Chromatin connectivity maps reveal dynamic promoter-enhancer long-range associations.

In multicellular organisms, transcription regulation is one of the central mechanisms modelling lineage differentiation and cell-fate determination. Transcription requires dynamic chromatin configurations between promoters and their corresponding distal regulatory elements. It is believed that their communication occurs within large discrete foci of aggregated RNA polymerases termed transcription factories in three-dimensional nuclear space. However, the dynamic nature of chromatin connectivity has not been characterized at the genome-wide level. Here, through a chromatin interaction analysis with paired-end tagging approach using an antibody that primarily recognizes the pre-initiation complexes of RNA polymerase II, we explore the transcriptional interactomes of three mouse cells of progressive lineage commitment, including pluripotent embryonic stem cells, neural stem cells and neurosphere stem/progenitor cells. Our global chromatin connectivity maps reveal approximately 40,000 long-range interactions, suggest precise enhancer-promoter associations and delineate cell-type-specific chromatin structures. Analysis of the complex regulatory repertoire shows that there are extensive colocalizations among promoters and distal-acting enhancers. Most of the enhancers associate with promoters located beyond their nearest active genes, indicating that the linear juxtaposition is not the only guiding principle driving enhancer target selection. Although promoter-enhancer interactions exhibit high cell-type specificity, promoters involved in interactions are found to be generally common and mostly active among different cells. Chromatin connectivity networks reveal that the pivotal genes of reprogramming functions are transcribed within physical proximity to each other in embryonic stem cells, linking chromatin architecture to coordinated gene expression. Our study sets the stage for the full-scale dissection of spatial and temporal genome structures and their roles in orchestrating development.

Flourishing or Frightening? Feelings about Natural and Built Green Spaces in Singapore.

The current study's aim was to better understand people's feelings towards different types of natural and built green space environments in the highly urbanized "garden city" of Singapore. We examined which types of green spaces elicited positive (eudemonic) or negative (apprehensive) affective responses. A total of 288 adult residents of Singapore completed a survey that asked them to report their affective states in response to images of 10 locally different environment types and to complete measures of childhood location, frequency of visiting natural/built environments, nature connectedness, and dispositional anxiety, as well as demographic items on age and gender. The 10 green space environment types were mapped onto an experiential state space representing feelings of apprehension and eudemonia in response to specific types of urban green spaces. In terms of a biophilic response, feelings of eudemonia were no different in natural green spaces compared to built green spaces. A higher frequency of experience in specific environments is associated with enhanced feelings of eudemonia in these environments. The findings indicate that people in Singapore can be apprehensive as much in natural green spaces as in built green spaces, and they can also find eudemonic experiences in built green spaces such as roof-top gardens or town parks.