School of Agriculture, Food and Ecosystem Sciences - Research Publications
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ItemIsolation and Functional Characterisation of a fads2 in Rainbow Trout (Oncorhynchus mykiss) with Δ5 Desaturase Activity(PUBLIC LIBRARY SCIENCE, 2016-03-04)Rainbow trout, Oncorhynchus mykiss, are intensively cultured globally. Understanding their requirement for long-chain polyunsaturated fatty acids (LC-PUFA) and the biochemistry of the enzymes and biosynthetic pathways required for fatty acid synthesis is important and highly relevant in current aquaculture. Most gnathostome vertebrates have two fatty acid desaturase (fads) genes with known functions in LC-PUFA biosynthesis and termed fads1 and fads2. However, teleost fish have exclusively fads2 genes. In rainbow trout, a fads2 cDNA had been previously cloned and found to encode an enzyme with Δ6 desaturase activity. In the present study, a second fads2 cDNA was cloned from the liver of rainbow trout and termed fads2b. The full-length mRNA contained 1578 nucleotides with an open reading frame of 1365 nucleotides that encoded a 454 amino acid protein with a predicted molecular weight of 52.48 kDa. The predicted Fads2b protein had the characteristic traits of the microsomal Fads family, including an N-terminal cytochrome b5 domain containing the heme-binding motif (HPPG), histidine boxes (HDXGH, HFQHH and QIEHH) and three transmembrane regions. The fads2b was expressed predominantly in the brain, liver, intestine and pyloric caeca. Expression of the fasd2b in yeast generated a protein that was found to specifically convert eicosatetraenoic acid (20:4n-3) to eicosapentaenoic acid (20:5n-3), and therefore functioned as a Δ5 desaturase. Therefore, rainbow trout have two fads2 genes that encode proteins with Δ5 and Δ6 desaturase activities, respectively, which enable this species to perform all the desaturation steps required for the biosynthesis of LC-PUFA from C18 precursors.
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ItemPlastic weed matting is better than jute or woodchips for controlling the invasive wetland grass Phalaris arundinacea, but not Phragmites australis.(Polymeria Publishing, 2016)Woven polypropylene (plastic) weed matting, jute and eucalypt woodchips were trialled for controlling reed canary grass (Phalaris arundinacea L.) and common reed (Phragmites australis (Cav.) Trin. ex Steud.). At two sites, one dominated by reed canary grass and the other by common reed, 50 m x 20 m was mowed and sprayed and ten (10 m x 10 m) plots established, eight of which were fenced. Plots were covered with either plastic weed matting, jute or eucalypt woodchips, or were controls. All plots were planted with native trees and shrubs and understorey plants. Plastic weed matting was the most effective at reducing regrowth of reed canary grass (<5% cover after one year) and promoting the growth of native plantings (>60% cover). Both plastic weed and jute matting were similarly effective at reducing its regrowth (to 10%), but both matting types were compromised by common reed regrowth. While trees and shrubs grew well across all fenced treatments ( 100% survival), understorey plants only established and grew where weed regrowth was controlled. Unfenced unguarded trees and shrubs were virtually eliminated by browsing. Plastic weed matting (combined with other control measures, and protection from browsers where necessary) may provide the best opportunity to control reed canary grass and facilitate wetland restoration.
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ItemTuning the properties of pH responsive nanoparticles to control cellular interactions in vitro and ex vivo(ROYAL SOC CHEMISTRY, 2016-01-01)Engineering the properties of nanoparticles to limit non-specific cellular interactions is critical for developing effective drug delivery systems. Differences between interactions with cultured cells and human blood highlights the need for appropriate assays
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ItemFire effects on pollination in a sexually deceptive orchid(CSIRO PUBLISHING, 2016)Research into the effectiveness of prescribed fire in managing pollination has only recently begun. The effects of fire on pollination have not been explored in sexually deceptive systems. Further, the potential for multiple effects operating at different spatial scales has not been explored in any pollination system despite multiscale effects on pollination observed in agricultural landscapes. We observed the frequency of pollinator visitation to flowers of sexually deceptive Caladenia tentaculata and related it to the post-fire age class of the vegetation at local and landscape scales. We also related the number of the pollinator’s putative larval hosts (scarab beetles) captured at these sites to age class. At the local scale (i.e. the sample location), visitation was highest in recently burnt sites. At the landscape scale, positive associations were observed between (1) putative pollinator hosts and vegetation burnt 36–50 years ago, and (2) pollinator visitation and vegetation burnt ≥50 years ago. Local- and landscape-scale effects on visitation were synergistic, such that visitation was greatest when fire age was heterogeneous within pollinator foraging range.
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ItemSentiment Analysis: ready for conservation(WILEY-BLACKWELL, 2016-12)
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ItemThe paleoclimate context and future trajectory of extreme summer hydroclimate in eastern Australia(AMER GEOPHYSICAL UNION, 2016-11-16)Eastern Australia recently experienced an intense drought (Millennium Drought, 2003-2009) and record-breaking rainfall and flooding (austral summer 2010-2011). There is some limited evidence for a climate change contribution to these events, but such analyses are hampered by the paucity of information on long-term natural variability. Analyzing a new reconstruction of summer (December-January-February) Palmer Drought Severity Index (the Australia-New Zealand Drought Atlas; ANZDA, 1500-2012 CE), we find moisture deficits during the Millennium Drought fall within the range of the last 500 years of natural hydroclimate variability. This variability includes periods of multi-decadal drought in the 1500s more persistent than any event in the historical record. However, the severity of the Millennium Drought, which was caused by autumn (March-April-May) precipitation declines, may be underestimated in the ANZDA because the reconstruction is biased towards summer and antecedent spring (September-October-November) precipitation. The pluvial in 2011, however, which was characterized by extreme summer rainfall faithfully captured by the ANZDA, is likely the wettest year in the reconstruction for Coastal Queensland. Climate projections (RCP 8.5 scenario) suggest that eastern Australia will experience long-term drying during the 21st century. While the contribution of anthropogenic forcing to recent extremes remains an open question, these projections indicate an amplified risk of multi-year drought anomalies matching or exceeding the intensity of the Millennium Drought.
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ItemAgricultural markets and marketing policies(WILEY, 2016-10)Agricultural markets and marketing policies in Australia have changed markedly in recent years. In part, this has occurred because of conscious deregulation of previous price support and stabilisation schemes. Occasionally, the changes occurred because of poor administration and spectacular default. Previous price and marketing policies schemes provided differential rates of assistance with adverse consequences for resource allocation. Pricing arrangements affected marketing institutions and marketing costs beyond the farm gate, domestically and internationally. The conceptual basis of agricultural marketing analysis was contested. Private and public roles were confused, including between Commonwealth and state governments. Key principles of agricultural marketing and policy development in Australia are illustrated in the paper by reference to commodities with different histories and economic characteristics: wool, wheat, dairying and meat. Special emphasis is given to market information and price discovery. In line with continuing urbanisation and modern logistics, retail marketing of agricultural products has also been transformed. This has become controversial as a policy issue. Competition issues, the economic behaviour and performance of supermarkets, and their effects on farmers and consumers are also introduced in the paper.
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ItemAntipodean agricultural and resource economics at 60: farm management(WILEY, 2016-10)From the beginning Agricultural economics in the Antipodes has encompassed farm management in various guises, from the farm economics of firms to the farm management economics of a firm to farm management research. Theoretical advances in the inter‐disciplinary task of farm management analysis, built on economics as the core discipline, make a sound foundation for farm management to be enriched by related disciplinary areas, which will further enhance analytical and problem‐solving capacities. Nowadays though, as in the past, the potential outstrips the application, meaning farmer advice, policy analysis and research investment evaluation are much the poorer.
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ItemPlant blindness and the implications for plant conservation(WILEY, 2016-12)Plant conservation initiatives lag behind and receive considerably less funding than animal conservation projects. We explored a potential reason for this bias: a tendency among humans to neither notice nor value plants in the environment. Experimental research and surveys have demonstrated higher preference for, superior recall of, and better visual detection of animals compared with plants. This bias has been attributed to perceptual factors such as lack of motion by plants and the tendency of plants to visually blend together but also to cultural factors such as a greater focus on animals in formal biological education. In contrast, ethnographic research reveals that many social groups have strong bonds with plants, including nonhierarchical kinship relationships. We argue that plant blindness is common, but not inevitable. If immersed in a plant-affiliated culture, the individual will experience language and practices that enhance capacity to detect, recall, and value plants, something less likely to occur in zoocentric societies. Therefore, conservation programs can contribute to reducing this bias. We considered strategies that might reduce this bias and encourage plant conservation behavior. Psychological research demonstrates that people are more likely to support conservation of species that have human-like characteristics and that support for conservation can be increased by encouraging people to practice empathy and anthropomorphism of nonhuman species. We argue that support for plant conservation may be garnered through strategies that promote identification and empathy with plants.
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ItemScale-dependency of effective hydraulic conductivity on fire-affected hillslopes(AMER GEOPHYSICAL UNION, 2016-07)Abstract Effective hydraulic conductivity (Ke) for Hortonian overland flow modeling has been defined as a function of rainfall intensity and runon infiltration assuming a distribution of saturated hydraulic conductivities (Ks). But surface boundary condition during infiltration and its interactions with the distribution of Ks are not well represented in models. As a result, the mean value of the Ks distribution ( ), which is the central parameter for Ke, varies between scales. Here we quantify this discrepancy with a large infiltration data set comprising four different methods and scales from fire‐affected hillslopes in SE Australia using a relatively simple yet widely used conceptual model of Ke. Ponded disk (0.002 m2) and ring infiltrometers (0.07 m2) were used at the small scales and rainfall simulations (3 m2) and small catchments (ca 3000 m2) at the larger scales. We compared between methods measured at the same time and place. Disk and ring infiltrometer measurements had on average 4.8 times higher values of than rainfall simulations and catchment‐scale estimates. Furthermore, the distribution of Ks was not clearly log‐normal and scale‐independent, as supposed in the conceptual model. In our interpretation, water repellency and preferential flow paths increase the variance of the measured distribution of Ks and bias ponding toward areas of very low Ks during rainfall simulations and small catchment runoff events while areas with high preferential flow capacity remain water supply‐limited more than the conceptual model of Ke predicts. The study highlights problems in the current theory of scaling runoff generation.