Hasil untuk "Biology"

Spend your few moment to read a book even only few pages. Reading book is not obligation and force for everybody. When you don't want to read, you can get punishment from the publisher. Read a book becomes a choice of your different characteristics. Many people with reading habit will always be enjoyable to read, or on the contrary. For some reasons, this ethylene in plant biology tends to be the representative book in this website.

C. Edwards, N. Arancon

Xuejun Jiang, B. Stockwell, M. Conrad

R. Kalluri, Valerie S. LeBleu

Clinical uses of cellular communication Exosomes are a type of extracellular vesicle that contain constituents (protein, DNA, and RNA) of the cells that secrete them. They are taken up by distant cells, where they can affect cell function and behavior. Intercellular communication through exosomes seems to be involved in the pathogenesis of various disorders, including cancer, neurodegeneration, and inflammatory diseases. In a Review, Kalluri and LeBleu discuss the biogenesis and function of exosomes in disease, highlighting areas where more research is needed. They also discuss the potential clinical applications of exosome profiling for diagnostics and exosome-mediated delivery of therapeutics to target disease cells. Science, this issue p. eaau6977 BACKGROUND All cells, prokaryotes and eukaryotes, release extracellular vesicles (EVs) as part of their normal physiology and during acquired abnormalities. EVs can be broadly divided into two categories, ectosomes and exosomes. Ectosomes are vesicles that pinch off the surface of the plasma membrane via outward budding, and include microvesicles, microparticles, and large vesicles in the size range of ~50 nm to 1 μm in diameter. Exosomes are EVs with a size range of ~40 to 160 nm (average ~100 nm) in diameter with an endosomal origin. Sequential invagination of the plasma membrane ultimately results in the formation of multivesicular bodies, which can intersect with other intracellular vesicles and organelles, contributing to diversity in the constituents of exosomes. Depending on the cell of origin, EVs, including exosomes, can contain many constituents of a cell, including DNA, RNA, lipids, metabolites, and cytosolic and cell-surface proteins. The physiological purpose of generating exosomes remains largely unknown and needs investigation. One speculated role is that exosomes likely remove excess and/or unnecessary constituents from cells to maintain cellular homeostasis. Recent studies reviewed here also indicate a functional, targeted, mechanism-driven accumulation of specific cellular components in exosomes, suggesting that they have a role in regulating intercellular communication. ADVANCES Exosomes are associated with immune responses, viral pathogenicity, pregnancy, cardiovascular diseases, central nervous system–related diseases, and cancer progression. Proteins, metabolites, and nucleic acids delivered by exosomes into recipient cells effectively alter their biological response. Such exosome-mediated responses can be disease promoting or restraining. The intrinsic properties of exosomes in regulating complex intracellular pathways has advanced their potential utility in the therapeutic control of many diseases, including neurodegenerative conditions and cancer. Exosomes can be engineered to deliver diverse therapeutic payloads, including short interfering RNAs, antisense oligonucleotides, chemotherapeutic agents, and immune modulators, with an ability to direct their delivery to a desired target. The lipid and protein composition of exosomes can affect their pharmacokinetic properties, and their natural constituents may play a role in enhanced bioavailability and in minimizing adverse reactions. In addition to their therapeutic potential, exosomes also have the potential to aid in disease diagnosis. They have been reported in all biological fluids, and the composition of the complex cargo of exosomes is readily accessible via sampling of biological fluids (liquid biopsies). Exosome-based liquid biopsy highlights their potential utility in diagnosis and determining the prognosis of patients with cancer and other diseases. Disease progression and response to therapy may also be ascertained by a multicomponent analysis of exosomes. OUTLOOK The study of exosomes is an active area of research. Ongoing technological and experimental advances are likely to yield valuable information regarding their heterogeneity and biological function(s), as well as enhance our ability to harness their therapeutic and diagnostic potential. As we develop more standardized purification and analytical procedures for the study of exosomes, this will likely reveal their functional heterogeneity. Nonetheless, functional readouts using EVs enriched for exosomes have already provided new insights into their contribution to various diseases. New genetic mouse models with the ability for de novo or induced generation of cell-specific exosomes in health and disease will likely show the causal role of exosomes in cell-to-cell communication locally and between organs. Whether exosome generation and content change with age needs investigation, and such information could offer new insights into tissue senescence, organ deterioration, and programmed or premature aging. Whether EVs and/or exosomes preceded the first emergence of the single-cell organism on the planet is tempting to speculate, and focused bioelectric and biochemical experiments in the future could reveal their cell-independent biological functions. Single-exosome identification and isolation and cryoelectron microscopy analyses have the potential to substantially improve our understanding of the basic biology of exosomes and their use in applied science and technology. Such knowledge will inform the therapeutic potential of exosomes for various diseases, including cancer and neurodegenerative diseases. Exosomes: A cell-to-cell transit system in the human body with pleiotropic functions. Exosomes are extracellular vesicles generated by all cells and they carry nucleic acids, proteins, lipids, and metabolites. They are mediators of near and long-distance intercellular communication in health and disease and affect various aspects of cell biology. The study of extracellular vesicles (EVs) has the potential to identify unknown cellular and molecular mechanisms in intercellular communication and in organ homeostasis and disease. Exosomes, with an average diameter of ~100 nanometers, are a subset of EVs. The biogenesis of exosomes involves their origin in endosomes, and subsequent interactions with other intracellular vesicles and organelles generate the final content of the exosomes. Their diverse constituents include nucleic acids, proteins, lipids, amino acids, and metabolites, which can reflect their cell of origin. In various diseases, exosomes offer a window into altered cellular or tissue states, and their detection in biological fluids potentially offers a multicomponent diagnostic readout. The efficient exchange of cellular components through exosomes can inform their applied use in designing exosome-based therapeutics.

P. V’kovski, A. Kratzel, Silvio Steiner et al.

The SARS-CoV-2 pandemic and its unprecedented global societal and economic disruptive impact has marked the third zoonotic introduction of a highly pathogenic coronavirus into the human population. Although the previous coronavirus SARS-CoV and MERS-CoV epidemics raised awareness of the need for clinically available therapeutic or preventive interventions, to date, no treatments with proven efficacy are available. The development of effective intervention strategies relies on the knowledge of molecular and cellular mechanisms of coronavirus infections, which highlights the significance of studying virus–host interactions at the molecular level to identify targets for antiviral intervention and to elucidate critical viral and host determinants that are decisive for the development of severe disease. In this Review, we summarize the first discoveries that shape our current understanding of SARS-CoV-2 infection throughout the intracellular viral life cycle and relate that to our knowledge of coronavirus biology. The elucidation of similarities and differences between SARS-CoV-2 and other coronaviruses will support future preparedness and strategies to combat coronavirus infections. In this Review, Thiel and colleagues discuss the key aspects of coronavirus biology and their implications for SARS-CoV-2 infections as well as for treatment and prevention strategies.

Stanca M. Ciupe, Virginia Tech, P. Nelson

Fertilities varying in time in an unpredictable manner raise the question of the maintenance of polymorphism, and the subsequent question of the minimal total number of generations spent by the system in impoverished polymorphism. In the one-locus two-allele model, level surfaces of this minimal time out of a given set K of constraints defining polymorphism are delineated. The surface of null minimal time is also the largest set of genotype frequencies from which there exists at least one route remaining in K forever. The influence of the range of admissible fertilities clarifies the trade-off between homozygotes and heterozygotes. Notably, ranges of fertility forbidding a system leaving K to ever return to it are determined. Generally, keeping a chance to regain polymorphism demands a sufficiently relatively high fertility for matings involving heterozygotes.

L. Kristensen, M. S. Andersen, L. V. W. Stagsted et al.

G. Niel, G. D’angelo, G. Raposo

R. Herbst, D. Morgensztern, C. Boshoff

H. Berg

This book is a lucid, straightforward introduction to the concepts and techniques of statistical physics that students of biology, biochemistry, and biophysics must know. It provides a sound basis for understanding random motions of molecules, subcellular particles, or cells, or of processes that depend on such motion or are markedly affected by it. Readers do not need to understand thermodynamics in order to acquire a knowledge of the physics involved in diffusion, sedimentation, electrophoresis, chromatography, and cell motility--subjects that become lively and immediate when the author discusses them in terms of random walks of individual particles.

B. Stockwell, J. Angeli, H. Bayır et al.

Ferroptosis is a form of regulated cell death characterized by the iron-dependent accumulation of lipid hydroperoxides to lethal levels. Emerging evidence suggests that ferroptosis represents an ancient vulnerability caused by the incorporation of polyunsaturated fatty acids into cellular membranes, and cells have developed complex systems that exploit and defend against this vulnerability in different contexts. The sensitivity to ferroptosis is tightly linked to numerous biological processes, including amino acid, iron, and polyunsaturated fatty acid metabolism, and the biosynthesis of glutathione, phospholipids, NADPH, and coenzyme Q10. Ferroptosis has been implicated in the pathological cell death associated with degenerative diseases (i.e., Alzheimer's, Huntington's, and Parkinson's diseases), carcinogenesis, stroke, intracerebral hemorrhage, traumatic brain injury, ischemia-reperfusion injury, and kidney degeneration in mammals and is also implicated in heat stress in plants. Ferroptosis may also have a tumor-suppressor function that could be harnessed for cancer therapy. This Primer reviews the mechanisms underlying ferroptosis, highlights connections to other areas of biology and medicine, and recommends tools and guidelines for studying this emerging form of regulated cell death.

R. Kalluri

A. Locke, Bratati Kahali, S. Berndt et al.

Marco Roos, M. S. Marshall, Andrew P. Gibson et al.

BackgroundHypothesis generation in molecular and cellular biology is an empirical process in which knowledge derived from prior experiments is distilled into a comprehensible model. The requirement of automated support is exemplified by the difficulty of considering all relevant facts that are contained in the millions of documents available from PubMed. Semantic Web provides tools for sharing prior knowledge, while information retrieval and information extraction techniques enable its extraction from literature. Their combination makes prior knowledge available for computational analysis and inference. While some tools provide complete solutions that limit the control over the modeling and extraction processes, we seek a methodology that supports control by the experimenter over these critical processes.ResultsWe describe progress towards automated support for the generation of biomolecular hypotheses. Semantic Web technologies are used to structure and store knowledge, while a workflow extracts knowledge from text. We designed minimal proto-ontologies in OWL for capturing different aspects of a text mining experiment: the biological hypothesis, text and documents, text mining, and workflow provenance. The models fit a methodology that allows focus on the requirements of a single experiment while supporting reuse and posterior analysis of extracted knowledge from multiple experiments. Our workflow is composed of services from the 'Adaptive Information Disclosure Application' (AIDA) toolkit as well as a few others. The output is a semantic model with putative biological relations, with each relation linked to the corresponding evidence.ConclusionWe demonstrated a 'do-it-yourself' approach for structuring and extracting knowledge in the context of experimental research on biomolecular mechanisms. The methodology can be used to bootstrap the construction of semantically rich biological models using the results of knowledge extraction processes. Models specific to particular experiments can be constructed that, in turn, link with other semantic models, creating a web of knowledge that spans experiments. Mapping mechanisms can link to other knowledge resources such as OBO ontologies or SKOS vocabularies. AIDA Web Services can be used to design personalized knowledge extraction procedures. In our example experiment, we found three proteins (NF-Kappa B, p21, and Bax) potentially playing a role in the interplay between nutrients and epigenetic gene regulation.

Michael Ashburner, C. Ball, J. Blake et al.

J. Holland

B. Halliwell, J. Gutteridge

R. Gentleman, V. Carey, D. Bates et al.

The Bioconductor project is an initiative for the collaborative creation of extensible software for computational biology and bioinformatics. The goals of the project include: fostering collaborative development and widespread use of innovative software, reducing barriers to entry into interdisciplinary scientific research, and promoting the achievement of remote reproducibility of research results. We describe details of our aims and methods, identify current challenges, compare Bioconductor to other open bioinformatics projects, and provide working examples.

P. Rice, Ian Longden, A. Bleasby