Climate Change in Queensland's Grazing Lands. I. Approaches and Climatic Trends

Climate change is an important global issue but is yet to be recognised as such by many rangelands users. This paper reviews some of the uncertainties relating to pre-instrumental and future climate change and documents current trends and fluctuations in climate of Queensland's grazing lands. Analysis of daily climate surfaces for Queensland's pastoral/cropping zone shows high variability in annual rainfall which is influenced by the El NiHo-Southern Oscillation (ENSO) phenomenon. This relationship, when examined using moving windows, has changed during this century with the 1930-40s being a period of low correlation. Minimum temperatures taken from the climate surfaces also changed, showing a significant (P<0.01) increase over time especially in May. Over the 40 years since 1957, annual minimum temperatures have increased by l.0°C for the pastoral/cropping zone and coastal sub-zone, winter minimum temperatures by 1.2°C for the pastoral/cropping zone (1.3°C for the coastal sub-zone), summer minimum temperatures by 0.7°C for the pastoral/cropping zone and coastal sub-zone, and May minimum temperatures by 2.8°C for the pastoral/cropping zone (3.0°C for the coastal sub-zone). Consistent significant trends in vapour pressure (increasing, P<0.001) and solar radiation (decreasing, P<0.05) also occurred in May. The mechanisms for the identified climate trends and unusual behaviour of ENS0 are the subject of speculation with attribution of causes to natural variability or the enhanced greenhouse effect being unresolved. Continued monitoring of these trends and fluctuations will be important for the future management of Queensland's grazing lands with this analysis highlighting the need for discrimination of trends from natural variability. In terms of grazing management and degradation processes, this work also highlights that general changes in climate averages may disguise important variation at yearly and decadal time scales

Effects of human anti-spike protein receptor binding domain antibodies on severe acute respiratory syndrome coronavirus neutralization escape and fitness

The receptor binding domain (RBD) of the spike (S) glycoprotein of severe acute respiratory syndrome coronavirus (SARS-CoV) is a major target of protective immunity in vivo. Although a large number of neutralizing antibodies (nAbs) have been developed, it remains unclear if a single RBD-targeting nAb or two in combination can prevent neutralization escape and, if not, attenuate viral virulence in vivo. In this study, we used a large panel of human nAbs against an epitope that overlaps the interface between the RBD and its receptor, angiotensin-converting enzyme 2 (ACE2), to assess their cross-neutralization activities against a panel of human and zoonotic SARS-CoVs and neutralization escape mutants. We also investigated the neutralization escape profiles of these nAbs and evaluated their effects on receptor binding and virus fitness in vitro and in mice. We found that some nAbs had great potency and breadth in neutralizing multiple viral strains, including neutralization escape viruses derived from other nAbs; however, no single nAb or combination of two blocked neutralization escape. Interestingly, in mice the neutralization escape mutant viruses showed either attenuation (Urbani background) or increased virulence (GD03 background) consistent with the different binding affinities between their RBDs and the mouse ACE2. We conclude that using either single nAbs or dual nAb combinations to target a SARS-CoV RBD epitope that shows plasticity may have limitations for preventing neutralization escape during in vivo immunotherapy. However, RBD-directed nAbs may be useful for providing broad neutralization and prevention of escape variants when combined with other nAbs that target a second conserved epitope with less plasticity and more structural constraint

Acclimation of photosynthesis to low temperature in Spinacia oleracea L. I. Effects of acclimation on CO2 assimilation and carbon partitioning

Acclimation of spinach plants grown at 25 °C to a temperature of 10°C for 10 d resulted in an increased capacity for leaf photosynthesis in saturating light and CO2, but not at ambient CO2 concentrations. Gas exchange and chlorophyll fluorescence measurements indicated that acclimation was accompanied by an increased capacity for the regeneration of ribulose-1,5-bisphosphate. Changes in starch, soluble carbohydrates and activities of sucrose-P synthase and ADP-glucose pyrophosphorylase were measured during the acclimation process. There was an initial increase in starch and sucrose during the first 2 d, but these then declined. There was an increase in the capacity for sucrose synthesis during low temperature acclimation, evidenced by an increase in the maximum activity of sucrose-P synthase activity and an increase in partitioning of 14CO2 into sucrose, but there was no increase in the activity of ADP-glucose pyrophosphorylase or carbon partitioning into starch

Acclimation of photosynthesis to low temperature in Spinacia oleracea L. II. Effects of nitrogen supply

The photosynthetic capacity of leaves of N-sufficient plants of Spinacia oleracea L. increases following transfer a constant temperature of 10°C for 10 d compared to plants maintained at 25°C. The effects of nitrogen nutrition on this low temperature acclimation have been investigated in respect of CO2 assimilation, the activites and activation states of key enzymes and the partitioning of recently fixed carbon. N-deficiency greatly restricted acclimation of photosynthetic CO2 assimilation to low temperature at both ambient and at saturating CO2 concentrations, indicating a restriction on acclimatory changes in both ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) and the reactions of ribulose-1,5-bisphosphate regeneration. Nitrogen limitation led to an increase in the partitioning of recently-fixed carbon into starch. Total protein increased during acclimation in both N-sufficient and N-deficient leaves and was much less affected than were the activities of enzymes. Increases in the activation state of Rubisco and the stromal fructose-1,6-bisphosphatase occurred in response to low temperature, but increases in the activities of Rubisco, sucrose-phosphate synthase or the cytosolic fructose-1,6-bisphosphatase could not be sustained in N-deficient plants throughout the period of acclimation, although the activities of these enzymes declined less precipitately than in non-acclimated N-deficient plants. These data are all consistent with the view that increases in the activities of key enzymes of carbon assimilation are a pre-requisite for acclimation to low temperature and that these increases are restricted under N-limitation

Predators and genetic fitness: key threatening factors for the conservation of a bettong species

Globally, many wildlife species are declining and an increasing number are threatened by extinction or are extinct. Active management is generally required to mitigate these trends and population viability analysis (PVA) enables different scenarios to be evaluated and informs management decisions. Based on population parameters obtained from a threatened bettong, the woylie (Bettongia penicillata ogilbyi), we developed and validated a PVA model. We identified the demographic and genetic responses to different threatening factors and developed a general framework that would facilitate similar work in other bettong species. The two main threatening processes are predation by introduced animals and its interaction with reduced fitness (e.g. due to inbreeding depression or a disease). Although predation alone can drive a decline in certain circumstances (e.g. when predation success is independent from prey population density), synergistically, predation and reduced fitness can be particularly relevant, especially for small populations. The minimum viable population size was estimated at 1000–2000 individuals. In addition, the models identified that research into age-specific mortality rates and predation rates by introduced animals should be the focus of future work. The PVA model created here provides a basis to investigate threatening processes and management strategies in woylie populations and other extant bettong species, given the ecological and physiological similarities among these threatened species