioenergetic challenge: growing and activated cells must increase ATP production and acquire or synthesize raw materials, including lipids, proteins and nucleic acids. To do so, they actively reprogram their intracellular metabolism from catabolic mitochondrial oxidative phosphorylation to glycolysis and other anabolic pathways. This metabolic reprogramming is under the control of specific signal transduction pathways whose underlying molecular mechanisms and relevance to physiology and disease are subject of considerable current interest and under intense study. Recent reports have elucidated the physiological role of metabolic reprogramming in macrophage and T cell activation and differentiation, B- and dendritic cell biology, as well as in the crosstalk of immune cells with endothelial and stem cells. It is also becoming increasingly evident that alterations of metabolic pathways play a major role in the pathogenesis of chronic inflammatory disorders. Due to the scientific distance between immunologists and experts in metabolism (e.g., clinicians and biochemists), however, there has been limited cross-talk between these communities. This collection of articles aims at promoting such cross-talk and accelerating discoveries in the emerging field of immunometabolism.

Advances in Seed Biology

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196753 Year: Pages: 238 DOI: 10.3389/978-2-88919-675-3 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany
Added to DOAB on : 2016-08-16 10:34:25
License:

Loading...
Export citation

Choose an application

Abstract

The seed plays a fundamental role in plant reproduction as well as a key source of energy, nutrients and raw materials for developing and sustaining humanity. With an expanding and generally more affluent world population projected to reach nine billion by mid-century, coupled to diminishing availability of inputs, agriculture is facing increasing challenges to ensure sufficient grain production. A deeper understanding of seed development, evolution and physiology will undoubtedly provide a fundamental basis to improve plant breeding practices and ultimately crop yields. Recent advances in genetic, biochemical, molecular and physiological research, mostly brought about by the deployment of novel high-throughput and high-sensitivity technologies, have begun to uncover and connect the molecular networks that control and integrate different aspects of seed development and help determine the economic value of grain crops with unprecedented details. The objective of this e-book is to provide a compilation of original research articles, reviews, hypotheses and perspectives that have recently been published in Frontiers in Plant Science, Plant Evolution and Development as part of the Research Topic entitled "Advances in Seed Biology". Editing this Research Topic has been an extremely interesting, educational and rewarding experience, and we sincerely thank all authors who contributed their expertise and in-depth knowledge of the different topics discussed. We hope that the information presented here will help to establish the state of the art of this field and will convey how exciting and important studying seeds is and hopefully will stimulate a new crop of scientists devoted to investigating the biology of seeds.

Transcellular Cycles Underlying Neurotransmission

Author:
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196548 Year: Pages: 105 DOI: 10.3389/978-2-88919-654-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Neurology
Added to DOAB on : 2016-08-16 10:34:25
License:

Loading...
Export citation

Choose an application

Abstract

Synaptic transmission demands the operation of a highly specialized metabolic machinery involving the transfer of metabolites and neurotransmitters between neurons, astrocytes and microvessels. In the last years, important advances have occurred in our understanding of the mechanisms underlying cerebral activation, neuroglial coupling and the associated neurovascular response. Briefly, exacerbated oxygen consumption in stimulated neurons is thought to trigger glycolytic lactate and glucose transfer from astrocytes which, in turn, obtain these fuels from the microvasculature. Neurotransmitter release is made possible by a combination of transcellular cycles exchanging metabolites between these three compartments, returning eventually the synapsis to its pre-firing situation in the resting periods. In spite of the enormous progresses achieved in recent years, the drivers determining the predominant direction of the fluxes, their quantitative contribution and their energy requirements, have remained until today incompletely understood, more particularly under the circumstances prevailing in vivo. In many instances, progress derived from the implementation of novel methodological approaches including advanced neuroimaging and neurospectroscopy methods. As a consequence, literature in the field became vast, diverse and spread within journals of different specialities. The e-book "Transcellular cycles underlying neurotransmission" aims to summaryze in a single volume, recent progress achieved in hypothesis, methods and interpretations on the trafficking of metabolites between neurons and glial cells, and the associated mechanisms of neurovascular coupling.

Design and Engineering of Microreactor and Smart-Scaled Flow Processes

Author:
ISBN: 9783038420385 9783038420392 Year: Pages: 252 DOI: 10.3390/books978-3-03842-039-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2015-10-22 07:00:06
License:

Loading...
Export citation

Choose an application

Abstract

Microreactors are small devices with sub-millimeter internals which have superb mass and heat transfer. Initially, they were used for reactions with very high demands on the latter, e.g. very exothermic reactions, gas-liquid reactions with interfacial transport issues, reactions with very fast kinetics which demands even faster mixing, and more. In this way, the processing window was opened widely and, also due to the minute volumes only present in the reaction zone, safe processing under otherwise hazardous conditions was enabled. This includes processing of reactions which are prone to thermal runaway and in the explosive regime. Scale-up of promising reactions and products which was hindered with conventional technology is now possible using the new equipment. This has widened the process development possibilities in chemical industry.In the last years, micro process technology was not only used for the very problematic synthetic issues which formerly had a dead-end position in industry’s process development. Rather, the scope of chemical reactions to be processed in microreactors was considerably widened by exploring new process conditions with regard to temperature, pressure, concentration, solvents, and more. This is commonly referred to as flow chemistry. This allowed to reduce the processing time-scale for many reactions to the minute range or even below which fits well to the residence times of microreactors. In addition, the process integration of several reactions in one flow to a multi-step synthesis has opened a new door in molecular diversity as well as system and process complexity. The same holds for the combination of reactions and separations in micro-flow. To achieve throughputs relevant for industrial production, smart scale-out to milli-flow units has established and supplemented the num­bering-up concept (parallelization of microchannels/-reactors operated under equal conditions).New innovations and enabling technologies need anyhow evaluation and benchmarking with conventional technology on the full-system level. Yet, microreactor technology has in the last years deepened so much into process intensification on a holistic scale that the focus increasingly is given towards the process dimension—to process design and automation, real-case applications, cost analysis, life-cycle assessment, and more. The impact on cost competitiveness and sustainability becomes well assessed.Facing this very recent scientific achievement, the special issue “Design and Engineering of Microreactor and Smart-Scaled Flow Processes” of the journal Processes aims to cover recent advances in the development of microreactor and smart-scaled flow processes towards the process level — in the sense as given above.

Nuclear Back-end and Transmutation Technology for Waste Disposal: Beyond the Fukushima Accident

Author:
ISBN: 9784431551102 9784431551119 Year: Pages: 341 DOI: 10.1007/978-4-431-55111-9 Language: English
Publisher: Springer Nature
Subject: Environmental Sciences --- Nuclear Physics
Added to DOAB on : 2014-11-12 12:10:32
License:

Loading...
Export citation

Choose an application

Abstract

This book covers essential aspects of transmutation technologies, highlighting especially the advances in Japan. The accident at the Fukushima Daiichi Nuclear Power Plant (NPP) has caused us to focus attention on a large amount of spent nuclear fuels stored in NPPs. In addition, public anxiety regarding the treatment and disposal of high-level radioactive wastes that require long-term control is growing. The Japanese policy on the back-end of the nuclear fuel cycle is still unpredictable in the aftermath of the accident. Therefore, research and development for enhancing the safety of various processes involved in nuclear energy production are being actively pursued worldwide. In particular, nuclear transmutation technology has been drawing significant attention after the accident.This publication is timely with the following highlights: 1) Development of accelerator-driven systems (ADSs), which is a brand-new reactor concept for transmutation of highly radioactive wastes; 2) Nuclear reactor systems from the point of view of the nuclear fuel cycle. How to reduce nuclear wastes or how to treat them including the debris from TEPCO’s Fukushima nuclear power stations is discussed; and 3) Environmental radioactivity, radioactive waste treatment and geological disposal policy.State-of-the-art technologies for overall back-end issues of the nuclear fuel cycle as well as the technologies of transmutation are presented here. The chapter authors are actively involved in the development of ADSs and transmutation-related technologies. The future of the back-end issues in Japan is very uncertain after the accident at the Fukushima Daiichi NPP and this book provides an opportunity for readers to consider the future direction of those issues.

Listing 1 - 9 of 9
Sort by
Narrow your search