THE ROLE AND REGULATION OF THE CAUDAL GENE IN TRIBOLIUM CASTANEUM SEGMENTATION

The embryo of the red flour beetle Tribolium castaneum develops sequentially by adding segments in an anterior-to-posterior progression using a “clock”-like mechanism similar to that of vertebrates. Previous studies indicate that the oscillations of this segmentation clock are driven by a gradient of the transcription factor caudal (cad), which activates and regulates the clock. Knocking down the cad gene using parental or early embryonic RNAi leads to animals with only head segments. We hypothesized that progressively later embryonic knockdowns would produce animals with progressively more segments if the function of cad does not change during segmentation. To examine this, we knocked down the gene using RNAi at three different timepoints prior to segmentation: 4, 8.5, and 11.5 hours after egg lay (hAEL). We found that segment addition was affected for the two earlier timepoints as expected, but late blastoderm embryos (11.5 hAEL) did not require cad to add segments despite having very few segments already patterned. Therefore, our results suggest that cad is regulating segmentation in very early development only, and we propose that a different regulatory network is controlling late segmentation. Additionally, it has been shown that the frequency of the clock changes during development, hence we hypothesized that cad might be dynamically regulated by various transcription factors during different phases. We performed bioinformatics analyses using the MCAST tool to establish predictions of transcription factor binding clusters that might be regulating cad gene expression, and used these predictions as the basis to clone putative enhancer regions for yeast one-hybrid and cross-species transgenics. We infer that a change in cad regulation causes its function to change through development as we observed in our knockdowns

Les voix d’une épidémie : la représentation littéraire du virus Ebola en Afrique de l’Ouest dans le roman En compagnie des hommes de Véronique Tadjo

Between 2014 and 2016, a devastating outbreak of the Ebola virus terrorized three countries in West Africa: Guinea, Liberia, and Sierra Leone. This epidemic has been widely depicted in various texts and films, including the novel In the Company of Men written by Ivorian poet, novelist, and artist Véronique Tadjo. Published in 2017—a year after the Ebola outbreak in West Africa ended—the novel considers the different voices that respond to this public health emergency. In her literary representation of the epidemic, Tadjo examines the experiences of people in different sectors, from healthcare and research professionals that selflessly gave their lives to help others, to the candid tales of patients and family members of the victims that succumbed to the disease. At the same time, she also considers the perspectives of natural elements— specifically bats, trees, and the Ebola virus itself—and their opinion on the epidemic. By analyzing the form and structure of the book (sixteen chapters with ten human narrators), I show that Tadjo wants us to remember the devastating reality of the epidemic and honor the lives that were lost. Her approach considers a plurality of human voices and experiences, which I focus on in my analysis. In addition, by examining her use of symbolism—more specifically, anthropomorphism—I illustrate how Tadjo establishes a cause-and-effect dichotomy in her narrative and highlights the lessons we can learn from other non-human elements that are usually overlooked. Through this literary portrayal of the Ebola epidemic in West Africa, I further demonstrate that Tadjo seeks to encourage a global conversation, the aim of which is to create peace and harmony among all different inhabitants of the world, including humans, animals, plants, and even non-living infectious agents