Combined application of nitrogen and phosphorus to enhance nitrogen use efficiency and close the wheat yield gap on varying soils in semi‐arid conditions

A primary driver of the wheat yield gap in Australia and globally is the supply of nitrogen (N) and options to increase N use efficiency (NUE) are fundamental to closure of the yield gap. Co‐application of N with phosphorus (P) is suggested as an avenue to increase fertiliser NUE, and inputs of N and P fertiliser are key variable costs in low rainfall cereal crops. Within field variability in the response to nutrients due to soil and season offers a further opportunity to refine inputs for increased efficiency. The response of wheat to N fertiliser input (0, 10, 20, 40 and 80 kg N ha‐1) under four levels of P fertiliser (0, 5, 10 and 20 kg P ha−1) was measured on three key low rainfall cropping soils (dune, mid‐slope and swale) across a dune‐swale system in a low rainfall semi‐arid environment in South Australia, for three successive cropping seasons. Wheat on sandy soils produced significant and linear yield and protein responses across all three seasons, while wheat on a clay loam only produced a yield response in a high rainfall season. Responses to P fertiliser were measured on the sandy soils but more variable in nature and a consistent effect of increased P nutrition leading to increased NUE was not measured

The information for catching fly balls: judging and intercepting virtual balls in a CAVE

Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy - keeping constant the rate of change of the tangent of the elevation angle (d(tan(α))/dt) - leads a catcher to the right location at the right time to intercept a fly ball. Previous studies showed the ability to detect the information and the consistency of running patterns with the use of the strategy. However, only direct manipulation of information can show its use. Participants were asked to intercept virtual balls in a Cave Automated Virtual Environment (CAVE) or to judge whether balls would pass behind or in front of them. Catchers in the CAVE successfully intercepted virtual balls with their forehead. Furthermore, the timing of judgments was related to the patterns of changing d(tan(α))/dt. The advantages and disadvantages of a CAVE as a tool for studying interceptive action are discussed

Break-crop effects on wheat production across soils and seasons in a semi-arid environment

In low-rainfall environments, a high frequency of cereal crops has been favoured for optimising productivity and risk. However, cereals at high intensity often lead to declining water-use efficiency and increasing inputs to cope with emergent nutritional, disease and weed problems. The value of including breaks in the cropping sequence can involve a high level of uncertainty in low-rainfall areas where non-cereal crops are more risky and profitability is largely determined by the subsequent benefit to cereal productivity. In this study, we aimed to improve understanding of the magnitude and primary source of break benefits such as nutrition, water and disease management in a low-rainfall environment where a high level of within-field soil variability can also contribute to uncertainty about the value of breaks. In on-farm field experiments near Karoonda in the South Australian Mallee, breaks were grown in 2009 or 2010 on four distinct soil types across a dune–swale catena. The effect of these breaks on subsequent cereal production was measured for up to 3 years. In addition, the effect of breaks on nutrition and water available, along with disease infection in subsequent cereal crops, was explored and actual yields were compared with nitrogen and water-limited potential yields. Consistent cumulative benefits to subsequent cereal crops of at least 1 t ha–1 after 3 years accrue from breaks grown on the different soil types. The inclusion of breaks had beneficial effects on the cycling and supply of nutrients along with some short-term impacts on infection by Rhizoctonia solani AG8 in subsequent cereals, whereas there were no conclusive effects of breaks on the supply of water to subsequent crops. This study suggests that the inclusion of both legume and brassica breaks is likely to be beneficial to subsequent cereal production where nitrogen is a factor limiting productivity in low-rainfall, semi-arid environments

Phenotypic Plasticity of Mouse Spermatogonial Stem Cells

BACKGROUND:Spermatogonial stem cells (SSCs) continuously undergo self-renewal division to support spermatogenesis. SSCs are thought to have a fixed phenotype, and development of a germ cell transplantation technique facilitated their characterization and prospective isolation in a deterministic manner; however, our in vitro SSC culture experiments indicated heterogeneity of cultured cells and suggested that they might not follow deterministic fate commitment in vitro. METHODOLOGY AND PRINCIPAL FINDINGS:In this study, we report phenotypic plasticity of SSCs. Although c-kit tyrosine kinase receptor (Kit) is not expressed in SSCs in vivo, it was upregulated when SSCs were cultured on laminin in vitro. Both Kit(-) and Kit(+) cells in culture showed comparable levels of SSC activity after germ cell transplantation. Unlike differentiating spermatogonia that depend on Kit for survival and proliferation, Kit expressed on SSCs did not play any role in SSC self-renewal. Moreover, Kit expression on SSCs changed dynamically once proliferation began after germ cell transplantation in vivo. CONCLUSIONS/SIGNIFICANCE:These results indicate that SSCs can change their phenotype according to their microenvironment and stochastically express Kit. Our results also suggest that activated and non-activated SSCs show distinct phenotypes

Molecular and cellular mechanisms underlying the evolution of form and function in the amniote jaw.

The amniote jaw complex is a remarkable amalgamation of derivatives from distinct embryonic cell lineages. During development, the cells in these lineages experience concerted movements, migrations, and signaling interactions that take them from their initial origins to their final destinations and imbue their derivatives with aspects of form including their axial orientation, anatomical identity, size, and shape. Perturbations along the way can produce defects and disease, but also generate the variation necessary for jaw evolution and adaptation. We focus on molecular and cellular mechanisms that regulate form in the amniote jaw complex, and that enable structural and functional integration. Special emphasis is placed on the role of cranial neural crest mesenchyme (NCM) during the species-specific patterning of bone, cartilage, tendon, muscle, and other jaw tissues. We also address the effects of biomechanical forces during jaw development and discuss ways in which certain molecular and cellular responses add adaptive and evolutionary plasticity to jaw morphology. Overall, we highlight how variation in molecular and cellular programs can promote the phenomenal diversity and functional morphology achieved during amniote jaw evolution or lead to the range of jaw defects and disease that affect the human condition

Influence of surface geometry on the culture of human cell lines: a comparative study using flat, round-bottom and v-shaped 96 well plates

© 2017 Shafaie et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.In vitro cell based models have been invaluable tools for studying cell behaviour and for investigating drug disposition, toxicity and potential adverse effects of administered drugs. Within this drug discovery pipeline, the ability to assess and prioritise candidate compounds as soon as possible offers a distinct advantage. However, the ability to apply this approach to a cell culture study is limited by the need to provide an accurate, in vitro-like, microenvironment in conjunction with a low cost and high-throughput screening (HTS) methodology. Although the geometry and/or alignment of cells has been reported to have a profound influence on cell growth and differentiation, only a handful of studies have directly compared the growth of a single cell line on different shaped multiwell plates the most commonly used substrate for HTS, in vitro, studies. Herein, the impact of various surface geometries (flat, round and v-shaped 96 well plates), as well as fixed volume growth media and fixed growth surface area have been investigated on the characteristics of three commonly used human cell lines in biopharmaceutical research and development, namely ARPE-19 (retinal epithelial), A549 (alveolar epithelial) and Malme-3M (dermal fibroblastic) cells. The effect of the surface curvature on cells was characterised using a combination of a metabolic activity assay (CellTiter AQ/MTS), LDH release profiles (CytoTox ONE) and absolute cell counts (Guava ViaCount), respectively. In addition, cell differentiation and expression of specific marker proteins were determined using flow cytometry. These in vitro results confirmed that surface topography had a significant effect (p < 0.05) on cell activity and morphology. However, although specific marker proteins were expressed on day 1 and 5 of the experiment, no significant differences were seen between the different plate geometries (p < 0.05) at the later time point. Accordingly, these results highlight the impact of substrate geometry on the culture of a cell line and the influence it has on the cells' correct growth and differentiation characteristics. As such, these results provide important implications in many aspects of cell biology the development of a HTS, in vitro, cell based systems to further investigate different aspects of toxicity testing and drug delivery.Peer reviewedFinal Published versio

β-Adrenergic Inhibition of Contractility in L6 Skeletal Muscle Cells

The β-adrenoceptors (β-ARs) control many cellular processes. Here, we show that β-ARs inhibit calcium depletion-induced cell contractility and subsequent cell detachment of L6 skeletal muscle cells. The mechanism underlying the cell detachment inhibition was studied by using a quantitative cell detachment assay. We demonstrate that cell detachment induced by depletion of extracellular calcium is due to myosin- and ROCK-dependent contractility. The β-AR inhibition of L6 skeletal muscle cell detachment was shown to be mediated by the β2-AR and increased cAMP but was surprisingly not dependent on the classical downstream effectors PKA or Epac, nor was it dependent on PKG, PI3K or PKC. However, inhibition of potassium channels blocks the β2-AR mediated effects. Furthermore, activation of potassium channels fully mimicked the results of β2-AR activation. In conclusion, we present a novel finding that β2-AR signaling inhibits contractility and thus cell detachment in L6 skeletal muscle cells by a cAMP and potassium channel dependent mechanism

The diffusion of policy in contexts of practice : flexible delivery in Australian vocational education and training

Significant changes have occurred over the last decade within the Australian Vocational Education and Training (VET) system. Not least amongst these has been a shift from a predominantly traditional face-to-face classroom model of programme delivery to more flexible models informed by the needs of clients. To lead this revolution, in 1991 the Australian Commonwealth and State Ministers for Training established the Flexible Delivery Working Party. A series of reports followed that sought to develop a policy framework, including a definition of flexible delivery, and its principles and characteristics. Despite these efforts, project funding and national staff development initiatives, several difficulties have been experienced in the &lsquo;take-up&rsquo; of flexible delivery; problems that we argue are related to how the dissemination of innovative practice is conceived. Specifically, the literature and research on the diffusion of innovations points to the efficacy of informal social networks &lsquo;in which individuals adopt the new idea as a result of talking with other individuals who have already adopted it&rsquo; (Valente, 1995, p. ix). Following a discussion of these issues, the article concludes by arguing the need for research of innovative practice transfer within VET in Australia, using qualitative case study in order to develop an in-depth and rich description of the process, and facilitate greater understanding of how it works in practice