Slow growing behavior in African trypanosomes during adipose tissue colonization.

When Trypanosoma brucei parasites, the causative agent of sleeping sickness, colonize the adipose tissue, they rewire gene expression. Whether this adaptation affects population behavior and disease treatment remained unknown. By using a mathematical model, we estimate that the population of adipose tissue forms (ATFs) proliferates slower than blood parasites. Analysis of the ATFs proteome, measurement of protein synthesis and proliferation rates confirm that the ATFs divide on average every 12 h, instead of 6 h in the blood. Importantly, the population of ATFs is heterogeneous with parasites doubling times ranging between 5 h and 35 h. Slow-proliferating parasites remain capable of reverting to the fast proliferation profile in blood conditions. Intravital imaging shows that ATFs are refractory to drug treatment. We propose that in adipose tissue, a subpopulation of T. brucei parasites acquire a slow growing behavior, which contributes to disease chronicity and treatment failure.

TERRA increases at short telomeres in yeast survivors and regulates survivor associated senescence (SAS).

Cancer cells achieve immortality by employing either homology-directed repair (HDR) or the telomerase enzyme to maintain telomeres. ALT (alternative lengthening of telomeres) refers to the subset of cancer cells that employ HDR. Many ALT features are conserved from yeast to human cells, with the yeast equivalent being referred to as survivors. The non-coding RNA TERRA, and its ability to form RNA-DNA hybrids, has been implicated in ALT/survivor maintenance by promoting HDR. It is not understood which telomeres in ALT/survivors engage in HDR, nor is it clear which telomeres upregulate TERRA. Using yeast survivors as a model for ALT, we demonstrate that HDR only occurs at telomeres when they become critically short. Moreover, TERRA levels steadily increase as telomeres shorten and decrease again following HDR-mediated recombination. We observe that survivors undergo cycles of senescence, in a similar manner to non-survivors following telomerase loss, which we refer to as survivor associated senescence (SAS). Similar to 'normal' senescence, we report that RNA-DNA hybrids slow the rate of SAS, likely through the elongation of critically short telomeres, however decreasing the rate of telomere shortening may contribute to this effect. In summary, TERRA RNA-DNA hybrids regulate telomere dysfunction-induced senescence before and after survivor formation.

A long noncoding RNA promotes parasite differentiation in African trypanosomes.

The parasite Trypanosoma brucei causes African sleeping sickness that is fatal to patients if untreated. Parasite differentiation from a replicative slender form into a quiescent stumpy form promotes host survival and parasite transmission. Long noncoding RNAs (lncRNAs) are known to regulate cell differentiation in other eukaryotes. To determine whether lncRNAs are also involved in parasite differentiation, we used RNA sequencing to survey the T. brucei genome, identifying 1428 previously uncharacterized lncRNA genes. We find that grumpy lncRNA is a key regulator that promotes parasite differentiation into the quiescent stumpy form. This function is promoted by a small nucleolar RNA encoded within the grumpy lncRNA. snoGRUMPY binds to messenger RNAs of at least two stumpy regulatory genes, promoting their expression. grumpy overexpression reduces parasitemia in infected mice. Our analyses suggest that T. brucei lncRNAs modulate parasite-host interactions and provide a mechanism by which grumpy regulates cell differentiation in trypanosomes.

Organizational resilience in the oil and gas industry: A scoping review.

Resilience derives from the study of socio-ecological systems and refers to the dynamical capacity to adapt to internal and external perturbations by changing its mode of operation without losing its ability to perform. The present article offers a scoping review of organizational research discussing the concept of resilience in the oil and gas industry. Rather than approaching a narrowly defined question as in systematic reviews, scoping reviews produce an overview of a body of knowledge covering broad questions. It reviews organizational research on resilience in the oil and gas industry by covering five main categories: conceptualizations; article type/methods; context/unit of analysis; relation between resilience and safety; and, central topics highlighted in the literature. The review of both empirical and conceptual literature reveals that the concept of resilience tends to be researched in terms of system capabilities or outcomes rather than processes. Integrated operations has provided new scenarios to discuss and investigate resilience in oil and gas production. However, findings demonstrate how resilience is often presented as a normative construct and there is little development in terms of understanding the dynamics of adaptive processes in the industry. The overall goal is to contribute to the study of organizational resilience by identifying areas for further study and by producing new knowledge that can permeate practices in organizations.

RNase H1 and H2 Are Differentially Regulated to Process RNA-DNA Hybrids.

RNA-DNA hybrids are tightly regulated to ensure genome integrity. The RNase H enzymes RNase H1 and H2 contribute to chromosomal stability through the removal of RNA-DNA hybrids. Loss of RNase H2 function is implicated in human diseases of the nervous system and cancer. To better understand RNA-DNA hybrid dynamics, we focused on elucidating the regulation of the RNase H enzymes themselves. Using yeast as a model system, we demonstrate that RNase H1 and H2 are controlled in different manners. RNase H2 has strict cell cycle requirements, in that it has an essential function in G2/M for both R-loop processing and ribonucleotide excision repair. RNase H1, however, can function independently of the cell cycle to remove R-loops and appears to become activated in response to high R-loop loads. These results provide us with a more complete understanding of how and when RNA-DNA hybrids are acted upon by the RNase H enzymes.

African trypanosomes expressing multiple VSGs are rapidly eliminated by the host immune system.

Trypanosoma brucei parasites successfully evade the host immune system by periodically switching the dense coat of variant surface glycoprotein (VSG) at the cell surface. Each parasite expresses VSGs in a monoallelic fashion that is tightly regulated. The consequences of exposing multiple VSGs during an infection, in terms of antibody response and disease severity, remain unknown. In this study, we overexpressed a high-mobility group box protein, TDP1, which was sufficient to open the chromatin of silent VSG expression sites, to disrupt VSG monoallelic expression, and to generate viable and healthy parasites with a mixed VSG coat. Mice infected with these parasites mounted a multi-VSG antibody response, which rapidly reduced parasitemia. Consequently, we observed prolonged survival in which nearly 90% of the mice survived a 30-d period of infection with undetectable parasitemia. Immunodeficient RAG2 knock-out mice were unable to control infection with TDP1-overexpressing parasites, showing that the adaptive immune response is critical to reducing disease severity. This study shows that simultaneous exposure of multiple VSGs is highly detrimental to the parasite, even at the very early stages of infection, suggesting that drugs that disrupt VSG monoallelic expression could be used to treat trypanosomiasis.

Acesso ao diagnóstico e tratamento da tuberculose multirresistente: análise discursiva* / Access to diagnosis and treatment of multi-resistant tuberculosis: discursive analysis

Objetivo: analisar discursivamente como os doentes de tuberculose multirresistente vivenciam o processo do diagnóstico e tratamento da doença, identificando as possíveis dificuldades e potencialidades, bem como a atuação da enfermagem. Método: trata-se de um estudo qualitativo, descritivo, com doentes em tratamento em duas instituições de referência. Realizaram-se entrevistas semiestruturadas e analisadas de acordo com o referencial da Análise do Discurso, matriz francesa. Resultados: apontaram-se dois blocos discursivos: "Acesso ao diagnóstico da tuberculose multirresistente" e "Acesso ao tratamento específico", ambos sob a atuação do enfermeiro. Conclusão: considera-se necessário um olhar diferenciado dos profissionais de saúde para o diagnóstico e o tratamento da tuberculose multirresistente para que a organização dos serviços não seja uma barreira para o controle da doença.(AU)

Objective: to discursively analyze how multidrug-resistant tuberculosis patients experience the process of diagnosis and treatment of the disease, identifying possible difficulties and potentialities, as well as nursing practice. Method: this is a qualitative, descriptive study of patients undergoing treatment at two reference institutions. Semi-structured interviews were conducted and analyzed according to the Discourse Analysis framework, French matrix. Results: two discursive blocks were pointed out: "Access to the diagnosis of multidrug-resistant tuberculosis" and "Access to specific treatment", both under the nurse's role. Conclusion: it is considered necessary a differentiated look of health professionals for the diagnosis and treatment of multidrug-resistant tuberculosis so that the organization of services is not a barrier to disease control.(AU)

Objetivo: analizar discursivamente cómo los pacientes con tuberculosis multirresistente experimentan el proceso de diagnóstico y tratamiento de la enfermedad, identificando posibles dificultades y potencialidades, así como la práctica de enfermería. Método: este es un estudio cualitativo, descriptivo de pacientes sometidos a tratamiento en dos instituciones de referencia. Se realizaron entrevistas semiestructuradas y se analizaron de acuerdo con el marco de Análisis del Discurso, matriz francesa. Resultados: se señalaron dos bloques discursivos: "Acceso al diagnóstico de tuberculosis multirresistente" y "Acceso a tratamiento específico", ambos bajo la actuación del enfermero. Conclusión: se considera necesario una mirada diferenciada de los profesionales de la salud para el diagnóstico y tratamiento de la tuberculosis multirresistente a fin de que la organización de los servicios no sea una barrera para el control de la enfermedad.(AU)

Trypanosoma brucei Parasites Occupy and Functionally Adapt to the Adipose Tissue in Mice.

Trypanosoma brucei is an extracellular parasite that causes sleeping sickness. In mammalian hosts, trypanosomes are thought to exist in two major niches: early in infection, they populate the blood; later, they breach the blood-brain barrier. Working with a well-established mouse model, we discovered that adipose tissue constitutes a third major reservoir for T. brucei. Parasites from adipose tissue, here termed adipose tissue forms (ATFs), can replicate and were capable of infecting a naive animal. ATFs were transcriptionally distinct from bloodstream forms, and the genes upregulated included putative fatty acid ß-oxidation enzymes. Consistent with this, ATFs were able to utilize exogenous myristate and form ß-oxidation intermediates, suggesting that ATF parasites can use fatty acids as an external carbon source. These findings identify the adipose tissue as a niche for T. brucei during its mammalian life cycle and could potentially explain the weight loss associated with sleeping sickness.