Beyond Afro-pessimism? British and French Print Media Discourse on Africa

Western media have come under intense scrutiny over the past 20 years for their propensity to marginalise Africa and to rely on colonial stereotypes, images and narratives. Both within and outside academia, commentators appeal to the concept of ‘Afro-pessimism’ to qualify and condemn this phenomenon. And yet, the notion is under-theorised and existing empirical studies insufficiently analyse and explain the phenomenon. Drawing on journalism, critical/cultural and postcolonial studies, this thesis seeks to answer the following questions: What is Afro-pessimism? Is it an adequate characterisation of media coverage, and if so, to what extent? Is media coverage moving beyond Afro-pessimism? In order to answer these theoretical and empirical questions, this thesis develops a conceptualisation of Afro-pessimism and provides a Critical Discourse Analysis of British and French print media. The analysis focuses on British and French broadsheet newspapers and news magazines. I critically analyse the visual and linguistic features of media texts against the background of their context of production and through interviews with foreign correspondents based in South Africa and Kenya. There are two sites of investigation: (1) the press coverage of the 50th anniversaries of independence (2007-2012); (2) the news magazines’ front covers dedicated to continental Africa (2011-2015). In site 1, I assess three recurring claims about Western media coverage of Africa, and investigate the discursive nature of the coverage in relation to Afro-pessimism and postcolonial memory. In site 2, I explore the emergence of an Afro-optimist discourse in media coverage of Africa. Finally, I offer a critical appraisal of the accounts of journalists at the heart of the production of Africa’s media image

Etude de l'activité antivirale d'extraits d'Euphorbia de Corse : recherche de nouveaux diterpènes d'intérêt biologique

Chikungunya fever is caused by an arthropod-borne virus that is associated with massive epidemics and severe morbidity (virus-induced arthralgia, fever, myalgia and rashes). Worldwide expansion of the mosquito vectors, such as Aedes albopictus ("Tiger moquito) is responsible for the spread of Chikungunya virus (CHIKV) throughout the world. A. albopictus has spread throughout Mediterranean areas, which could lead to epidemics outbreaks. Currently, no antiviral drugs or vaccines are available for the treatment or prevention of CHIKV infection. Since ten years, however, recent results showed that diterpene esters from Trignostemon (Euphorbiaceae) possess inhibiting activity of CHIKV replication.With the objective to discover new compounds with antiviral activities, 45 extracts from various plant parts of 11 Euphorbiaceae species native to Corsica were evaluated for selective inhibition of CHIKV replication. In collaboration with Dr. Leyssen (KU Leuven, Belgium), several extracts made from 10 Euphorbia species exhibited significant and selective anti-CHIKV activity in a virus-cell-based assay. The antiviral activities of 29 commercially available phorboïds were studied. Some phorboïds were potent inhibitors of CHIKV and human immunodeficiency virus (VIH) replication. Results allowed drawing new structure-activity relationships, which supported the hypothesis that PKC may be an important target in CHIKV replication. In order to confirm or infirm the presence of phorboïds with anti-CHIKV activity in Euphorbia extracts, a liquid chromatography (LC) coupled to linear ion trap mass spectrometry (MSn) method was developed using standard compounds. Application of this methodology indicated that none anti-CHIKV phorboïds was present in Euphorbia extracts. A second LC-MSn procedure was developed to profile untargeted phorboïdes. Results suggested that numerous other diterpene esters were present in the Euphorbia extracts. The species Euphorbia amygdaloides ssp. semiperfoliata was selected to perform a bioassay-guided purification procedure, which led to the isolation and identification of 14 jatrophane esters, including eight new components. Among them, antiviral evaluation indicated that one jatrophane ester was possessing anti-CHIKV and anti-HIV activities. Furthermore, the structure of an atypical jatrophane ester derivative, jatrohemiketal, was determined unambiguously through an original strategy combining NMR spectroscopy and molecular modeling. Finally, an original tandem mass spectrometry (MS/MS)-targeted supercritical fluid chromatography (SFC) method was developed and used to study bioactive fractions of E. amygdaloïdes ssp. semiperfoliata. The MS/MS data were analyzed by molecular networking. Thanks to this approach, four 4-deoxyphorbol esters and two new jatrophane esters were targeted, isolated and identified. Collaboration with the group of Pr. Alcami (CNM, Espagne) was started to explore the anti-HIV properties of the isolated diterpene esters. Thus, one compound derived from 4-deoxyphorbol esters proved to possess a potent inhibiting activity of HIV-1 replication (IC50 = 8 nM, and selectivity index > 6250). The investigation of the mechanism of this component indicated that it acted like prostratin, but with antiviral effect more than 28-fold. Furthermore, the evaluation of the anti-CHIKV activity indicated that another 4-deoxyphorbol derivative was one of the strongest inhibitor of CHIKV replication isolated up to date (EC50 = 0.34 ± 0.12 µM and selectivity index > 638).Le chikungunya est une maladie transmise par des moustiques du genre Aedes (dont A. albopictus, dit "moustique tigre"). Cette maladie provoque d'intenses fièvres et des douleurs articulaires chroniques fortement invalidantes. Les moustiques potentiellement vecteurs du virus du chikungunya (CHIKV) sont des espèces invasives qui, à la faveur du réchauffement climatique, se sont récemment implantés dans plusieurs régions du monde, dont la région méditerranéenne. Sa présence constitue un terreau favorable à la survenue d'épidémie. A l'heure actuelle, il n'existe ni vaccin, ni traitement médicamenteux efficace. Toutefois, des articles scientifiques ont récemment rapporté que des esters de diterpène isolés du genre Trigonostemon (Euphorbiaceae), avaient une activité inhibitrice de la réplication du CHIKV.Dans le cadre de ces travaux de thèse, des extraits de plantes du genre Euphorbia de Corse ont été étudiés dans le but d'isoler de nouvelles molécules douées d'activité antivirale sur la réplication du CHIKV. En collaboration avec le Dr. P. Leyssen (KU Leuven, Belgique), l'évaluation de l'activité anti-CHIKV de 45 extraits, obtenus à partir de 11 Euphorbiaceae de Corse, a permis de mettre en évidence la forte activité inhibitrice et sélective de des extraits d'espèces du genre Euphorbia in cellulo. L'activité antivirale d'une série de 27 diterpènes de type phorboïde, disponibles commercialement, a également été étudiée. Les résultats ont montré que certains dérivés avaient une forte activité inhibitrice de la réplication du CHIKV, mais aussi sur celle du virus de l'immunodéficience humaine (VIH). Ces études ont permis d'une part, de déduire des relations structure-activité inédites et d'autre part, de soutenir l'hypothèse d'un mécanisme d'action anti-CHIKV impliquant la modulation des protéines kinases C (PKCs) par les phorboïdes. Dans le but de confirmer ou d'infirmer la présence des phorboïdes dans les extraits d'Euphorbia, une première méthode utilisant la chromatographie liquide (LC) haute performance couplée à un spectromètre de masse à trappe d'ions (MSn), a été développée à partir des composés standards. L'application de cette méthodologie a révélé qu'aucun des phorboïdes ciblés n'était présent dans les extraits d'Euphorbia. Ainsi, une seconde procédure LC-MSn a été mise en œuvre afin de détecter - de manière non ciblée - différents types d’esters diterpéniques. L'utilisation de cette approche a révélé que de nombreux diterpènes, non-apparentés aux phorboïdes, étaient présents dans les extraits. Un extrait de l'espèce Euphorbia amygdaloides subsp. semiperfoliata a été sélectionné pour réaliser un fractionnement bio-guidé, aboutissant à l'isolement et l'identification de 14 esters de jatrophane, dont neuf nouveaux composés. Parmi eux, l'un s'est avéré inhiber la réplication du CHIKV et du VIH. Par ailleurs, la structure d'un ester de jatrophane atypique, le jatrohémicétal, a été élucidée grâce à une approche originale combinant modélisation moléculaire et spectroscopie par résonance magnétique nucléaire (RMN). Enfin, une nouvelle procédure de purification ciblée par spectrométrie de masse tandem (MS/MS) en chromatographie en phase fluide supercritique (SFC) a été développée et appliquée sur des fractions bioactives d'E. amygdaloïdes subsp. semiperfoliata. L’interprétation des données MS/MS s’est appuyée sur la génération de réseaux moléculaires. Par cette méthodologie, quatre nouvelles molécules ont pu être détectées, purifiées et identifiées ; il s’agit de deux nouveaux esters de jatrophane et de quatre esters dérivés du 4-déoxyphorbol. L'activité anti-VIH des constituants isolés a également pu être explorée dans le cadre d’une collaboration avec l'équipe du Pr. Alcami (CNM, Espagne). Ainsi, l’un des esters de 4-deoxyphorbol s’est révélé être doué d'un exceptionnel pouvoir inhibiteur de la réplication du VIH-1 (IC50 = 8 nM et index de sélectivité > 6250). Son mécanisme d'action semble s'apparenter à celui de la prostratine (molécule antivirale de référence) mais avec des propriétés antivirales environ 28 fois supérieur. Un deuxième ester de 4-déoxyphorbol s’est avéré être un des plus puissants inhibiteurs du CHIKV isolé à ce jour (EC50 = 0,34 ± 0,12 µM and SI > 638). Mots clés : Euphorbia, activité antivirale, chikungunya, diterpène, spectrométrie de mass

Digital Surveillance, Civil Society and the Media during the Covid-19 Pandemic

As the COVID-19 pandemic unfolded, so did many digital technologies promising to improve the public health response. These technologies raised various concerns for civil liberties in the digital age, from infringing on privacy to institutionalizing mass surveillance capacities. This media monitoring projects explores how English-language news organizations worldwide reported on these digital surveillance initiatives over the period of a year. By analyzing news framing, it provides insights into the contours of public debates on digitally driven public health surveillance. The report sheds light on the evolution of coverage over time, its geographic distribution, whose voices were included and excluded from these debates, and the prevalence of mis/dis-information. It also highlights the place of civil society in these narratives; which civil society organizations appeared most often in the media; what roles they played vis-à-vis digital surveillance; and the racial and gender make up of civil society voices appearing in news coverage. It provides a set of recommendations and resources for civil society groups and journalists working on the intersection of civil liberties, public health, and digital technologies

Distinct roles of c-Jun N-terminal kinase isoforms in neurite initiation and elongation during axonal regeneration

c-Jun N-terminal kinases (JNKs) (comprising JNK1-3 isoforms) are members of the MAPK (mitogen-activated protein kinase) family, activated in response to various stimuli including growth factors and inflammatory cytokines. Their activation is facilitated by scaffold proteins, notably JNK-interacting protein-1 (JIP1). Originally considered to be mediators of neuronal degeneration in response to stress and injury, recent studies support a role of JNKs in early stages of neurite outgrowth, including adult axonal regeneration. However, the function of individual JNK isoforms, and their potential effector molecules, remained unknown. Here, we analyzed the role of JNK signaling during axonal regeneration from adult mouse dorsal root ganglion (DRG) neurons, combining pharmacological JNK inhibition and mice deficient for each JNK isoform and for JIP1. We demonstrate that neuritogenesis is delayed by lack of JNK2 and JNK3, but not JNK1. JNK signaling is further required for sustained neurite elongation, as pharmacological JNK inhibition resulted in massive neurite retraction. This function relies on JNK1 and JNK2. Neurite regeneration of jip1(-/-) DRG neurons is affected at both initiation and extension stages. Interestingly, activated JNKs (phospho-JNKs), as well as JIP1, are also present in the cytoplasm of sprouting or regenerating axons, suggesting a local action on cytoskeleton proteins. Indeed, we have shown that JNK1 and JNK2 regulate the phosphorylation state of microtubule-associated protein MAP1B, whose role in axonal regeneration was previously characterized. Moreover, lack of MAP1B prevents neurite retraction induced by JNK inhibition. Thus, signaling by individual JNKs is differentially implicated in the reorganization of the cytoskeleton, and neurite regeneration

MEMO: mass spectrometry-based sample vectorization to explore chemodiverse datasets

In natural products research, chemodiverse extracts coming from multiple organisms are explored for novel bioactive molecules, sometimes over extended periods. Samples are usually analyzed by liquid chromatography coupled with fragmentation mass spectrometry to acquire informative mass spectral ensembles. Such data is then exploited to establish relationships among analytes or samples (e.g., via molecular networking) and annotate metabolites. However, the comparison of samples profiled in different batches is challenging with current metabolomics methods since the experimental variation-changes in chromatographical or mass spectrometric conditions - hinders the direct comparison of the profiled samples. Here we introduce MEMO-MS2 BasEd SaMple VectOrization-a method allowing to cluster large amounts of chemodiverse samples based on their LC-MS/MS profiles in a retention time agnostic manner. This method is particularly suited for heterogeneous and chemodiverse sample sets. MEMO demonstrated similar clustering performance as state-of-the-art metrics considering fragmentation spectra. More importantly, such performance was achieved without the requirement of a prior feature alignment step and in a significantly shorter computational time. MEMO thus allows the comparison of vast ensembles of samples, even when analyzed over long periods of time, and on different chromatographic or mass spectrometry platforms. This new addition to the computational metabolomics toolbox should drastically expand the scope of large-scale comparative analysis

Metabolomics in Ecology and Bioactive Natural Products Discovery: Challenges and Prospects for a Comprehensive Study of the Specialised Metabolome

Metabolomics is playing an increasingly prominent role in chemical ecology and in the discovery of bioactive natural products (NPs). The identification of metabolites is a common/central objective in both research fields. NPs have significant biological properties and play roles in multiple chemical-ecological interactions. Classically, in pharmacognosy, their chemical structure is determined after a complex process of isolating and interpreting spectroscopic data. With the advent of powerful analytical techniques such as liquid chromatography-mass spectrometry (LC-MS) the annotation process of the specialised metabolome of plants and microorganisms has improved considerably. In this article, we summarise the possibilities opened by these advances and illustrate how we harnessed them in our own research to automate annotations of NPs and target the isolation of key compounds. In addition, we are also discussing the analytical and computational challenges associated with these emerging approaches and their perspective

Genomic and Metabolomic Analysis of the Potato Common Scab Pathogen Streptomyces scabiei

Streptomyces scabiei is a key causative agent of common scab disease, which causes significant economic losses to potato growers worldwide. This organism produces several phytotoxins that are known or suspected to contribute to host–pathogen interactions and disease development; however, the full metabolic potential of S. scabiei has not been previously investigated. In this study, we used a combined metabolomic and genomic approach to investigate the metabolites that are produced by S. scabiei. The genome sequence was analyzed using antiSMASH and DeepBGC to identify specialized metabolite biosynthetic gene clusters. Using untargeted liquid chromatography-coupled tandem mass spectrometry (LC-MS2), the metabolic profile of S. scabiei was compared after cultivation on three different growth media. MS2 data were analyzed using Feature-Based Molecular Networking and hierarchical clustering in BioDendro. Metabolites were annotated by performing a Global Natural Products Social Molecular Networking (GNPS) spectral library search or using Network Annotation Propagation, SIRIUS, MetWork, or Competitive Fragmentation Modeling for Metabolite Identification. Using this approach, we were able to putatively identify new analogues of known metabolites as well as molecules that were not previously known to be produced by S. scabiei. To our knowledge, this study represents the first global analysis of specialized metabolites that are produced by this important plant pathogen

Specialized Metabolites from Ribosome Engineered Strains of Streptomyces clavuligerus

Bacterial specialized metabolites are of immense importance because of their medicinal, industrial, and agricultural applications. Streptomyces clavuligerus is a known producer of such compounds; however, much of its metabolic potential remains unknown, as many associated biosynthetic gene clusters are silent or expressed at low levels. The overexpression of ribosome recycling factor (frr) and ribosome engineering (induced rpsL mutations) in other Streptomyces spp. has been reported to increase the production of known specialized metabolites. Therefore, we used an overexpression strategy in combination with untargeted metabolomics, molecular networking, and in silico analysis to annotate 28 metabolites in the current study, which have not been reported previously in S. clavuligerus. Many of the newly described metabolites are commonly found in plants, further alluding to the ability of S. clavuligerus to produce such compounds under specific conditions. In addition, the manipulation of frr and rpsL led to different metabolite production profiles in most cases. Known and putative gene clusters associated with the production of the observed compounds are also discussed. This work suggests that the combination of traditional strain engineering and recently developed metabolomics technologies together can provide rapid and cost-effective strategies to further speed up the discovery of novel natural products