Structure and activity investigations of the cell fate determinant, SpoIIE, from Bacillus subtilis

For many years the Gram positive bacterium Bacillus subtilis has been a model organism for prokaryotic cell and molecular biology. The asymmetric cell division which B. subtilis undergoes during sporulation is a simple system by which to study the process of cell differentiation. Sporulation is governed by a series of genetic temporal and spatial controls. Gene regulation brought about by a series of σ factors and transcriptional regulators is coupled to key morphological stages or checkpoints. σF initiates the first step in a cascade of complex genetic control which eventually produces a resilient endospore. The activation of σF, the first compartment-specific sigma factor, in the forespore and its regulation through interaction between three proteins; SpoIIAA, SpoIIAB and SpoIIE, is of particular interest. SpoIIE, a protein phosphatase which binds to the asymmetric division septum, is a crucial factor in the selective activation of σF in the forespore. Of three putative domains in SpoIIE only the C-terminal PP2C phosphatase domain has been structurally characterised. The central domain, domain II, of SpoIIE has been assigned a role in interaction with the cell division machinery; however mutational studies have shown that, in addition, this domain is also responsible for the regulation of phosphatase activity. This work describes the isolation and characterisation of three new fragments of SpoIIE containing elements of the central cytoplasmic domain of SpoIIE. These include a fragment found to accurately represent the N-terminal solubility limit of domain II which shows a high degree of oligomeric character. The fragments isolated show specific phosphatase activity against SpoIIAA~P, albeit at reduced rates compared to the free phosphatase domain, which indicates an inhibitory role for SpoIIE domain II against the PP2C domain. Three ultimately unsuccessful approaches were attempted to isolate a co-complex of SpoIIE and SpoIIAA~P for structural characterisation. A tendency for domain II containing SpoIIE fragments to precipitate in the presence of Mn(2+) is also identified. An in vivo investigation into the sporulation efficiencies of amino acid substitutions in a potential regulatory interface between domains II and III of SpoIIE indicated no strong sporulation defects

Uncoupled continuous-time random walks: Solution and limiting behavior of the master equation

A detailed study is presented for a large class of uncoupled continuous-time random walks (CTRWs). The master equation is solved for the Mittag-Leffler survival probability. The properly scaled diffusive limit of the master equation is taken and its relation with the fractional diffusion equation is discussed. Finally, some common objections found in the literature are thoroughly reviewed.Comment: Preprint version of an already published paper. 8 page

Self-Objectification Among Physically Active Women

This article discusses self-objectification among physically active women

Young and Elderly Fashion Influencers

The aim of this paper is to analyse a new phenomenon that has emerged in the fashion system: the advent of female fashion influencers over 70. To outline all the novelties this brings with it, we produced a comparison between elderly and young fashion influencers along the evolution of the fashion system in the last decade. We considered both the first wave of fashion blogging (2012–15) populated by young fashion bloggers and the second wave (2015–19) in which we considered especially elderly fashion influencers. At the operational level, we selected the four fashion bloggers who were most followed on Facebook in 2011 in Italy: Chiara Ferragni (theblondesalad.com), Veronica Ferraro (thefashionfruit.com), Nicoletta Reggio (scentofobsession.com), and Irene Colzi (ireneccloset.com). Regarding old women, in 2019 we selected the top 20 elderly influencers over 70, identified using Instagram’s search feature to detect age-related trends (i.e., using hashtags such as #over70 or #advancedstyle). While the four young fashion influencers are Italian, for the older fashion influencers we needed to select English-speaking women from across the globe, as this phenomenon is still just beginning in Italy. We applied qualitative and quantitative methods to capture bloggers’ online strategies and activities for two weeks at both the discursive and visual levels. The results show that while young fashion influencers have been incorporated into the fashion system, fashion influencers over 70 are still producing an important discourse for women, the elderly, and the whole society, although the initial attempts on the part of fashion houses to colonize them are emerging