Understanding tropical seagrass light requirements and resilience to effectively manage seagrass health during major dredging projects

Major dredging projects have the potential to impact on tropical seagrass communities through direct removal and burial and indirectly through turbid dredge plumes reducing the amount of light available to seagrasses. This is a major concern in Australia and elsewhere in the Asia Pacific region where substantial expansion of tropical ports associated with the resources boom is occurring. In the majority of cases managing the impacts from turbid plumes has focussed on a turbidity threshold that has not been related to the true light requirements of the various seagrass species potentially impacted. Here we report on the value of an approach based on determining the minimum light requirements of species, their resilience to impacts and ability to recover and designing a dredge mitigation approach that is focussed on maintaining critical windows of light to support seagrass growth and longer term survival. Results show the value of experimentally determining locally relevant light requirements and the importance of understanding the relationships between light requirements, tidal exposure, shifts in spectral quality of light, seasonality and capacity for species to recover from light stress in determining ecologically relevant triggers. This information combined with a robust toolkit for assessing sub-lethal light stress provides an effective dredge mitigation strategy to protect seagrasses

Co- and Post-translocation Roles for HSP90 in Cholera Intoxication

Cholera toxin (CT) moves from the cell surface to the endoplasmic reticulum (ER) where the catalytic CTA1 subunit separates from the rest of the toxin. CTA1 then unfolds and passes through an ER translocon pore to reach its cytosolic target. Due to its intrinsic instability, cytosolic CTA1 must be refolded to achieve an active conformation. The cytosolic chaperone Hsp90 is involved with the ER to cytosol export of CTA1, but the mechanistic role of Hsp90 in CTA1 translocation remains unknown. Moreover, potential post-translocation roles for Hsp90 in modulating the activity of cytosolic CTA1 have not been explored. Here, we show by isotope-edited Fourier transform infrared spectroscopy that Hsp90 induces a gain-of-structure in disordered CTA1 at physiological temperature. Only the ATP-bound form of Hsp90 interacts with disordered CTA1, and refolding of CTA1 by Hsp90 is dependent upon ATP hydrolysis. In vitro reconstitution of the CTA1 translocation event likewise required ATP hydrolysis by Hsp90. Surface plasmon resonance experiments found that Hsp90 does not release CTA1, even after ATP hydrolysis and the return of CTA1 to a folded conformation. The interaction with Hsp90 allows disordered CTA1 to attain an active state, which is further enhanced by ADP-ribosylation factor 6, a host cofactor for CTA1. Our data indicate CTA1 translocation involves a process that couples the Hsp90-mediated refolding of CTA1 with CTA1 extraction from the ER. The molecular basis for toxin translocation elucidated in this study may also apply to several ADP-ribosylating toxins that move from the endosomes to the cytosol in an Hsp90-dependent process

Intranasal immunisation with recombinant adenovirus vaccines protects against a lethal 2 challenge with pneumonia virus of mice

Pneumonia virus of mice (PVM) infection of BALB/c mice induces bronchiolitis leading to a fatal pneumonia in a dose-dependent manner, closely paralleling the development of severe disease during human respiratory syncytial virus infection in man, and is thus a recognised model in which to study the pathogenesis of pneumoviruses. This model system was used to investigate delivery of the internal structural proteins of PVM as a potential vaccination strategy to protect against pneumovirus disease. Replication-deficient recombinant human adenovirus serotype 5 (rAd5) vectors were constructed that expressed the M or N gene of PVM pathogenic strain J3666. Intranasal delivery of these rAd5 vectors gave protection against a lethal challenge dose of PVM in three different mouse strains, and protection lasted for at least 20 weeks post-immunisation. Whilst the PVM-specific antibody response isuch animals was weak and inconsistent, rAd5N primed a strong PVM-specific CD8+ T cell response and, to a lesser extent, a CD4+ T cell response. These findings suggest that protection induced by rAd5N was mediated by T-cells rather than serum antibody

Modelling intonational structure using hidden markov models.

A method is introduced for using hidden Markov models (HMMs) to model intonational structure. HMMs are probabilistic and can capture the variability in structure which previous finite state network models lack. We show how intonational tunes can be modelled by separate HMMs and how HMMs can be used in a recognition system to automatically determine the tune type of an utterance

Tuberculosis in Dr Granville's mummy: a molecular re-examination of the earliest known Egyptian mummy to be scientifically examined and given a medical diagnosis

‘Dr Granville's mummy’ was described to the Royal Society of London in 1825 and was the first ancient Egyptian mummy to be subjected to a scientific autopsy. The remains are those of a woman, Irtyersenu, aged about 50, from the necropolis of Thebes and dated to about 600 BC. Augustus Bozzi Granville (1783–1872), an eminent physician and obstetrician, described many organs still in situ and attributed the cause of death to a tumour of the ovary. However, subsequent histological investigations indicate that the tumour is a benign cystadenoma. Histology of the lungs demonstrated a potentially fatal pulmonary exudate and earlier studies attempted to associate this with particular disease conditions. Palaeopathology and ancient DNA analyses show that tuberculosis was widespread in ancient Egypt, so a systematic search for tuberculosis was made, using specific DNA and lipid biomarker analyses. Clear evidence for Mycobacterium tuberculosis complex DNA was obtained in lung tissue and gall bladder samples, based on nested PCR of the IS6110 locus. Lung and femurs were positive for specific M. tuberculosis complex cell-wall mycolic acids, demonstrated by high-performance liquid chromatography of pyrenebutyric acid–pentafluorobenzyl mycolates. Therefore, tuberculosis is likely to have been the major cause of death of Irtyersenu

The impact of ensemble meteorology on inverse modeling estimates of volcano emissions and ash dispersion forecasts: Grímsvötn 2011

Volcanic ash can interact with the earth system on many temporal and spatial scales and is a significant hazard to aircraft. In the event of a volcanic eruption, fast and robust decisions need to be made by aviation authorities about which routes are safe to operate. Such decisions take into account forecasts of ash location issued by Volcanic Ash Advisory Centers (VAACs) which are informed by simulations from Volcanic Ash Transport and Dispersion (VATD) models. The estimation of the time-evolving vertical distribution of ash emissions for use in VATD simulations in real time is difficult which can lead to large uncertainty in these forecasts. This study presents a method for constraining the ash emission estimates by combining an inversion modeling technique with an ensemble of meteorological forecasts, resulting in an ensemble of ash emission estimates. These estimates of ash emissions can be used to produce a robust ash forecast consistent with observations. This new ensemble approach is applied to the 2011 eruption of the Icelandic volcano Grímsvötn. The resulting emission profiles each have a similar temporal evolution but there are differences in the magnitude of ash emitted at different heights. For this eruption, the impact of precipitation uncertainty (and the associated wet deposition of ash) on the estimate of the total amount of ash emitted is larger than the impact of the uncertainty in the wind fields. Despite the differences that are dominated by wet deposition uncertainty, the ensemble inversion provides confidence that the reduction of the unconstrained emissions (a priori), particularly above 4 km, is robust across all members. In this case, the use of posterior emission profiles greatly reduces the magnitude and extent of the forecast ash cloud. The ensemble of posterior emission profiles gives a range of ash column loadings much closer in agreement with a set of independent satellite retrievals in comparison to the a priori emissions. Furthermore, airspace containing volcanic ash concentrations deemed to be associated with the highest risk (likelihood of exceeding a high concentration threshold) to aviation are reduced by over 85%. Such improvements could have large implications in emergency response situations. Future research will focus on quantifying the impact of uncertainty in precipitation forecasts on wet deposition in other eruptions and developing an inversion system that makes use of the state-of-the-art meteorological ensembles which has the potential to be used in an operational setting

The relationship between the beliefs of early childhood teachers and their use of scaffold, instruction and negotiation as teaching strategies

This study investigates the relationship between the beliefs of early childhood education teachers and their use of the teaching strategies instruction and negotiation in relation to the scaffold process. Consideration of thinking skills and the ability to problem solve through the vehicle of play provided the background to the research focus. The research was undertaken in two differently structured early childhood education centres in New Zealand with a case study design framing the gathering of data through observations and interviews. It is a small qualitative study driven by socio-cultural theory and therefore considered from a social constructivist position. The main findings from observations and interviews revealed that not all teachers had congruency between their beliefs and practice, that instruction could be the only mediation within a scaffolding process and by considering the power relations in the learning and teaching situation, a model of how different teaching strategies could be related to different states of thinking. A key finding was that of a definition of negotiation as a teaching strategy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

On the multiphoton ionisation photoelectron spectra of phenol

The phenol molecule is a prototype for non-adiabatic dynamics and the excited-state photochemistry of biomolecules. In this article, we report a joint theoretical and experimental investigation on the resonance enhanced multiphoton ionisation photoelectron (REMPI) spectra of the two lowest ionisation bands of phenol. The focus is on the theoretical interpretation of the measured spectra using quantum dynamics simulations. These were performed by numerically solving the time-dependent Schrödinger equation using the multi-layer variant of the multiconfiguration time-dependent Hartree algorithm together with a vibronic coupling Hamiltonian model. The ionising laser pulse is modelled explicitly within the ionisation continuum model to simulate experimental femtosecond 1+1 REMPI photoelectron spectra. These measured spectra are sensitive to very short lived electronically excited states, providing a rigorous benchmark for our theoretical methods. The match between experiment and theory allows for an interpretation of the features of the spectra at different wavelengths and shows that there are features due to both 'direct' and 'indirect' ionisation, resulting from non-resonant and resonant excitation by the pump pulse