The Architecture of the Cytoplasmic Region of Type III Secretion Systems

Type III secretion systems (T3SSs) are essential devices in the virulence of many Gram-negative bacterial pathogens. They mediate injection of protein effectors of virulence from bacteria into eukaryotic host cells to manipulate them during infection. T3SSs involved in virulence (vT3SSs) are evolutionarily related to bacterial flagellar protein export apparatuses (fT3SSs), which are essential for flagellar assembly and cell motility. The structure of the external and transmembrane parts of both fT3SS and vT3SS is increasingly well-defined. However, the arrangement of their cytoplasmic and inner membrane export apparatuses is much less clear. Here we compare the architecture of the cytoplasmic regions of the vT3SSs of Shigella flexneri and the vT3SS and fT3SS of Salmonella enterica serovar Typhimurium at ~5 and ~4 nm resolution using electron cryotomography and subtomogram averaging. We show that the cytoplasmic regions of vT3SSs display conserved six-fold symmetric features including pods, linkers and an ATPase complex, while fT3SSs probably only display six-fold symmetry in their ATPase region. We also identify other morphological differences between vT3SSs and fT3SSs, such as relative disposition of their inner membrane-attached export platform, C-ring/pods and ATPase complex. Finally, using classification, we find that both types of apparatuses can loose elements of their cytoplasmic region, which may therefore be dynamic

Mucin transiently sustains coronavirus infectivity through heterogenous changes in phase morphology of evaporating aerosol

Respiratory pathogens can be spread though the transmission of aerosolised expiratory secretions in the form of droplets or particulates. Understanding the fundamental aerosol parameters that govern how such pathogens survive whilst airborne is essential to understanding and developing methods of restricting their dissemination. Pathogen viability measurements made using Controlled Electrodynamic Levitation and Extraction of Bioaerosol onto Substrate (CELEBS) in tandem with a comparative kinetics electrodynamic balance (CKEDB) measurements allow for a direct comparison between viral viability and evaporation kinetics of the aerosol with a time resolution of seconds. Here, we report the airborne survival of mouse hepatitis virus (MHV) and determine a comparable loss of infectivity in the aerosol phase to our previous observations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Through the addition of clinically relevant concentrations of mucin to the bioaerosol, there is a transient mitigation of the loss of viral infectivity at 40% RH. Increased concentrations of mucin promoted heterogenous phase change during aerosol evaporation, characterised as the formation of inclusions within the host droplet. This research demonstrates the role of mucus in the aerosol phase and its influence on short-term airborne viral stability

Public interest in the exemption provisions of the Freedom of Information Act 1982 (cth)

There are arguably at least four situations where public interest considerations have a role in the exemption provisions in the Freedom of Information Act 1982 (Cth). Firstly, there is an argument that public interest considerations provide the basis for the presence of each of the exemption provisions in the Act as an essential public interest. Secondly, it may also be argued that some of the exemption provisions also require consideration of the public interest as a separate element in deciding whether a document ought to be exempt from disclosure. This arises from the reference in sections 33, 33A, 36, 39, 40 and 44 to `public interest'. Thirdly, assuming that public interest can be a separate element for consideration in one or more of these provisions, it can be argued that in such circumstances it looks in general terms to ensuring the well-being of the Australian community through balancing public interests which are relevant to a resolution of the tension between openness and confidentiality. However, questions arise as to the more specific function/s which public interest performs in particular exemption provisions. Fourthly, there may also be an argument that public interest considerations are reflected in the operation of exemption provisions even where the concept is not explicitly referred to

E Coli Oxidative Stress

Data for "Oxidative Stress Contributes to Bacterial Airborne Loss of Viability" published in Microbiology Spectrum