Superpriming of synaptic vesicles as a common basis for intersynapse variability and modulation of synaptic strength.

Glutamatergic synapses show large variations in strength and short-term plasticity (STP). We show here that synapses displaying an increased strength either after posttetanic potentiation (PTP) or through activation of the phospholipase-C-diacylglycerol pathway share characteristic properties with intrinsically strong synapses, such as (i) pronounced short-term depression (STD) during high-frequency stimulation; (ii) a conversion of that STD into a sequence of facilitation followed by STD after a few conditioning stimuli at low frequency; (iii) an equalizing effect of such conditioning stimulation, which reduces differences among synapses and abolishes potentiation; and (iv) a requirement of long periods of rest for reconstitution of the original STP pattern. These phenomena are quantitatively described by assuming that a small fraction of "superprimed" synaptic vesicles are in a state of elevated release probability (p ∼ 0.5). This fraction is variable in size among synapses (typically about 30%), but increases after application of phorbol ester or during PTP. The majority of vesicles, released during repetitive stimulation, have low release probability (p ∼ 0.1), are relatively uniform in number across synapses, and are rapidly recruited. In contrast, superprimed vesicles need several seconds to be regenerated. They mediate enhanced synaptic strength at the onset of burst-like activity, the impact of which is subject to modulation by slow modulatory transmitter systems

Impact of Pediatric Obesity on Grades in Elementary School

Objective: The current study examines the relationship between obesity and academic performance among second grade students. We hypothesized that students who were overweight or obese would have poorer grades than students who were normal weight. Design: Cross-sectional. Setting: Seven elementary schools from a southeast Texas Independent School District. Participants: The sample was composed of 798 ethnically and racially diverse elementary school children. Students were classified as normal weight, overweight, and obese. Main Outcome Measures: Differences in cumulative grades (math, science, and reading) across weight classifications were examined using sex, race/ethnicity, and school socioeconomic level as covariates. Additionally, all subject areas were analyzed independently. Analysis: Linear mixed models and follow-up pairwise comparisons. Results:The linear mixed model revealed significant differences in grades across weight classifications (p\u3c.05). Conclusions and Implications: This study suggests that weight status is an important marker of scholastic success. Addressing overweight may bolster efforts to improve academic performance

Diprotonated Parabanic Acid: A Vicinal or 1,3‐Dication?

Reacting parabanic acid with the superacidic systems XF/MF5 (X = H, D; M = As, Sb) in different ratios, led to the formation of the mono‐ and diprotonated species. Salts in terms of [C3H3N2O3][AsF6], [C3H3N2O3][SbF6], [C3H4N2O3][AsF6]2, [C3H4N2O3][SbF6]2, [C3D3N2O3][AsF6] and [C3D4N2O3][AsF6]2 were obtained and characterized by low‐temperature infrared and Raman spectroscopy. Single‐crystal X‐ray structure analyses were performed for [C3H3N2O3][SbF6] and [C3H4N2O3][AsF6]2·4HF. Additionally, quantum chemical calculations were carried out on the B3LYP/aug‐cc‐pVTZ level of theory for the mono‐ and dication. Mapped Electrostatic Potentials together with Natural Population Analysis charges were calculated in order to localize the two positive charges of the diprotonated parabanic acid. The diprotonated parabanic acid can be described as an 1,2‐C,C‐dication, stabilized by electron delocalization over the five‐membered ring

Teashirt 1 (Tshz1) is essential for the development, survival and function of hypoglossal and phrenic motor neurons in mouse

Feeding and breathing are essential motor functions and rely on the activity of hypoglossal and phrenic motor neurons that innervate the tongue and diaphragm, respectively. Little is known about the genetic programs that control the development of these neuronal subtypes. The transcription factor Tshz1 is strongly and persistently expressed in developing hypoglossal and phrenic motor neurons. We used conditional mutation of Tshz1 in the progenitor zone of motor neurons (Tshz1(MNΔ)) to show that Tshz1 is essential for survival and function of hypoglossal and phrenic motor neurons. Hypoglossal and phrenic motor neurons are born in correct numbers, but many die between embryonic day 13.5 and 14.5 in Tshz1(MNΔ) mutant mice. In addition, innervation and electrophysiological properties of phrenic and hypoglossal motor neurons are altered. Severe feeding and breathing problems accompany this developmental deficit. Although motor neuron survival can be rescued by elimination of the pro-apoptotic factor Bax, innervation, feeding and breathing defects persist in Bax(-/-); Tshz1(MNΔ) mutants. We conclude that Tshz1 is an essential transcription factor for the development and physiological function of phrenic and hypoglossal motor neurons

Alternative 3' UTRs direct localization of functionally diverse protein isoforms in neuronal compartments

The proper subcellular localization of RNAs and local translational regulation is crucial in highly compartmentalized cells, such as neurons. RNA localization is mediated by specific cis-regulatory elements usually found in mRNA 3'UTRs. Therefore, processes that generate alternative 3'UTRs-alternative splicing and polyadenylation-have the potential to diversify mRNA localization patterns in neurons. Here, we performed mapping of alternative 3'UTRs in neurites and soma isolated from mESC-derived neurons. Our analysis identified 593 genes with differentially localized 3'UTR isoforms. In particular, we have shown that two isoforms of Cdc42 gene with distinct functions in neuronal polarity are differentially localized between neurites and soma of mESC-derived and mouse primary cortical neurons, at both mRNA and protein level. Using reporter assays and 3'UTR swapping experiments, we have identified the role of alternative 3'UTRs and mRNA transport in differential localization of alternative CDC42 protein isoforms. Moreover, we used SILAC to identify isoform-specific Cdc42 3'UTR-bound proteome with potential role in Cdc42 localization and translation. Our analysis points to usage of alternative 3'UTR isoforms as a novel mechanism to provide for differential localization of functionally diverse alternative protein isoforms

Single synapse glutamate imaging reveals multiple levels of release mode regulation in mammalian synapses

Mammalian central synapses exhibit vast heterogeneity in signaling strength. In order to understand the extent of this diversity, how it is achieved, and its functional implications, characterization of a large number of individual synapses is required. Using glutamate imaging, we characterized the evoked release probability and spontaneous release frequency of over 24,000 individual synapses. We found striking variability and no correlation between action potential-evoked and spontaneous synaptic release strength, suggesting distinct regulatory mechanisms. Subpixel localization of individual evoked and spontaneous release events reveals tight spatial regulation of evoked release and enhanced spontaneous release outside of evoked release region. Using on-stage post hoc immune-labeling of vesicle-associated proteins, Ca(2+)-sensing proteins, and soluble presynaptic proteins we were able to show that distinct molecular ensembles are associated with evoked and spontaneous modes of synaptic release

Discovery of new colonies by Sentinel2 reveals good and bad news for emperor

The distribution of emperor penguins is circumpolar, with 54 colony locations currently reported of which 50 are currently extant as of 2019. Here we report on eight newly discovered colonies and confirm the rediscovery of three breeding sites, only previously reported in the era before Very High Resolution satellite imagery was available, making a total of 61 breeding locations. This represents an increase of ~20% in the number of breeding sites, but, as most of the colonies appear to be small, they may only increase the total population by around 5–10%. The discoveries have been facilitated by the use of Sentinel2 satellite imagery, which has a higher resolution and more efficient search mechanism than the Landsat data previously used to search for colonies. The small size of these new colonies indicates that considerations of reproductive output in relation to metabolic rate during huddling is likely to be of interest. Some of the colonies exist in offshore habitats, something not previously reported for emperor penguins. Comparison with recent modelling results show that the geographic locations of all the newly found colonies are in areas likely to be highly vulnerable under business‐as‐usual greenhouse gas emissions scenarios, suggesting that population decreases for the species will be greater than previously thought

Antarctic penguin response to habitat change as Earth's troposphere reaches 2°C above preindustrial levels

Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Monographs 80 (2010): 49–66, doi:10.1890/08-2289.1.We assess the response of pack ice penguins, Emperor (Aptenodytes forsteri) and Adélie (Pygoscelis adeliae), to habitat variability and, then, by modeling habitat alterations, the qualitative changes to their populations, size and distribution, as Earth's average tropospheric temperature reaches 2°C above preindustrial levels (ca. 1860), the benchmark set by the European Union in efforts to reduce greenhouse gases. First, we assessed models used in the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) on penguin performance duplicating existing conditions in the Southern Ocean. We chose four models appropriate for gauging changes to penguin habitat: GFDL-CM2.1, GFDL-CM2.0, MIROC3.2(hi-res), and MRI-CGCM2.3.2a. Second, we analyzed the composited model ENSEMBLE to estimate the point of 2°C warming (2025–2052) and the projected changes to sea ice coverage (extent, persistence, and concentration), sea ice thickness, wind speeds, precipitation, and air temperatures. Third, we considered studies of ancient colonies and sediment cores and some recent modeling, which indicate the (space/time) large/centennial-scale penguin response to habitat limits of all ice or no ice. Then we considered results of statistical modeling at the temporal interannual-decadal scale in regard to penguin response over a continuum of rather complex, meso- to large-scale habitat conditions, some of which have opposing and others interacting effects. The ENSEMBLE meso/decadal-scale output projects a marked narrowing of penguins' zoogeographic range at the 2°C point. Colonies north of 70° S are projected to decrease or disappear: 50% of Emperor colonies (40% of breeding population) and 75% of Adélie colonies (70% of breeding population), but limited growth might occur south of 73° S. Net change would result largely from positive responses to increase in polynya persistence at high latitudes, overcome by decreases in pack ice cover at lower latitudes and, particularly for Emperors, ice thickness. Adélie Penguins might colonize new breeding habitat where concentrated pack ice diverges and/or disintegrating ice shelves expose coastline. Limiting increase will be decreased persistence of pack ice north of the Antarctic Circle, as this species requires daylight in its wintering areas. Adélies would be affected negatively by increasing snowfall, predicted to increase in certain areas owing to intrusions of warm, moist marine air due to changes in the Polar Jet Stream.This project was funded by the World Wildlife Fund and the National Science Foundation, NSF grant OPP-0440643 (D. G. Ainley), and a Marie-Curie Fellowship to S. Jenouvrier

Dual-view light-sheet imaging through a tilted glass interface using a deformable mirror

Light-sheet microscopy has become indispensable for imaging developing organisms, and imaging from multiple directions (views) is essential to improve its spatial resolution. We combine multi-view light-sheet microscopy with microfluidics using adaptive optics (deformable mirror) which corrects aberrations introduced by the 45°-tilted glass coverslip. The optimal shape of the deformable mirror is computed by an iterative algorithm that optimizes the point-spread function in two orthogonal views. Simultaneous correction in two optical arms is achieved via a knife-edge mirror that splits the excitation path and combines the detection paths. Our design allows multi-view light-sheet microscopy with microfluidic devices for precisely controlled experiments and high-content screening

Dual-view light-sheet imaging through tilted glass interface using a deformable mirror

Light-sheet microscopy has become one of the primary tools for imaging live developing organisms because of its high speed, low phototoxicity, and optical sectioning capabilities. Detection from multiple sides (multi-view imaging) additionally allows nearly isotropic resolution via computational merging of the views. However, conventional light-sheet microscopes require that the sample is suspended in a gel to allow optical access from two or more sides. At the same time, the use of microfluidic devices is highly desirable for many experiments, but geometric constrains and strong optical aberrations caused by the coverslip titled relative to objectives make the use of multi-view lightsheet challenging for microfluidics. In this paper we describe the use of adaptive optics (AO) to enable multi-view light-sheet microscopy in such microfluidic setup by correcting optical aberrations introduced by the tilted coverslip. The optimal shape of deformable mirror is computed by an iterative stochastic gradient-descent algorithm that optimizes PSF in two orthogonal planes simultaneously. Simultaneous AO correction in two optical arms is achieved via a knife-edge mirror that splits excitation path and combines the detection path. We characterize the performance of this novel microscope setup and, by dual-view light-sheet imaging of C. elegans inside a microfluidic channel, demonstrate a drastic improvement of image quality due to AO and dual-view reconstruction. Our microscope design allows multi-view light-sheet microscopy with microfluidic devices for precisely controlled experimental conditions and high-content screening