627 resultados para Ectodomain Shedding


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In recent years the contribution of the marketing function has changed and interest now centres on its contribution to a firm’s financial performance. The Marketing Science Institute in the USA has stated that it is the number one marketing issue facing corporate America. The Australian Marketing Institute is promoting a set of marketing metrics that will help Australian firms measure the function’s contribution to shareholder value creation. Much of the literature relates notions such as customer satisfaction and other marketing activities with a firm’s profit. A missing link appears to be the choice firms make in terms of which customer groups to target and the resultant impact on shareholder value performance. The generic customer groups comprise: existing customers, former customers and prospects. A review of the literature reveals that marketing costs and benefits vary across these groups. The challenge for management is to determine which group represents the best target and to allocate scarce marketing resources accordingly. The task is made even more challenging because the economic value of members within each group also varies and some product lines may be unprofitable and therefore, may not be worth pursuing. To generate superior shareholder value it may not simply be the case of acquiring the maximum number of new customers from any source but to find the appropriate mix of the generic customer groups and manage the individual customer relationships accordingly. This paper seeks to firstly summarise and review the recent literature on marketing and its relationship to shareholder value and secondly to propose a model for allocating marketing resources across generic customer groups in order to generate improved shareholder value performance. Importantly, the model not only covers increasing business with customers but also shedding customers or shedding the extent of business conducted with customers as means of generating shareholder value.

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Extracellular adenosine 5′-triphosphate (ATP) is an agonist for the P2Z receptor of human leukaemic lymphocytes and opens a Ca 2+-selective ion channel, which also conducts Ba2+, Sr2+ and the small fluorescent dye, ethidium+. A wide range of receptor agonists, many of which raise cytosolic [Ca2+] activate phospholipase D (PLD). In the present study, it was shown that both ATP and 3′-O-(4-benzoylbenzoyl)-ATP (BzATP) stimulated PLD activity in a concentration-dependent manner, and the inhibitory effects of suramin, oxidised ATP, extracellular Na+ and Mg2+ suggested that the effect of these agonists is mediated by P2Z receptors. The role of divalent cations in ATP-stimulated PLD activity was investigated. Several agonists (eg ATP, thapsigargin, ionomycin) stimulated a rise in cytosolic [Ca2+] in human lymphocytes, but only ATP and ionomycin stimulated PLD activity. When Ca2+ influx was prevented by EGTA, the majority of ATP-stimulated and all of ionomycin-stimulated PLD activity was inhibited. Preloading cells with the Ca2+ chelator, BAPTA, reduced cytosolic [Ca2+] and, paradoxically, ATP-stimulated PLD activity was potentiated. ATP-stimulated PLD activity was supported by both Ba2+ and Sr2+ when they were substituted for extracellular Ca2+. Furthermore, both ATP-stimulated PLD activity and ATP-stimulated 133Ba2+ influx showed a linear dependence on extracellular [Ba2+]. Thus it was concluded that ATP stimulated PLD activity in direct proportion to the influx of divalent cations through the P2Z ion channel and this PLD activity was insensitive to changes in bulk cytosolic [Ca2+]. The calmodulin (Ca2+/CaM) inhibitor, trifluoperazine (TFP) inhibited ionomycin- and ATP-stimulated PLD activity and ATP-stimulated apoptosis, but had no effect on PLD activity already activated by ATP. However, TFP inhibited ATP-stimulated Ca2+, Ba2+ and ethidium+ fluxes, at concentrations below those which inhibit Ca2+/CaM, suggesting that TFP inhibits the P2Z receptor. Similarly, the isoquinolinesulphonamide, KN-62, a selective inhibitor of Ca2+/CaM-dependent protein kinase II (CaMKII), also prevented ATP-stimulated apoptosis, but had no effect on pre-activated PLD. In addition, KN-62, and an analogue, KN-04, which has no effect on CaMKII, potently inhibited ATP-stimulated Ba2+ influx (IC50 12.7 ± 1.5 and 17.3 ± 2.7 nM, respectively), ATP-stimulated ethidium+ uptake (IC50 13.1 ± 2.6 and 37.2 ± 8.9 nM, respectively), ATP-stimulated phospholipase D activity (50% inhibition 5.9 ± 1.2 and 9.7 ± 2.8 nM, respectively) and ATP-induced shedding of the surface adhesion molecule, L-selectin (IC50 31.5 ± 4.5 and 78.7 ± 10.8 nM, respectively). They did not inhibit phorbol ester- or ionomycin-stimulated PLD activity or phorbol ester-induced L-selectin shedding. Neither KN-62 nor KN-04 (both 500 nM) have any effect on UTP-stimulated Ca2+ transients in fura-2-loaded human neutrophils, a response which is mediated by the P2Y2 receptor, neither did they inhibit ATP-stimulated contractile responses mediated by the P2X1 receptor of guinea pig urinary bladder. Thus, KN-62 and KN-04 are almost equipotent as P2Z inhibitors with IC50s in the nanomolar, indicating that their actions cannot be due to CaMKII inhibition, but rather that they are potent and direct inhibitors of the P2Z receptor. Extracellular ATP-induced shedding of L-selectin from lymphocytes into the medium is a Ca2+-independent response. L-selectin is either cleaved by a metalloproteinase or a PLD with specificity for glycosylphosphatidylinositol (GPI). The novel hydroxamic acid-based zinc chelator, Ro-31-9790 blocks ATP-induced L-selectin shedding, but was without effect on ATP-induced Ba2+ influx or ATP-stimulated PLD activity. Furthermore, another zinc chelator, 1,10-phenanthroline, an inhibitor of a GPI-PLD, potentiated rather than inhibited ATP-stimulated PLD activity, suggesting that ATP-induced L-selectin shedding and ATP-stimulated PLD activity are independent of each other. Although extracellular ATP is the natural ligand for the lymphocyte P2Z receptor, it is less potent than BzATP in stimulating Ba2+ influx. Concentration-response curves for BzATP- and ATP-stimulated ethidium+ influx gave EC50s 15.4 ± 1.4 µM and 85.6 ± 8.8 µM, respectively. The maximal response to ATP was only 69.8 ± 1.9% of that for BzATP. Hill coefficients were 3.17 ± 0.24 and 2.09 ± 0.45 for BzATP and ATP respectively, suggesting greater positive cooperativity for BzATP than for ATP in opening the P2Z-operated ion channel. A rank order of agonist potency of BzATP > ATP = 2MeSATP > ATPγS was observed for agonist-stimulated ethidium+ influx, while maximal influxes followed a rank order of BzATP > ATP > 2MeSATP > ATPγS. When ATP (300 -1000 µM) was added simultaneously with 30 µM BzATP (EC90), it reduced both ethidium+ and Ba2+ fluxes by 30 - 40% relative to values observed with BzATP alone. KN-62, previously shown to be a specific inhibitor of the lymphocyte P2Z receptor, was a less potent antagonist of BzATP-induced fluxes than ATP, when maximal concentrations of both agonists (50 and 500 µM respectively) were used. However, when BzATP (18 µM) was used at a concentration equiactive with a maximally effective ATP concentration, KN-62 showed the same inhibitory potency for both agonists. The ecto-ATPase antagonist, ARL-67156, inhibited both ATP- and BzATP-stimulated Ba2+ influx, suggesting that the lower efficacy of ATP compared with BzATP was not due to preferential hydrolysis of ATP. Thus, the natural ligand, ATP, is a partial agonist for the P2Z receptor while BzATP is a full agonist. Moreover the competitive studies show that only a single class of P2-receptor (P2Z class) is expressed on human leukaemic lymphocytes. Both ATP- and BzATP-stimulated PLD activity were significantly inhibited (P < 0.05) when cells were suspended in iso-osmotic choline Cl medium. Choline+ was found to be a permeant for the P2Z ion channel, since ATP induced a large uptake of [14C]choline+ (60 to 150 µmol/ml intracellular water) during a 5 min incubation, which remained in the cells for several hours, and ATP was used to load cells with these levels of choline+. Intracellular choline+ inhibited ATP-, BzATP-, PMA- and ionomycin-stimulated PLD activity. Brief exposure of lymphocytes to ATP increased the subsequent basal rate of ethidium+ uptake, and this was prevented by intracellular choline+. It is proposed that P2Z-mediated Ca2+ influx in lymphocytes activates PLD leading to significantly changes of the phospholipid composition of the plasma membrane, which subsequently produces a permeability lesion, which in turn contributes to cell death.

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The proliferation of the malaria parasite Plasmodium falciparum within the human host is dependent upon invasion of erythrocytes. This process is accomplished by the merozoite, a highly specialized form of the parasite. Secretory organelles including micronemes and rhoptries play a pivotal role in the invasion process by storing and releasing parasite proteins. The mechanism of protein sorting to these compartments is unclear. Using a transgenic approach we show that trafficking of the most abundant micronemal proteins (members of the EBL-family: EBA-175, EBA-140/BAEBL, and EBA-181/JSEBL) is independent of their cytoplasmic and transmembrane domains, respectively. To identify the minimal sequence requirements for microneme trafficking, we generated parasites expressing EBAGFP chimeric proteins and analyzed their distribution within the infected erythrocyte. This revealed that: (i) a conserved cysteine-rich region in the ectodomain is necessary for protein trafficking to the micronemes and (ii) correct sorting is dependent on accurate timing of expression.

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Cattle grow and shed fibre which assists them adapt to seasonal changes in the environment. In the absence of cattle fibre production data for southern Australia, Angus, Hereford, Simmental and Limousin cows and crosses between these breeds grazing perennial pastures at Hamilton, Victoria were sampled in late winter. The fibre-growing area on the sides of cattle was measured, fibre sampled at the mid-side site and the sampling area determined. Fibre was tested for fibre diameter distribution, clean washing yield and fibre length measured. Cows were 3-7 years of age, liveweights were 412-712 kg and the mean fibre-growing area was 2.2 m2. This produced an average 682 g of total fibre (range 3461-175 g). The mean fibre diameter of all fibres was 51.7 μm (range 43-62 μm) and 18% of fibres were 36 μm (range 6-39%). The clean washing yield was 92.4% (range 87.4-95.8%). Fibre length averaged 21 mm. Increasing the age, liveweight and condition score of cows and increasing weight of clean fibre were associated with significant increases in mean fibre diameter. Breed of cattle did not affect fibre production (P > 0.1) but did affect mean fibre diameter (P < 0.05). The quantity of fibre production indicates potential for low value textile production. The high level of total fibre production, twice that of an earlier report, and fibre shedding from cattle suggests that white fibre-producing animals such as Merino sheep, Angora and cashmere goats and alpaca should avoid using cattle-handling facilities, particularly in the month before shearing.

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EGF domains are extracellular protein modules cross-linked by three intradomain disulfides. Past studies suggest the existence of two types of EGF domain with three-disulfides, human EGF-like (hEGF) domains and complement C1r-like (cEGF) domains, but to date no functional information has been related to the two different types, and they are not differentiated in sequence or structure databases. We have developed new sequence patterns based on the different C-termini to search specifically for the two types of EGF domains in sequence databases. The exhibited sensitivity and specificity of the new pattern-based method represents a significant advancement over the currently available sequence detection techniques. We re-annotated EGF sequences in the latest release of Swiss-Prot looking for functional relationships that might correlate with EGF type. We show that important post-translational modifications of three-disulfide EGFs, including unusual forms of glycosylation and post-translational proteolytic processing, are dependent on EGF subtype. For example, EGF domains that are shed from the cell surface and mediate intercellular signaling are all hEGFs, as are all human EGF receptor family ligands. Additional experimental data suggest that functional specialization has accompanied subtype divergence. Based on our structural analysis of EGF domains with three-disulfide bonds and comparison to laminin and integrin-like EGF domains with an additional interdomain disulfide, we propose that these hEGF and cEGF domains may have arisen from a four-disulfide ancestor by selective loss of different cysteine residues.

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The conceptual understanding of museums as ‘contact zones’ has been widely appropriated in the museum literature and beyond. But the discussion lacks empirical insights into actual experiences: What does ‘contact’ mean for the person experiencing it? How is it lived, negotiated and contested? Drawing on a long-term narrative study of global visitors to the Museum of New Zealand Te Papa Tongarewa (Te Papa), this paper offers an empirical interrogation and theoretical refinement of the ‘contact zone’. It moves beyond the more usual focus on museological production by shedding light on the meanings made by museum visitors. This paper augments current normative and theoretical approaches with an ethnographic study of processes of intercultural mediation during cross-cultural encounters, translation and dialogue. This is done through a hermeneutic analysis of visitors’ acts of interpretation that facilitates an understanding of ‘cultural action’ in ‘contact zones’ as an interpretive ontological endeavour of the shifting Self within a pluralist cosmopolitan space.

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Climate change adaptation and mitigation continues to be a prevalent discourse in this country and internationally in both the sciences and the arts. While various types and degrees of change are evident, the quantification of these changes including their scope and diversity have challenged conventional sciences. This is demonstrated in their inability to succinctly answer key questions about change including the degree of change and associated patterns and consequences. Most of this discourse is nested in a temporal band comprising the last 100-200 years of data and evidence, and very much informed by Western science perspectives and protocols. Little attempt has been made to engage with Australian Indigenous communities whom possess environmental knowledge of some 10,000-100,000 years albeit embedded in their artistic and oral narrative 'histories'. This paper explores the role and values that Australian Aboriginals, the Indigenous peoples of the Australian content, can offer in shedding new light on this discourse While focusing upon a cross-peri-urban Indigenous investigation, it examines this discourse though the lens of their words, terms, sentences as a vehicle to better understand a longitudinal perspective about climate change adaptation pertinent to Australia.

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Nick Dyer-Witheford’s Cyber-Marx was published nearly 15 years ago, but there are continuing echoes of its dire promises today. The trends that Dyer-Witheford outlined—the growth of tech-giants in the communications field at the expense of democratic media practices and the radical shedding of jobs in the traditional mass media context—are confirmed by recent events. In November 2013, Twitter launched itself on the public share register, despite having no visible means of financial support, or even much of a business plan. The Twitter IPO tells us a lot about the economy of cyber-capitalism. Aligned to the trend of ‘technological unemployment’ is the rise of what some commentators call ‘digital serfdom’. This is not just growing unemployment, but also drastic under-employment of talented media professionals and an alarming rise in the number of media outlets that want to pay contributors in ‘exposure’, rather than in corporeal, fungible dollars and cents. This articlediscusses these trends and events in the context of the political economy of digital communication.

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Results of experiments conducted in a 2m high flume at large Reynolds numbers are reported in this paper. The flume was partitioned into two compartments. Flow entered the bottom of the upstream test compartment as a wall jet, at jet Reynolds number ranging from 11,000 to 170,000. Periodic oscillations of the free surface in the two compartments resembling the oscillatory flow in a liquid-filled U-tube, and large coherent structures formed above the potential core of the wall jet were observed. Coupling of the U-tube oscillations and vortex shedding is attributed to fluid-dynamic and fluid-resonant feedback processes. For test compartment length, Lc=0.8m , fluid-resonant feedback was found to be dominant, and the shear layer was observed to oscillate at the natural frequency of the two-compartment, U-tube system. The observed U-tube oscillations are initiated by the oscillations of the shear layer at a frequency equal to the subharmonic component for the U-tube. The flow oscillations were generally weaker for Lc=1.2 and 2.0m with oscillation frequencies governed by fluid-dynamic feedback, verified from a comparison with the results from a previously reported study.

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Measurements of the horizontal velocity component were made for a horizontal wall-jet emanating from a submerged sluice gate forming one side of a large flow compartment. The existence of large-scale vortex structures was quantified by spectral analysis of the velocity measurements taken at various distances from the floor of the flow compartment, for different measurement stations from the jet exit. Close to the jet exit, the spectra of the velocity measurements within the potential core exhibit multiple peaks. Further downstream, the spectra are more defined and peak at the same frequency, irrespective of whether the measurements were made within the potential core or the mixing layer. The spectral peak corresponds to the passage frequency of large-scale vortex structures. Downstream of the potential core, the peak frequencies of the velocity spectra increase as the measurement location was moved towards the floor of the flow compartment. The increase in peak frequencies is attributed to fluctuations associated with the wall boundary layer. Predictions of the mixing layer instabilities were made using linear stability analysis. The predictions are in good agreement with the observed vortex shedding frequencies in the mixing layer

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Cancer as a genetic disorder is one of the leading causes of death worldwide. Conventional anticancer options such as chemo- and/or radio-therapy have their own drawbacks and could not provide a cure in most cases at present. More effective therapeutic strategies with less side effects are urgently needed. Aptamers, also known as chemical antibodies, are single strand DNA or RNA molecules that can bind to their target molecules with high affinity and specificity. Such site-specific binding ability of aptamers facilitates the delivery and interaction of exogenous nucleic acids with diseased genes. Thus, aptamer-guided gene therapy has emerged as a promising anticancer strategy in addition to the classic treatment regimen. Aptamers can directly deliver anti-cancer nucleic acids, e.g. small interfering RNA, micro RNA, antimicroRNA and small hairpin RNA, to cancer cells or function as a targeting ligand to guide nanoparticles containing therapeutic nucleic acids. This review focuses on recent progress in aptamer-mediated gene therapy for the treatment of hepatocellular carcinoma and other types of cancers, shedding light on the potential of this novel approach of targeted cancer gene therapy.

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Migratory and resident hosts have been hypothesized to fulfil distinct roles in infectious disease dynamics. However, the contribution of resident and migratory hosts to wildlife infectious disease epidemiology, including that of low pathogenic avian influenza virus (LPAIV) in wild birds, has largely remained unstudied. During an autumn H3 LPAIV epizootic in free-living mallards (Anas platyrhynchos) - a partially migratory species - we identified resident and migratory host populations using stable hydrogen isotope analysis of flight feathers. We investigated the role of migratory and resident hosts separately in the introduction and maintenance of H3 LPAIV during the epizootic. To test this we analysed (i) H3 virus kinship, (ii) temporal patterns in H3 virus prevalence and shedding and (iii) H3-specific antibody prevalence in relation to host migratory strategy. We demonstrate that the H3 LPAIV strain causing the epizootic most likely originated from a single introduction, followed by local clonal expansion. The H3 LPAIV strain was genetically unrelated to H3 LPAIV detected both before and after the epizootic at the study site. During the LPAIV epizootic, migratory mallards were more often infected with H3 LPAIV than residents. Low titres of H3-specific antibodies were detected in only a few residents and migrants. Our results suggest that in this LPAIV epizootic, a single H3 virus was present in resident mallards prior to arrival of migratory mallards followed by a period of virus amplification, importantly associated with the influx of migratory mallards. Thus migrants are suggested to act as local amplifiers rather than the often suggested role as vectors importing novel strains from afar. Our study exemplifies that a multifaceted interdisciplinary approach offers promising opportunities to elucidate the role of migratory and resident hosts in infectious disease dynamics in wildlife.

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Wildlife pathogens can alter host fitness. Low pathogenic avian influenza virus (LPAIV) infection is thought to have negligible impacts on wild birds; however, effects of infection in free-living birds are largely unstudied. We investigated the extent to which LPAIV infection and shedding were associated with body condition and immune status in free-living mallards (Anas platyrhynchos), a partially migratory key LPAIV host species. We sampled mallards throughout the species' annual autumn LPAIV infection peak, and we classified individuals according to age, sex, and migratory strategy (based on stable hydrogen isotope analysis) when analyzing data on body mass and five indices of immune status. Body mass was similar for LPAIV-infected and noninfected birds. The degree of virus shedding from the cloaca and oropharynx was not associated with body mass. LPAIV infection and shedding were not associated with natural antibody (NAbs) and complement titers (first lines of defense against infections), concentrations of the acute phase protein haptoglobin (Hp), ratios of heterophils to lymphocytes (H:L ratio), and avian influenza virus (AIV)-specific antibody concentrations. NAbs titers were higher in LPAIV-infected males and local (i.e., short distance) migrants than in infected females and distant (i.e., long distance) migrants. Hp concentrations were higher in LPAIV-infected juveniles and females compared to infected adults and males. NAbs, complement, and Hp levels were lower in LPAIV-infected mallards in early autumn. Our study demonstrates weak associations between infection with and shedding of LPAIV and the body condition and immune status of free-living mallards. These results may support the role of mallards as asymptomatic carriers of LPAIV and raise questions about possible coevolution between virus and host.

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A hematopoiese representa uma cascata de eventos de proliferação e diferenciação celular precisamente regulada, onde uma população de células tronco pluripotentes indiferenciadas origina todas as células sangüíneas. Durante o período embrionário o principal órgão hematopoiético é o fígado. A partir do desenvolvimento dos ossos longos, a hematopoiese é deslocada para a medula óssea, sendo este, na vida adulta, o sítio de produção das células sangüíneas. O microambiente da medula óssea, composto pelas células estromais, componentes de matriz extracelular e fatores de crescimento ou citocinas, desempenha importância fundamental na proliferação e diferenciação das células progenitoras hematopoiéticas. Em algumas condições patológicas, na vida adulta, a hematopoiese pode ser observada em sítios extramedulares, especialmente no fígado, que demonstra assim preservar um potencial hematopoiético. Este fenômeno é descrito como hematopoiese extramedular e pode estar associado a reações fibrogranulomatosas, como a esquistossomose mansônica. No presente estudo avaliou-se a hipótese de que os gangliosídios possam participar do microambiente carregado negativamente necessário para o suporte da hematopoiese. Para isso, analisou-se o conteúdo, síntese e liberação (shedding) de gangliosídios de dois estromas extramedulares, GRWT e GR(IFN-Ro/o), que expressam GM-CSF de maneira semelhante, mas têm capacidades diferentes de suporte da mielopoiese in vitro. A capacidade de suporte da hematopoiese pelos dois estromas foi monitorada através da proliferação das células FDC-P1, uma linhagem precursora mielóide. Observamos que os dois estromas sintetizam e liberam os mesmos gangliosídios, embora em proporções diferentes. Também verificamos que a inibição da síntese de gangliosídios diminui a proliferação mielopoiética em ambos os estromas extramedulares.

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Esta dissertação mapeia a rede de relações intertextuais em Half a Life (2001) e sua continuação Magic Seeds (2004), os romances mais recentes do Prêmio Nobel de Literatura de 2001, V. S. Naipaul, como contribuição para o estudo da obra do autor. A noção de intertextualidade permeia os estudos literários, e o termo tem sido largamente empregado desde que foi cunhado por Julia Kristeva nos anos sessenta. Desde então as mais variadas, e muitas vezes divergentes, teorias sobre intertextualidade compartilham a idéia de que um texto só adquire significado pleno na interação com outros textos. A abordagem metodológica proposta é baseada na teoria da transtextualidade de Gérard Genette. Esta escolha implica o estudo de intertextos, paratextos, metatextos, arquitextos e hipertextos que constituem a interface entre os dois romances e outros escritos. O nome do protagonista "William Somerset Chandran" constitui o fio que guia o estudo das várias relações transtextuais nos dois romances. A partir do prenome do protagonista – William – este estudo situa os romances no contexto da tradição do Bildungsroman, e argumenta que estes estabelecem uma paródia arquitextual do gênero na medida em que subvertem seu cerne, ou seja, a formação do caráter do protagonista. O nome do meio do protagonista – Somerset – remete à ficcionalização do escritor Somerset Maugham na narrativa, ao mesmo tempo em que esta desmistifica a ótica ocidental sobre o hinduísmo popularizada por Maugham em The Razor's Edge. O sobrenome do protagonista – Chandran – leva ao estudo do conjunto de referências à origem indiana de Naipaul e o papel desta na produção do autor. Este nome se reporta ao romance de Narayan The Bachelor of Arts, cujo protagonista também é nomeado Chandran. Narayan é um escritor de destaque na literatura anglo-indiana e referência recorrente na obra de Naipaul. Os temas de migração e choque cultural apresentados nos dois romances têm sido presença constante na obra de Naipaul. Esta pesquisa mapeia a relação de continuidade entre os dois romances em questão e o conjunto da obra de Naipaul, salientando o papel da ambientação geográfica da narrativa, marcada pela jornada do protagonista através de três continentes. A teoria da transtextualidade é uma ferramenta operacional para a pesquisa, a qual examina a densidade das referências geográficas, históricas e literárias em Half a Life e Magic Seeds, visando aportar elementos para o estudo da produção literária de Naipaul, na medida em que estes romances recentes condensam e revisitam a visão de mundo deste autor.