41 resultados para Motifs
Resumo:
The application of computational techniques to the analysis of heritage artifacts enables scholars to bring together diverse fragments of surviving evidence, construe "best-fit" strategies and unearth implicit or hidden relationships. This paper reports a hybrid approach for recovering the surface geometry of temples. The approach combines physical measurements, architectural photogrammetry and generative rules to create a parametric model of the surface. The computing of surface geometry is broken into three parts, a global model governing the overall form of the superstructure, local models governing the geometry of individual motifs and finally the global and local models are combined into a single geometry. In this paper, the technique for recovering surface geometry is applied to a tenth century stone superstructure: the temple of Ranakdevi at Wadhwan in Western India. The global model of the superstructure and the local model of one individual motif are presented.
Resumo:
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.
Resumo:
Human telomerase reverse transcriptase (hTERT) underlies cancer cell immortalization, and the expression of hTERT is regulated strictly at the gene transcription. Here, we report that transcription factor Ets2 is required for hTERT gene expression and breast cancer cell proliferation. Silencing Ets2 induces a decrease of hTERT gene expression and increase in human breast cancer cell death. Reconstitution with recombinant hTERT rescues the apoptosis induced by Ets2 depression. In vitro and in vivo analyses show that Ets2 binds to the EtsA and EtsB DNA motifs on the hTERT gene promoter. Mutation of either Ets2 binding site reduces the hTERT promoter transcriptional activity. Moreover, Ets2 forms a complex with c-Myc as demonstrated by co-immunoprecipitation and glutathione S-transferase pulldown assays. Immunological depletion of Ets2, or mutation of the EtsA DNA motif, disables c-Myc binding to the E-box, whereas removal of c-Myc or mutation of the E-box also compromises Ets2 binding to EtsA. Thus, hTERT gene expression is maintained by a mechanism involving Ets2 interactions with the c-Myc transcription factor and the hTERT gene promoter, a protein-DNA complex critical for hTERT gene expression and breast cancer cell proliferation.
Resumo:
This thesis is submitted within the discipline of Women's Studies. It attempts to assess the life of women in a tribal society at the brink of dissolution. Wales at the eve of and during the first century of the Norman occupation is representative of such a society and historians admit that what little we know of its social conditions can be gleaned from the pages of the narrative prose collection The Mabinogion. Consequently this study uses an interdisciplinary approach. Eight stories from The Mabinogion collection have been studied: The Four Branches, comprising Pwyll Prince of Dyfed, Branwen Daughter of Llyr, Manawydan Son of Llyr and Math Son of Mathonwwy; the story of Culhwch and Olwen and the Three Romances, comprising The Lady of the Fountain, Peredur Son of Efrawg and Gereint Son of Erbin. The Four Branches are a fourfold narrative held together by the figure of Sovereignty (formerly the Celtic goddess of the land), her chosen consort and her son. The protagonists are now represented as superhuman men and women and encoded in their lifestories are the rules for gender-related 'right' behaviour of princes and their spouses. The Three Romances still show the same constellation, but the figures of Sovereignty and her consort have been replaced by the Knight and his Lady with considerable loss of behavioural certainty for both genders. The romances are also indicative of growing economic insecurity. Culhwch and Olwen has been included for contrast and for its richness in folkloric motifs. Apart from studying the gender-roles in leading families at the time, the thesis advances the theory that The Four Branches may have been the work of a Welsh noblewoman - a theory based on the inherent knowledge of Welsh pre-Christian dynastic traditions, legal and political practices and the realities of women's lives at the time. The study also shows that the status of women and their legal rights in pre-Norman Wales were much more restricted and cannot generally be compared with that of women in England or Ireland.
Resumo:
The major component of the thesis is a manuscript of poetry titled How do detectives make love? which includes forty poems written over a period of two years. Many of these; poems have been published in literary journals and magazines both in Australia and internationally as well as being performed at various performance poetry venues. How do detectives make love? was accepted for publication by Penguin Books, Australia in 1994. Also included is a 12,000 word exegesis in support of the manuscript titled How do detectives make love? Themes of the survival of the child: corruption in relation to innocence. The exegesis explores various themes and motifs occurring throughout the work, including the motif of birds and dogs, and the themes of love and the police, guns and weaponry, the outback and parklands, the parents, the change from childhood to adolescence and adolescence to adulthood, and the survival of the child. The current vital social relevance of these themes and motifs is explored in the poems. The literary use of the themes is explored comparatively with the work of other Australian poets including Gig Ryan, Kenneth Slessor and Les Murray. The purpose of the exegesis is to give the reader insights into the poet's intellectual processes and literary concerns throughout the work itself.
Resumo:
In this paper, I examine some of the key management literature of the neoliberal 1990s to make a series of wider observations about contemporary ideology. Post-structuralist or post-modernist theory is often presented as the arch-enemy of neoliberal capitalism, as the orthodoxy of late capitalism. However, adding to work by Frederic Jameson, Thomas Frank and others, this paper examines uncanny proximity between neoliberal ideas about disaggregating, outsourcing, networking, etc. and the learning motifs of postmodernist theory. Its guiding hypothesis is that postmodernism in the academy, despite its own self-misrecognition as "racial", is a further ideological expression of the samr neoliberal drive to overcome "Fordist", "authoritarian" ways of organising producation and social regulation.
Resumo:
In molluscs, the neurotransmitter serotonin (5-HT) has been linked to a variety of biological roles including gamete maturation and spawning. The possible involvement of 5-HT in abalone gamete release was demonstrated by a dose-dependent increase in Haliotis rubra gonad contractile bioactivity following 5-HT stimulation. Physiological functions associated with 5-HT, are mediated through binding to 5-HT receptors. A cDNA encoding a putative 5-HT receptor consisting of 359 amino acids was isolated from the tropical abalone H. asinina, termed 5-HT1 ha. The 5-HT1 ha shares G-protein-coupled receptor motifs with metazoan 5-HT receptors, including predicted transmembrane domains, active sites for protein kinase action, and N-linked glycosylation sites. However, the third intracellular loop of 5-HT1 ha is relatively short, and only six transmembrane domains are predicted, implying a truncated receptor. Phylogenetic analysis with known 5-HT receptor genes suggests that 5-HT1 ha belongs to the type 1 5-HT receptor family. Expression analysis by RT-PCR showed that 5-HT1 ha mRNA was present in all tissues examined, including the neural ganglia and gonad tissues. Immunocytochemistry revealed the presence of 5-HT1 ha specifically within the soma of neuronal cells located in the outer cortex of both cerebral and pleuropedal ganglia. In ovarian and testicular tissues, 5-HT1 ha immunoreactivity was observed in epithelial cells of the outer capsule and connective tissue of the trabeculae to which the gamete follicles adhere. Whether this receptor transcript is translated to a functional protein needs to be verified, but if so, it could play a role in reproduction.
Resumo:
The project focusses on the discovery of conserved DNA sequences in bacterial genomes and comparative analysis of bacterial genomes to elicit evolutionary trends. The outcomes have produced novel techniques for modelling motifs in DNA and the characterisation of evolutionary processes in medically significant bacterial pathogens.
Resumo:
Objective
Glucosamine has been previously shown to suppress cartilage aggrecan catabolism in explant cultures. We determined the effect of glucosamine on ADAMTS5 (a disintegrin-like and metalloprotease domain (reprolysin type) with thrombospondin type-1 motifs 5), a major aggrecanase in osteoarthritis, and investigated a potential mechanism underlying the observed effects.
Design
HEK293F and CHO-K1 cells transiently transfected with ADAMTS5 cDNA were treated with glucosamine or the related hexosamine mannosamine. Glucosamine effects on FURIN transcription were determined by quantitative RT-PCR. Effects on furin-mediated processing of ADAMTS5 zymogen, and aggrecan processing by glucosamine-treated cells, were determined by western blotting. Post-translational modification of furin and N-glycan deficient furin mutants generated by site-directed mutagenesis was analyzed by western blotting, and the mutants were evaluated for their ADAMTS5 processing ability in furin-deficient CHO-RPE.40 cells.
Results
Ten mM glucosamine and 5–10 mM mannosamine reduced excision of the ADAMTS5 propeptide, indicating interference with the propeptide excision mechanism, although mannosamine compromised cell viability at these doses. Although glucosamine had no effect on furin mRNA levels, western blot of furin from glucosamine-treated cells suggested altered post-translational modification. Glucosamine treatment led to decreased glycosylation of cellular furin, with reduced furin autoactivation as the consequence. Recombinant furin treated with peptide N-glycanase F had reduced activity against a synthetic peptide substrate. Indeed, site-directed mutagenesis of two furin N-glycosylation sites, Asn387 and Asn440, abrogated furin activation and this mutant was unable to rescue ADAMTS5 processing in furin-deficient cells.
Conclusions
Ten mM glucosamine reduces excision of the ADAMTS5 propeptide via interference with post-translational modification of furin and leads to reduced aggrecanase activity of ADAMTS5.
Resumo:
Pathogenic viruses have developed a molecular defense arsenal for their survival by counteracting the host anti-viral system known as RNA interference (RNAi). Cellular RNAi, in addition to regulating gene expression through microRNAs, also serves as a barrier against invasive foreign nucleic acids. RNAi is conserved across the biological species, including plants, animals and invertebrates. Viruses in turn, have evolved mechanisms that can counteract this anti-viral defense of the host. Recent studies of mammalian viruses exhibiting RNA silencing suppressor (RSS) activity have further advanced our understanding of RNAi in terms of host–virus interactions. Viral proteins and non-coding viral RNAs can inhibit the RNAi (miRNA/siRNA) pathway through different mechanisms. Mammalian viruses having dsRNA-binding regions and GW/WG motifs appear to have a high chance of conferring RSS activity. Although, RSSs of plant and invertebrate viruses have been well characterized, mammalian viral RSSs still need in-depth investigations to present the concrete evidences supporting their RNAi ablation characteristics. The information presented in this review together with any perspective research should help to predict and identify the RSS activity-endowed new viral proteins that could be the potential targets for designing novel anti-viral therapeutics.
Resumo:
Many nuclear and nucleolar small RNAs are accumulated as nonpolyadenylated species and require 3′-end processing for maturation. Here, we show that several genes coding for box C/D and H/ACA snoRNAs and for the U5 and U2 snRNAs contain sequences in their 3′ portions which direct cleavage of primary transcripts without being polyadenylated. Genetic analysis of yeasts with mutations in different components of the pre-mRNA cleavage and polyadenylation machinery suggests that this mechanism of 3"-end formation requires cleavage factor IA (CF IA) but not cleavage and polyadenylation factor activity. However, in vitro results indicate that other factors participate in the reaction besides CF IA. Sequence analysis of snoRNA genes indicated that they contain conserved motifs in their 3" noncoding regions, and mutational studies demonstrated their essential role in 3"-end formation. We propose a model in which CF IA functions in cleavage and polyadenylation of pre-mRNAs and, in combination with a different set of factors, in 3"-end formation of nonpolyadenylated polymerase II transcripts.
Resumo:
In mammals the M1 aminopeptidase family consists of nine different proteins, five of which are integral membrane proteins. The aminopeptidases are defined by two motifs in the catalytic domain; a zinc binding motif HEXXH-(X18)-E and an exopeptidase motif GXMEN. Aminopeptidases of this family are able to cleave a broad range of peptides down to only to a single peptide. This ability to either generate or degrade active peptide hormones is the focus of this review. In addition to their capacity to degrade a range of peptides a number of these aminopeptidases have novel functions that impact on cell signalling and will be discussed.
Resumo:
Peptide inhibitors of insulin-regulated aminopeptidase (IRAP) accelerate spatial learning and facilitate memory retention and retrieval by binding competitively to the catalytic site of the enzyme and inhibiting its catalytic activity. IRAP belongs to the M1 family of Zn2+-dependent aminopeptidases characterized by a catalytic domain that contains two conserved motifs, the HEXXH(X)18E Zn2+-binding motif and the GXMEN exopeptidase motif. To elucidate the role of GXMEN in binding peptide substrates and competitive inhibitors, site-directed mutagenesis was performed on the motif. Non-conserved mutations of residues G428, A429 and N432 resulted in mutant enzymes with altered catalytic activity, as well as divergent changes in kinetic properties towards the synthetic substrate leucine β-naphthalamide. The affinities of the IRAP inhibitors angiotensin IV, Nle1-angiotensin IV, and LVV-hemorphin-7 were selectively decreased. Substrate degradation studies using the in vitro substrates vasopressin and Leu-enkephalin showed that replacement of G428 by either D, E or Q selectively abolished the catalysis of Leu-enkephalin, while [A429G]IRAP and [N432A]IRAP mutants were incapable of cleaving both substrates. These mutational studies indicate that G428, A429 and N432 are important for binding of both peptide substrates and inhibitors, and confirm previous results demonstrating that peptide IRAP inhibitors competitively bind to its catalytic site.
Resumo:
What follows is a work of critical reconstruction of Camus' thought. It aims to answer to the wish Camus expressed in his later notebooks, that he at least be read closely. Specifically, I hope to do three things. In Part I, we will show how Camus' famous philosophy of the absurd represents a systematic scepticism whose closest philosophical predecessor is Descartes' method of doubt, and whose consequence, as in Descartes, is the discovery of a single, orienting certainty, on the basis of which Camus would proceed to pass beyond the 'nihilism' that conservative critics continued to level against him (MS 34). Part II will unfold the central tenets of Camus' mature thought of rebellion, and show how Camus' central political claims follow from his para-Cartesian claim to have found an irreducible or 'invincible' basis for a post-metaphysical ethics, consistent with the most thoroughgoing epistemic scepticism. Part III then undertakes to show that the neoclassical rhetoric and positioning Camus claimed for his postwar thought—as a thought of moderation or mesure, and a renewed Greek or Mediterranean naturalism—is more than a stylistic pretension. It represents, so I argue, a singular amalgam of modern and philosophical classical motifs which makes Camus' voice nearly unique in twentieth century ideas, and all the more worth reconsidering today. So let us proceed.
Resumo:
The essay critically discusses the predominant role played by water in the lives of people from Vedic times to the present day, in the Hindu world. A number of ceremonies both happy or auspicious-making and secular have been associated with water. Several hymns of the Vedas, Brāhmanas, Mahābhārata, Āgamic and Purānic texts are drawn upon to bring out the legends and myths, and genuine beliefs, connected with water that underscore the sacred and profane, purificatory, healing and resuscitating dimensions of water. The essay treats readers to many ancient motifs concerning the pervasive value and utility of water. These comprise, variously, sacrifice, fertility rites, water-medium birth, divine metamorphosis, self-conceiving cosmic birth, totemism life-cycle rites, sanctifications, consecration and installation of icons and edifices, food rituals, monsoon rites, to pacifications, possession and exorcism, death, after-life and rebirth rituals. Reference is also made to the ecology of water resources, the economy of water scarcity, ‘war-wars’ or water imperialism, and water justice in the socio-political arenas of post independent India, in a rapidly liberalising and globalising world. In that regard practical applications of the knowledge-base are explored through the work of NGOs and Water Swamis in the subcontinent.