Relative impact of seasonal and oceanographic drivers on surface chlorophyll a along a Western Boundary Current

Strengthening Western Boundary Currents (WBCs) advect warm, low nutrient waters into temperate latitudes, displacing more productive waters. WBCs also influence phytoplankton distribution and growth through current-induced upwelling, mesoscale eddy intrusion and seasonal changes in strength and poleward penetration. Here we examine dynamics of chlorophyll a (Chl. a) in the western Pacific Ocean, a region strongly influenced by the East Australian Current (EAC). We interpreted a spatial and temporal analysis of satellite-derived surface Chl. a, using a hydrodynamic model, a wind-reanalysis product and an altimetry-derived eddy-census. Our analysis revealed regions of persistently elevated surface Chl. a along the continental shelf and showed that different processes have a dominant effect in different locations. In the northern and central zones, upwelling events tend to regulate surface Chl. a patterns, with peaks in phytoplankton biomass corresponding to two known upwelling locations south of Cape Byron (28.5°S) and Smoky Cape (31°S). Within the central EAC separation zone, positive surface Chl. a anomalies occurred 65% of the time when both wind-stress (τw) and bottom-stress (τB) were upwelling-favourable, and only 17% of the time when both were downwelling-favourable. The interaction of wind and the EAC was a critical driver of surface Chl. a dynamics, with upwelling-favourable τW resulting in a 70% increase in surface Chl. a at some locations, when compared to downwelling-favourable τW. In the southern zone, surface Chl. a was driven by a strong seasonal cycle, with phytoplankton biomass increasing up to 152% annually each spring. The Stockton Bight region (32.25-33.25°S) contained ≥20% of the total shelf Chl. a on 27% of occasions due to its location downstream of upwelling locations, wide shelf area and reduced surface velocities. This region is analogous to productive fisheries regions in the Aghulus Current (Natal Bight) and Kuroshio Current (Enshu-nada Sea). These patterns of phytoplankton biomass show contrasting temporal dynamics north and south of the central EAC separation zone with more episodic upwelling-driven Chl. a anomalies to the north, compared with regular annual spring bloom dynamics to the south. We expect changes in the strength of the EAC to have greater influence on shelf phytoplankton dynamics to the north of the separation zone. © 2013 Elsevier Ltd

Towards the development of a reflective radiographer: challenges and constraints

Currently there is overwhelming support from the health professions for universities to devise curricular approaches that lead to the development of undergraduate reflective skills, and over time, reflective practice. However, in the case of radiography, irrespective of the degree to which radiographers might engage in reflective practice they constantly struggle to shed the perception they are little more than technical operatives. The four-year Bachelor of Radiography and Medical Imaging was introduced by Monash University in 1998 with an overt commitment to the development of a reflective radiographer. Findings from student and supervisor surveys generally support the program and its aims. However, as the findings and student feedback will attest, many challenges and constraints continue to face educators who seek to situate their curriculum within the reflective practice paradigm

Identification of Select Fumonisin Forming Fusarium Species Using PCR Applications of the Polyketide Synthase Gene and its Relationship to Fumonisin Production in vitro

A polymerase chain reaction (PCR) based diagnostic assay was used to develop markers for detection of Fusarium verticillioides (=F. moniliforme), a fumonisin producing fungus in maize tissues. Species-specific primers were designed based on sequence data from the polyketide synthase (PKS) gene (FUM1- previously FUM5) responsible for fumonisin production in fungi. Four sets of oligonucleotide primers were tested for their specificity using 24 strains of F. verticillioides, 10 F. proliferatum, and 12 of other Fusarium species. In addition, 13 species of other fungal genera, from four phyla, were tested as negative controls. Among the four sets, primer set B consistently amplified a 419-bp fragment from the DNA 96% of all F. verticillioides strains and 83% of F. proliferatum. All other fungi tested were negative using primer set B. A total of 38% of the F. verticillioides strains grown on a selective liquid medium produced fumonisin and 92% formed the toxin on standard rice medium. When fumonisin formed in culture, PCR assay using primer set B detected every strain of F. verticillioides, but only amplified 80% of F. proliferatum strains that produced the toxin. PCR detection was consistent at 100 pg/μl concentration of genomic DNA from 4 F. verticillioides strains, but varied at 10 pg/μl. Two duplicate greenhouse tests using artificially inoculated maize plants, had greater levels of F. verticillioides detected after re-evaluting using primer set B than from culturing of the tissues. The molecular protocols described in this study requires only 1 day for completion compared to approximately 10 days for cultural work and morphological determination. In conclusion, conventional PCR assay using primer set B provides a sensitive and accurate detection assay that can be used as a primary or secondary confirmation method for identification and occurrence of F. verticillioides within the maize tissues. However, studies using primer set B for fumonisin production determined by strains of F. verticillioides and F. proliferatum will require further verification

Information content of in situ and remotely sensed chlorophyll-a: Learning from size-structured phytoplankton model

© 2018 Chlorophyll-a measurements in the form of in situ observations and satellite ocean colour products are commonly used in data assimilation to calibrate marine biogeochemical models. Here, a two size-class phytoplankton biogeochemical model, with a 0D configuration, was used to simulate the surface chlorophyll-a dynamics (simulated surface Chl-a) for cyclonic and anticyclonic eddies off East Australia. An optical model was then used to calculate the inherent optical properties from the simulation and convert them into remote-sensing reflectance (Rrs). Subsequently, Rrs was used to produce a satellite-like estimate of the simulated surface Chl-a concentrations through the MODIS OC3M algorithm (simulated OC3M Chl-a). Identical parameter optimisation experiments were performed through the assimilation of the two separate datasets (simulated surface Chl-a and simulated OC3M Chl-a), with the purpose of investigating the contrasting information content of simulated surface Chl-a and remotely-sensed data sources. The results we present are based on the analysis of the distribution of a cost function, varying four parameters of the biogeochemical model. In our idealized experiments the simulated OC3M Chl-a product is a poor proxy for the total simulated surface Chl-a concentration. Furthermore, our result show the OC3M algorithm can underestimate the simulated chlorophyll-a concentration in offshore eddies off East Australia (Case I waters), because of the weak relationship between large-sized phytoplankton and remote-sensing reflectance. Although Case I waters are usually characteristic of oligotrophic environments, with a photosynthetic community typically represented by relatively small-sized phytoplankton, mesoscale features such as eddies can generate seasonally favourable conditions for a photosynthetic community with a greater proportion of large phytoplankton cells. Furthermore, our results show that in mesoscale features such as eddies, in situ chlorophyll-a observations and the ocean colour products can carry different information related to phytoplankton sizes. Assimilating both remote-sensing reflectance and measurements of in situ chlorophyll-a concentration reduces the uncertainty of the parameter values more than either data set alone, thus reducing the spread of acceptable solutions, giving an improved simulation of the natural environment

Paid parental leave evaluation: Phase 2 report

Since 1 January 2011, most Australian families in which a mother was in paid employment before the birth or adoption of a child have been eligible for the new Australian Government funded Paid Parental Leave (PPL) scheme.2 The scheme provides eligible parents with up to 18 weeks of Parental Leave Pay (PLP), paid at the rate of the National Minimum Wage, following the birth or recent adoption of a child. The PPL scheme brings Australia into line with all other Organisation for Economic Cooperation and Development (OECD) countries, except the United States, in having a national scheme for paid leave available to mothers following childbirth. This report describes the results of an evaluation of the initial operation of the scheme

Monitoring Keap1-Nrf2 interactions in single live cells

AbstractThe transcription factor NF-E2 p45-related factor 2 (Nrf2) and its negative regulator Kelch-like ECH associated protein 1 (Keap1) control the expression of nearly 500 genes with diverse cytoprotective functions. Keap1, a substrate adaptor protein for Cullin3/Rbx1 ubiquitin ligase, normally continuously targets Nrf2 for degradation, but loses this ability in response to electrophiles and oxidants (termed inducers). Consequently, Nrf2 accumulates and activates transcription of its downstream target genes. Many inducers are phytochemicals, and cruciferous vegetables represent one of the richest sources of inducer activity among the most commonly used edible plants. Here we summarize the discovery of the isothiocyanate sulforaphane as a potent inducer which reacts with cysteine sensors of Keap1, leading to activation of Nrf2. We then describe the development of a quantitative Förster resonance energy transfer (FRET)-based methodology combined with multiphoton fluorescence lifetime imaging microscopy (FLIM) to investigate the interactions between Keap1 and Nrf2 in single live cells, and the effect of sulforaphane, and other cysteine-reactive inducers, on the dynamics of the Keap1–Nrf2 protein complex. We present the experimental evidence for the “cyclic sequential attachment and regeneration” or “conformation cycling” model of Keap1-mediated Nrf2 degradation. Finally, we discuss the implications of this mode of regulation of Nrf2 for achieving a fine balance under normal physiological conditions, and the consequences and mechanisms of disrupting this balance for tumor biology

Near-Real-Time Acoustic Monitoring of Beaked Whales and Other Cetaceans Using a Seaglider™

In most areas, estimating the presence and distribution of cryptic marine mammal species, such as beaked whales, is extremely difficult using traditional observational techniques such as ship-based visual line transect surveys. Because acoustic methods permit detection of animals underwater, at night, and in poor weather conditions, passive acoustic observation has been used increasingly often over the last decade to study marine mammal distribution, abundance, and movements, as well as for mitigation of potentially harmful anthropogenic effects. However, there is demand for new, cost-effective tools that allow scientists to monitor areas of interest autonomously with high temporal and spatial resolution in near-real time. Here we describe an autonomous underwater vehicle – a glider – equipped with an acoustic sensor and onboard data processing capabilities to passively scan an area for marine mammals in near-real time. The glider was tested extensively off the west coast of the Island of Hawai'i, USA. The instrument covered approximately 390 km during three weeks at sea and collected a total of 194 h of acoustic data. Detections of beaked whales were successfully reported to shore in near-real time. Manual analysis of the recorded data revealed a high number of vocalizations of delphinids and sperm whales. Furthermore, the glider collected vocalizations of unknown origin very similar to those made by known species of beaked whales. The instrument developed here can be used to cost-effectively screen areas of interest for marine mammals for several months at a time. The near-real-time detection and reporting capabilities of the glider can help to protect marine mammals during potentially harmful anthropogenic activities such as seismic exploration for sub-sea fossil fuels or naval sonar exercises. Furthermore, the glider is capable of under-ice operation, allowing investigation of otherwise inaccessible polar environments that are critical habitats for many endangered marine mammal species

Fusion of short telomeres in human cells is characterized by extensive deletion and microhomology, and can result in complex rearrangements

Telomere fusion is an important mutational event that has the potential to lead to large-scale genomic rearrangements of the types frequently observed in cancer. We have developed single-molecule approaches to detect, isolate and characterize the DNA sequence of telomere fusion events in human cells. Using these assays, we have detected complex fusion events that include fusion with interstitial loci adjacent to fragile sites, intra-molecular rearrangements, and fusion events involving the telomeres of both arms of the same chromosome consistent with ring chromosome formation. All fusion events were characterized by the deletion of at least one of the telomeres extending into the sub-telomeric DNA up to 5.6 kb; close to the limit of our assays. The deletion profile indicates that deletion may extend further into the chromosome. Short patches of DNA sequence homology with a G:C bias were observed at the fusion point in 60% of events. The distinct profile that accompanies telomere fusion may be a characteristic of the end-joining processes involved in the fusion event

Diagnosis of Human Visceral Pentastomiasis

Visceral pentastomiasis in humans is caused by the larval stages (nymphs) of the arthropod-related tongue worms Linguatula serrata, Armillifer armillatus, A. moniliformis, A. grandis, and Porocephalus crotali. The majority of cases has been reported from Africa, Malaysia, and the Middle East, where visceral pentastomiasis may be an incidental finding in autopsies, and less often from China and Latin America. In Europe and North America, the disease is only rarely encountered in immigrants and long-term travelers, and the parasitic lesions may be confused with malignancies, leading to a delay in the correct diagnosis. Since clinical symptoms are variable and serological tests are not readily available, the diagnosis often relies on histopathological examinations. This laboratory symposium focuses on the diagnosis of this unusual parasitic disease and presents its risk factors and epidemiology