University of Western Australia

About: University of Western Australia is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Poison control. The organization has 29613 authors who have published 87405 publications receiving 3064466 citations. The organization is also known as: UWA & University of WA.

Microalgal biofactories: a promising approach towards sustainable omega-3 fatty acid production

Abstract: Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) provide significant health benefits and this has led to an increased consumption as dietary supplements. Omega-3 fatty acids EPA and DHA are found in animals, transgenic plants, fungi and many microorganisms but are typically extracted from fatty fish, putting additional pressures on global fish stocks. As primary producers, many marine microalgae are rich in EPA (C20:5) and DHA (C22:6) and present a promising source of omega-3 fatty acids. Several heterotrophic microalgae have been used as biofactories for omega-3 fatty acids commercially, but a strong interest in autotrophic microalgae has emerged in recent years as microalgae are being developed as biofuel crops. This paper provides an overview of microalgal biotechnology and production platforms for the development of omega-3 fatty acids EPA and DHA. It refers to implications in current biotechnological uses of microalgae as aquaculture feed and future biofuel crops and explores potential applications of metabolic engineering and selective breeding to accumulate large amounts of omega-3 fatty acids in autotrophic microalgae.

Short-term biochar-induced increase in soil CO2 release is both biotically and abiotically mediated

Abstract: The application of biochar to soil has been shown to cause an apparent increase in soil respiration. In this study we investigated the mechanistic basis of this response. We hypothesized that increased CO2 efflux could occur by: (1) Biochar-induced changes in soil physical properties (bulk density, porosity, moisture content); (2) The biological breakdown of organic carbon (C) released from the biochar; (3) The abiotic release of inorganic C contained in the biochar; (4) A biochar-induced stimulation of decomposition of native soil organic matter (SOM) which could occur both biotically or abiotically; (5) The intrinsic biological activity of the biochar results in the liberation of CO2. Our results show that most of the extra CO2 produced after biochar addition to soil came from the equal breakdown of organic C and the release of inorganic C contained in the biochar. Using long-term 14C-labelled SOM, we show that biochar repressed native SOM breakdown, counteracting the release of CO2 from the biochar. A range of mechanisms to describe this negative priming response is presented. Although biochar-induced significant changes in the physical characteristics of the soil, overall this made no contribution to changes in soil respiration. Similarly, the evidence from our study suggests that changes in soluble polyphenols do not help explain the respiration response. In summary, biochar induced a net release of CO2 from the soil; however, this C loss was very small relative to the amount of C stored within the biochar itself (ca. 0.1%). This short-term C release should therefore not compromise its ability to contribute to long-term C sequestration in soil environments.

Remember-know: a matter of confidence.

Abstract: This article critically examines the view that the signal detection theory (SDT) interpretation of the remember– know (RK) paradigm has been ruled out by the evidence. The author evaluates 5 empirical arguments against a database of 72 studies reporting RK data under 400 different conditions. These arguments concern (a) the functional independence of remember and know rates, (b) the invariance of estimates of sensitivity, (c) the relationship between remember rates and overall hit and false alarm rates, (d) the relationship between RK responses and confidence judgments, and (e) dissociations between remember and overall hit rates. Each of these arguments is shown to be flawed, and despite being open to refutation, the SDT interpretation is consistent with existing data from both the RK and remember– know– guess paradigms and offers a basis for further theoretical development. The remember– know (RK) paradigm was introduced by Tulving (1985) in order to measure the different states of awareness thought to underlie memory retrieval. Participants in a memory experiment were asked to indicate the basis on which they judged that an item had been previously studied. They were asked if they were able to “remember” its prior occurrence or whether they simply “knew” on some other basis that it was old. Tulving (1985) interpreted remember (or R) responses as indicating a state of autonoetic awareness associated with retrieval from episodic memory and interpreted know (or K) responses as indicating a state of noetic awareness associated with retrieval from semantic memory. The RK paradigm was further refined by Gardiner (1988), who developed operational definitions of both remembering and knowing. Remembering was defined as the ability to become consciously aware of some aspect or aspects of what occurred or was experienced at the time the test item was first presented. Knowing was defined as recognition that the test item had been presented earlier but without the ability to recollect consciously anything about its actual occurrence or what had happened or was experienced at that time. In addition, Gardiner (1988) reported a dissociation between R and K responses. He found that levels of processing manipulations affected the proportion of R responses but had no effect on the proportion of K responses. Since these two pioneering studies, there has been growing interest in the RK paradigm (Gardiner & Richardson-Klavehn, 2000). Much of this research has investigated the extent to which R and K responses can be dissociated by different experimental variables. The results are clear—R and K responses are functionally dissociable such that “all possible relations between these two states of awareness have been observed” (Gardiner, Ramponi, & Richardson-Klavehn, 1998, p. 2). It is thus possible to identify variables that affect R responses but not K responses, variables that affect K responses but not R responses, variables that affect R and K responses in the same direction, and variables that affect these responses in opposite directions (Gardiner, 2001).

Rice direct seeding: Experiences, challenges and opportunities

Abstract: Rice is one of the most important food crops in the world, and staple for more than half of the global population. Looming water crisis, water-intensive nature of rice cultivation and escalating labour costs drive the search for alternative management methods to increase water productivity in rice cultivation. Direct seeded rice (DSR) has received much attention because of its low-input demand. It involves sowing pre-germinated seed into a puddled soil surface (wet seeding), standing water (water seeding) or dry seeding into a prepared seedbed (dry seeding). In Europe, Australia and the United States, DSR is highly mechanised. The development of early-maturing varieties and improved nutrient management techniques along with increased availability of chemical weed control methods has encouraged many farmers in the Philippines, Malaysia, Thailand and India to switch from transplanted to DSR culture. This shift should substantially reduce crop water requirements, soil organic-matter turnover, nutrient relations, carbon sequestering, weed biota and greenhouse-gas emissions. Still, weed infestation can cause large yield losses in DSR. In addition, recent incidences of blast disease, crop lodging, impaired kernel quality and stagnant yields across the years are major challenges in this regard. In this review, we discuss the experiences, potential advantages and problems associated with DSR, and suggest likely future patterns of changes in rice cultivation.

The promotive effect of smoke derived from burnt native vegetation on seed germination of Western Australian plants

Abstract: Exposure of dormant seed to cold smoke derived from burnt native vegetation had a positive influence on germination in one or more seed provenances in 45 out of 94 species of native Western Australian plants that are normally hard to germinate. When tested under controlled conditions some species showed earlier germination in smoke treatments than controls; in others smoke-treated seeds continued to germinate for several weeks after controls had achieved full germination. In the remainder, treated and control seeds germinated to similar time schedules. A group of 23 species which responded positively had previously been recorded as extremely difficult or impossible to germinate using conventional techniques. These included members of the genera Geleznowia (Rutaceae), Hibbertia (Dilleniaceae), Stirlingia (Proteaceae), Verticordia (Myrtaceae), Actinostrobus (Cupressaceae) and Pimelea (Thymelaeaceae). Both large- and small-seeded species were encountered amongst the positively responding taxa, which encompassed representatives of 15 families and 26 genera of dicotyledons, 5 families and 8 genera of monocotyledons and the gymnosperm Actinostrobus acuminatus. Sowing seeds on smoke-fumigated filter papers or watering with aqueous eluates of smoke elicited similar degrees of stimulation of germination, as did exposure to gaseous smoke in a readily germinating species Anigozanthos manglesii (Haemodoraceae) and the normally intractable species Lysinema ciliatum (Epacridaceae). Exposing recently burnt and unburnt natural bushland sites to smoke, smoked water or smoked dry sand elicited a significant germination response in 15 species. Over one third of the species sampled in the burnt site exhibited germination additional to that caused by the fire. Data are discussed in relation to previous germination studies on Australian and other taxa.