84 research outputs found

    Characterization of Glyphosate Resistance in Hordeum glaucum Steud (Barley grass)

    Get PDF
    Hordeum glaucum Steud. is a major grass weed in South Australia in crops and pastures across the agricultural region. Control of this grass species has become a problem in recent decades as a consequence of the evolution of herbicide-resistance to several of the herbicides frequently used. Glyphosate is used for non-selective control of Hordeum species in non-cropped situations, such as fence lines and crop margins, and is also used effectively for pre-sowing knockdown control or spray-topping to stop seed set of Hordeum species in pastures. The repeated use of glyphosate has resulted in the evolution of resistance to glyphosate in this species. Glyphosate resistant H. glaucum populations were found along fence lines and around stockyards after more than a decade of repeated herbicide application. This study was undertaken to characterise resistance in these populations and investigate the mechanisms responsible for glyphosate resistance. Better understanding of the evolution of resistance to glyphosate in H. glaucum will improve resistance management strategies to delay or prevent resistance evolution in this species. Glyphosate resistant H. glaucum populations were collected from non-cropped areas along fence lines and stockyards in the years 2016, 2017 respectively with a subsequent collection in 2019 from the same farm. In a series of dose-response experiments the resistance level of the suspected resistant populations (YP-16, YP-17 and YP-19) and susceptible populations (RW, TW and YN) were investigated. These confirmed glyphosate resistance in these populations with resistance level of 2.8 to 6.6- fold higher than the susceptible populations as determined by ratio of their LD50 values. Screening of these populations for mechanisms conferring resistance showed no differences in glyphosate absorption and translocation that could account for resistance and no mutation in the EPSPS gene. However, 9-12 fold increase in EPSPS gene copy number in the resistant populations compared to the susceptible was observed, which is likely to be the basis of resistance in these resistant populations. The mechanism of gene amplification is known to be influenced by selection pressure and therefore unstable. A study was conducted to determine whether glyphosate selection could alter copy number in H. glaucum populations and in their subsequent progenies. Clones were generated from individual plants by splitting plants into two and applying glyphosate on one of the clones of each plant. Results showed that progenies of H. glaucum clones exposed to one cycle of glyphosate selection had higher EPSPS gene copies and increased resistance to glyphosate compared the untreated clones. LD50 values of treated clones increased by 75% to 79% compared to the untreated clones. Similarly, gene copy numbers of the treated clones increased from 1.5 to 4- fold that of the untreated clones. This suggests that this species responds rapidly to glyphosate selection pressure through increased EPSPS copy number and continued application of glyphosate will increase the level of resistance. A study into the inheritance pattern of glyphosate resistance in H. glaucum found no evidence of a single-gene Mendelian inheritance pattern. F2 individuals had gene copy numbers ranging from the same as the susceptible parent to more than the resistant parent with no obvious pattern. Elevated EPSPS gene copies were observed in F2 individuals following glyphosate treatment which may likely influence spread and persistence of resistance. Results from this study confirm EPSPS gene amplification is the molecular basis of resistance in glyphosate resistant H. glaucum. Amplified gene copies in H. glaucum are unstable and increases with glyphosate selection and resistance inheritance is complex and non-Mendelian.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 202

    Use of Drug-level Testing and Single-genome Sequencing to Unravel a Case of Human Immunodeficiency Virus Seroconversion on Pre-exposure Prophylaxis

    Get PDF
    Cases of seroconversion on pre-exposure prophylaxis (PrEP) should be carefully investigated, given their public health implications and rarity. We report a case of transmitted drug resistance causing seroconversion on PrEP in spite of high adherence, confirmed with dried blood spot and segmental hair drug-level testing and single-genome sequencing

    Using experience-based co-design with older patients, their families and staff to improve palliative care experiences in the emergency department: a reflective critique on the process and outcomes

    Get PDF
    Background: Increasing use of emergency departments among older patients with palliative needs has led to the development of several service-level interventions intended to improve care quality. There is little evidence of patient and family involvement in developmental processes, and little is known about the experiences of − and preferences for − palliative care delivery in this setting. Participatory action research seeking to enable collaborative working between patients and staff should enhance the impact of local quality improvement work but has not been widely implemented in such a complex setting. Objectives: To critique the feasibility of this methodology as a quality improvement intervention in complex healthcare settings, laying a foundation for future work. Setting: an Emergency Department in a large teaching hospital in the United Kingdom. Methods: Experience-based Co-design incorporating: 150 hours of nonparticipant observation; semi-structured interviews with 15 staff members about their experiences of palliative care delivery; 5 focus groups with 64 staff members to explore challenges in delivering palliative care; 10 filmed semi-structured interviews with palliative care patients or their family members; a co-design event involving staff, patients and family members. Findings: the study successfully identified quality improvement priorities leading to changes in Emergency Department-palliative care processes. Further outputs were the creation of a patient-family-staff experience training DVD to encourage reflective discussion and the identification and application of generic design principles for improving palliative care in the Emergency Department. There were benefits and challenges associated with using Experience-based Co-design in this setting. Benefits included the flexibility of the approach, the high levels of engagement and responsiveness of patients, families and staff, and the impact of using filmed narrative interviews to enhance the ‘voice' of seldom heard patients and families. Challenges included high levels of staff turnover during the 19 month project, significant time constraints in the Emergency Department and the ability of older patients and their families to fully participate in the co-design process. Conclusion: Experience-based Co-design is a useful approach for encouraging collaborative working between vulnerable patients, family and staff in complex healthcare environments. The flexibility of the approach allows the specific needs of participants to be accounted for, enabling fuller engagement with those who typically may not be invited to contribute to quality improvement work. Recommendations for future studies in this and similar settings include testing the ‘accelerated' form of the approach and experimenting with alternative ways of increasing involvement of patients/families in the co-design phase

    A natural product compound inhibits coronaviral replication in vitro by binding to the conserved Nsp9 SARS-CoV-2 protein

    Get PDF
    The Nsp9 replicase is a conserved coronaviral protein that acts as an essential accessory component of the multi-subunit viral replication/transcription complex. Nsp9 is the predominant substrate for the essential nucleotidylation activity of Nsp12. Compounds specifically interfering with this viral activity would facilitate its study. Using a native mass-spectrometry-based approach to screen a natural product library for Nsp9 binders, we identified an ent-kaurane natural product, oridonin, capable of binding to purified SARS-CoV-2 Nsp9 with micromolar affinities. By determining the crystal structure of the Nsp9-oridonin complex, we showed that oridonin binds through a conserved site near Nsp9’s C-terminal GxxxG-helix. In enzymatic assays, oridonin’s binding to Nsp9 reduces its potential to act as substrate for Nsp12’s Nidovirus RdRp-Associated Nucleotidyl transferase (NiRAN) domain. We also showed using in vitro cellular assays oridonin, while cytotoxic at higher doses has broad antiviral activity, reducing viral titer following infection with either SARS-CoV-2 or, to a lesser extent, MERS-CoV. Accordingly, these preliminary findings suggest that the oridonin molecular scaffold may have the potential to be developed into an antiviral compound to inhibit the function of Nsp9 during coronaviral replication

    Long-term risk of medical conditions associated with breast cancer treatment

    Get PDF
    Early and late effects of cancer treatment are of increasing concern with growing survivor populations, but relevant data are sparse. We sought to determine the prevalence and hazard ratio of such effects in breast cancer cases

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

    Get PDF
    Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

    Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8

    Get PDF
    Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1) and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling
    corecore