Basic coding activities of populations of Xenopus laevis olfactory receptor neurons recorded with a fast confocal line illumination microscope

Das Geruchssystem ist in der Lage, mittels sogenannter kombinatorischer Kodierung einen hochdimensionalen Geruchsraum durch eine begrenzte Anzahl von olfaktorischen Rezeptorneuronen (ORN) abzutasten. Hierbei weisen verschiedene ORN-Klassen eine breite und gleichzeitig spezifische Geruchssensitivität auf, durch welche ein geruchsspezifisches Antwortmuster auf Populationen von Mitral-/Tufted Zellen (M/T) des bulbus olfactoris (OB) abgebildet wird. Neueren Untersuchungen zufolge sind diese Antwortmuster nicht notwendigerweise statisch, sondern enthalten Information in ihrer zeitlichen Entwicklung. Im OB von Larven des Krallenfrosches Xenopus laevis wurde herausgefunden, dass sowohl Geruchsidentität als auch -Konzentration besser vorhergesagt wird durch M/T Antwortlatenzmuster als durch durchschnittliche Feuerraten. Diese Arbeit befasst sich mit der Messung von ORN-Aktivität auf verschiedenen raumzeitlichen Skalen. Auf der Ebene von ORN Populationen wurde mit Hilfe von konfokaler Mikroskopie und [Ca2+] -sensitiven Fluoreszenzfarbstoffen untersucht, in wie weit Latenzmuster auftreten. Es wurde gezeigt, dass Latenzmuster im Unterschied zu M/T Zellen eine geringere Vorhersagekraft für die Geruchsstoffkonzentration besitzen als Feuerratenmuster. Außerdem wiesen Ensemble-Feuerraten einen größeren dynamischen Bereich bezüglich der Geruchsstoffkonzentration auf als Latenzen. Durch eine Kombination von schneller (1,25 kHz) [Ca2+] -Bildgebung und whole-cell Patch-Clamp Technik in einzelnen ORNs wurde die zeitliche Entwicklung der dreidimensionalen intrazellulären Ca2+ -Konzentration während eines Depolarisationspulses gemessen. Mit Hilfe von pixelweiser Angleichung eines numerischen Modells wurden Ballungen spannungsabhängiger Ca2+ Kanäle (VGCC) auf der Oberfläche von ORN-Somata lokalisiert. Da der durchschnittliche gemessene VGCC-Kalziumioneneinstrom einen geringen Beitrag im Vergleich zum Ca2+ Generatorstrom darstellt (<80 pA bzw. geschätzt 900 pA), erklärte sich, warum einzelne Aktionspotentiale nicht mittels [Ca2+] Bildgebung gemessen werden konnten. Bezüglich VGCC-Häufung und möglicher Kolokalisation mit Kaliumkanälen hoher Leitfähigkeit (BK) wurde der Effekt von BK Blocker Iberiotoxin auf ORN-Reizantworten untersucht. In einer Untergruppe aller ORNs wurde eine Verringerung der Antwortamplituden nach Anwendung von Iberiotoxin festgestellt. Aus den gezeigten Ergebnissen wurde geschlossen, dass eine wichtige Funktion von Glomeruli im OB die Konversion von Geruchsinformation zwischen Feuerratenkodierung und Latenzkodierung sein müsse

Τάσεις στον Σύγχρονο Ελληνικό Κινηματογράφο

Εδώ και τουλάχιστον μία δεκαετία περίπου διαρκεί η συζήτηση μεταξύ δημοσιογράφων, κριτικών, ερευνητών και ακαδημαϊκών σχετικά με το φαινόμενο της δυναμικής παρουσίας και της αξιόλογης πορείας στα διεθνή κινηματογραφικά φεστιβάλ όλο και περισσότερων ταινιών νεαρών σκηνοθετών από την Ελλάδα, οι οποίες απολαμβάνουν σταθερά θετικής αποδοχής και συνεχίζουν να προσελκύουν το ενδιαφέρον του συνόλου της κινηματογραφικής κοινότητας. Η κριτική μέσα σε αυτό το χρονικό παράθυρο έχει ήδη διακρίνει κοινά χαρακτηριστικά μεταξύ των εν λόγω ταινιών, τις έχει ομαδοποιήσει, έχει ήδη ονοματίσει την κινηματογραφική τάση και έχει προσπαθήσει να εξερευνήσει το ερώτημα της ύπαρξης σχέσης της τάσης αυτής με την ελληνική πραγματικότητα. Την ίδια στιγμή οι ίδιοι οι δημιουργοί, αρνούνται την ύπαρξη ενός ενιαίου ρεύματος με κοινά χαρακτηριστικά. Η ελληνική πραγματικότητα δεν είναι άλλη από την (σχεδόν) δεκαετίας πλέον οικονομική κρίση με τις κοινωνικοπολιτικές της προεκτάσεις, η οποία συγκέντρωσε στο ξεκίνημά της, την διεθνή προσοχή και εκτίναξε το παγκόσμιο ειδησεογραφικό ενδιαφέρον και της οποίας η αφετηρία συμπίπτει χρονικά με την εμφάνιση του παραπάνω κινηματογραφικού ρεύματος. Και ενώ επί του παρόντος η εγχώρια κριτική βιάζεται να μιλήσει για το τέλος της σύγχρονης αυτής ελληνικής κινηματογραφικής τάσης, εμφανίζονται νέες μελέτες, άρθρα και βιβλία, τα οποία προσφέρουν νέα οπτική εξερευνώντας τα όρια και τις δυνατότητες αυτού του κινηματογράφου και ανοίγουν την συζήτηση σχετικά με την τρέχουσα πολιτιστική στιγμή όσον αφορά τόσο στο κινηματογραφικό όσο και στο πολιτικό και κοινωνικό μέλλον που περιμένει αυτή τη χώρα. Είναι προφανές πως η συζήτηση έχει μετακινηθεί από το αν υπάρχει ξεκάθαρο ρεύμα του ελληνικού σινεμά με κοινά χαρακτηριστικά και ποιες είναι οι ταινίες που ανήκουν σε αυτό, προς το αν υπάρχει άμεση σχέση αυτών με την ελληνική κρίση, τί είδους σχέση είναι αυτή και στο ποιο είναι τελικά το αποτύπωμα που αφήνει στην κινηματογραφική κουλτούρα αυτό το σινεμά και ποιες είναι οι τάσεις που το διαμορφώνουν, μέσα στο ευρύτερο πολιτιστικό και πολιτικό περιβάλλον και μέσα στην παρατεταμένη οικονομική επισφάλεια και κοινωνική αστάθεια που συνεχίζουμε να διανύουμε.For over a decade, there has been a debate between journalists, critics, researchers and scholars about the phenomenon of the dynamic presence and the remarkable course at the international film festivals of more and more young Greek filmmakers&apos; films, which steadily enjoy a positive acceptance and continue to attract the interest of the entire film community. The criticism within this time frame has already distinguished common features among these films, grouped them, named the cinematic trend and sought to explore the question of the relationship of this trend with the Greek reality. At the same time, the authors themselves deny the existence of a single wave with common features. The Greek reality is no other than the (almost) decade-old economic crisis with its sociopolitical extensions, which at its inception gathered international attention and has skyrocketed in terms of the world news&apos; interest and whose starting point coincides with the appearance of the above cinema trend. And while domestic criticism is currently hurrying to talk about the end of this modern Greek film trend, new studies, articles and books emerge, offering a new perspective exploring the limits and possibilities of this cinema and opening up the discussion about the current cultural moment in terms of both the cinematic and the political and social future that awaits this country. It is obvious that the conversation has moved from whether there is an explicit wave of Greek Cinema with common features and which are the films that belong to it, to whether there is a direct relationship of the above with the Greek crisis, what kind of relationship this is and finally what is the footprint that this Cinema leaves in the cinematic culture and what are the trends that shape it, within the wider cultural and political environment and within the prolonged economic downturn and social instability that Greece is continuously going through

Protein lifetimes in aged brains reveal a proteostatic adaptation linking physiological aging to neurodegeneration

Aging is a prominent risk factor for neurodegenerative disorders (NDDs); however, the molecular mechanisms rendering the aged brain particularly susceptible to neurodegeneration remain unclear. Here, we aim to determine the link between physiological aging and NDDs by exploring protein turnover using metabolic labeling and quantitative pulse-SILAC proteomics. By comparing protein lifetimes between physiologically aged and young adult mice, we found that in aged brains protein lifetimes are increased by ~20% and that aging affects distinct pathways linked to NDDs. Specifically, a set of neuroprotective proteins are longer-lived in aged brains, while some mitochondrial proteins linked to neurodegeneration are shorter-lived. Strikingly, we observed a previously unknown alteration in proteostasis that correlates to parsimonious turnover of proteins with high biosynthetic costs, revealing an overall metabolic adaptation that preludes neurodegeneration. Our findings suggest that future therapeutic paradigms, aimed at addressing these metabolic adaptations, might be able to delay NDD onset

Correction: Circumvention of common labelling artefacts using secondary nanobodies

Correction for ‘Circumvention of common labelling artefacts using secondary nanobodies’ by Shama Sograte-Idrissi et al., Nanoscale, 2020, 12, 10226–10239, DOI: 10.1039/D0NR00227E

TAp73 is a central transcriptional regulator of airway multiciliogenesis.

Motile multiciliated cells (MCCs) have critical roles in respiratory health and disease and are essential for cleaning inhaled pollutants and pathogens from airways. Despite their significance for human disease, the transcriptional control that governs multiciliogenesis remains poorly understood. Here we identify TP73, a p53 homolog, as governing the program for airway multiciliogenesis. Mice with TP73 deficiency suffer from chronic respiratory tract infections due to profound defects in ciliogenesis and complete loss of mucociliary clearance. Organotypic airway cultures pinpoint TAp73 as necessary and sufficient for basal body docking, axonemal extension, and motility during the differentiation of MCC progenitors. Mechanistically, cross-species genomic analyses and complete ciliary rescue of knockout MCCs identify TAp73 as the conserved central transcriptional integrator of multiciliogenesis. TAp73 directly activates the key regulators FoxJ1, Rfx2, Rfx3, and miR34bc plus nearly 50 structural and functional ciliary genes, some of which are associated with human ciliopathies. Our results position TAp73 as a novel central regulator of MCC differentiation

miR449 Protects Airway Regeneration by Controlling AURKA/HDAC6-Mediated Ciliary Disassembly

Airway mucociliary regeneration and function are key players for airway defense and are impaired in chronic obstructive pulmonary disease (COPD). Using transcriptome analysis in COPD-derived bronchial biopsies, we observed a positive correlation between cilia-related genes and microRNA-449 (miR449). In vitro, miR449 was strongly increased during airway epithelial mucociliary differentiation. In vivo, miR449 was upregulated during recovery from chemical or infective insults. miR0449−/− mice (both alleles are deleted) showed impaired ciliated epithelial regeneration after naphthalene and Haemophilus influenzae exposure, accompanied by more intense inflammation and emphysematous manifestations of COPD. The latter occurred spontaneously in aged miR449−/− mice. We identified Aurora kinase A and its effector target HDAC6 as key mediators in miR449-regulated ciliary homeostasis and epithelial regeneration. Aurora kinase A is downregulated upon miR449 overexpression in vitro and upregulated in miR449−/− mouse lungs. Accordingly, imaging studies showed profoundly altered cilia length and morphology accompanied by reduced mucociliary clearance. Pharmacological inhibition of HDAC6 rescued cilia length and coverage in miR449−/− cells, consistent with its tubulin-deacetylating function. Altogether, our study establishes a link between miR449, ciliary dysfunction, and COPD pathogenesis

miR449 Protects Airway Regeneration by Controlling AURKA/HDAC6-Mediated Ciliary Disassembly

Airway mucociliary regeneration and function are key players for airway defense and are impaired in chronic obstructive pulmonary disease (COPD). Using transcriptome analysis in COPD-derived bronchial biopsies, we observed a positive correlation between cilia-related genes and microRNA-449 (miR449). In vitro, miR449 was strongly increased during airway epithelial mucociliary differentiation. In vivo, miR449 was upregulated during recovery from chemical or infective insults. miR0449-/- mice (both alleles are deleted) showed impaired ciliated epithelial regeneration after naphthalene and Haemophilus influenzae exposure, accompanied by more intense inflammation and emphysematous manifestations of COPD. The latter occurred spontaneously in aged miR449-/- mice. We identified Aurora kinase A and its effector target HDAC6 as key mediators in miR449-regulated ciliary homeostasis and epithelial regeneration. Aurora kinase A is downregulated upon miR449 overexpression in vitro and upregulated in miR449-/- mouse lungs. Accordingly, imaging studies showed profoundly altered cilia length and morphology accompanied by reduced mucociliary clearance. Pharmacological inhibition of HDAC6 rescued cilia length and coverage in miR449-/- cells, consistent with its tubulin-deacetylating function. Altogether, our study establishes a link between miR449, ciliary dysfunction, and COPD pathogenesis

miR449 Protects Airway Regeneration by Controlling AURKA/HDAC6-Mediated Ciliary Disassembly

Airway mucociliary regeneration and function are key players for airway defense and are impaired in chronic obstructive pulmonary disease (COPD). Using transcriptome analysis in COPD-derived bronchial biopsies, we observed a positive correlation between cilia-related genes and microRNA-449 (miR449). In vitro, miR449 was strongly increased during airway epithelial mucociliary differentiation. In vivo, miR449 was upregulated during recovery from chemical or infective insults. miR0449−/− mice (both alleles are deleted) showed impaired ciliated epithelial regeneration after naphthalene and Haemophilus influenzae exposure, accompanied by more intense inflammation and emphysematous manifestations of COPD. The latter occurred spontaneously in aged miR449−/− mice. We identified Aurora kinase A and its effector target HDAC6 as key mediators in miR449-regulated ciliary homeostasis and epithelial regeneration. Aurora kinase A is downregulated upon miR449 overexpression in vitro and upregulated in miR449−/− mouse lungs. Accordingly, imaging studies showed profoundly altered cilia length and morphology accompanied by reduced mucociliary clearance. Pharmacological inhibition of HDAC6 rescued cilia length and coverage in miR449−/− cells, consistent with its tubulin-deacetylating function. Altogether, our study establishes a link between miR449, ciliary dysfunction, and COPD pathogenesis

Spine neck plasticity regulates compartmentalization of synapses

Dendritic spines have been proposed to transform synaptic signals through chemical and electrical compartmentalization. However, the quantitative contribution of spine morphology to synapse compartmentalization and its dynamic regulation are still poorly understood. We used time-lapse super-resolution stimulated emission depletion (STED) imaging in combination with fluorescence recovery after photobleaching (FRAP) measurements, two-photon glutamate uncaging, electrophysiology and simulations to investigate the dynamic link between nanoscale anatomy and compartmentalization in live spines of CA1 neurons in mouse brain slices. We report a diversity of spine morphologies that argues against common categorization schemes and establish a close link between compartmentalization and spine morphology, wherein spine neck width is the most critical morphological parameter. We demonstrate that spine necks are plastic structures that become wider and shorter after long-term potentiation. These morphological changes are predicted to lead to a substantial drop in spine head excitatory postsynaptic potential (EPSP) while preserving overall biochemical compartmentalization