Sphingolipid metabolic flow controls phosphoinositide turnover at the trans Golgi network

Sphingolipids are membrane lipids, which are globally required for eukaryotic life. Sphingolipid composition varies among endomembranes with pre- and post-Golgi compartments being poor and rich in sphingolipids, respectively. Thanks to this different sphingolipid content, pre- and post-Golgi membranes serve different cellular functions. Nevertheless, how subcellular sphingolipid levels are maintained in spite of trafficking and metabolic fluxes is only partially understood. Here we describe a homeostatic control circuit that controls sphingolipid levels at the trans Golgi network. Specifically, we show that sphingomyelin production at the trans Golgi network triggers a signalling reaction leading to PtdIns(4)P dephosphorylation. Since PtdIns(4)P is required for cholesterol, and sphingolipid transport to the trans Golgi network, PtdIns(4)P consumption leads to the interruption of this transport in response to excessive sphingomyelin production. Based on this evidence we envisage a model where this homeostatic circuit maintains the lipid composition of trans Golgi network and thus of post-Golgi compartments constant, against instant fluctuations in the sphingolipid biosynthetic flow.Peer ReviewedPostprint (author's final draft

Metadata matters: access to image data in the real world

Data sharing is important in the biological sciences to prevent duplication of effort, to promote scientific integrity, and to facilitate and disseminate scientific discovery. Sharing requires centralized repositories, and submission to and utility of these resources require common data formats. This is particularly challenging for multidimensional microscopy image data, which are acquired from a variety of platforms with a myriad of proprietary file formats (PFFs). In this paper, we describe an open standard format that we have developed for microscopy image data. We call on the community to use open image data standards and to insist that all imaging platforms support these file formats. This will build the foundation for an open image data repository

Virtual reality crowd simulation: effects of agent density on user experience and behaviour

Agent-based crowd simulations are used for modelling building and space usage, allowing designers to explore hypothetical real-world scenarios, including extraordinary events such as evacuations. Existing work which engages virtual reality (VR) as a platform for crowd simulations has been primarily focussed on the validation of simulation models through observation; the use of interactions such as gaze to enhance a sense of immersion; or studies of proxemics. In this work, we extend previous studies of proxemics and examine the effects of varying crowd density on user experience and behaviour. We have created a simulation in which participants walk freely and perform a routine manual task, whilst interacting with agents controlled by a typical social force simulation model. We examine and report the effects of crowd density on both affective state and behaviour. Our results show a significant increase in negative affect with density, measured using a self-report scale. We further show significant differences in some aspects of user behaviours, using video analysis, and discuss how our results relate to VR simulation design for mixed human–agent scenarios

PRIMA CARATTERIZZAZIONE MOLECOLARE DEL COMPLESSO Natrix natrix

Natrix natrix è un colubride con distribuzione eurasiatica. La sistematica sottospecifica, basata unicamente su caratteri morfologici e anatomici, è stata storicamente oggetto di numerose revisioni ed è tuttora in via di definizione. L’integrazione di un approccio molecolare può offrire utili indicazioni per la caratterizzazione del complesso Natrix natrix. Le analisi molecolari sono state effettuate su campioni biologici di varia natura (tessuto muscolare, squame ventrali e tamponi buccali) di individui provenienti da tutto l’areale italiano ed eseguite mediante amplificazione di geni mitocondriali. I dati molecolari sono stati analizzati secondo un classico approccio DNA barcoding. Dall’analisi molecolare non è emersa una differenza tale da indicare la presenza di specie criptiche all’interno del complesso, ma la distinzione di MOTU (Molecular Operational Taxonomic Units) ben supportate può essere ricondotta ad altrettante sottospecie morfologiche. In particolare si osserva la distinzione di N. natrix natrix rispetto alle altre sottospecie. La variabilità morfologica indotta da pressioni ecologiche locali non si traduce necessariamente in una divergenza molecolare e, sebbene i risultati molecolari non combacino esattamente con la classificazione morfologica, si osserva una certa strutturazione a livello intraspecifico. Ulteriori analisi sono auspicabili per chiarire le relazioni tra le popolazioni di N. natrix