Responding to chromosomal breakage during M-phase: insights from a cell-free system

DNA double strand breaks (DSBs) activate ATM and ATR dependent checkpoints that prevent the onset of mitosis. However, how cells react to DSBs occurring when they are already in mitosis is poorly understood. The Xenopus egg extract has been utilized to study cell cycle progression and DNA damage checkpoints. Recently this system has been successfully used to uncover an ATM and ATR dependent checkpoint affecting centrosome driven spindle assembly. These studies have led to the identification of XCEP63 as major target of this pathway. XCEP63 is a coiled-coil rich protein localized at centrosome essential for proper spindle assembly. ATM and ATR directly phosphorylate XCEP63 on serine 560 inducing its delocalization from centrosome, which in turn delays spindle assembly. This pathway might contribute to regulate DNA repair or mitotic cell survival in the presence of chromosome breakage

Indoor thermal environments in Chinese residential buildings responding to the diversity of climates

China has a diversity of climates and a unique historic national heating policy which greatly affects indoor thermal environment and the occupants’ thermal response. This paper quantitatively analyzes the data from a large-scale field study across the country conducted from 2008 to 2011 in residential buildings. The study covers nine typical cities located in the five climate zones including Severe Cold (SC), Cold (C), Hot Summer and Cold Winter (HSCW), Hot Summer and Warm Winter (HSWW) and Mild (M) zones. It is revealed that there exists a large regional discrepancy in indoor thermal environ- ment, the worst performing region being the HSCW zone. Human’s long-term climate adaptation leads to wider range of acceptable thermal comfort temperature. Different graphic comfort zones with accept- able range of temperature and humidity for the five climate zones are obtained using the adaptive Predictive Mean Vote (aPMV) model. The results show that occupants living in the poorer thermal environments in the HSCW and HSWW zones are more adaptive and tolerant to poor indoor conditions than those living in the north part of China where central heating systems are in use. It is therefore recommended to develop regional evaluation standards of thermal environments responding to climate characteristics as well as local occupants’ acclimatization and adaptation in order to meeting dual targets of energy conservation and indoor thermal environment improvement

Structure of human Cdc45 and implications for CMG helicase function.

Cell division cycle protein 45 (Cdc45) is required for DNA synthesis during genome duplication, as a component of the Cdc45-MCM-GINS (CMG) helicase. Despite its essential biological function, its biochemical role in DNA replication has remained elusive. Here we report the 2.1-Å crystal structure of human Cdc45, which confirms its evolutionary link with the bacterial RecJ nuclease and reveals several unexpected features that underpin its function in eukaryotic DNA replication. These include a long-range interaction between N- and C-terminal DHH domains, blocking access to the DNA-binding groove of its RecJ-like fold, and a helical insertion in its N-terminal DHH domain, which appears poised for replisome interactions. In combination with available electron microscopy data, we validate by mutational analysis the mechanism of Cdc45 association with the MCM ring and GINS co-activator, critical for CMG assembly. These findings provide an indispensable molecular basis to rationalize the essential role of Cdc45 in genomic duplication.We would like to thank Ben Luisi for help with X-ray data collection, Alessandro Costa for sharing the cryoEM data of the CMG complex before publication and Joseph Maman for help with the analysis of Cdc45-DNA interactions. This work was supported by a Wellcome Trust Senior Investigator award to LP (104641/Z/14/Z) and a Cambridge Gates PhD scholarship to ACS. VC is funded by the Associazione Italiana per Ricerca sul Cancro (AIRC), the European Research Council (ERC) consolidator grant (614541), the Association for International Cancer Research (AICR), the Giovanni-Armenise award to VC, the Epigen Progetto Bandiera and the Fondazione Telethon.This is the final version of the article. It first appeared from Nature via https://doi.org/10.1038/ncomms1163

A review of daylighting strategies in schools: state of the art and expected future trends

The study of daylight conditions within educational buildings has been a topic of interest since the nineteenth century in western countries, and European ones in particular. Although it has been argued that providing a view outside—or even using daylight instead of more stable and manageable artificial light—could reduce students’ performance without providing a pleasant and healthy environment, nowadays it seems that a large consensus upon the need to design well daylit spaces is being reached. This paper reviews how the research community has tackled the task of understanding and solving the complex relationships amongst local climate, users’ needs and design constraints in school buildings by showing the different approaches used and technological solutions suggested. The reported case studies, based either on experimental measurements or on simulations, highlight the need of a comprehensive approach to the topic to fully understand the non‐trivial requirements of a daylit educational environment

Stressing the passive behavior of a Passivhaus: an evidence-based scenario analysis for a Mediterranean case study

This paper first reports the outcomes of a one-year measurement campaign of a passive house built in the Mediterranean climate of Cesena (Italy) in terms of thermal comfort parameters temperature and relative humidity and Indoor Environmental Quality (IEQ) parameter CO2 concentrations. The design carried out with the help of the steady state Passive House Planning Package (PHPP) was able to guarantee good comfort conditions during the heating period, but on the other hand, overheating occurrences during the cooling season have been recorded for almost 50% time according to EN 15251 Standard. Further analyses conducted with the help of dynamic simulations in EnergyPlus allowed identifying the insulation levels and ventilation mode as the key design factors to change in order to reduce overheating to less than 20% of time while keeping a comfortable indoor environment in winter. The simplifications that can be made by reducing the insulation material thickness (up to a third of the original value) on the roof and on the walls, replacing triple-glazed windows with double-glazed windows and implementing a hybrid ventilation strategy instead of using Mechanical Ventilation with Heat Recovery (MVHR) alone could also lead to economic savings. These savings, due to both lower construction costs and operational energy savings, amount to 8755 euros in terms of Net Present Value (NPV) over 30 years' time. The Passivhaus Standard can still be regarded as a good reference for designing low-energy and comfortable houses in a Mediterranean climate if some simplifications are made according to detailed building performance simulations

A Macroscopic Mathematical Model For Cell Migration Assays Using A Real-Time Cell Analysis

Experiments of cell migration and chemotaxis assays have been classically performed in the so-called Boyden Chambers. A recent technology, xCELLigence Real Time Cell Analysis, is now allowing to monitor the cell migration in real time. This technology measures impedance changes caused by the gradual increase of electrode surface occupation by cells during the course of time and provide a Cell Index which is proportional to cellular morphology, spreading, ruffling and adhesion quality as well as cell number. In this paper we propose a macroscopic mathematical model, based on \emph{advection-reaction-diffusion} partial differential equations, describing the cell migration assay using the real-time technology. We carried out numerical simulations to compare simulated model dynamics with data of observed biological experiments on three different cell lines and in two experimental settings: absence of chemotactic signals (basal migration) and presence of a chemoattractant. Overall we conclude that our minimal mathematical model is able to describe the phenomenon in the real time scale and numerical results show a good agreement with the experimental evidences

Refurbishing an existing apartment block in Mediterranean climate: towards the Passivhaus standard

The Passivhaus standard, although widely appreciated in cold regions, is seldom regarded as a reference in the energy renovation of existing buildings in warm countries. This paper evaluates the effectiveness of a series of strategies for the energy refurbishment of an existing apartment block in Southern Italy, based on dynamic energy simulations. The paper aims to show that, in warm Mediterranean areas, a building refurbishment must not be oriented towards an excessive insulation level. Conversely, if aimed to comply with the Passivhaus standard, the renovation must look above all at those strategies that mitigate the energy needs for space cooling and improve thermal comfort in summer

In vivo evaluation of renal function using intravital multiphoton microscopy on rats and mice with induced or spontaneous renal injury

Multiphoton microscopy is a powerful tool for the in vivo imaging of renal processes thanks to the improved tissue penetration and the high spatial and temporal resolution. Intravital imaging permits to evaluate dynamic processes and pathophysiological parameters in real time using non-invasive methods. This project aims to use existing multiphoton microscopy approaches to evaluate in vivo many renal parameters in our animal models and, at the same time, to develop an original application for the assessment of single nephron glomerular filtration rate. In addition, a method for detection and quantification of renal fibrosis ex vivo was developed coupling multiphoton microscopy and machine learning-based segmentation software. The linescan-based innovative methodology offered a great improvement in terms of temporal resolution and provided reliable values of single nephron glomerular filtration rate comparable with previous methods. The validation of this approach was carried out measuring renal filtration in low-dose dopamine and ischemic treated rats, which showed significantly higher and lower values of single nephron glomerular filtration rate, respectively, compared to the control group. The dynamic process of renal glucose reabsorption was elucidated in GLUT2 cKO mice mimicking the Fanconi Bickel Syndrome. Intravital multiphoton microscopy of the renal tubules after the continuous infusion of fluorescent 2-NBDG demonstrated an impaired utilization of glucose in these mice compared to the control. We also developed a novel approach based on second harmonic generation tool provided by the multiphoton microscopy and a machine learning-based segmentation software to detect and quantify renal fibrosis in kidney slices. These multiphoton applications highlighted the great potential of intravital microscopy to elucidate in real time the mechanisms involved in renal pathophysiology at cellular and subcellular resolutio

Distinct Mitotic Functions of Nucleolar and Spindle-Associated Protein 1 ({NuSAP}1) Are Controlled by Two Consensus {SUMOylation} Sites

Nucleolar and Spindle-Associated Protein 1 (NuSAP1) is an important mitotic regulator, implicated in control of mitotic microtubule stability and chromosome segregation. NuSAP1 regulates these processes by interacting with several protein partners. Its abundance, activity and interactions are therefore tightly regulated during mitosis. Protein conjugation with SUMO (Small Ubiquitin-like MOdifier peptide) is a reversible post-translational modification that modulates rapid changes in the structure, interaction(s) and localization of proteins. NuSAP1 was previously found to interact with RANBP2, a nucleoporin with SUMO ligase and SUMO-stabilizing activity, but how this interaction affects NuSAP1 activity has remained elusive. Here, we show that NuSAP1 interacts with RANBP2 and forms proximity ligation products with SUMO2/3 peptides in a RANBP2-dependent manner at key mitotic sites. A bioinformatic search identified two putative SUMO consensus sites in NuSAP1, within the DNA-binding and the microtubule-binding domains, respectively. Site-specific mutagenesis, and mitotic phenotyping in cell lines expressing each NuSAP1 mutant version, revealed selective roles of each individual site in control of NuSAP1 localization and in generation of specific mitotic defects and distinct fates in daughter cells. These results identify therefore two new regulatory sites for NuSAP1 functions and implicate RANBP2 in control of NuSAP1 activity

Thermal and visual comfort assessment of natural ventilated office buildings in Europe and North America

Natural ventilation has the potential to significantly improve indoor comfort conditions and provide good indoor air quality by increasing both the indoor air velocity and the rate of air changes inside the building. However, the performance of this technique strongly depends on various parameters, such as climate, urban form and building characteristics (geometrical and thermal). With the aim of showing how natural ventilation can be successfully applied to existing office buildings in many different urban climates, an extensive parametric study has been carried out that takes into account the factors most likely to be relevant. Firstly, a characterization of different climates and the cities representative of them has been developed. Then, representative office buildings for each city have been modelled both in their base configurations and when natural ventilation is employed, in representative urban configurations. This task has been accomplished by coupling three different simulation tools in an integrated approach. CFD, thermal and daylighting simulations allowed exploration of which are the most relevant parameters that affect thermal comfort and have some implications on visual comfort as well. The large number of models simulated (almost 13 thousand) also provided the team with the opportunity to develop a new methodology for finding the best performing thermal models, based on Givoni’s thermal comfort theory rather than monthly or annual energy needs