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Ecological interactions among microbial functional guilds in the plant-soil system and implications for ecosystem function
No full textBackground
Soils harbour a remarkable diversity of interacting fungi, bacteria, and other microbes: together these perform a wide variety of ecological roles from nutrient cycling and organic matter breakdown, to pathogenic and symbiotic interactions with plants. Many studies demonstrate the role of microbes in plant-soil feedbacks and their interactions with plants. However, interactions among microbes are seldom addressed, and there is no consensus regarding the nature and outcomes of interactions among microbial functional guilds.
Scope
Here, we critically review what is known about microbe-microbe interactions among functional guilds within the plant-soil system, with the aim to initiate a path to disentangling the “microbe black-box”. Our review confirms that the nature of microbial interactions among major functional guilds is explained by niche theory. This means that, among microbes, a competitive relationship is likely when their benefits to plants, source of carbon and nutrients, or nutrient scavenging mechanisms overlap, while a neutral-to-facilitative relationship is likely when these microbial traits differ or complement each other.
Conclusions
We highlight the numerous knowledge gaps and provide a framework to characterise microbe-microbe interactions that offers insight into the contributions of microbes to key ecosystem functions such as carbon sequestration and nutrient cycling
Fire and rain: A systematic review of the impacts of wildfire and associated runoff on aquatic fauna
No full textClimate and land-use changes are expected to increase the future occurrence of wildfires, with potentially devastating consequences for freshwater species and ecosystems. Wildfires that burn in close proximity to freshwater systems can significantly alter the physicochemical properties of water. Following wildfires and heavy rain, freshwater species must contend with complex combinations of wildfire ash components (nutrients, polycyclic aromatic hydrocarbons, and metals), altered light and thermal regimes, and periods of low oxygen that together can lead to mass mortality events. However, the responses of aquatic fauna to wildfire disturbances are poorly understood. Here we provide a systematic review of available evidence on how aquatic animals respond to and recover from wildfire disturbance. Two databases (Web of Science and Scopus) were used to identify key literature. A total of 83 studies from across 11 countries were identified to have assessed the risk of wildfires on aquatic animals. We provide a summary of the main ecosystem-level changes associated with wildfires and the main responses of aquatic fauna to such disturbances. We pay special focus to physiological tools and biomarkers used to assess how wildfires impact aquatic animals. We conclude by providing an overview of how physiological biomarkers can further our understanding of wildfire-related impacts on aquatic fauna, and how different physiological tools can be incorporated into management and conservation plans and serve as early warning signs of wildfire disturbances
Cannula cricothyroidotomy in the impalpable neck: An observational study of simulated ‘can’t intubate, can’t oxygenate’ scenarios by teams following a cannula-first algorithm in live anaesthetised pigs
No full textLive animal models can be used to train anaesthetists to perform emergency front-of-neck-access. Cannula cricothyroidotomy success reported in previous wet lab studies contradicts human clinical data. This prospective, observational study reports success of a cannula-first ‘can't intubate, can't oxygenate’ algorithm for impalpable anatomy during high fidelity team simulations using live, anaesthetised pigs.
Forty-two trained anaesthesia teams were instructed to follow the Royal Perth Hospital can't intubate, can't oxygenate algorithm to re-oxygenate a desaturating pig with impalpable neck anatomy (mean (standard deviation, SD) 16.2 (3.5) kg); mean (SD) tracheal internal diameter 11 (1.4) mm. Teams were informed that failure would prompt veterinary-led euthanasia.
All teams performed percutaneous cannula cricothyroidotomy as the initial technique, with a median (interquartile range, IQR (range)) start time of 42 (35–50 (24–93)) s. First-pass percutaneous cannula success was 29% to both insufflate tracheal oxygen and re-oxygenate. Insufflation success improved with repeated percutaneous attempts (up to three), but prolonged hypoxia time increasingly necessitated euthanasia (insufflation 57%; re-oxygenation 48%). First, second and third percutaneous attempts achieved insufflation at median (IQR (range)) 74 (64–91 (46–110)) s, 111 (95–136 (79–150)) s and 141 (127–159 (122–179)) s, respectively. Eighteen teams failed with percutaneous cannulae and performed scalpel techniques, predominantly dissection cannulation (n = 17) which achieved insufflation in all cases (insufflation 100%; re-oxygenation 47%). Scalpel attempts were started at median (IQR (range)) 142 (133–218 (97–293)) s and achieved insufflation at 232 (205–303 (152–344)) s.
While percutaneous cannula cricothyroidotomy could rapidly re-oxygenate, the success rate was low and teams repeated attempts beyond the recommended 60 s time frame, delaying transition to the more successful dissection cannula technique. We recommend this ‘cannula-first’ can't intubate, can't oxygenate algorithm adopts a ‘single best effort’ strategy for percutaneous cannula, with failure prompting a scalpel technique
Earth Biogenome Project: Present status and future plans
No full textEarth Biogenome Project (EBP) is an ambitious project targeted to provide high-quality reference genome sequences for all 1.8 million named extant (living) eukaryote species. The project was launched on 1 November 2018 with an initial 2 years’ pilot phase (2018–2020) followed by Phase I (2020–2023), during which genomes of 9400 species will be sequenced. The genomes of the remaining ~1.7 million species will be sequenced in a planned manner during Phase II (2024–2027) and Phase III (2028–2030). In view of the excitement generated and the progress already made, the subject was covered in a Special Feature of a recent issue of PNAS (25 January 2022). The present status and future plans of EBP along with challenges faced are briefly discussed in this article
Induction of water repellency by leaves of contrasting Australian native species: effects of composition and heating
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This study identifies the contribution of leaf matter from individual plant species on water repellency with a focus on the composition of organic compounds and the role of heat in releasing these compounds to soil.
Methods
Leaf powder from four plant species (Banksia menziesii, Eucalyptus marginata, Allocasuarina fraseriana, Xanthorrhoea preissii) was mixed with acid-washed sand (AWS) under a range of temperatures and WR measured. Plant chemical composition was characterized by extraction of leaf powder and GC/MS analysis.
Results
Increasing concentrations of plant powder mixed with AWS increased WR for three species; whereas for X. preissii there was no WR at any concentration. Heating increased WR for all species over the range of 30 to 120 °C. B. menziesii had the greatest WR, which was associated with the largest diversity of fatty acids and n-alcohols and highest concentration of alkanes, whereas X. preissii with the smallest WR had only C16 alcohol and C16 fatty acids at relatively low concentration.
Conclusions
Physically mixing leaf powder with AWS allows the contribution of different plant species on WR to be directly examined. WR appears to be related to differences in the concentrations and diversity of n-alcohols, n-fatty acids, and high n-alkanes in the leaves. The observed temperature effects on WR provide insights into the kinetics of release and dispersal of organic compounds from interstitial material
A cross‐sectional survey of risk factors for the presence of Coxiella burnetii in Australian commercial dairy goat farms
Get PDFThe largest Australian farm-based outbreak of Q fever originated from a dairy goat herd. We surveyed commercial dairy goat farms across Australia by testing bulk tank milk (BTM) samples using a commercial indirect enzyme-linked immunosorbent assay and two quantitative polymerase chain reactions (PCRs). Of the 66 commercial dairy goat herds on record, managers from 61 herds were contacted and 49 provided BTM samples. Five of the surveyed herds were positive on at least one of the diagnostic tests, thus herd-level apparent prevalence was 10% (95% confidence interval [CI] 4 to 22). True prevalence was estimated to be 3% (95% credible interval: 0 to 18). Herd managers completed a questionnaire on herd management, biosecurity and hygiene practices and risk factors were investigated using multivariable logistic regression. Herds with >900 milking does (the upper quartile) were more likely to be Coxiella burnetii positive (odds ratio = 6.75; 95% CI 1.65 to 27.7) compared with farms with ≤900 milking does. The odds of BTM positivity increased by a factor of 2.53 (95% CI 1.51 to 4.22) for each order of magnitude increase in the number of goats per acre. C. burnetii was not detected in samples from the majority of the Australian dairy goat herds suggesting there is an opportunity to protect the industry and contain this disease with strengthened biosecurity practices. Intensification appeared associated with an increased risk of positivity. Further investigation is required to discriminate the practices associated with an increased risk of introduction to disease-free herds, from practices associated with maintenance of C. burnetii infection in infected dairy goat herds
Bird and Nature Tourism in Australia
Get PDFNature-based and bird-focused tourism continues to attract interest from domestic and international tourists and while it is still relatively small compared to some other jurisdictions, it is a fast-growing niche tourism market in Australia (Steven et al. 2015a, b). A small proportion of tourists are specifically focused on the avifauna of their travel destinations. However, avitourists are not a homogenous group (Steven et al. 2021). Many domestic and international tourists incorporating birdwatching into an itinerary that includes other general nature-based activities and cultural experiences. In Australia, this include, but is not limited to: taking tours offering insights into Indigenous Peoples’ culture and history; participating in whale watching or other marine megafauna tours; visiting regions that exhibit exemplary landscape or seascape features (e.g. geomorphological sites of interest, rainforests, coral reefs); or enjoying the high quality of food and wine offerings in many parts of Australia (Kim et al. 2010; Steven et al. unpublished data [collected at UK Birdfair 2015]). Further)
Accounting for the neglected: Invertebrate species and the 2019–2020 Australian megafires
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Invertebrates make up the vast majority of fauna species but are often overlooked in impact assessment and conservation response. The extent to which the 2019–2020 Australian megafires overlapped with the range of vertebrate species has been well documented; consequently, substantial resourcing has been directed towards their recovery. Here, we attempt to document the extent of overlap of these megafires with invertebrate species. In doing so, we seek to demonstrate that it is possible and worthwhile to assess the effect of a catastrophic event on a large number of poorly known species.
Location
Temperate and subtropical Australia.
Time period
2019–2020.
Major taxa
Australian invertebrates.
Methods
We adapted a published analytical pathway for the assessment of distributional fire overlap on vertebrate species. Overlaps with fire for 32,163 invertebrate taxa were determined using point records and polygons.
Results
We found that 13,581 invertebrate taxa had part of their range burnt in the 2019–2020 Australian megafires. Of these, 382 taxa had the whole of their known range burnt, and a further 405 taxa had 50–99.9% of their range burnt. Five examples are described.
Main conclusions
Poorly known groups of biodiversity can be impacted significantly by major disturbance events, but such impact is often overlooked. This oversight has the consequences of under-estimating the magnitude of impacts and the potential failure to direct conservation responses to those species most in need of them. Our analysis demonstrates that the 2019–2020 megafires burnt ≥50% of the known range of nearly 800 Australian invertebrate taxa, a tally far higher than for vertebrates (19 taxa). Assessment of the real impact (i.e., beyond simply overlap with fire) requires more consideration of susceptibility and/or post-fire survey and monitoring. The magnitude of overlap of the 2019–2020 megafires on invertebrate species justifies a conservation response that is less biased towards iconic vertebrate species
The correlation between volatile compounds emitted from Sitophilus granarius (L.) and its electrophysiological and behavioral responses
Get PDFThe granary weevil Sitophilus granarius (L.) is one of the most serious primary insect pests of stored products. When S. granarius present in grains, various volatile organic compounds are released as chemical signals which can be used to detect the insects. In this study, volatile chemical compounds released from S. granarius were analyzed using the headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography (GC)–mass spectrometry (MS) techniques. Two key compounds, 3-hydroxy-2-butanone and 1-pentadecene, were identified from mixed gender of S. granarius adults at high density. Moreover, both male and female adults showed dose-dependent electroantennography (EAG) responses to 3-hydroxy-2-butanone. In behavioral assays, S. granarius was attracted to 3-hydroxy-2-butanone at 0.001 µg/10 µL but repelled at 10 µg/10 µL or higher. S. granarius was consistently repelled by 1-pentadecene at concentrations at 0.001 and 1000 µg/10 µL. 3-hydroxy-2-butanone and 1-pentadecene have considerable potential to offer in the development of new approaches for the monitoring and management of this destructive stored grain insect pest
One percent of the clinical dose used for antenatal steroid therapy is sufficient to induce lung maturation when administered directly to the preterm ovine fetus
No full textAntenatal steroids (ANSs) are routinely administered to women judged to be at imminent risk of preterm delivery. Their principal benefit is precocious functional maturation of the preterm fetal lung. Current dosing regimens expose the mother and fetus to high steroid levels that may be unnecessary, increasing the potential risks of disruption to the maternal and fetal hypothalamic-pituitary-adrenal (HPA) axis and glucose regulation, alterations in placental function, and reduced fetal growth. Using a sheep model of pregnancy, we tested the hypothesis that direct fetal administration of an ultra-low dose course of betamethasone phosphate (∼0.33 mg) would be sufficient to elicit functional maturation of the fetal lung. A jugular catheter was installed in singleton ovine fetuses at 122-day gestation under general anesthesia. Animals were randomized to receive either: 1) fetal intravenous betamethasone phosphate to target fetal plasma betamethasone mean levels of 2 ng/mL for 26 h (fetal treatment group; n = 16); 2) fetal intravenous saline for 26 h and two maternal intramuscular injections of 0.25 mg/kg betamethasone phosphate + betamethasone acetate, simulating a standard clinical treatment (maternal treatment group; n = 12); or 3) fetal intravenous saline only for 26 h (negative control group; n = 10). Fetuses were delivered 48 h after surgery, ventilated for 30 min to allow the collection of lung function and physiological data, and euthanized. Quantitative PCR and Western blots were used to assess markers of lung maturation. The average total betamethasone phosphate dose for the fetal treatment group was 1% (0.3 mg) of the maternal treatment group (31-mg betamethasone phosphate + betamethasone acetate). At 30 min of ventilation, arterial PaCO2, pH, heart rate, and ventilation efficacy index (VEI) were significantly (P < 0.05) and equivalently improved in both the fetal treatment group and maternal treatment group, relative to the negative control group. Similarly, SP-A, SP-C, and AQ-5 mRNA expression was significantly higher in both the fetal treatment group and maternal treatment group, relative to negative control. Maternal steroid administration was not required to generate preterm fetal lung maturation in sheep. Using a low dose and targeting steroid treatments directly to the fetus has the potential to significantly reduce maternal exposures, while simultaneously reducing the potential risk of adverse outcomes associated with current clinical dosing regimens