Imaging pheromone sensing in a mouse vomeronasal acute tissue slice preparation.

Peter Karlson and Martin Lüscher used the term pheromone for the first time in 1959 to describe chemicals used for intra-species communication. Pheromones are volatile or non-volatile short-lived molecules secreted and/or contained in biological fluids, such as urine, a liquid known to be a main source of pheromones. Pheromonal communication is implicated in a variety of key animal modalities such as kin interactions, hierarchical organisations and sexual interactions and are consequently directly correlated with the survival of a given species. In mice, the ability to detect pheromones is principally mediated by the vomeronasal organ (VNO), a paired structure located at the base of the nasal cavity, and enclosed in a cartilaginous capsule. Each VNO has a tubular shape with a lumen allowing the contact with the external chemical world. The sensory neuroepithelium is principally composed of vomeronasal bipolar sensory neurons (VSNs). Each VSN extends a single dendrite to the lumen ending in a large dendritic knob bearing up to 100 microvilli implicated in chemical detection. Numerous subpopulations of VSNs are present. They are differentiated by the chemoreceptor they express and thus possibly by the ligand(s) they recognize. Two main vomeronasal receptor families, V1Rs and V2Rs, are composed respectively by 240 and 120 members and are expressed in separate layers of the neuroepithelium. Olfactory receptors (ORs) and formyl peptide receptors (FPRs) are also expressed in VSNs. Whether or not these neuronal subpopulations use the same downstream signalling pathway for sensing pheromones is unknown. Despite a major role played by a calcium-permeable channel (TRPC2) present in the microvilli of mature neurons TRPC2 independent transduction channels have been suggested. Due to the high number of neuronal subpopulations and the peculiar morphology of the organ, pharmacological and physiological investigations of the signalling elements present in the VNO are complex. Here, we present an acute tissue slice preparation of the mouse VNO for performing calcium imaging investigations. This physiological approach allows observations, in the natural environment of a living tissue, of general or individual subpopulations of VSNs previously loaded with Fura-2AM, a calcium dye. This method is also convenient for studying any GFP-tagged pheromone receptor and is adaptable for the use of other fluorescent calcium probes. As an example, we use here a VG mouse line, in which the translation of the pheromone V1rb2 receptor is linked to the expression of GFP by a polycistronic strategy

Effectiveness of ready-to-use therapeutic food compared to a corn/soy-blend-based pre-mix for the treatment of childhood moderate acute malnutrition in Niger.

Standard nutritional treatment of moderate acute malnutrition (MAM) relies on fortified blended flours though their importance to treat this condition is a matter of discussion. With the newly introduced World Health Organization growth standards, more children at an early stage of malnutrition will be treated following the dietary protocols as for severe acute malnutrition, including ready-to-use therapeutic food (RUTF). We compared the effectiveness of RUTF and a corn/soy-blend (CSB)-based pre-mix for the treatment of MAM in the supplementary feeding programmes (SFPs) supported by Médecins Sans Frontières, located in the Zinder region (south of Niger). Children measuring 65 to <110 cm, newly admitted with MAM [weight-for-height (WHM%) between 70% and <80% of the NCHS median] were randomly allocated to receive either RUTF (Plumpy'Nut®, 1000 kcal day(-1)) or a CSB pre-mix (1231 kcal day(-1)). Other interventions were similar in both groups (e.g. weekly family ration and ration at discharge). Children were followed weekly up to recovery (WHM% ≥ 85% for 2 consecutive weeks). In total, 215 children were recruited in the RUTF group and 236 children in the CSB pre-mix group with an overall recovery rate of 79.1 and 64.4%, respectively (p < 0.001). There was no evidence for a difference between death, defaulter and non-responder rates. More transfers to the inpatient Therapeutic Feeding Centre (I-TFC) were observed in the CSB pre-mix group (19.1%) compared to the RUTF group (9.3%) (p = 0.003). The average weight gain up to discharge was 1.08 g kg(-1) day(-1) higher in the RUTF group [95% confidence interval: 0.46-1.70] and the length of stay was 2 weeks shorter in the RUTF group (p < 0.001). For the treatment of childhood MAM in Niger, RUTF resulted in a higher weight gain, a higher recovery rate, a shorter length of stay and a lower transfer rate to the I-TFC compared to a CSB pre-mix. This might have important implications on the efficacy and the quality of SFPs

The use of built-in digital backchannels in professional communication within academic conferences in virtual worlds: A comparison with the use of Twitter in real life conferences

This paper deals with the use of built-in digital backchannels within academic conferences in three dimensional virtual worlds (VW) and combines qualitative and quantitative methods to answer the following research questions: does the use of built-in digital backchannels enhance communication, collaboration and knowledge expansion amongst participants in professional communication academic conferences within VW? How can those benefits be articulated? And how does communication in built-in digital backchannels in VW conferences compare to communication through Twitter in real life conferences? This paper builds upon authors’ previous research in which, through purely qualitative methods, six distinct categories of learning were identified and provided insights on how participants should behave in a socially acceptable way in such virtual conferences, as well as on how VW presentations were received by members of the audienc

The Grueneberg ganglion controls odor-driven food choices in mice under threat.

The ability to efficiently search for food is fundamental for animal survival. Olfactory messages are used to find food while being aware of the impending risk of predation. How these different olfactory clues are combined to optimize decision-making concerning food selection remains elusive. Here, we find that chemical danger cues drive the food selection in mice via the activation of a specific olfactory subsystem, the Grueneberg ganglion (GG). We show that a functional GG is required to decipher the threatening quality of an unfamiliar food. We also find that the increase in corticosterone, which is GG-dependent, enhances safe food preference acquired during social transmission. Moreover, we demonstrate that memory retrieval for food preference can be extinguished by activation of the GG circuitry. Our findings reveal a key function played by the GG in controlling contextual food responses and illustrate how mammalian organisms integrate environmental chemical stress to optimize decision-making

Morphological and physiological species-dependent characteristics of the rodent Grueneberg ganglion.

In the mouse, the Grueneberg ganglion (GG) is an olfactory subsystem implicated both in chemo- and thermo-sensing. It is specifically involved in the recognition of volatile danger cues such as alarm pheromones and structurally-related predator scents. No evidence for these GG sensory functions has been reported yet in other rodent species. In this study, we used a combination of histological and physiological techniques to verify the presence of a GG and investigate its function in the rat, hamster, and gerbil comparing with the mouse. By scanning electron microscopy (SEM) and transmitted electron microscopy (TEM), we found isolated or groups of large GG cells of different shapes that in spite of their gross anatomical similarities, display important structural differences between species. We performed a comparative and morphological study focusing on the conserved olfactory features of these cells. We found fine ciliary processes, mostly wrapped in ensheating glial cells, in variable number of clusters deeply invaginated in the neuronal soma. Interestingly, the glial wrapping, the amount of microtubules and their distribution in the ciliary processes were different between rodents. Using immunohistochemistry, we were able to detect the expression of known GG proteins, such as the membrane guanylyl cyclase G and the cyclic nucleotide-gated channel A3. Both the expression and the subcellular localization of these signaling proteins were found to be species-dependent. Calcium imaging experiments on acute tissue slice preparations from rodent GG demonstrated that the chemo- and thermo-evoked neuronal responses were different between species. Thus, GG neurons from mice and rats displayed both chemo- and thermo-sensing, while hamsters and gerbils showed profound differences in their sensitivities. We suggest that the integrative comparison between the structural morphologies, the sensory properties, and the ethological contexts supports species-dependent GG features prompted by the environmental pressure

Video and course content discussion on Massive Open Online Courses: An exploratory research

This paper deals with the ways in which Massive Open Online Courses (MOOC) participants use course related forums and the contribution of those forums to the learning experience of their virtual students. We focused on the comparison between, on one hand, video content provided by the course organizers and on the other hand, the content provided by user discussions in the forums. Our methodology frame is based on natural sociological inquiry. Video Lectures, as well as the most active forum threads and their posts were collected during a 6 weeks long xMOOC that took place in fall 2013 on a well-known MOOC platform. Content analysis was performed and the study concludes that the forum included a very high level of interactions involving mostly course related exchange of information amongst students, placing this course at the intersection between a constructivist MOOC (cMOOC) and a classical information transmission based MOOC (xMOOC)

The competency building process of human computer interaction in game-based teaching: Adding the flexibility of an asynchronous format

This paper builds upon the authors’ previous research in which the competency building process of individuals was analyzed in a purely synchronous computer game-based teaching technology. The issue of heterogeneity of speed of adaptation to the learning tool, identified in the synchronous context, is here addressed by introducing the flexibility of an asynchronous format, in which students are given the opportunity to complete the game at their own pace. Experts count game-based teaching amongst the technologies likely to have the largest impact on education over the next five years. Massively Multiplayer Online Games (MMOG) are based on multiple interactions between different humans in virtual worlds. A MMOG teaching game was created in a virtual world. Participant discourses based on written chats were collected and exploited by netnography. Visual data was filmed and analyzed by the semiotics method then compared to the discourse analysis. First results show interesting differences between synchronous and asynchronous modes, in the interaction and collaboration within and across teams

Amperometric Nitrosothiol Sensor Using Immobilized Organoditelluride Species as Selective Catalytic Layer

A new amperometric sensor capable of responding to various biological S -nitrosothiol species (RSNOs) is described. The sensor is prepared using an organoditelluride-tethered poly(allyamine hydrochloride) (PAH) polymer crosslinked within a dialysis membrane support mounted at the distal surface of an amperometric NO probe. The surface immobilized organoditelluride layer serves as a selective catalyst to decompose various RSNO species to NO in the presence of a thiol reducing agent added to the sample. The proposed sensor responds directly and reversibly to various low molecular weight (LMW) RSNOs in the range of 0.1 14ΜM to 10 14ΜM with nearly equal sensitivity. The main advantage of this sensor over previously reported Cu(II/I) and organodiselenium-based RSNO sensors is its long operational life-time (at least one month). A discussion regarding solution phase transnitrosation reactions potentially allowing the measurement of higher molecular weight S -nitrosoproteins is provided, along with data showing preliminary results in this direction. Further, the direct detection of endogenous RSNO species in diluted fresh whole sheep blood is also demonstrated using this new sensor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57918/1/270_ftp.pd