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Daughter of fortune: Isabel Allende's popularity from a readership perspective
No full textThe primary aim of this thesis is to explore and critically interrogate Isabel Allende’s popularity cross-culturally in Britain and Spain. It analyses readers’ responses to Allende’s works as well as the discourses surrounding her public representation, an approach that is ‘readerly’ but must also take account of production and text. This approach is intended to further the understanding of Allende’s work which so far has always been analysed from a textual perspective. However, the relationship between Allende’s popularity, her texts, public representation and readers has not been yet analysed in detail.This thesis is innovative in other ways too. Methodologically, it approaches readers through the under studied cultural form of the reading group. It also incorporates a comparative dimension by looking at the reception of Allende in two different cultural contexts: the British and Spanish respectively. Finding out about Allende’s popularity has involved asking readers about their reading experiences as well as analysing the production of discourses around her public representation. Paul Ricoeur’s (1984, 1988) perspective on authorial intentions and readers’ responses to texts helps in understanding the intricacies surrounding what is involved in reading any text. It draws attention to Allende’s and her publishers’ authorial strategies, her ‘strategies of persuasion’ and the specificity of the lives and contexts of British and Spanish reading publics. Equally, this ‘readerly’ approach draws on feminist audience research and primarily on the work of Ien Ang and Janice Radway. Their work with viewers and readers respectively is particularly useful in establishing and developing methodological parameters for the study of reading groups. As a whole, this thesis contributes to the understanding of Allende’s cross-cultural popularity by situating readers at the centre
The languages of parasite communication
No full textAlthough it is regarded as self-evident that parasites interact with their hosts, with the primary aim of enhancing their own survival and transmission, the extent to which unicellular parasites communicate with each has been severely underestimated. Recent publications show that information is commonly exchanged between parasites of the same species and that this can govern their decisions to divide, to differentiate or to migrate as a group. Communication can take the form of soluble secreted factors, extra- cellular vesicles or contact between cells. Extracellular parasites can do this directly, while intracellular parasites use the infected host cell – or components derived from it – as an intermediary. By emitting signals that can be dispersed within the host, parasites can also have long-distance effects on the course of an infection and its pathology. This article presents an overview of recent developments in this field and draws attention to some older work that merits re-examination
Role of the stage-regulated nucleoside transporter TbNT10 in differentiation and adenosine uptake in Trypanosoma brucei
No full textRodent-free cyclical transmission of Trypanosoma brucei brucei.
No full textWe provide a simple protocol enabling cyclical transmission of Trypanosoma brucei brucei to be performed without the need for mammals. These procedures have two advantages: they are in line with 3R principles of animal use - replace, refine, reduce - and may enable more laboratories to study the complete life cycle
A Discussion About Writing Fiction and Creative Prose with Isabel Huggan
No full textAward-winning Canadian author Isabel Huggan talks to students about writing, with a focus on fiction and creative non-fiction.Presentation for English 2905 (Introduction to Creative Writing), taught by Dr. Stepanie McKenzie
The sweet and sour sides of trypanosome social motility.
No full textRecent studies showed that the formation of elegant geometric patterns by communities of Trypanosoma brucei on semi-solid surfaces, dubbed social motility (SoMo) by its discoverers, is a manifestation of pH taxis. This is caused by procyclic forms generating and responding to pH gradients through glucose metabolism and cAMP signalling. These findings established that trypanosomes can sense and manipulate gradients, potentially helping them to navigate through host tissues. At the same time, the host itself and bystanders such as endosymbionts have the potential to shape the environment and influence the chances of successful transmission. We postulate that the ability to sense and contribute to the gradient landscape may also underlie the tissue tropism and migration of other parasites in their hosts
The Social Life of African Trypanosomes
No full textThe unicellular parasite Trypanosoma brucei shuttles between its definitive host, the tsetse fly, and various mammals including humans. In the fly digestive tract, T. brucei must first migrate to the ectoperitrophic space, establish a persistent infection of the midgut and then migrate to the salivary glands before being transmitted to a new mammalian host. In 2010, it was shown that insect stages of the parasite (procyclic forms) exhibit social motility (SoMo) when cultured on a semi-solid surface, and it was postulated that this behaviour might reflect a migration step in the tsetse fly. Now, almost 5 years after the initial report, several new publications shed some light on the biological function of SoMo and provide insights into the underlying signalling pathways
Insights into the regulation of GPEET procyclin during differentiation from early to late procyclic forms of Trypanosoma brucei.
No full textThe procyclic form of Trypanosoma brucei colonises the gut of its insect vector, the tsetse fly. GPEET and EP procyclins constitute the parasite's surface coat at this stage of the life cycle, and the presence or absence of GPEET distinguishes between early and late procyclic forms, respectively. Differentiation from early to late procyclic forms in vivo occurs in the fly midgut and can be mimicked in culture. Our analysis of this transition in vitro delivered new insights into the process of GPEET repression. First, we could show that parasites followed a concrete sequence of events upon triggering differentiation: after undergoing an initial growth arrest, cells lost GPEET protein, and finally late procyclic forms resumed proliferation. Second, we determined the stability of both GPEET and EP mRNA during differentiation. GPEET mRNA is exceptionally stable in early procyclic forms, with a half-life >6h. The GPEET mRNA detected in late procyclic form cultures is a mixture of transcripts from both bona fide late procyclic forms and GPEET-positive 'laggard' parasites present in these cultures. However, its stability was clearly reduced during differentiation and in late procyclic form cultures. Alternatively processed GPEET transcripts were enriched in samples from late procyclic forms, suggesting that altered mRNA processing might contribute to repression of GPEET in this developmental stage. In addition, we detected GPEET transcripts with non-templated oligo(U) tails that were enriched in late procyclic forms. To the best of our knowledge, this is the first study reporting a uridylyl-tailed, nuclear-encoded mRNA species in trypanosomatids or any other protozoa
Expression of procyclin mRNAs during cyclical transmission of <i>Trypanosoma brucei</i>
No full text<i>Trypanosoma brucei</i>, the parasite causing human sleeping sickness, relies on the tsetse fly for its transmission. In the insect, EP and GPEET procyclins are the major surface glycoproteins of procyclic (midgut) forms of the parasite, with GPEET predominating in the early procyclic form and two isoforms of EP in the late procyclic form. EP procyclins were previously detected on salivary gland trypanosomes, presumably epimastigotes, by immunoelectron microscopy. However, no procyclins could be detected by mass spectrometry when parasites were isolated from infected glands. We have used qualitative and quantitative RT-PCR to analyse the procyclin mRNAs expressed by trypanosomes in the tsetse midgut and salivary glands at different time points after infection. The coding regions of the three EP isoforms (EP1, EP2 and EP3) are extremely similar, but their 3′ untranslated regions contain unique sequences that make it possible to assign the cDNAs amplified by this technique. With the exception of EP2, we found that the spectrum of procyclin mRNAs expressed in the midgut mirrors the protein repertoire of early and established procyclic forms. Surprisingly, procyclin mRNAs, including that of GPEET, are present at relatively high levels in salivary gland trypanosomes, although the proteins are rarely detected by immunofluorescence. Additional experiments using transgenic trypanosomes expressing reporter genes or mutant forms of procyclin point to a mechanism of translational or post-translational control, involving the procyclin coding regions, in salivary gland trypanosomes. It is widely accepted that T. brucei always has a coat of either variant surface glycoprotein or procyclin. It has been known for many years that the epimastigote form does not have a variant surface glycoprotein coat. The finding that this life cycle stage is usually negative for procyclin as well is new, and means that the paradigm will need to be revis
Interactions between trypanosomes and tsetse flies
No full textAfrican trypanosomes are insect-borne parasites that cause sleeping sickness in humans and nagana in domesticated animals. Successful transmission is the outcome of crosstalk between the trypanosome and its insect vector, the tsetse fly. This enables the parasite to undergo successive rounds of differentiation, proliferation and migration, culminating in the infection of a new mammalian host. Several stage- and species-specific parasite surface molecules have been identified and there are new insights into their regulation in the fly. Tsetse flies are often refractory to infection with trypanosomes. While many environmental and physiological factors are known to influence infection, our detailed understanding of tsetse-trypanosome relationships is still in its infancy. Recent studies have identified a number of tsetse genes that show altered expression patterns in response to microbial infections, some of which have also been implicated in modulating trypanosome transmission
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