Microbial light-activatable proton pumps as neuronal inhibitors to functionally dissect neuronal networks in C. elegans

Essentially any behavior in simple and complex animals depends on neuronal network function. Currently, the best-defined system to study neuronal circuits is the nematode Caenorhabditis elegans, as the connectivity of its 302 neurons is exactly known. Individual neurons can be activated by photostimulation of Channelrhodopsin-2 (ChR2) using blue light, allowing to directly probe the importance of a particular neuron for the respective behavioral output of the network under study. In analogy, other excitable cells can be inhibited by expressing Halorhodopsin from Natronomonas pharaonis (NpHR) and subsequent illumination with yellow light. However, inhibiting C. elegans neurons using NpHR is difficult. Recently, proton pumps from various sources were established as valuable alternative hyperpolarizers. Here we show that archaerhodopsin-3 (Arch) from Halorubrum sodomense and a proton pump from the fungus Leptosphaeria maculans (Mac) can be utilized to effectively inhibit excitable cells in C. elegans. Arch is the most powerful hyperpolarizer when illuminated with yellow or green light while the action spectrum of Mac is more blue-shifted, as analyzed by light-evoked behaviors and electrophysiology. This allows these tools to be combined in various ways with ChR2 to analyze different subsets of neurons within a circuit. We exemplify this by means of the polymodal aversive sensory ASH neurons, and the downstream command interneurons to which ASH neurons signal to trigger a reversal followed by a directional turn. Photostimulating ASH and subsequently inhibiting command interneurons using two-color illumination of different body segments, allows investigating temporal aspects of signaling downstream of ASH

Avant-propos

L’événement de la fin de l’année académique 2002 a été le départ à la retraite de Jacques Coenen-Huther, lui qui depuis plus de vingt ans a apporté au Département de Sociologie et à l’Université de Genève sa vaste culture, sa rigueur intellectuelle, son imagination créatrice, ainsi que son enthousiasme pédagogique sans concession – ce qu’atteste une fois de plus sa contribution au présent ouvrage. Comment, à l’occasion de cette transition si décisive, manifester à Jacques notre estime, notre ..

Avant-propos

L’événement de la fin de l’année académique 2002 a été le départ à la retraite de Jacques Coenen-Huther, lui qui depuis plus de vingt ans a apporté au Département de Sociologie et à l’Université de Genève sa vaste culture, sa rigueur intellectuelle, son imagination créatrice, ainsi que son enthousiasme pédagogique sans concession – ce qu’atteste une fois de plus sa contribution au présent ouvrage. Comment, à l’occasion de cette transition si décisive, manifester à Jacques notre estime, notre ..

Optogenetic Long-Term Manipulation of Behavior and Animal Development

Channelrhodopsin-2 (ChR2) is widely used for rapid photodepolarization of neurons, yet, as it requires high-intensity blue light for activation, it is not suited for long-term in vivo applications, e.g. for manipulations of behavior, or photoactivation of neurons during development. We used “slow” ChR2 variants with mutations in the C128 residue, that exhibit delayed off-kinetics and increased light sensitivity in Caenorhabditis elegans. Following a 1 s light pulse, we could photodepolarize neurons and muscles for minutes (and with repeated brief stimulation, up to days) with low-intensity light. Photoactivation of ChR2(C128S) in command interneurons elicited long-lasting alterations in locomotion. Finally, we could optically induce profound changes in animal development: Long-term photoactivation of ASJ neurons, which regulate larval growth, bypassed the constitutive entry into the “dauer” larval state in daf-11 mutants. These lack a guanylyl cyclase, which possibly renders ASJ neurons hyperpolarized. Furthermore, photostimulated ASJ neurons could acutely trigger dauer-exit. Thus, slow ChR2s can be employed to long-term photoactivate behavior and to trigger alternative animal development

In-depth transcriptomic analysis of human retina reveals molecular mechanisms underlying diabetic retinopathy

Diabetic Retinopathy (DR) is among the major global causes for vision loss. With the rise in diabetes prevalence, an increase in DR incidence is expected. Current understanding of both the molecular etiology and pathways involved in the initiation and progression of DR is limited. Via RNA-Sequencing, we analyzed mRNA and miRNA expression profiles of 80 human post-mortem retinal samples from 43 patients diagnosed with various stages of DR. We found differentially expressed transcripts to be predominantly associated with late stage DR and pathways such as hippo and gap junction signaling. A multivariate regression model identified transcripts with progressive changes throughout disease stages, which in turn displayed significant overlap with sphingolipid and cGMP-PKG signaling. Combined analysis of miRNA and mRNA expression further uncovered disease-relevant miRNA/mRNA associations as potential mechanisms of post-transcriptional regulation. Finally, integrating human retinal single cell RNA-Sequencing data revealed a continuous loss of retinal ganglion cells, and Müller cell mediated changes in histidine and β-alanine signaling. While previously considered primarily a vascular disease, attention in DR has shifted to additional mechanisms and cell-types. Our findings offer an unprecedented and unbiased insight into molecular pathways and cell-specific changes in the development of DR, and provide potential avenues for future therapeutic intervention

LAight® therapy is an effective treatment option to maintain long-term remission of Hurley I and II Hidradenitis Suppurativa: results from period B of RELIEVE, a multicenter randomized, controlled trial

Background: Hidradenitis suppurativa is a chronic, inflammatory, burdensome skin disease where current first-line treatments are limited to topical and/or systemic antibiotics which cannot be applied for long-term disease management. Period B of the RELIEVE study analyzes whether LAight® therapy can sustain or even increase remission after a first topical antibiotic treatment cycle. Methods: The RELIEVE study was performed as a two-period multicenter randomized controlled trial with blinded assessment. For period A from week 0 to week 16, the 88 participating Hurley I and II patients were randomized to either a group receiving topical clindamycin 1% solution combined with 8 additional bi-weekly treatments with LAight® therapy (group TC + L) or a group which was treated with topical clindamycin 1% solution only (group TC). After 16 weeks, patients entered open-label period B and both groups were treated exclusively with LAight® therapy for an additional 16 weeks (8 sessions, group TC + L/L and group TC/L). Results: In total, 88 patients were enrolled in RELIEVE. Seventy-eight patients entered period B; 39 belonged to group TC + L/L and 39 to group TC/L. The IHS4-response at the start of period B was 62% (group TC + L/L) and 33% (group TC + L). During the 16 weeks of additional monotherapy with LAight, in both groups >90% of patients who responded to therapy in period A maintained their IHS4-response at week 32. IHS4 response rates continued to rise up to 79% of the TC + L/L group and up to 71% of the TC/L group during period B at week 32. Achievement of HiSCR and certain patient reported outcomes confirmed primary endpoint results. Conclusion: LAight® therapy is an effective approved therapy option for Hurley I and II HS that can be used continuously to maintain treatment success. During 16 weeks of follow-up in period B, over 90% of patients with response after period A maintained their treatment outcome, while more than 60% of prior nonresponders gained response. The fact that LAight® therapy can be applied continuously, is very effective and is well tolerated makes it a valuable treatment tool in the design of HS long- term treatment modalities

Attentional distribution and spatial language

Kluth T, Schultheis H. Attentional distribution and spatial language. In: Freksa C, Nebel B, Hegarty M, Barkowsky T, eds. Spatial Cognition IX. Lecture Notes in Computer Science. Vol 8684. Springer International Publishing; 2014: 76-91.Whether visual spatial attention can be split to several discontinuous locations concurrently is still an open and intensely debated question. We address this question in the domain of spatial language use by comparing two existing and three newly proposed computational models. All models are assessed regarding their ability to account for human acceptability ratings for how well a given spatial term describes the spatial arrangement of two functionally related objects. One of the existing models assumes that taking the functional relations into account involves split attention. All new models incorporate functional relations without assuming split attention. Our simulations suggest that not assuming split attention is more appropriate for taking the functional relations into account than assuming split attention. At the same time, the simulations raise doubt as to whether any of the models appropriately captures the impact of functional relations on spatial language use

The Milky Way's bulge star formation history as constrained from its bimodal chemical abundance distribution

We conduct a quantitative analysis of the star formation history (SFH) of the Milky Way's bulge by exploiting the constraining power of its stellar [Fe/H] and [Mg/Fe] distribution functions. Using APOGEE data, we confirm the previously-established bimodal [Mg/Fe]--[Fe/H] distribution within 3 kpc of the inner Galaxy. Compared to that in the solar vicinity, the high-$\alpha$ population in the bulge peaks at a lower [Fe/H]. To fit these observations, we use a simple but flexible star formation framework, which assumes two distinct stages of gas accretion and star formation, and systematically evaluate a wide multi-dimensional parameter space. We find that the data favor a three-phase SFH that consists of an initial starburst, followed by a rapid star formation quenching episode and a lengthy, quiescent secular evolution phase. The metal-poor, high-$\alpha$ bulge stars ([Fe/H]0.15) are formed rapidly (<2 Gyr) during the early starburst. The density gap between the high- and low-$\alpha$ sequences is due to the quenching process. The metal-rich, low-$\alpha$ population ([Fe/H]>0.0 and [Mg/Fe]<0.15) then accumulates gradually through inefficient star formation during the secular phase. This is qualitatively consistent with the early SFH of the inner disk. Given this scenario, a notable fraction of young stars (age<5 Gyr) is expected to persist in the bulge. Combined with extragalactic observations, these results suggest that a rapid star formation quenching process is responsible for bimodal distributions in both the Milky Way's stellar populations and in the general galaxy population and thus plays a critical role in galaxy evolution.Comment: 16 pages, 12 figures. MNRAS in pres

Enhanced Bcr-Abl-specific antileukemic activity of arsenic trioxide through glutathione-depletion in imatinib-resistant cells

The development of resistance to imatinib mesylate may partly depend on high Bcr-Abl-expression levels. Arsenic trioxide (ATO) has Bcr-Abl suppressing activity in vitro. Here we investigated means to improve ATO activity in CML by modulating cellular glutathione (GSH), a key regulator of ATO-activity in malignant disease. Our studies demonstrate that depletion of cellular glutathione using dl-buthionine-[S,R]-sulfoximine (BSO) enhances ATO activity against CML cells. GSH-depletion promotes enhanced Bcr-Abl specific activity of ATO through avid repression of Bcr-Abl protein levels and total cellular Bcr-Abl activity. These data provide a rationale for the clinical development of optimized ATO-based regimens through incorporation of GSH-modulators in CML treatment

The Milky Way bar and bulge revealed by APOGEE and Gaia EDR3

We investigate the inner regions of the Milky Way using data from APOGEE and Gaia EDR3. Our inner Galactic sample has more than 26 500 stars within |XGal|< 5 kpc, |YGal|< 3.5 kpc, |ZGal|< 1 kpc, and we also carry out the analysis for a foreground-cleaned subsample of 8000 stars that is more representative of the bulge-bar populations. These samples allow us to build chemo-dynamical maps of the stellar populations with vastly improved detail. The inner Galaxy shows an apparent chemical bimodality in key abundance ratios [α/Fe], [C/N], and [Mn/O], which probe different enrichment timescales, suggesting a star formation gap (quenching) between the high- and low-α populations. Using a joint analysis of the distributions of kinematics, metallicities, mean orbital radius, and chemical abundances, we can characterize the different populations coexisting in the innermost regions of the Galaxy for the first time. The chemo-kinematic data dissected on an eccentricity-|Z|max plane reveal the chemical and kinematic signatures of the bar, the thin inner disc, and an inner thick disc, and a broad metallicity population with large velocity dispersion indicative of a pressure-supported component. The interplay between these different populations is mapped onto the different metallicity distributions seen in the eccentricity-|Z|max diagram consistently with the mean orbital radius and Vφ distributions. A clear metallicity gradient as a function of |Z|max is also found, which is consistent with the spatial overlapping of different populations. Additionally, we find and chemically and kinematically characterize a group of counter-rotating stars that could be the result of a gas-rich merger event or just the result of clumpy star formation during the earliest phases of the early disc that migrated into the bulge. Finally, based on 6D information, we assign stars a probability value of being on a bar orbit and find that most of the stars with large bar orbit probabilities come from the innermost 3 kpc, with a broad dispersion of metallicity. Even stars with a high probability of belonging to the bar show chemical bimodality in the [α/Fe] versus [Fe/H] diagram. This suggests bar trapping to be an efficient mechanism, explaining why stars on bar orbits do not show a significant, distinct chemical abundance ratio signature