Neocortical areas communicate through extensive axonal projections, but the logic of information transfer remains poorly understood, because the projections of individual neurons have not been ...systematically characterized. It is not known whether individual neurons send projections only to single cortical areas or distribute signals across multiple targets. Here we determine the projection patterns of 591 individual neurons in the mouse primary visual cortex using whole-brain fluorescence-based axonal tracing and high-throughput DNA sequencing of genetically barcoded neurons (MAPseq). Projections were highly diverse and divergent, collectively targeting at least 18 cortical and subcortical areas. Most neurons targeted multiple cortical areas, often in non-random combinations, suggesting that sub-classes of intracortical projection neurons exist. Our results indicate that the dominant mode of intracortical information transfer is not based on 'one neuron-one target area' mapping. Instead, signals carried by individual cortical neurons are shared across subsets of target areas, and thus concurrently contribute to multiple functional pathways.
Platelets are classically known as essential mediators of hemostasis and thrombosis. However, in recent years, platelets have gained recognition for their inflammatory functions, which modulate the ...immune response during infectious diseases. Platelets contain various immunoreceptors that enable them to act as sentinels to recognize intravascular pathogens. Upon activation, platelets directly limit pathogen growth through the release of AMPs (antimicrobial proteins) and ensure pathogen clearance through activation of immune cells. However, aberrant platelet activation can lead to inflammation and thrombotic events.
Fluorescent proteins with pH-sensitive fluorescence are valuable tools for the imaging of exocytosis and endocytosis. The Aequorea green fluorescent protein mutant superecliptic pHluorin (SEP) is ...particularly well suited to these applications. Here we describe pHuji, a red fluorescent protein with a pH sensitivity that approaches that of SEP, making it amenable for detection of single exocytosis and endocytosis events. To demonstrate the utility of the pHuji plus SEP pair, we perform simultaneous two-color imaging of clathrin-mediated internalization of both the transferrin receptor and the β2 adrenergic receptor. These experiments reveal that the two receptors are differentially sorted at the time of endocytic vesicle formation.
Light-sheet microscopy is an ideal technique for imaging large cleared samples; however, the community is still lacking instruments capable of producing volumetric images of centimeter-sized cleared ...samples with near-isotropic resolution within minutes. Here, we introduce the mesoscale selective plane-illumination microscopy initiative, an open-hardware project for building and operating a light-sheet microscope that addresses these challenges and is compatible with any type of cleared or expanded sample ( www.mesospim.org ).
Histone Modifications and Cancer Audia, James E; Campbell, Robert M
Cold Spring Harbor perspectives in biology,
2016-Apr-01, 2016-04-00, 20160401, Letnik:
8, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Histone posttranslational modifications represent a versatile set of epigenetic marks involved not only in dynamic cellular processes, such as transcription and DNA repair, but also in the stable ...maintenance of repressive chromatin. In this article, we review many of the key and newly identified histone modifications known to be deregulated in cancer and how this impacts function. The latter part of the article addresses the challenges and current status of the epigenetic drug development process as it applies to cancer therapeutics.
Intensiometric genetically encoded biosensors, based on allosteric modulation of the fluorescence of a single fluorescent protein, are powerful tools for enabling imaging of neural activities and ...other cellular biochemical events. The archetypical example of such biosensors is the GCaMP series of Ca
biosensors, which have been steadily improved over the past two decades and are now indispensable tools for neuroscience. However, no other biosensors have reached levels of performance, or had revolutionary impacts within specific disciplines, comparable to that of the Ca
biosensors. Of the many reasons why this has been the case, a critical one has been a general black-box view of biosensor structure and mechanism. With this Perspective, we aim to summarize what is known about biosensor structure and mechanisms and, based on this foundation, provide guidelines to accelerate the development of a broader range of biosensors with performance comparable to that of the GCaMP series.
Neurotransmission between neurons, which can occur over the span of a few milliseconds, relies on the controlled release of small molecule neurotransmitters, many of which are amino acids. ...Fluorescence imaging provides the necessary speed to follow these events and has emerged as a powerful technique for investigating neurotransmission. In this review, we highlight some of the roles of the 20 canonical amino acids, GABA and β-alanine in neurotransmission. We also discuss available fluorescence-based probes for amino acids that have been shown to be compatible for live cell imaging, namely those based on synthetic dyes, nanostructures (quantum dots and nanotubes), and genetically encoded components. We aim to provide tool developers with information that may guide future engineering efforts and tool users with information regarding existing indicators to facilitate studies of amino acid dynamics.
Life, on a day to day basis, is a sequence of emotional states: hope, disappointment, irritation, anger, affection, envy, pride, embarrassment, joy, sadness and many more. We know intuitively that ...these states express deep things about our character and our view of the world. But what are emotions and why are they so important to us? In one of the most extensive investigations of the emotions ever published, Robert Roberts develops a novel conception of what emotions are and then applies it to a large range of types of emotion and related phenomena. In so doing he lays the foundations for a deeper understanding of our evaluative judgments, our actions, our personal relationships and our fundamental well-being. Aimed principally at philosophers and psychologists, this book will certainly be accessible to readers in other disciplines such as religion and anthropology.
Calpains are a family of complex multi-domain intracellular enzymes that share a calcium-dependent cysteine protease core. These are not degradative enzymes, but instead carry out limited cleavage of ...target proteins in response to calcium signalling. Selective cutting of cytoskeletal proteins to facilitate cell migration is one such function. The two most abundant and extensively studied members of this family in mammals, calpains 1 and 2, are heterodimers of an isoform-specific 80 kDa large subunit and a common 28 kDa small subunit. Structures of calpain-2, both Ca2+-free and bound to calpastatin in the activated Ca2+-bound state, have provided a wealth of information about the enzyme's structure-function relationships and activation. The main association between the subunits is the pairing of their C-terminal penta-EF-hand domains through extensive intimate hydrophobic contacts. A lesser contact is made between the N-terminal anchor helix of the large subunit and the penta-EF-hand domain of the small subunit. Up to ten Ca2+ ions are co-operatively bound during activation. The anchor helix is released and individual domains change their positions relative to each other to properly align the active site. Because calpains 1 and 2 require ~30 and ~350 μM Ca2+ ions for half-maximal activation respectively, it has long been argued that autoproteolysis, subunit dissociation, post-translational modifications or auxiliary proteins are needed to activate the enzymes in the cell, where Ca2+ levels are in the nanomolar range. In the absence of robust support for these mechanisms, it is possible that under normal conditions calpains are transiently activated by high Ca2+ concentrations in the microenvironment of a Ca2+ influx, and then return to an inactive state ready for reactivation.
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