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1.
Future Healthc J ; 11(2): 100135, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38766625

RESUMO

Healthcare systems around the world have set ambitious targets to design and deliver more environmentally sustainable healthcare. To achieve these targets, individuals, teams, organisations, and whole systems will have to change current attitudes, practices and processes. Change management theory advocates for early identification of the influencing forces to change, so that actions can be taken to overcome the barriers and strengthen the facilitators to increase the likelihood of success. This project undertook a forcefield analysis exercise to identify the barriers and facilitators to the design and delivery of sustainable healthcare in Scotland. The exercise identified 12 facilitators and 12 barriers to sustainable change and formulated ten recommendations to strengthen the former and overcome the latter. It is hoped that the results will raise awareness of the factors that influence the design and delivery of sustainable healthcare and will inform what actions can be taken to increase the likelihood of success.

2.
J Clin Med ; 12(15)2023 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-37568373

RESUMO

Concerns remain regarding the rare cardiovascular adverse events, myocarditis and pericarditis (myo/pericarditis), particularly in younger individuals following mRNA COVID-19 vaccination. Our study aimed to comprehensively assess potential safety signals related to these cardiac events following the primary and booster doses, with a specific focus on younger populations, including children as young as 6 months of age. Using the Vaccine Adverse Events Reporting System (VAERS), the United States national passive surveillance system, we conducted a retrospective pharmacovigilance study analyzing spontaneous reports of myo/pericarditis. We employed both frequentist and Bayesian methods and conducted subgroup analyses by age, sex, and vaccine dose. We observed a higher reporting rate of myo/pericarditis following the primary vaccine series, particularly in males and mainly after the second dose. However, booster doses demonstrated a lower number of reported cases, with no significant signals detected after the fourth or fifth doses. In children and young adults, we observed notable age and sex differences in the reporting of myo/pericarditis cases. Males in the 12-17 and 18-24-year-old age groups had the highest number of cases, with significant signals for both males and females after the second dose. We also identified an increased reporting for a spectrum of cardiovascular symptoms such as chest pain and dyspnea, which increased with age, and were reported more frequently than myo/pericarditis. The present study identified signals of myo/pericarditis and related cardiovascular symptoms after mRNA COVID-19 vaccination, especially among children and adolescents. These findings underline the importance for continued vaccine surveillance and the need for further studies to confirm these results and to determine their clinical implications in public health decision-making, especially for younger populations.

3.
Nature ; 620(7975): 813-823, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37558877

RESUMO

Twenty-five years since foundational publications on valuing ecosystem services for human well-being1,2, addressing the global biodiversity crisis3 still implies confronting barriers to incorporating nature's diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever4. Notwithstanding agreements to incorporate nature's values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)5 and the UN Sustainable Development Goals6, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature7. Arguably, a 'values crisis' underpins the intertwined crises of biodiversity loss and climate change8, pandemic emergence9 and socio-environmental injustices10. On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature's diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions7,11. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures.


Assuntos
Ecossistema , Justiça Ambiental , Política Ambiental , Objetivos , Desenvolvimento Sustentável , Humanos , Biodiversidade , Desenvolvimento Sustentável/economia , Política Ambiental/economia , Mudança Climática
4.
Nat Commun ; 14(1): 4848, 2023 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-37563108

RESUMO

Binding of transcription factors (TFs) promotes the subsequent recruitment of coactivators and preinitiation complexes to initiate eukaryotic transcription, but this time course is usually not visualized. It is commonly assumed that recruited factors eventually co-reside in a higher-order structure, allowing distantly bound TFs to activate transcription at core promoters. We use live imaging of endogenously tagged proteins, including the pioneer TF Zelda, the coactivator dBrd4, and RNA polymerase II (RNAPII), to define a cascade of events upstream of transcriptional initiation in early Drosophila embryos. These factors are sequentially and transiently recruited to discrete clusters during activation of non-histone genes. Zelda and the acetyltransferase dCBP nucleate dBrd4 clusters, which then trigger pre-transcriptional clustering of RNAPII. Subsequent transcriptional elongation disperses clusters of dBrd4 and RNAPII. Our results suggest that activation of transcription by eukaryotic TFs involves a succession of distinct biomolecular condensates that culminates in a self-limiting burst of transcription.


Assuntos
Proteínas de Drosophila , Fatores de Transcrição , Animais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Drosophila/genética , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Regiões Promotoras Genéticas/genética , Transcrição Gênica , Ativação Transcricional
5.
BMJ Open ; 13(6): e065687, 2023 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-37339840

RESUMO

OBJECTIVE: To summarise the available evidence on the risk of myocarditis and/or pericarditis following mRNA COVID-19 vaccination, compared with the risk among unvaccinated individuals in the absence of COVID-19 infection. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Electronic databases (Medline, Embase, Web of Science and WHO Global Literature on Coronavirus Disease), preprint repositories (medRxiv and bioRxiv), reference lists and grey literature were searched from 1 December 2020 until 31 October 2022. STUDY SELECTION: Epidemiological studies of individuals of any age who received at least one dose of an mRNA COVID-19 vaccine, reported a risk of myo/pericarditis and compared the risk of myo/pericarditis to individuals who did not receive any dose of an mRNA COVID-19 vaccine. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently conducted screening and data extraction. The rate of myo/pericarditis among vaccinated and unvaccinated groups was recorded, and the rate ratios were calculated. Additionally, the total number of individuals, case ascertainment criteria, percentage of males and history of SARS-CoV-2 infection were extracted for each study. Meta-analysis was done using a random-effects model. RESULTS: Seven studies met the inclusion criteria, of which six were included in the quantitative synthesis. Our meta-analysis indicates that within 30-day follow-up period, vaccinated individuals were twice as likely to develop myo/pericarditis in the absence of SARS-CoV-2 infection compared to unvaccinated individuals, with a rate ratio of 2.05 (95% CI 1.49-2.82). CONCLUSION: Although the absolute number of observed myo/pericarditis cases remains quite low, a higher risk was detected in those who received mRNA COVID-19 vaccinations compared with unvaccinated individuals in the absence of SARS-CoV-2 infection. Given the effectiveness of mRNA COVID-19 vaccines in preventing severe illnesses, hospitalisations and deaths, future research should focus on accurately determining the rates of myo/pericarditis linked to mRNA COVID-19 vaccines, understanding the biological mechanisms behind these rare cardiac events and identifying those most at risk.


Assuntos
Vacinas contra COVID-19 , COVID-19 , Miocardite , Pericardite , Humanos , Masculino , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19/efeitos adversos , Miocardite/epidemiologia , Miocardite/etiologia , Pericardite/epidemiologia , Pericardite/etiologia , RNA Mensageiro , SARS-CoV-2/genética , Vacinação
6.
Risk Anal ; 43(3): 498-515, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-35460101

RESUMO

A number of investigators have explored the use of value of information (VOI) analysis to evaluate alternative information collection procedures in diverse decision-making contexts. This paper presents an analytic framework for determining the value of toxicity information used in risk-based decision making. The framework is specifically designed to explore the trade-offs between cost, timeliness, and uncertainty reduction associated with different toxicity-testing methodologies. The use of the proposed framework is demonstrated by two illustrative applications which, although based on simplified assumptions, show the insights that can be obtained through the use of VOI analysis. Specifically, these results suggest that timeliness of information collection has a significant impact on estimates of the VOI of chemical toxicity tests, even in the presence of smaller reductions in uncertainty. The framework introduces the concept of the expected value of delayed sample information, as an extension to the usual expected value of sample information, to accommodate the reductions in value resulting from delayed decision making. Our analysis also suggests that lower cost and higher throughput testing also may be beneficial in terms of public health benefits by increasing the number of substances that can be evaluated within a given budget. When the relative value is expressed in terms of return-on-investment per testing strategy, the differences can be substantial.


Assuntos
Técnicas de Apoio para a Decisão , Incerteza , Análise Custo-Benefício
7.
Cell Rep ; 41(3): 111507, 2022 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-36261005

RESUMO

Collisions between transcribing RNA polymerases and DNA replication forks are disruptive. The threat of collisions is particularly acute during the rapid early embryonic cell cycles of Drosophila when S phase occupies the entirety of interphase. We hypothesize that collision-avoidance mechanisms safeguard this early transcription. Real-time imaging of endogenously tagged RNA polymerase II (RNAPII) and a reporter for nascent transcripts in unperturbed embryos shows clustering of RNAPII at around 2 min after mitotic exit, followed by progressive dispersal as associated nascent transcripts accumulate later in interphase. Abrupt inhibition of various steps in DNA replication, including origin licensing, origin firing, and polymerization, suppresses post-mitotic RNAPII clustering and transcription in nuclear cycles. We propose that replication dependency defers the onset of transcription so that RNAPII transcribes behind advancing replication forks. The resulting orderly progression can explain how early embryos circumvent transcription-replication conflicts to express essential developmental genes.


Assuntos
Proteínas de Drosophila , Drosophila , Animais , Drosophila/metabolismo , RNA Polimerase II/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Fase S
8.
Proc Natl Acad Sci U S A ; 119(31): e2119009119, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35881807

RESUMO

Unknown processes promote the accumulation of mitochondrial DNA (mtDNA) mutations during aging. Accumulation of defective mitochondrial genomes is thought to promote the progression of heteroplasmic mitochondrial diseases and degenerative changes with natural aging. We used a heteroplasmic Drosophila model to test 1) whether purifying selection acts to limit the abundance of deleterious mutations during development and aging, 2) whether quality control pathways contribute to purifying selection, 3) whether activation of quality control can mitigate accumulation of deleterious mutations, and 4) whether improved quality control improves health span. We show that purifying selection operates during development and growth but is ineffective during aging. Genetic manipulations suggest that a quality control process known to enforce purifying selection during oogenesis also suppresses accumulation of a deleterious mutation during growth and development. Flies with nuclear genotypes that enhance purifying selection sustained higher genome quality, retained more vigorous climbing activity, and lost fewer dopaminergic neurons. A pharmacological agent thought to enhance quality control produced similar benefits. Importantly, similar pharmacological treatment of aged mice reversed age-associated accumulation of a deleterious mtDNA mutation. Our findings reveal dynamic maintenance of mitochondrial genome fitness and reduction in the effectiveness of purifying selection during life. Importantly, we describe interventions that mitigate and even reverse age-associated genome degeneration in flies and in mice. Furthermore, mitigation of genome degeneration improved well-being in a Drosophila model of heteroplasmic mitochondrial disease.


Assuntos
Genoma Mitocondrial , Doenças Mitocondriais , Fatores Etários , Animais , DNA Mitocondrial/genética , Modelos Animais de Doenças , Drosophila melanogaster , Genoma Mitocondrial/genética , Camundongos , Doenças Mitocondriais/genética , Mutação
9.
Proc Natl Acad Sci U S A ; 119(26): e2200780119, 2022 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-35733247

RESUMO

In the metazoan S phase, coordinated firing of clusters of origins replicates different parts of the genome in a temporal program. Despite advances, neither the mechanism controlling timing nor that coordinating firing of multiple origins is fully understood. Rif1, an evolutionarily conserved inhibitor of DNA replication, recruits protein phosphatase 1 (PP1) and counteracts firing of origins by S-phase kinases. During the midblastula transition (MBT) in Drosophila embryos, Rif1 forms subnuclear hubs at each of the large blocks of satellite sequences and delays their replication. Each Rif1 hub disperses abruptly just prior to the replication of the associated satellite sequences. Here, we show that the level of activity of the S-phase kinase, DDK, accelerated this dispersal program, and that the level of Rif1-recruited PP1 retarded it. Further, Rif1-recruited PP1 supported chromatin association of nearby Rif1. This influence of nearby Rif1 can create a "community effect" counteracting kinase-induced dissociation such that an entire hub of Rif1 undergoes switch-like dispersal at characteristic times that shift in response to the balance of Rif1-PP1 and DDK activities. We propose a model in which the spatiotemporal program of late replication in the MBT embryo is controlled by self-stabilizing Rif1-PP1 hubs, whose abrupt dispersal synchronizes firing of associated late origins.


Assuntos
Proteínas de Transporte , Replicação do DNA , Proteínas de Drosophila , Drosophila melanogaster , Proteína Fosfatase 1 , Origem de Replicação , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Proteína Fosfatase 1/genética , Proteína Fosfatase 1/metabolismo , Fase S/genética , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismo
10.
Vaccines (Basel) ; 10(5)2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35632478

RESUMO

There have been reports of cases of myocarditis and pericarditis as rare complications following mRNA COVID-19 vaccinations among young adults. While most reported cases are mild, this potential vaccine safety signal should be closely monitored. Using data from the CDC and the Vaccine Adverse Event Reporting System (VAERS), we calculated the combined reporting rate of myocarditis and pericarditis stratified by age group, sex, vaccine dose, and manufacturer, and compared these rates to the crude background incidence rates. Compared to the general population prior to the administration of the first COVID-19 vaccines in December 2020, we identified a higher-than-expected reporting rate of myocarditis and pericarditis following mRNA vaccination; the risk was higher after a second vaccine dose, higher in males than in females, and decreased with age. The highest risk was seen in males 12-17 years of age with approximately 6 cases per 100,000 second doses. Our findings suggest an increased risk of myocarditis and pericarditis in young males following a second dose of an mRNA COVID-19 vaccine. Since these findings are based on safety signals derived from passive surveillance data, confirmatory epidemiological studies should be undertaken.

11.
ALTEX ; 39(4): 656-666, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35353900

RESUMO

Exposure-response assessment methods have shifted towards more quantitative approaches, with health risk assessors exploring more statistically driven techniques. These assessments, however, usually rely on one critical health effect from a single key study. Categorical regression addresses this limitation by incorporating data from all relevant studies ­ including human, animal, and mechanistic studies ­ thereby including a broad spectrum of health endpoints and exposure levels for exposure-response analysis in an objective manner. Categorical regression requires the establishment of ordered response categories corresponding to increasingly severe adverse health outcomes and the availability of a comprehensive database that summarizes all data on different outcomes from different studies, including the exposure or dose at which these out-comes are observed and their severity. It has found application in the risk assessment of essential nutrients and trace metals. Since adverse effects may arise from either deficient or excess exposure, the exposure-response curve is U-shaped, which provides a basis for determining optimal intake levels that minimize the joint risks of deficiency and excess. This article provides an overview of the use of categorical regression fit exposure-response models incorporating data from multiple evidence streams. An extension of categorical regression that permits the simultaneous analysis of excess and deficiency toxicity data is presented and applied to comprehensive databases on copper and manganese. Future applications of cat-egorical regression will be able to make greater use of diverse data sets developed using new approach methodologies, which can be expected to provide valuable information on toxic responses of varying severity.


Assuntos
Cobre , Nutrientes , Animais , Humanos , Cobre/toxicidade , Bases de Dados Factuais , Nutrientes/deficiência , Medição de Risco
12.
Math Med Biol ; 38(4): 516-551, 2021 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-34791309

RESUMO

Mathematical modelling of ionic electrodiffusion and water movement is emerging as a powerful avenue of investigation to provide a new physiological insight into brain homeostasis. However, in order to provide solid answers and resolve controversies, the accuracy of the predictions is essential. Ionic electrodiffusion models typically comprise non-trivial systems of non-linear and highly coupled partial and ordinary differential equations that govern phenomena on disparate time scales. Here, we study numerical challenges related to approximating these systems. We consider a homogenized model for electrodiffusion and osmosis in brain tissue and present and evaluate different associated finite element-based splitting schemes in terms of their numerical properties, including accuracy, convergence and computational efficiency for both idealized scenarios and for the physiologically relevant setting of cortical spreading depression (CSD). We find that the schemes display optimal convergence rates in space for problems with smooth manufactured solutions. However, the physiological CSD setting is challenging: we find that the accurate computation of CSD wave characteristics (wave speed and wave width) requires a very fine spatial and fine temporal resolution.


Assuntos
Encéfalo , Movimentos da Água , Simulação por Computador
13.
Phys Rev Lett ; 126(17): 177801, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33988388

RESUMO

A phenomenological free energy model is proposed to describe the behavior of smectic liquid crystals, an intermediate phase that exhibits orientational order and layering at the molecular scale. Advantageous properties render the functional amenable to numerical simulation. The model is applied to a number of scenarios involving geometric frustration, leading to emergent structures such as focal conic domains and oily streaks and enabling detailed elucidation of the very rich energy landscapes that arise in these problems.

14.
J Obstet Gynaecol Can ; 43(7): 888-892.e1, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33785466

RESUMO

We report on the perinatal outcomes of pregnant patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from 2 hospitals in Montréal, Québec. Outcomes of 45 patients with SARS-CoV-2 during pregnancy were compared with those of 225 patients without infection. Sixteen percent of patients with SARS-CoV-2 delivered preterm, compared with 9% of patients without (P = 0.28). Median gestational age at delivery (39.3 (interquartile range [IQR] 37.7-40.4) wk vs. 39.1 [IQR 38.3-40.1] wk) and median birth weight (3250 [IQR 2780-3530] g vs. 3340 [IQR 3025-3665] g) were similar between groups. The rate of cesarean delivery was 29% for patients with SARS-CoV-2. Therefore, we did not find important differences in outcomes associated with SARS-CoV-2. Our findings may be limited to women with mild COVID-19 diagnosed in the third trimester.


Assuntos
COVID-19 , Complicações Infecciosas na Gravidez , Nascimento Prematuro , Feminino , Humanos , Recém-Nascido , Transmissão Vertical de Doenças Infecciosas , Gravidez , Complicações Infecciosas na Gravidez/epidemiologia , Resultado da Gravidez/epidemiologia , Nascimento Prematuro/epidemiologia , SARS-CoV-2
15.
PLoS Biol ; 18(10): e3000891, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33090988

RESUMO

Externally deposited eggs begin development with an immense cytoplasm and a single overwhelmed nucleus. Rapid mitotic cycles restore normality as the ratio of nuclei to cytoplasm (N/C) increases. A threshold N/C has been widely proposed to activate zygotic genome transcription and onset of morphogenesis at the mid-blastula transition (MBT). To test whether a threshold N/C is required for these events, we blocked N/C increase by down-regulating cyclin/Cdk1 to arrest early cell cycles in Drosophila. Embryos that were arrested two cell cycles prior to the normal MBT activated widespread transcription of the zygotic genome including genes previously described as N/C dependent. Zygotic transcription of these genes largely retained features of their regulation in space and time. Furthermore, zygotically regulated post-MBT events such as cellularization and gastrulation movements occurred in these cell cycle-arrested embryos. These results are not compatible with models suggesting that these MBT events are directly coupled to N/C. Cyclin/Cdk1 activity normally declines in tight association with increasing N/C and is regulated by N/C. By experimentally promoting the decrease in cyclin/Cdk1, we uncoupled MBT from N/C increase, arguing that N/C-guided down-regulation of cyclin/Cdk1 is sufficient for genome activation and MBT.


Assuntos
Blástula/citologia , Pontos de Checagem do Ciclo Celular , Núcleo Celular/metabolismo , Drosophila melanogaster/embriologia , Embrião não Mamífero/citologia , Regulação da Expressão Gênica no Desenvolvimento , Interfase , Zigoto/metabolismo , Animais , Pontos de Checagem do Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/genética , Gastrulação , Interfase/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transcrição Gênica , Transcriptoma/genética
16.
Heliyon ; 6(3): e03614, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32258470

RESUMO

Within this work, we describe the design and synthesis of a range of novel chromanones and quinolinones, based on natural products reported to possess anti-leishmanial action. The core heterocycles were obtained either via classical or ionic liquid mediated Kabbe condensation in the case of chromanones, or aqueous Sonogashira based alkynylation followed by acid-catalysed cyclisation in the case of quinolinones. Upon testing in promastigotes, axenic amastigotes and Leishmania-infected macrophages, compound 13c was identified as displaying interesting activity, inhibiting axenic amastigotes and intracellular amastigotes with IC50s of 25.3 and 24.6µM respectively.

17.
Ambio ; 49(6): 1211-1221, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31564051

RESUMO

A horizon scan was conducted to identify emerging and intensifying issues for biodiversity conservation in South Africa over the next 5-10 years. South African biodiversity experts submitted 63 issues of which ten were identified as priorities using the Delphi method. These priority issues were then plotted along axes of social agreement and scientific certainty, to ascertain whether issues might be "simple" (amenable to solutions from science alone), "complicated" (socially agreed upon but technically complicated), "complex" (scientifically challenging and significant levels of social disagreement) or "chaotic" (high social disagreement and highly scientifically challenging). Only three of the issues were likely to be resolved by improved science alone, while the remainder require engagement with social, economic and political factors. Fortunately, none of the issues were considered chaotic. Nevertheless, strategic communication, education and engagement with the populace and policy makers were considered vital for addressing emerging issues.


Assuntos
Biodiversidade , Conservação dos Recursos Naturais , Política , África do Sul
18.
Curr Biol ; 29(24): 4330-4336.e3, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31786061

RESUMO

A mutant mitochondrial genome arising amid the pool of mitochondrial genomes within a cell must compete with existing genomes to survive to the next generation. Even weak selective forces can bias transmission of one genome over another to affect the inheritance of mitochondrial diseases and guide the evolution of mitochondrial DNA (mtDNA). Studies in several systems suggested that purifying selection in the female germline reduces transmission of detrimental mitochondrial mutations [1-7]. In contrast, some selfish genomes can take over despite a cost to host fitness [8-13]. Within individuals, the outcome of competition is therefore influenced by multiple selective forces. The nuclear genome, which encodes most proteins within mitochondria, and all external regulators of mitochondrial biogenesis and dynamics can influence the competition between mitochondrial genomes [14-18], yet little is known about how this works. Previously, we established a Drosophila line transmitting two mitochondrial genomes in a stable ratio enforced by purifying selection benefiting one genome and a selfish advantage favoring the other [8]. Here, to find nuclear genes that impact mtDNA competition, we screened heterozygous deletions tiling ∼70% of the euchromatic regions and examined their influence on this ratio. This genome-wide screen detected many nuclear modifiers of this ratio and identified one as the catalytic subunit of mtDNA polymerase gene (POLG), tam. A reduced dose of tam drove elimination of defective mitochondrial genomes. This study suggests that our approach will uncover targets for interventions that would block propagation of pathogenic mitochondrial mutations.


Assuntos
DNA Polimerase gama/metabolismo , DNA Mitocondrial/genética , Genoma Mitocondrial/genética , Animais , DNA Polimerase gama/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Evolução Molecular , Mitocôndrias/genética , Mutação , Seleção Genética/genética
19.
Vaccine ; 37(47): 7090-7099, 2019 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-31630940

RESUMO

A flow cytometry-based assay was developed to assess the infective titer of two recombinant viruses: a recombinant herpes simplex type 2 (rHSV-2) and a recombinant canary pox (rALVAC.gfp). This method uses granularity of infected Vero and QT-35 cells, respectively, and correlates this to the infectious titer of virus samples. The percent of the cell populations with a high level of granularity could accurately be correlated to viral titers obtained through a traditional plaque assay, with R2 values greater than 0.8 using a semi-logarithmic scale. This approach offers a rapid, high-throughput method for infectious virus titration with similar accuracy to a traditional plaque assay.


Assuntos
Citometria de Fluxo/métodos , Herpesvirus Humano 2/isolamento & purificação , Viroses/virologia , Animais , Linhagem Celular , Chlorocebus aethiops , Células Vero , Carga Viral/métodos , Ensaio de Placa Viral/métodos
20.
Genes Dev ; 33(7-8): 403-417, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30808658

RESUMO

Acquisition of chromatin modifications during embryogenesis distinguishes different regions of an initially naïve genome. In many organisms, repetitive DNA is packaged into constitutive heterochromatin that is marked by di/trimethylation of histone H3K9 and the associated protein HP1a. These modifications enforce the unique epigenetic properties of heterochromatin. However, in the early Drosophila melanogaster embryo, the heterochromatin lacks these modifications, which appear only later, when rapid embryonic cell cycles slow down at the midblastula transition (MBT). Here we focus on the initial steps restoring heterochromatic modifications in the embryo. We describe the JabbaTrap, a technique for inactivating maternally provided proteins in embryos. Using the JabbaTrap, we reveal a major requirement for the methyltransferase Eggless/SetDB1 in the establishment of heterochromatin. In contrast, other methyltransferases contribute minimally. Live imaging reveals that endogenous Eggless gradually accumulates on chromatin in interphase but then dissociates in mitosis, and its accumulation must restart in the next cell cycle. Cell cycle slowing as the embryo approaches the MBT permits increasing accumulation and action of Eggless at its targets. Experimental manipulation of interphase duration shows that cell cycle speed regulates Eggless. We propose that developmental slowing of the cell cycle times embryonic heterochromatin formation.


Assuntos
Ciclo Celular/fisiologia , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Heterocromatina/metabolismo , Animais , Proteínas de Drosophila/genética , Drosophila melanogaster/citologia , Heterocromatina/genética , Histona-Lisina N-Metiltransferase , Fatores de Tempo
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