Response of periodontopathogens to environmental changes

Periodontal diseases are associated with inflammation, loss of gingival attachment and erosion of alveolar bone. More than 300 species of bacteria have been isolated from human subgingival plaque samples. Of these, certain species including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum have been specifically implicated in the aetiology of one or more of the periodontal diseases. The microenvironment of the periodontal pocket is extremely complex and it is likely that there will be continual variation in the environmental conditions operating in this habitat. The aim of this thesis was to study the effect of environmental factors on the growth and virulence potential of periodontopathogenic bacteria. The redox potential (Eh) of the environment was found to profoundly affect the growth and survival of P. gingivalis and F. nucleatum. Addition of the redoxmodifying agent, methylene blue (MB), to suspensions of P. gingivalis and F. nucleatum caused an increase in the Eh of the medium and this was associated with killing of both organisms. In a small-scale clinical trial, application of MB to the periodontal pocket was associated with changes in the subgingival microflora which represented a shift towards a microflora more compatible with gingival health. The effect of growth medium and incubation atmosphere on the acid (AcP) and alkaline (AIP) phosphatase activity of A. actinomycetemcomitans was studied. AcP activity was greater under anaerobic conditions compared to CO2-enriched aerobic conditions. The effect of IL-1β and IL-6 on the growth of P. gingivalis and A. actinomycetemcomitans and the ability of these two organisms to degrade IL-1β, IL-6 and IL-1ra was determined. Neither IL-1β nor IL-6 affected the growth of either organism. However, P. gingivalis was shown to rapidly degrade these cytokines both in the absence and presence of serum. A. actinomycetemcomitans exhibited no cytokine-degrading activity. The effect of a range of environmental conditions (growth in a CO2-enriched aerobic atmosphere versus anaerobic growth, presence of serum or blood, biofilm versus planktonic mode of growth and iron depletion) on the surface protein and antigen profiles of A. actinomycetemcomitans was examined. Up-regulation and down-regulation of a number of proteins was observed when growth conditions were altered. This study has shown that environmental conditions do affect the growth and virulence potential of periodontopathogenic bacteria and furthermore, that environmental modification may represent an alternative to traditional antimicrobial agents in eliminating these microorganisms from the periodontal pocket

An analysis of the morphology and submarine landslide potential of the upper and middle continental slope offshore Fraser Island, Queensland, Australia

This study presents an investigation into the geomorphological, sedimentological and geotechnical properties of submarine landslides present on the continental slope offshore Fraser Island. An extensive range of previously undiscovered features including marginal plateaus, linear rills, ridges and gullies, canyon systems, as well as slides and slumps were identified. Gravity cores (5.65 m and 3.64 m long) taken in the ‘Upper Slope Slide’ (25 km2 in area, 200-300 m thick), and the ‘Middle Slope Slide’ (11 km2 in area, 100-150 m thick) indicate the slide scars contain drapes of Pleistocene to Recent hemipelagic mud. Shorter gravity cores (1.33 m and 0.43 m long) taken adjacent to both slides terminated in stiff muds of upper Pliocene to lower Pleistocene age (Upper Slope Slide), and upper Miocene to lower Pliocene age (Middle Slope Slide). This unique pattern shows that the sediment is being accumulated and protected inside the slide hollows, while being actively removed from the exposed adjacent slopes, most likely by abrasion. Biostratigraphic ages determined for the basal material demonstrate that the seafloor surfaces at both sites are effectively erosional unconformities. The basal, stiff sediments on the upper slope was deposited between 2 and 2.5 Ma BP; this material was scoured and then buried beneath a 1 m thick sediment drape at 0.45 Ma BP. Sediments exposed on the seafloor adjacent to the Middle Slope Slide were dated at around 6-8.5 Ma BP. This indicates that the smooth upper continental slope developed its morphology by the late-mid Pleistocene, while the middle slope is a Post-Pliocene feature. It is thought that Pliocene-Pleistocene geological events including fluctuations in the intensity of surface and abyssal ocean currents are responsible for re-sculpting the continental slope’s morphology and have a) increased abrasion and erosion of the middle and upper slope; while b) suppressed sediment delivery

Consumers' Online Deliberation about Food-Related Risks and Benefits: The Case of Red Meat

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Women’s work: Women leading women in a teaching-focussed first year college

In 2018, a community of practice initiative was introduced to enhance the career opportunities for the 53 women academics in the First Year College (FYC) at Victoria University. The FYC is a teaching-oriented college and thus the traditional career advancement through research is largely not applicable to women in the college – many of whom are teaching-focussed academics. The Women in First Year (WiFY) executive developed and implemented workshops with the aim of aiding women on their career trajectory and in getting more women to senior levels and into leadership positions. In this article we will argue that the WiFY initiative has resulted in greater career achievements for women in the FYC. Using data collected from semi-structured interviews as well as relevant research and FYC statistics on career progression, we will argue that WiFY has had a positive effect on the career trajectory of women in the FYC who have participated in their workshops

Correlated fluorescence microscopy and multi-ion beam secondary ion mass spectrometry imaging reveals phosphatidylethanolamine increases in the membrane of cancer cells over-expressing the molecular chaperone subunit CCTδ

Changes in the membrane composition of sub-populations of cells can influence different properties with importance to tumour growth, metastasis and treatment efficacy. In this study, we use correlated fluorescence microscopy and ToF-SIMS with C60+ and (CO2)6k+ ion beams to identify and characterise sub-populations of cells based on successful transfection leading to over-expression of CCTδ, a component of the multi-subunit molecular chaperone named chaperonin-containing tailless complex polypeptide 1 (CCT). CCT has been linked to increased cell growth and proliferation and is known to affect cell morphology but corresponding changes in lipid composition of the membrane have not been measured until now. Multivariate analysis of the surface mass spectra from single cells, focused on the intact lipid ions, indicates an enrichment of phosphatidylethanolamine species in the transfected cells. While the lipid changes in this case are driven by the structural changes in the protein cytoskeleton, the consequence of phosphatidylethanolamine enrichment may have additional implications in cancer such as increased membrane fluidity, increased motility and an ability to adapt to a depletion of unsaturated lipids during cancer cell proliferation. This study demonstrates a successful fluorescence microscopy-guided cell by cell membrane lipid analysis with broad application to biological investigation. Graphical abstrac

Virgin Birth in a Hammerhead Shark

Parthenogenesis has been documented in all major jawed vertebrate lineages except mammals and cartilaginous fishes (class Chondrichthyes: sharks, batoids and chimeras). Reports of captive female sharks giving birth despite being held in the extended absence of males have generally been ascribed to prior matings coupled with long-term sperm storage by the females. Here, we provide the first genetic evidence for chondrichthyan parthenogenesis, involving a hammerhead shark (Sphyrna tiburo). This finding also broadens the known occurrence of a specific type of asexual development (automictic parthenogenesis) among vertebrates, extending recently raised concerns about the potential negative effect of this type of facultative parthenogenesis on the genetic diversity of threatened vertebrate species

How bad are life expectancy trends across the UK, and what would it take to get back to previous trends?

Background: Within the UK, there has been debate on whether life expectancy is increasing or decreasing in particular single or 3-year periods, but there has been less thinking whether overall trends have changed. This paper considers the extent to which the trends in life expectancy for the UK and its nations have changed before and after 2011. Methods: We used the Office for National Statistics period life expectancy data for the UK and its nations. We used Lee’s approach to project life expectancy based on repeated sampling of year-to-year change in the baseline periods (1990–2011 and 1980–2011) and applied that to 2012 onwards. Findings: Improvements in period life expectancy were substantially and consistently lower between 2012 and 2018 than predicted from the trends from 1980 and, especially, from 1990. By 2018, life expectancy was lower than projected for females and males, respectively, by 1.22 and 1.52 years (England), 1.44 and 0.95 years (Northern Ireland), 1.30 and 1.44 years (Scotland), 1.53 and 1.63 years (Wales) and 1.24 and 1.49 years (UK overall), based on the 1990–2011 baseline period. Using a longer baseline period, which includes the slower rates of improvement during the 1980s, slightly reduces the gap between the current life expectancies and the projected medians. Interpretation: Future academic and policy focus should be on the deviation of the life expectancy trends from the baseline projection rather than on year-to-year variation. Concerted policy focus to return life expectancy to the projected trends is now urgently required