Dynamics of Multiple Trafficking Behaviors of Individual Synaptic Vesicles Revealed by Quantum-Dot Based Presynaptic Probe

Although quantum dots (QDs) have provided invaluable information regarding the diffusive behaviors of postsynaptic receptors, their application in presynaptic terminals has been rather limited. In addition, the diffraction-limited nature of the presynaptic bouton has hampered detailed analyses of the behaviors of synaptic vesicles (SVs) at synapses. Here, we created a quantum-dot based presynaptic probe and characterized the dynamic behaviors of individual SVs. As previously reported, the SVs exhibited multiple exchanges between neighboring boutons. Actin disruption induced a dramatic decrease in the diffusive behaviors of SVs at synapses while microtubule disruption only reduced extrasynaptic mobility. Glycine-induced synaptic potentiation produced significant increases in synaptic and inter-boutonal trafficking of SVs, which were NMDA receptor- and actin-dependent while NMDA-induced synaptic depression decreased the mobility of the SVs at synapses. Together, our results show that sPH-AP-QD revealed previously unobserved trafficking properties of SVs around synapses, and the dynamic modulation of SV mobility could regulate presynaptic efficacy during synaptic activity

Negative Regulation of Active Zone Assembly by a Newly Identified SR Protein Kinase

A neuronal serine-arginine protein kinase that localizes to the presynaptic active zone is required for kinase-dependent repression of active zone assembly

Application of wood waste ash in concrete making: revisited

Portland cement production is a carbon dioxide trigger responsible for almost 5% of the worlds CO2 emissions. Pozzolanic inclusions could contribute to sustainability particularly if they are derived from waste. Managing solid waste is increasingly becoming a global challenge as a result of increasing volume of accumulated waste from industrial and agricultural by-products. Environmental concerns as well as economic implications related with disposal of these wastes have prompted many researches in order to provide viable solutions. Recycling of these waste materials into the construction industry seems to be a more promising and viable alternative most especially in the manufacturing of greener and sustainable concrete material. Wood ash (WA) is a by-product derived from incineration of wood as well as its products such as sawdust, wood bark and chips. This paper presents an overview on investigations performed on the applicability of this material in mortar and concrete making. Specifics on physical, chemical, mineralogical and elemental characteristics of the waste material are discussed. It highpoints the impact of wood ash on workability, compressive and flexure strengths, water absorption, drying shrinkage, carbonation, alkali–silica reaction (ASR) and chloride permeability of concrete

Cryo-electron tomography of cells: connecting structure and function

Cryo-electron tomography (cryo-ET) allows the visualization of cellular structures under close-to-life conditions and at molecular resolution. While it is inherently a static approach, yielding structural information about supramolecular organization at a certain time point, it can nevertheless provide insights into function of the structures imaged, in particular, when supplemented by other approaches. Here, we review the use of experimental methods that supplement cryo-ET imaging of whole cells. These include genetic and pharmacological manipulations, as well as correlative light microscopy and cryo-ET. While these methods have mostly been used to detect and identify structures visualized in cryo-ET or to assist the search for a feature of interest, we expect that in the future they will play a more important role in the functional interpretation of cryo-tomograms

Rapid and Long-Lasting Increase in Sites for Synapse Assembly during Late-Phase Potentiation in Rat Hippocampal Neurons

Long-term potentiation in hippocampal neurons has stages that correspond to the stages of learning and memory. Early-phase (10–30 min) potentiation is accompanied by rapid increases in clusters or puncta of presynaptic and postsynaptic proteins, which depend on actin polymerization but not on protein synthesis. We have now examined changes in pre- and postsynaptic puncta and structures during glutamate-induced late-phase (3 hr) potentiation in cultured hippocampal neurons. We find that (1) the potentiation is accompanied by long-lasting maintenance of the increases in puncta, which depends on protein synthesis, (2) most of the puncta and synaptic structures are very dynamic, continually assembling and disassembling at sites that are more stable than the puncta or structures themselves, (3) the increase in presynaptic puncta appears to be due to both rapid and more gradual increases in the number of sites where the puncta may form, and also to the stabilization of existing puncta, (4) under control conditions, puncta of postsynaptic proteins behave similarly to puncta of presynaptic proteins and share sites with them, and (5) the increase in presynaptic puncta is accompanied by a similar increase in presumably presynaptic structures, which may form at distinct as well as shared sites. The new sites could contribute to the transition between the early and late phase mechanisms of plasticity by serving as seeds for the formation and maintenance of new synapses, thus acting as local “tags” for protein synthesis-dependent synaptic growth during late-phase plasticity

Mutations in Wnt2 Alter Presynaptic Motor Neuron Morphology and Presynaptic Protein Localization at the Drosophila Neuromuscular Junction

Wnt proteins are secreted proteins involved in a number of developmental processes including neural development and synaptogenesis. We sought to determine the role of the Drosophila Wnt7b ortholog, Wnt2, using the neuromuscular junction (NMJ). Mutations in wnt2 produce an increase in the number of presynaptic branches and a reduction in immunolabeling of the active zone proteins, Bruchpilot and synaptobrevin, at the NMJ. There was no change, however, in immunolabeling for the presynaptic proteins cysteine-string protein (CSP) and synaptotagmin, nor the postsynaptic proteins GluRIIA and DLG at the NMJ. Consistent with the presynaptic defects, wnt2 mutants exhibit approximately a 50% reduction in evoked excitatory junctional currents. Rescue, RNAi, and tissue-specific qRT-PCR experiments indicate that Wnt2 is expressed by the postsynaptic cell where it may serve as a retrograde signal that regulates presynaptic morphology and the localization of presynaptic proteins

Neurobiology of rodent self-grooming and its value for translational neuroscience

Self-grooming is a complex innate behaviour with an evolutionarily conserved sequencing pattern and is one of the most frequently performed behavioural activities in rodents. In this Review, we discuss the neurobiology of rodent self-grooming, and we highlight studies of rodent models of neuropsychiatric disorders-including models of autism spectrum disorder and obsessive compulsive disorder-that have assessed self-grooming phenotypes. We suggest that rodent self-grooming may be a useful measure of repetitive behaviour in such models, and therefore of value to translational psychiatry. Assessment of rodent self-grooming may also be useful for understanding the neural circuits that are involved in complex sequential patterns of action.National Institutes of Health (U.S.) (Grant NS025529)National Institutes of Health (U.S.) (Grant HD028341)National Institutes of Health (U.S.) (Grant MH060379

Clearing up cloudy waters: A review of sediment impacts to unionid freshwater mussels.

Freshwater unionid mussels are among the most imperiled fauna in North America, and their decline has been partially attributed to sediment from anthropogenic activities. However, there remains a debate regarding the role played by sediment in mussel declines due to a lack of field and laboratory evidence. If sediment is responsible for mussel declines, then a lack of information will likely impede efforts to mitigate species declines and protect remaining habitat. However, if the impacts of sediment are overstated, time and resources may be wasted on a threat that has little bearing on mussel declines or habitat loss. Given this knowledge gap, the purpose of this paper is to review the literature focused on the potential impact of suspended sediment and sedimentation on freshwater mussels. We focused our search on suspended sediment, expressed either as suspended sediment concentration (SSC) or total suspended solids (TSS), and sediment deposition and scour. We found increases in suspended solids could impact mussels by decreasing food availability, physically interfering with filter feeding and respiration, and impeding various aspects of the mussel–host relationship. We also found mussel–sediment thresholds, wherein certain concentrations of sediment caused significant declines in population performance, which could serve as reference points for ecological research and management. Specifically, we found clearance rates (a measure of feeding) were negatively impacted by TSS concentrations >8 mg/L, and respiratory stress occurred at ∼600 mg/L. Declines in fertilization success and glochidial (i.e., mussel larvae) development were observed at TSS values of 15 mg/L, and reproductive failure occurred at 20 mg/L. Impacts on host fish attachment and glochidial encystment occurred at TSS concentrations of 1250–5000 mg/L. Impacts on fish varied depending on the biological endpoint but typically occurred at TSS values ranging from 20 to 5000 mg/L. We also found mussels were sensitive to smothering and mortality occurred at depths as low as 0.6–2.5 cm of substrate. Finally, we found relative shear stress (RSS) values >1, which is a measure of substrate stability in response to scour and entrainment, resulted in significant declines in mussel biodiversity.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author