Search results: Found 11

Listing 1 - 10 of 11 << page
of 2
>>
Sort by
The Proteins of Plastid Nucleoids - Structure, Function and Regulation

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199273 Year: Pages: 111 DOI: 10.3389/978-2-88919-927-3 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany
Added to DOAB on : 2016-01-19 14:05:46
License:

Loading...
Export citation

Choose an application

Abstract

Plastids are plant cell-specific organelles of endosymbiotic origin that contain their own genome, the so-called plastome. Its proper expression is essential for faithful chloroplast biogenesis during seedling development and for the establishment of photosynthetic and other biosynthetic functions in the organelle. The structural organisation, replication and expression of this plastid genome, thus, has been studied for many years, but many essential steps are still not understood. Especially, the structural and functional involvement of various regulatory proteins in these processes is still a matter of research. Studies from the last two decades demonstrated that a plethora of proteins act as specific regulators during replication, transcription, post-transcription, translation and post-translation accommodating a proper inheritance and expression of the plastome. Their number exceeds by far the number of the genes encoded by the plastome suggesting that a strong evolutionary pressure is maintaining the plastome in its present stage. The plastome gene organisation in vascular plants was found to be highly conserved, while algae exhibit a certain flexibility in gene number and organisation. These regulatory proteins are, therefore, an important determinant for the high degree of conservation in plant plastomes. A deeper understanding of individual roles and functions of such proteins would improve largely our understanding of plastid biogenesis and function, a knowledge that will be essential in the development of more efficient and productive plants for agriculture. The latter represents a major socio-economic need of fast growing mankind that asks for increased supply of food, fibres and biofuels in the coming decades despite the threats exerted by global change and fast spreading urbanisation.

DNA Replication Origins in Microbial Genomes

Author:
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197798 Year: Pages: 115 DOI: 10.3389/978-2-88919-779-8 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
License:

Loading...
Export citation

Choose an application

Abstract

DNA replication, a central event for cell proliferation, is the basis of biological inheritance. Complete and accurate DNA replication is integral to the maintenance of the genetic integrity of organisms. In all three domains of life, DNA replication begins at replication origins. In bacteria, replication typically initiates from a single replication origin (oriC), which contains several DnaA boxes and the AT-rich DNA unwinding element (DUE). In eukaryotic genomes, replication initiates from significantly more replication origins, activated simultaneously at a specific time. For eukaryotic organisms, replication origins are best characterized in the unicellular eukaryote budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe. The budding yeast origins contain an essential sequence element called the ARS (autonomously replicating sequence), while the fission yeast origins consist of AT-rich sequences. Within the archaeal domain, the multiple replication origins have been identified by a predict-and-verify approach in the hyperthermophilic archaeon Sulfolobus. The basic structure of replication origins is conserved among archaea, typically including an AT-rich unwinding region flanked by several short repetitive DNA sequences, known as origin recognition boxes (ORBs). It appears that archaea have a simplified version of the eukaryotic replication apparatus, which has led to considerable interest in the archaeal machinery as a model of that in eukaryotes. The research on replication origins is important not only in providing insights into the structure and function of the replication origins but also in understanding the regulatory mechanisms of the initiation step in DNA replication. Therefore, intensive studies have been carried out in the last two decades. The pioneer work to identify bacterial oriCs in silico is the GC-skew analysis. Later, a method of cumulative GC skew without sliding windows was proposed to give better resolution. Meanwhile, an oligomer-skew method was also proposed to predict oriC regions in bacterial genomes. As a unique representation of a DNA sequence, the Z-curve method has been proved to be an accurate and effective approach to predict bacterial and archaeal replication origins. Budding yeast origins have been predicted by Oriscan using similarity to the characterized ones, while the fission yeast origins have been identified initially from AT content calculation. In comparison with the in silico analysis, the experimental methods are time-consuming and labor-intensive, but convincing and reliable. To identify microbial replication origins in vivo or in vitro, a number of experimental methods have been used including construction of replicative oriC plasmids, microarray-based or high-throughput sequencing-based marker frequency analysis, two-dimensional gel electrophoresis analysis and replication initiation point mapping (RIP mapping). The recent genome-wide approaches to identify and characterize replication origin locations have boosted the number of mapped yeast replication origins. In addition, the availability of increasing complete microbial genomes and emerging approaches has created challenges and opportunities for identification of their replication origins in silico, as well as in vivo and in vitro. The Frontiers in Microbiology Research Topic on DNA replication origins in microbial genomes is devoted to address the issues mentioned above, and aims to provide a comprehensive overview of current research in this field.

Maintenance of Genome Integrity: DNA Damage Sensing, Signaling, Repair and Replication in Plants

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198207 Year: Pages: 129 DOI: 10.3389/978-2-88919-820-7 Language: English
Publisher: Frontiers Media SA
Subject: Botany --- Science (General)
Added to DOAB on : 2016-01-19 14:05:46
License:

Loading...
Export citation

Choose an application

Abstract

Environmental stresses and metabolic by-products can severely affect the integrity of genetic information by inducing DNA damage and impairing genome stability. As a consequence, plant growth and productivity are irreversibly compromised. To overcome genotoxic injury, plants have evolved complex strategies relying on a highly efficient repair machinery that responds to sophisticated damage perception/signaling networks. The DNA damage signaling network contains several key components: DNA damage sensors, signal transducers, mediators, and effectors. Most of these components are common to other eukaryotes but some features are unique to the plant kingdom. ATM and ATR are well-conserved members of PIKK family, which amplify and transduce signals to downstream effectors. ATM primarily responds to DNA double strand breaks while ATR responds to various forms of DNA damage. The signals from the activated transducer kinases are transmitted to the downstream cell-cycle regulators, such as CHK1, CHK2, and p53 in many eukaryotes. However, plants have no homologue of CHK1, CHK2 nor p53. The finding of Arabidopsis transcription factor SOG1 that seems functionally but not structurally similar to p53 suggests that plants have developed unique cell cycle regulation mechanism. The double strand break repair, recombination repair, postreplication repair, and lesion bypass, have been investigated in several plants. The DNA double strand break, a most critical damage for organisms are repaired non-homologous end joining (NHEJ) or homologous recombination (HR) pathway. Damage on template DNA makes replication stall, which is processed by translesion synthesis (TLS) or error-free postreplication repair (PPR) pathway. Deletion of the error-prone TLS polymerase reduces mutation frequencies, suggesting PPR maintains the stalled replication fork when TLS is not available. Unveiling the regulation networks among these multiple pathways would be the next challenge to be completed. Some intriguing issues have been disclosed such as the cross-talk between DNA repair, senescence and pathogen response and the involvement of non-coding RNAs in global genome stability. Several studies have highlighted the essential contribution of chromatin remodeling in DNA repair. DNA damage sensing, signaling and repair have been investigated in relation to environmental stresses, seed quality issues, mutation breeding in both model and crop plants and all these studies strengthen the idea that components of the plant response to genotoxic stress might represent tools to improve stress tolerance and field performance. This focus issue gives researchers the opportunity to gather and interact by providing Mini-Reviews, Commentaries, Opinions, Original Research and Method articles which describe the most recent advances and future perspectives in the field of DNA damage sensing, signaling and repair in plants. A comprehensive overview of the current progresses dealing with the genotoxic stress response in plants will be provided looking at cellular and molecular level with multidisciplinary approaches. This will hopefully bring together valuable information for both plant biotechnologists and breeders.

Animal model studies on viral infections

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194568 Year: Pages: 173 DOI: 10.3389/978-2-88919-456-8 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-02-05 17:24:33
License:

Loading...
Export citation

Choose an application

Abstract

Understanding viral replication and pathogenicity properties in infected individuals is a major mission of animal virology. Animal models are essential to analyze the in vivo viral characteristics and to develop countermeasures against viruses. To fight against a wide variety of viruses, basic studies with specific and/ or common approaches are required. This Research Topic collects articles that describe studies on numerous virus species at various stages toward animal experiments: (i) description/evaluation/ new challenges of animal model studies; (ii) experimental material/methods for animal model studies; (iii) observations for upcoming animal model studies.Numbers of DNA and RNA viruses such as HHV-6, HPV, Ebola virus, HCV, dengue virus, HTLV-1, HIV-1, SIV, and measles virus are covered by this special issue consisting of original research, methods, review, mini-review, and opinion articles. All readers would understand, we believe and hope, that animal model studies are critical for current virology as always.

Epigenetic Modifications Associated with Abiotic and Biotic Stresses in Plants: An Implication for Understanding Plant Evolution

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453818 Year: Pages: 177 DOI: 10.3389/978-2-88945-381-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Botany --- Physiology
Added to DOAB on : 2018-11-16 17:17:57
License:

Loading...
Export citation

Choose an application

Abstract

Alterations in gene expression are essential during growth and development phases and when plants are exposed to environmental challenges. Stress conditions induce gene expression modifications, which are associated with changes in the biochemical and physiological processes that help plants to avoid or reduce potential damage resulting from these stresses.After exposure to stress, surviving plants tend to flower earlier than normal and therefore transfer the accumulated epigenetic information to their progenies, given that seeds, where this information is stored, are formed at a later stage of plant development.DNA methylation is correlated with expression repression. Likewise, miRNA produced in the cell can reduce the transcript abundance or even prevent translation of mRNA. However, histone modulation, such as histone acetylation, methylation, and ubiquitination, can show distinct effects on gene expression. These alterations can be inherited, especially if the plants are consistently exposed to a particular environmental stress. Retrotransposons and retroviruses are foreign movable DNA elements that play an important role in plant evolution. Recent studies have shown that epigenetic alterations control the movement and the expression of genes harbored within these elements. These epigenetic modifications have an impact on the morphology, and biotic and abiotic tolerance in the subsequent generations because they can be inherited through the transgenerational memory in plants. Therefore, epigenetic modifications, including DNA methylation, histone modifications, and small RNA interference, serve not only to alter gene expression but also may enhance the evolutionary process in eukaryotes.In this E-book, original research and review articles that cover issues related to the role of DNA methylation, histone modifications, and small RNA in plant transgenerational epigenetic memory were published.The knowledge published on this topic may add new insight on the involvement of epigenetic factors in natural selection and environmental adaptation. This information may also help to generate a modeling system to study the epigenetic role in evolution.

The Bacterial Cell: Coupling between Growth, Nucleoid Replication, Cell Division and Shape

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198177 Year: Pages: 324 DOI: 10.3389/978-2-88919-817-7 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-01-19 14:05:46
License:

Loading...
Export citation

Choose an application

Abstract

Bacterial Physiology was inaugurated as a discipline by the seminal research of Maaløe, Schaechter and Kjeldgaard published in 1958. Their work clarified the relationship between cell composition and growth rate and led to unravel the temporal coupling between chromosome replication and the subsequent cell division by Helmstetter et al. a decade later. Now, after half a century this field has become a major research direction that attracts interest of many scientists from different disciplines. The outstanding question how the most basic cellular processes - mass growth, chromosome replication and cell division - are inter-coordinated in both space and time is still unresolved at the molecular level. Several particularly pertinent questions that are intensively studied follow: (a) what is the primary signal to place the Z-ring precisely between the two replicating and segregating nucleoids? (b) Is this coupling related to the structure and position of the nucleoid itself? (c) How does a bacterium determine and maintain its shape and dimensions? Possible answers include gene expression-based mechanisms, self-organization of protein assemblies and physical principles such as micro-phase separations by excluded volume interactions, diffusion ratchets and membrane stress or curvature. The relationships between biochemical reactions and physical forces are yet to be conceived and discovered. This e-book discusses the above mentioned and related questions. The book also serves as an important depository for state-of-the-art technologies, methods, theoretical simulations and innovative ideas and hypotheses for future testing. Integrating the information gained from various angles will likely help decipher how a relatively simple cell such as a bacterium incorporates its multitude of pathways and processes into a highly efficient self-organized system. The knowledge may be helpful in the ambition to artificially reconstruct a simple living system and to develop new antibacterial drugs.

Advances in Plastid Biology and Its Applications

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889450480 Year: Pages: 159 DOI: 10.3389/978-2-88945-048-0 Language: English
Publisher: Frontiers Media SA
Subject: Botany --- Science (General)
Added to DOAB on : 2017-07-06 13:27:36
License:

Loading...
Export citation

Choose an application

Abstract

One of the distinguishing features of plants is the presence of membrane-bound organelles called plastids. Starting from proplastids (undifferentiated plastids) they readily develop into specialised types, which are involved in a range of cellular functions such as photosynthesis, nitrogen assimilation, biosynthesis of sucrose, starch, chlorophyll, carotenoids, fatty acids, amino acids, and secondary metabolites as well as a number of metabolic reactions. The central role of plastids in many aspects of plant cell biology means an in-depth understanding is key for a holistic view of plant physiology. Despite the vast amount of research, the molecular details of many aspects of plastid biology remains limited. Plastids possess their own high-copy number genome known as the plastome. Manipulation of the plastid genome has been developed as an alternative way to developing transgenic plants for various biotechnological applications. High-copy number of the plastome, site-specific integration of transgenes through homologous recombination, and potential to express proteins at high levels (>70% of total soluble proteins has been reported in some cases) are some of the technologies being developed. Additionally, plastids are inherited maternally, providing a natural gene containment system, and do not follow Mendelian laws of inheritance, allowing each individual member of the progeny of a transplastomic line to uniformly express transgene(s). Both algal and higher plant chloroplast transformation has been demonstrated, and with the ability to be propagated either in bioreactors or in the field, both systems are well suited for scale up of production. The manipulation of chloroplast genes is also essential for many approaches that attempt to increase biomass accumulation or re-routing metabolic pathways for biofortification, food and fuel production. This includes metabolic engineering for lipid production, adapting the light harvesting apparatus to improve solar conversion efficiencies and engineering means of suppressing photorespiration in crop species, which range from the introduction of artificial carbon concentrating mechanisms, or those pre-existing elsewhere in nature, to bypassing ribulose bisphosphate carboxylase/oxygenase entirely. The purpose of this eBook is to provide a compilation of the latest research on various aspects of plastid biology including basic biology, biopharming, metabolic engineering, bio-fortification, stress physiology, and biofuel production.One of the distinguishing features of plants is the presence of membrane-bound organelles called plastids. Starting from proplastids (undifferentiated plastids) they readily develop into specialised types, which are involved in a range of cellular functions such as photosynthesis, nitrogen assimilation, biosynthesis of sucrose, starch, chlorophyll, carotenoids, fatty acids, amino acids, and secondary metabolites as well as a number of metabolic reactions. The central role of plastids in many aspects of plant cell biology means an in-depth understanding is key for a holistic view of plant physiology. Despite the vast amount of research, the molecular details of many aspects of plastid biology remains limited. Plastids possess their own high-copy number genome known as the plastome. Manipulation of the plastid genome has been developed as an alternative way to developing transgenic plants for various biotechnological applications. High-copy number of the plastome, site-specific integration of transgenes through homologous recombination, and potential to express proteins at high levels (>70% of total soluble proteins has been reported in some cases) are some of the technologies being developed. Additionally, plastids are inherited maternally, providing a natural gene containment system, and do not follow Mendelian laws of inheritance, allowing each individual member of the progeny of a transplastomic line to uniformly express transgene(s). Both algal and higher plant chloroplast transformation has been demonstrated, and with the ability to be propagated either in bioreactors or in the field, both systems are well suited for scale up of production. The manipulation of chloroplast genes is also essential for many approaches that attempt to increase biomass accumulation or re-routing metabolic pathways for biofortification, food and fuel production. This includes metabolic engineering for lipid production, adapting the light harvesting apparatus to improve solar conversion efficiencies and engineering means of suppressing photorespiration in crop species, which range from the introduction of artificial carbon concentrating mechanisms, or those pre-existing elsewhere in nature, to bypassing ribulose bisphosphate carboxylase/oxygenase entirely. The purpose of this eBook is to provide a compilation of the latest research on various aspects of plastid biology including basic biology, biopharming, metabolic engineering, bio-fortification, stress physiology, and biofuel production.

Modulating Prokaryotic Lifestyle by DNA-Binding Proteins

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451050 Year: Pages: 296 DOI: 10.3389/978-2-88945-105-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General)
Added to DOAB on : 2017-07-06 13:27:36
License:

Loading...
Export citation

Choose an application

Abstract

The Overview of the Topic was the following: “One of the most active areas of research in molecular microbiology has been the study of how bacteria modulate their genetic activity and its consequences. The prokaryotic world has received much interest not only because the resulting phenomena are important to cells, but also because many of the effects often can be readily measured. Contributing to the interest of the present topic is the fact that modulation of gene activity involves the sensing of intra- and inter-cellular conditions, DNA binding and DNA dynamics, and interaction with the replication/transcription machinery of the cell. All of these processes are fundamental to the operation of a genetic entity and condition their lifestyle. Further, the discoveries achieved in the bacterial world have been of ample use in eukaryotes. In addition to the fundamental interest of understanding modulation of prokaryotic lifestyle by DNA-binding proteins, there is an added interest from the healthcare point of view. As it is well known the antibiotic-resistance strains of pathogenic bacteria are a major world problem, so that there is an urgent need of innovative technologies to tackle it. Most of the acquired resistances are spread by processes of horizontal gene transfer mediated by mobile elements in which DNA replication and gene expression are of basic interest. There is an imperative of finding new alternatives to the ‘classical’ way of treatment of bacterial infections and these new alternatives include the discovery of new drugs and of new bacterial targets. Nevertheless, these new alternatives will find a dead-end if we are unable to obtain a better understanding of the basic processes modulating bacterial gene expression. Our goal to achieve with this Topic of Frontiers is to accelerate our understanding of protein-DNA interactions. First, the topic will bring together several very active researchers in the study of gene replication, gene regulation, the strategies applied by the different proteins that participate in these processes, and their consequences. We will also acquire an in-depth knowledge of some of the mechanisms of gene regulation, gene transfer and gene replication. Further, the readers of the papers will realize the importance of the topic and will learn the most recent thinking, results, and approaches in the area”. We are fully confident that we have exceeded our expectations. Now we are proud to present the final output of the Topic, which is the eBook. It includes 24 articles contributed by 118 authors. As of today, Monday, 16th, January 2017, the total number of readings has reached 19,284, 14,921 article views, and 2,944 article downloads.

Molecular Biology of Bamboo mosaic Virus - A Type Member of the Potexvirus Genus

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889454396 Year: Pages: 109 DOI: 10.3389/978-2-88945-439-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology --- Botany
Added to DOAB on : 2018-11-16 17:17:57
License:

Loading...
Export citation

Choose an application

Abstract

The flexible filamentous plant viruses are responsible for more than half of all agricultural loss worldwide. Potexvirus is one of the two most important flexible filamentous plant viruses. Bamboo mosaic virus (BaMV), a single-stranded positive-sense RNA virus, is a member of the Potexvirus genus of Alphaflexiviridae. It can infect at least 12 species of bamboo, causing a huge economic impact on the bamboo industry in Taiwan. The study of BaMV did not start extensively until the completion of the full-length sequencing of genomic RNA of BaMV and generation of the BaMV infectious cDNA clone in the early 1990s. Since then, BaMV has been extensively studied at the molecular, cellular and ecological level, covering both basic and applied researches, by a group of researchers in Taiwan. In this eBook, the content comprises 6 reviews and 4 articles. Seven of them are involved in the infection of BaMV covering viral RNA replication, viral RNA trafficking, and the host factors. Two of them are related to the vector transmission and the ecology of BaMV. The last one is the application of using BaMV as a viral vector to produce vaccines in plants.

Kaposi's Sarcoma-Associated Herpesvirus

ISBN: 9783038420774 9783038420767 Year: Pages: 356 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2015-10-22 09:09:45
License:

Loading...
Export citation

Choose an application

Abstract

The discovery of KSHV in 1994 was a historical landmark in tumor virology and human cancer research. Its subsequent identification as a cause of Kaposi sarcoma and in association with primary effusion lymphoma and multicentric Castleman disease soon attracted up to hundreds of research laboratories and thousands of virologists and oncologists to switch their research directions. To date, PubMed has collected nearly 5000 papers on KSHV from numerous journal publications in the world. These studies reiterate that the global fight against human cancers will continue to receive great support from our tremendous efforts in searching for new tumor-causing viruses and in understanding the basic biology of tumor viruses. To celebrate the 20th years of KSHV discovery, I am very proud to be an invited Guest Editor for a special issue on KSHV in the journal "Viruses" and happy to assemble all published articles from the special issue into this book, Kaposi Sarcoma Associated Herpesvirus. The collected articles cover almost all aspects of KSHV, including updated reviews and research articles on KSHV epidemiology and transmission, KSHV interaction with host cell receptors and cell entry, KSHV latency and latency-associated nuclear antigen (LANA), molecular biology of KSHV lytic reactivation and lytic switch control by KSHV ORF50 and other factors, KSHV post-transcriptional regulator ORF57, molecular biology of KSHV polyadenylated nuclear RNA (PAN RNA) and PAN as a lncRNA in epigenetic gene regulation of KSHV, viral mimics of cellular genes in KSHV infection and disease, KSHV targeted therapy, KSHV miRNAs and vGPCR, etc. In particular, I am greatly honored to have Yuan Chang and Patrick Moore to mark the first 20 years of KSHV research by recounting the historical stories leading to their astonish discovery and Science publication of KSHV that has led us where we are today. The book is also intended to assist Medical students and residents, dermatologists, hematologist, oncologists, and other related specialties to understand what we have known about KSHV and its infections and pathogenesis.

Listing 1 - 10 of 11 << page
of 2
>>
Sort by
Narrow your search

Publisher

Frontiers Media SA (10)

MDPI - Multidisciplinary Digital Publishing Institute (1)


License

CC by (11)


Language

english (11)


Year
From To Submit

2018 (2)

2017 (1)

2016 (5)

2015 (3)