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This work discusses microLED arrays as light sources for implementing optical sectioning structured illumination microscopy (OS‐SIM) and targeted illumination (TI) for neural imaging applications. We demonstrated a microstripe array to generate patterned light for OS‐SIM and an individually addressable 20 × 20 microLED array as a light source for implementing TI in a widefield imaging setup. [ABSTRACT FROM AUTHOR]

The hydrolysis conditions (enzyme:substrate [E:S] ratio and time) of a whey protein concentrate obtained by ultrafiltration of double‐cream cheese whey were optimized for the production of antioxidant and angiotensin‐converting enzyme (ACE) inhibitory hydrolysates; subsequently, the hydrolysates were fractionated and characterized by chromatography techniques. The results showed that the E:S ratio and time significantly affected (p <.05) the soluble protein content, free amino acids (FAA), degree of hydrolysis (DH), and antioxidant capacity. A decrease in the protein content and an increase in the FAA concentration, DH, and antioxidant activity were observed when both parameters increased. The most adequate conditions to obtain a hydrolysate with antioxidant potential were an E:S ratio of 1:20 (w/w), and time of hydrolysis of 7 hr for alcalase, 2 hr for chymotrypsin, and 6 hr for flavourzyme. After fractionation, different peptides were detected in the hydrolysates, which could contribute to antioxidant and ACE‐inhibitory activities of hydrolysates. Practical applications: Hydrolysates with antioxidant and angiotensin‐converting enzyme‐inhibitory activities were obtained from double‐cream cheese whey, which could become in an industrial innovation strategy based on the use of by‐products that can significantly impact on the circular economy of the dairy industry, the environment, and the production of functional compounds with potential use in the food, feed, pharmaceutical, or cosmetic industries. [ABSTRACT FROM AUTHOR]

Key points Despite sparse connectivity, population-level interactions between mitral cells (MCs) and granule cells (GCs) can generate synchronized oscillations in the rodent olfactory bulb., Intraglomerular gap junctions between MCs at the same glomerulus can greatly enhance synchronized activity of MCs at different glomeruli., The facilitating effect of intraglomerular gap junctions on interglomerular synchrony is through triggering of mutually synchronizing interactions between MCs and GCs., Divergent connections between MCs and GCs make minimal direct contribution to synchronous activity., Abstract A dominant feature of the olfactory bulb response to odour is fast synchronized oscillations at beta (15-40 Hz) or gamma (40-90 Hz) frequencies, thought to be involved in integration of olfactory signals. Mechanistically, the bulb presents an interesting case study for understanding how beta/gamma oscillations arise. Fast oscillatory synchrony in the activity of output mitral cells (MCs) appears to result from interactions with GABAergic granule cells (GCs), yet the incidence of MC-GC connections is very low, around 4%. Here, we combined computational and experimental approaches to examine how oscillatory synchrony can nevertheless arise, focusing mainly on activity between 'non-sister' MCs affiliated with different glomeruli (interglomerular synchrony). In a sparsely connected model of MCs and GCs, we found first that interglomerular synchrony was generally quite low, but could be increased by a factor of 4 by physiological levels of gap junctional coupling between sister MCs at the same glomerulus. This effect was due to enhanced mutually synchronizing interactions between MC and GC populations. The potent role of gap junctions was confirmed in patch-clamp recordings in bulb slices from wild-type and connexin 36-knockout (KO) mice. KO reduced both beta and gamma local field potential oscillations as well as synchrony of inhibitory signals in pairs of non-sister MCs. These effects were independent of potential KO actions on network excitation. Divergent synaptic connections did not contribute directly to the vast majority of synchronized signals. Thus, in a sparsely connected network, gap junctions between a small subset of cells can, through population effects, greatly amplify oscillatory synchrony amongst unconnected cells. [ABSTRACT FROM AUTHOR]

The objective of this work was to synthesize functional polymers, with boron removal properties, from high molecular weight linear polyols based on N-methyl-D-glucamine (NMDG) and polyurethane units as crosslinking reagent. For that, (4-vinylbenzyl)-N-methyl-D-glucamine monomer (VbNMDG) was synthesized from vinylbenzyl chloride and NMDG, and subsequently, high molecular weight linear poly(VbNMDG) was obtained by radical free polymerization. Later, polymer dots were obtained from poly( VbNMDG) and urethanization reactions using methylene diphenyl diisocyanate at room temperature. Monomers and polymers were characterized by different techniques (FTIR, DLS, elemental analysis, H1-NMR). In addition, boron retention properties were studied by diafiltration technique using the azomethine-H method. It was concluded that synthesis of polymer dots, with high boron retention capacity, can be easily synthesized by procedure described. [ABSTRACT FROM AUTHOR]

Ablation of microRNAs in VIP+ interneurons impairs olfactory discrimination and decreases neural activity in the olfactory bulb. Finally, Wu et al1 showed that Dicer ablation restricted to the OB produced similar results. [Extracted from the article]

ABSTRACT Genetic variations in olfactory receptors likely contribute to the diversity of odorant-specific sensitivity phenotypes. Our working hypothesis is that genetic variations in auxiliary olfactory genes, including those mediating transduction and sensory neuronal development, may constitute the genetic basis for general olfactory sensitivity ( GOS) and congenital general anosmia ( CGA). We thus performed a systematic exploration for auxiliary olfactory genes and their documented variation. This included a literature survey, seeking relevant functional in vitro studies, mouse gene knockouts and human disorders with olfactory phenotypes, as well as data mining in published transcriptome and proteome data for genes expressed in olfactory tissues. In addition, we performed next-generation transcriptome sequencing ( RNA-seq) of human olfactory epithelium and mouse olfactory epithelium and bulb, so as to identify sensory-enriched transcripts. Employing a global score system based on attributes of the 11 data sources utilized, we identified a list of 1,680 candidate auxiliary olfactory genes, of which 450 are shortlisted as having higher probability of a functional role. For the top-scoring 136 genes, we identified genomic variants (probably damaging single nucleotide polymorphisms, indels, and copy number deletions) gleaned from public variation repositories. This database of genes and their variants should assist in rationalizing the great interindividual variation in human overall olfactory sensitivity (http://genome.weizmann.ac.il/GOSdb). [ABSTRACT FROM AUTHOR]

Recent anatomical tracing experiments in rodents have established that a subset of mitral cells in the main olfactory bulb (MOB) projects directly to the medial amygdala (MeA), traditionally considered a target of the accessory olfactory bulb. Neurons that project from the MOB to the MeA also show activation in response to conspecific (opposite sex) volatile urine exposure, establishing a direct role of the MOB in semiochemical processing. In addition, olfactory sensory neurons (OSNs) that express the transient receptor potential M5 (TRPM5) channel innervate a subset of glomeruli that respond to putative semiochemical stimuli. In this study, we examined whether the subset of glomeruli targeted by TRPM5-expressing OSNs is innervated by the population of mitral cells that projects to the MeA. We injected the retrograde tracer cholera toxin B (CTB) into the MeA of mice in which the TRPM5 promoter drives green fluorescent protein (GFP). We found overlapping clusters of CTB-labeled mitral cell dendritic branches (CTB+) in TRPM5-GFP+ glomeruli at significantly greater frequency than expected by chance. Despite the significant degree of colocalization, some amygdalopetal mitral cells extended dendrites to non-TRPM5-GFP glomeruli and vice versa, suggesting that, although significant overlapping glomerular innervation is observed between these two features, it is not absolute J. Comp. Neurol. 520:1819-1830, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Microvillous cells of the main olfactory epithelium have been described variously as primary olfactory neurons, secondary chemosensory cells or non-sensory cells. Here we generated an IP3R3 mouse in which the coding region for a fusion protein of tau and green fluorescent protein replaces the first exon of the Itpr3 gene. We provide immunohistochemical and functional characterization of the cells expressing IP3 receptor type 3 in the olfactory epithelium. These cells bear microvilli at their apex, and we therefore termed them IP3R3 MV cells. The cell body of these IP3R3 MV cells lies in the upper third of the main olfactory epithelium; a long thick basal process projects towards the base of the epithelium without penetrating the basal lamina. Retrograde labeling and unilateral bulbectomy corroborated that these IP3R3 MV cells do not extend axons to the olfactory bulb and therefore are not olfactory sensory neurons. The immunohistochemical features of IP3R3 MV cells varied, suggesting either developmental stages or the existence of subsets of these cells. Thus, for example, subsets of the IP3R3 MV cells make contact with substance P fibers or express the purinergic receptor P2X3. In addition, in recordings of intracellular calcium, these cells respond to ATP and substance P as well as to a variety of odors. The characterization of IP3R3 MV cells as non-neuronal chemoresponsive cells helps to explain the differing descriptions of microvillous cells in the literature. [ABSTRACT FROM AUTHOR]

Signal transduction depends critically on the spatial localization of protein constituents. A key question in odor transduction is whether chemotransduction proteins organize into discrete molecular complexes throughout olfactory cilia or distribute homogeneously along the ciliary membrane. Our recordings of Ca2+ changes in individual cilia with unprecedented spatial and temporal resolution, by the use of two-photon microscopy, provide solid evidence for Ca2+ microdomains (transducisomes). Dissociated frog olfactory neurons were preloaded with caged-cAMP and fluo-4 acetoxymethyl ester probe Ca2+ indicator. Ca2+ influx through cyclic nucleotide-gated (CNG) channels was evoked by uniformly photoreleasing cAMP, while ciliary Ca2+ was measured. Discrete fluorescence events were clearly resolved. Events were missing in the absence of external Ca2+, consistent with the absence of internal Ca2+ sources. Fluorescence events at individual microdomains resembled single-CNG channel fluctuations in shape, mean duration and kinetics, indicating that transducisomes typically contain one to three CNG channels. Inhibiting the Na+/Ca2+ exchanger or the Ca2+-ATPase prolonged the decay of evoked intraciliary Ca2+ transients, supporting the participation of both transporters in ciliary Ca2+ clearance, and suggesting that both molecules localize close to the CNG channel. Chemosensory transducisomes provide a physical basis for the low amplification and for the linearity of odor responses at low odor concentrations. [ABSTRACT FROM AUTHOR]

Although it is now established that sensory neurons in both the main olfactory epithelium and the vomeronasal organ may be activated by both general and pheromonal odorants, it remains unclear what initiates sampling by the vomeronasal organ. Anterograde transport of wheat germ agglutinin–horseradish peroxidase was used to determine that adequate intranasal syringing with zinc sulfate interrupted all inputs to the main olfactory bulb but left intact those to the accessory olfactory bulb. Adult male treated mice were frankly anosmic when tested with pheromonal and non-pheromonal odors and failed to engage in aggressive behavior. Treated juvenile females failed to show puberty acceleration subsequent to exposure to bedding from adult males. Activation of the immediate early gene c-Fos and electrovomeronasogram recording confirmed the integrity of the vomeronasal system in zinc sulfate-treated mice. These results support the hypothesis that odor detection by the main olfactory epithelium is required to initiate sampling by the vomeronasal system. [ABSTRACT FROM AUTHOR]

Recent work from our laboratory in awake behaving animals shows that olfactory bulb processing changes depending profoundly on behavioral context. Thus, we find that when recording from the olfactory bulb in a mouse during a go–no go association learning task, it is not unusual to find a mitral cell that initially does not respond to the rewarded or unrewarded odors but develops a differential response to the stimuli during the learning session. This places a challenge on how to approach understanding of olfactory bulb processing, because neural interactions differ depending on the status of the animal. Here we address the question of how the different approaches to study olfactory bulb neuron responses, including studies in anesthetized and unanesthetized animals in vivo and recordings in slices, complement each other. We conclude that more critical understanding of the relationship between the measurements in the different preparations is necessary for future advances in the understanding of olfactory bulb processing of odor information. [ABSTRACT FROM AUTHOR]

Abstract: Evidence has accumulated to support a model for odorant detection in which individual olfactory receptor neurons (ORNs) express one of a large family of G protein-coupled receptor proteins that are activated by a small number of closely related volatile chemicals. However, the issue of whether an individual ORN expresses one or multiple types of receptor proteins has yet to be definitively addressed. Physiological data indicate that some individual ORNs can be activated by odorants differing substantially in structure and/or perceived quality, suggesting multiple receptors or one nonspecific receptor per cell. In contrast, molecular biological studies favor a scheme with a single, fairly selective receptor per cell. The present studies directly assessed whether individual rat ORNs can express multiple receptors using single-cell PCR techniques with degenerate primers designed to amplify a wide variety of receptor sequences. We found that whereas only a single OR sequence was obtained from most ORNs examined, one ORN produced two distinct receptor sequences that represented different receptor gene families. Double-label in situ hybridization studies indicated that a subset of ORNs co-express two distinct receptor mRNAs. A laminar segregation analysis of the cell nuclei of ORNs labeled with the two OR mRNA probes showed that for one probe, the histogram of the distribution of the cell nuclei along the depth of the epithelium was bimodal, with one peak overlapping the (unimodal) histogram for the other probe. These results are consistent with co-expression of two OR mRNAs in a population of single ORNs. [ABSTRACT FROM AUTHOR]

The most important task of the olfactory system is to generate a precise representation of odour information under different brain and behavioural states. As the first processing stage in the olfactory system and a crucial hub, the olfactory bulb plays a key role in the neural representation of odours, encoding odour identity, intensity and timing. Although the neural circuits and coding strategies used by the olfactory bulb for odour representation were initially identified in anaesthetized animals, a large number of recent studies focused on neural representation of odorants in the olfactory bulb in awake behaving animals. In this review, we discuss these recent findings, covering (a) the neural circuits for odour representation both within the olfactory bulb and the functional connections between the olfactory bulb and the higher order processing centres; (b) how related factors such as sniffing affect and shape the representation; (c) how the representation changes under different states; and (d) recent progress on the processing of temporal aspects of odour presentation in awake, behaving rodents. We highlight discussion of the current views and emerging proposals on the neural representation of odorants in the olfactory bulb. [ABSTRACT FROM AUTHOR]

The article reports on epidemiological studies on how the olfactory system gives rise to the perception of a smell, which were discussed at the International Symposium on Olfaction and Taste in San Francisco, California, in July 2008. The Symposium sought to understand the underlying mechanisms of neural processing. The author says that the Heisenberg uncertainty principle of physics applies to studies of olfaction and understanding of how the measurement affects the system.

Signal transduction depends critically on the spatial localization of protein constituents. A key question in odor transduction is whether chemotransduction proteins organize into discrete molecular complexes throughout olfactory cilia or distribute homogeneously along the ciliary membrane. Our recordings of Ca(2+) changes in individual cilia with unprecedented spatial and temporal resolution, by the use of two-photon microscopy, provide solid evidence for Ca(2+) microdomains (transducisomes). Dissociated frog olfactory neurons were preloaded with caged-cAMP and fluo-4 acetoxymethyl ester probe Ca(2+) indicator. Ca(2+) influx through cyclic nucleotide-gated (CNG) channels was evoked by uniformly photoreleasing cAMP, while ciliary Ca(2+) was measured. Discrete fluorescence events were clearly resolved. Events were missing in the absence of external Ca(2+) , consistent with the absence of internal Ca(2+) sources. Fluorescence events at individual microdomains resembled single-CNG channel fluctuations in shape, mean duration and kinetics, indicating that transducisomes typically contain one to three CNG channels. Inhibiting the Na(+) /Ca(2+) exchanger or the Ca(2+) -ATPase prolonged the decay of evoked intraciliary Ca(2+) transients, supporting the participation of both transporters in ciliary Ca(2+) clearance, and suggesting that both molecules localize close to the CNG channel. Chemosensory transducisomes provide a physical basis for the low amplification and for the linearity of odor responses at low odor concentrations., (© 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.)