21 resultados para Bee

em Deakin Research Online - Australia


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Artificial Neural Networks (ANN) performance depends on network topology, activation function, behaviors of data, suitable synapse's values and learning algorithms. Many existing works used different learning algorithms to train ANN for getting high performance. Artificial Bee Colony (ABC) algorithm is one of the latest successfully Swarm Intelligence based technique for training Multilayer Perceptron (MLP). Normally Gbest Guided Artificial Bee Colony (GGABC) algorithm has strong exploitation process for solving mathematical problems, however the poor exploration creates problems like slow convergence and trapping in local minima. In this paper, the Improved Gbest Guided Artificial Bee Colony (IGGABC) algorithm is proposed for finding global optima. The proposed IGGABC algorithm has strong exploitation and exploration processes. The experimental results show that IGGABC algorithm performs better than that standard GGABC, BP and ABC algorithms for Boolean data classification and time-series prediction tasks.

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The segment C-terminal to the hydrophobic motif at the V5 domain of protein kinase C (PKC) is the least conserved both in length and in amino acid identity among all PKC isozymes. By generating serial truncation mutants followed by biochemical and functional analyses, we show here that the very C terminus of PKCα is critical in conferring the full catalytic competence to the kinase and for transducing signals in cells. Deletion of one C-terminal amino acid residue caused the loss of ~60% of the catalytic activity of the mutant PKCα, whereas deletion of 10 C-terminal amino acid residues abrogated the catalytic activity of PKCα in immune complex kinase assays. The PKCα C-terminal truncation mutants were found to lose their ability to activate mitogen-activated protein kinase, to rescue apoptosis induced by the inhibition of endogenous PKC in COS cells, and to augment melatonin-stimulated neurite outgrowth. Furthermore, molecular dynamics simulations revealed that the deletion of 1 or 10 C-terminal residues results in the deformation of the V5 domain and the ATP-binding pocket, respectively. Finally, PKCα immunoprecipitated using an antibody against its C terminus had only marginal catalytic activity compared with that of the PKCα immunoprecipitated by an antibody against its N terminus. Therefore, the very C-terminal tail of PKCα is a novel determinant of the catalytic activity of PKC and a promising target for selective modulation of PKCα function. Molecules that bind preferentially to the very C terminus of distinct PKC isozymes and suppress their catalytic activity may constitute a new class of selective inhibitors of PKC.

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Protein kinase C (PKC) is a family of serine/threonine protein kinases that are pivotal in cellular regulation. Since its discovery in 1977, PKCs have been known as cytosolic and peripheral membrane proteins. However, there are reports that PKC can insert into phospholipids vesicles in vitro. Given the intimate relationship between the plasma membrane and the activation of PKC, it is important to determine whether such “membrane-inserted” form of PKC exists in mammalian cells or tissues. Here, we report the identification of an integral plasma membrane pool for all the 10 PKC isozymes in vivo by their ability to partition into the detergent-rich phase in Triton X-114 phase partitioning, and by their resistance to extractions with 0.2 M sodium carbonate (pH 11.5), 2 M urea and 2 M sodium chloride. The endogenous integral membrane pool of PKC in mouse fibroblasts is found to be acutely regulated by phorbol ester or diacylglycerol, suggesting that this pool of PKC may participate in cellular processes known to be regulated by PKC. At least for PKCα, the C2–V3 region at the regulatory domain of the kinase is responsible for membrane integration. Further exploration of the function of this novel integral plasma membrane pool of PKC will not only shed new light on molecular mechanisms underlying its cellular functions but also provide new strategies for pharmaceutical modulation of this important group of kinases.

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Protein kinase C (PKC) is a key regulator of cell proliferation, differentiation, and apoptosis and is one of the drug targets of anticancer therapy. Recently, a single point mutation (D294G) in PKCα has been found in pituitary and thyroid tumors with more invasive phenotype. Although the PKCα-D294G mutant is implicated in the progression of endocrine tumors, no apparent biochemical/cell biological abnormalities underlying tumorigenesis with this mutant have been found. We report here that the PKCα-D294G mutant is unable to bind to cellular membranes tightly despite the fact that it translocates to the membrane as efficiently as the wild-type PKCα upon treatment of phorbol ester. The impaired membrane binding is associated with this mutant's inability to transduce several antitumorigenic signals as it fails to mediate phorbol ester–stimulated translocation of myristoylated alanine–rich protein kinase C substrate (MARCKS), to activate mitogen-activated protein kinase and to augment melatonin-stimulated neurite outgrowth. Thus, the PKCα-D294G is a loss-of-function mutation. We propose that the wild-type PKCα may play important antitumorigenic roles in the progression of endocrine tumors. Therefore, developing selective activators instead of inhibitors of PKCα might provide effective pharmacological interventions for the treatment of certain endocrine tumors.

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In this article, we explore the role of the C-terminus (V5 domain) of PKCvar epsilon plays in the catalytic competence of the kinase using serial truncations followed by immune-complex kinase assays. Surprisingly, removal of the last seven amino acid residues at the C-terminus of PKCvar epsilon resulted in a PKCvar epsilon-Δ731 mutant with greatly reduced intrinsic catalytic activity while truncation of eight amino acid residues at the C-terminus resulted in a catalytically inactive PKCvar epsilon mutant. Computer modeling and molecular dynamics simulations showed that the last seven and/or eight amino acid residues of PKCvar epsilon were involved in interactions with residues in the catalytic core. Further truncation analyses revealed that the hydrophobic phosphorylation motif was dispensable for the physical interaction between PKCvar epsilon and 3-phosphoinositide-dependent kinase-1 (PDK-1) as the PKCvar epsilon mutant lacking both the turn and the hydrophobic motifs could still be co-immunoprecipitated with PDK-1. These results provide fresh insights into the biochemical and structural basis underlying the isozyme-specific regulation of PKC and suggest that the very C-termini of PKCs constitute a promising new target for the development of novel isozyme-specific inhibitors of PKC.

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PRK1/PKN is a member of the protein kinase C (PKC) superfamily of serine/threonine protein kinases. Despite its important role as a RhoA effector, limited information is available regarding how this kinase is regulated. We show here that the last seven amino acid residues at the C-terminus is dispensable for the catalytic activity of PRK1 but is critical for the in vivo stability of this kinase. Surprisingly, the intact hydrophobic motif in PRK1 is dispensable for 3-phosphoinositide-dependent kinase-1 (PDK-1) binding and phosphorylation of the activation loop, as the PRK1-Δ940 mutant lacking the last two residues of the hydrophobic motif and the last 5 residues at the C-terminus interacts with PDK-1 in vivo and has a similar specific activity as the wild-type protein. We also found that the last four amino acid residues at the C-terminus of PRK1 is critical for the full lipid responsiveness as the PRK1-Δ942 deletion mutant is no longer activated by arachidonic acid. Our data suggest that the very C-terminus in PRK1 is critically involved in the control of the catalytic activity and activation by lipids. Since this very C-terminal segment is the least conserved among members of the PKC superfamily, it would be a promising target for isozyme-specific pharmaceutical interventions.

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PRK1 is a lipid- and Rho GTPase-activated serine/threonine protein kinase implicated in the regulation of receptor trafficking, cytoskeletal dynamics and tumorigenesis. Although Rho binding has been mapped to the HR1 region in the regulatory domain of PRK1, the mechanism involved in the control of PRK1 activation following Rho binding is poorly understood. We now provide the first evidence that the very C-terminus beyond the hydrophobic motif in PRK1 is essential for the activation of this kinase by RhoA. Deletion of the HR1 region did not completely abolish the binding of PRK1-ΔHR1 to GTPγS-RhoA nor the activation of this mutant by GTPγS-RhoA in vitro. In contrast, removing of the last six amino acid residues from the C-terminus of PRK1 or truncating of a single C-terminal residue from PRK1-ΔHR1 completely abrogated the activation of these mutants by RhoA both in vitro and in vivo. The critical dependence of the very C-terminus of PRK1 on the signaling downstream of RhoA was further demonstrated by the failure of the PRK1 mutant lacking its six C-terminal residues to augment lisophosphatidic acid-elicited neurite retraction in neuronal cells. Thus, we show that the HR1 region is necessary but not sufficient in eliciting a full activation of PRK1 upon binding of RhoA. Instead, such activation is controlled by the very C-terminus of PRK1. Our results also suggest that the very C-terminus of PRK1, which is the least conserved among members of the protein kinase C superfamily, is a potential drug target for pharmacological intervention of RhoA-mediated signaling pathways

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Choreographer Kim Vincs and Scenographer Matthew Delbridge worked with dancer, Carlee Mellow, musicians Rob Vincs, Scott Dunbabin and Eugene Ughetti to create a virtual visual performance where performer's movement was rendered using a motion capture system and projected onto translucent screens.

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PRK2/PKNγ is a Rho effector and a member of the protein kinase C superfamily of serine/threonine kinases. Here, we explore the structure–function relationship between various motifs in the C-terminal half of PRK2 and its kinase activity and regulation. We report that two threonine residues at conserved phosphoacceptor position in the activation loop and the turn motif are essential for the catalytic activity of PRK2, but the phosphomimetic Asp-978 at hydrophobic motif is dispensable for kinase catalytic  competence. Moreover, the PRK2-Δ958 mutant with the turn motif truncated still interacts with 3-phosphoinositide-dependent kinase-1 (PDK-1). Thus, both the intact hydrophobic motif and the turn motif in PRK2 are dispensable for the binding of PDK-1. We also found that while the last seven amino acid residues at the C-terminus of PRK2 are not required for the activation of the kinase by RhoA in vitro, however, the extreme C-terminal segment is critical for the full activation of PRK2 by RhoA in cells in a GTP-dependent manner. Our data suggest that the extreme C-terminus of PRK2 may represent a potential drug target for effector-specific pharmacological intervention of Rho-medicated biological processes.

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Sustainability is a critical aim of Malaysian public policy and an important aim in education. Nonetheless, what sustainability means as it relates to education and the relationship between education and a sustainable future is unclear. In this paper I shall investigate the role that Universities in Malaysia play in shifting the practice and culture of innovation and creativity towards more sustainable values and outcomes. Sustainable education is based on ensuring that the capacities of students and the broader society are reengaged and empowered through connecting education to the needs and aspirations of civil society and moving away from neoliberal ideas of education as a practice of consumption towards, sustainable values of advancing human dignity.

Creativity and innovation within such an educational framework are goals and practices deeply connected and embedded within sustainable commitments to social justice, the public good, as well as individual growth and development which provide a critical legitimizing principle for university research and teaching. One of the key theoretical influences in making this argument will draw from the arguments of Amartya Sen whose theorization of capability may provide us with a way of thinking about social growth and development that is not possessively individualistic but rather socially concerned. I will discuss this in reference to the approach of University Sains Malaysia which provides an example of a public University seeking to engage sustainability and tie educational creativity and innovation back to the common good and a sustainable future.

The philosophical aim of this paper is to show how universities can pursue creativity and innovation as socially useful practices for advancing humane and sustainable values throughout Malaysian society and avoid the fusion of creativity with possessive individualism, consummerization and social irresponsibility. In this respect this paper addresses directly the theme of the conference: ‘Thinking Minds: Nurturing the Design of a Better Future'. '

To realise our national aspirations, a concerted effort is needed to increase our nation’s competitiveness, productivity and innovativeness. Attributes such as desire for knowledge, innovative thinking, creativity and competitiveness must be imbued within our people. The inculcation of moral values, progressiveness and performance-based cultures must also be instilled if we are to nurture successful individuals of the highest quality. This will determine our success as a knowledge-based economy.’ (Badawi 2007)

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Waterbirds, particularly Anatidae, are natural reservoirs for low-pathogenic avian influenza and have been implicated as the primary source of infection in outbreaks of highly pathogenic avian influenza. An understanding of the movements of birds and the ecology of avian influenza viruses within the wild bird population is essential in assessing the risks to human health and production industries. Marked differences in the movements of Australian birds from those of the Northern Hemisphere emphasises the danger of generalising trends of disease prevalence to Australian conditions. Populations of Anatidae in Australia are not migratory, as they are in the Northern Hemisphere, but rather display typical nomadic traits, sometimes moving large distances across continental Australia in response to flooding or drought. There is little known regular interchange of anatids between Australia and Asia. In contrast, species such as shorebirds and some seabirds are annual migrants to Australia along recognised flyways from breeding grounds in the Northern Hemisphere. Movement into Australia by these species mainly occurs into the north-west and along the east coast over the Pacific Ocean. These species primarily arrive during the Australian spring and form large aggregations along the coastline and on inland wetlands. Other Australian migratory species (passerines, bee-eaters, dollar-birds, cuckoos, doves) regularly move to and from Asia through the Torres Strait Islands. The disease status of these birds is unknown. The movements of some species, particularly anatids and ardeids, which have ranges including Australia and regions where the virus is known to occur, have been poorly studied and there is potential for introduction of avian influenza subtypes via this route. Avian influenza viruses are highly unpredictable and can undergo reassortment to more pathogenic forms. There is insufficient knowledge of the epidemiology and transmission of these viruses in Australia and broad-scale surveillance of wild birds is logistically difficult. Long-term studies of anatids that co-habit with Charadriiformes are recommended. This would provide an indication of the spatial and temporal patterns of subtypes entering Australia and improve our understanding of the ecology of endemic viruses. Until such time as these data become available, Australia's preparedness for avian influenza must focus on biosecurity at the wild bird–poultry interface.

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This study employs the Global Entrepreneurship Monitor (GEM) Model to examine the entrepreneurial environment of fourteen APEC economies, members of the GEM Consortium. If “the positive and statistically robust link between entrepreneurship and economic growth has been indisputably verified” (Audretsch et al. 2002), then the supply of entrepreneurship is critical for sustained economic activity in a country. We exploit the GEM 2002 dataset in a “Scorecard Approach” to compare and contrast the level of entrepreneurial framework conditions within these APEC economies.

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The Bee Hut is a moving and powerful conclusion to the career of a well-loved poet that displays her consistent belief in the transformative powers of the imagination, writes David McCooey.

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The nature, consequences and benefits of practice-based learning in architecture are explored nationally / transnationally from both student and practitioner perspectives. The findings suggest that the strengths of learning in practice contexts should be utilised and better integrated with formal learning at university for Australian architectural education in the 21st century.