Dartmouth Institute for Health Policy and Clinical Practice
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Evolution and Adaptation to Temperature in Thermotogota
Get PDFLife thrives across incredibly diverse environmental conditions, yet most organisms are restricted to growing within a narrow range around their optimum growth temperature (OGT). The evolutionary events leading to changes in OGT are poorly understood, and it is uncertain if specific genes are required to thrive at a particular temperature. The bacterial phylum Thermotogota is an excellent model for the evolution of OGT. It comprises mesophilic, thermophilic, and hyperthermophilic members that collectively grow between 20°C and 90°C.
In this work, I analyze the history of OGT in the Thermotogota phylum and show how horizontal gene transfer contributes to the evolution of OGT. I initially tested the phylogeny for topological artifacts and established a reliable reference phylogeny. An analysis of genes from Mesoaciditoagles showed that the deeply branching moderate thermophiles of the phylum contain a large proportion of genes that are more closely related to other moderate thermophiles in the phylum based on phylogenetic relationships. Next, I used ancestral sequence reconstruction to estimate that the OGT of the last common ancestor of Thermotogota was 66°C, followed by multiple OGT increases and decreases in descendants during Thermotogota diversification. Finally, I correlated the presence/absence of gene families with OGT using genome-wide association studies. I identified 158 gene families associated with OGT. While many of the OGT-associated genes are poorly characterized, most are cytoplasmic or membrane-bound, and many are involved in metabolism. I reconstructed the phylogenies of individual families and modeled their gain and loss throughout Thermotogota history. The genes were repeatedly gained and transferred within the phylum and are often more closely related to taxa outside the phylum. These findings suggest hyperthermophily is often a secondary adaptation arising from an ancestral phenotype of lower OGT. My results suggest that parallel gains via horizontal gene transfer may promote independent adaptations to similar OGTs across the phylum
Emotional Regulation on Modulating Associations between Depression and Physical Activity as Characterized via Deep Learning
Get PDFEmotional regulation and physical activity are known to be associated with depression; however, a deeper understanding of how emotional regulation may strengthen or weaken the bonds between depressive symptoms and physical activity may aid clinicians and researchers in developing cognitive behavioral therapy (CBT) for those adversely affected by depression. As part of the Tracking Depression Study, this analysis uses data collected from 306 participants diagnosed with Major Depressive Disorder. To study their behavior, we analyze actigraphy data, or longitudinal physical activity intensity data, as it relates to depression severity, quantified by the daily PHQ-9 questionnaires. We study these associations through deep learning models, including a novel state-of-the-art pre-trained actigraphy transformer model, to analyze and characterize the association between physical activity and depression severity for two different groups, low and high emotional regulation. The findings of this study indicate that emotional regulation significantly modulates the association between actigraphy and depression symptoms. Specifically, in the group with high emotional regulation, there was a moderate correlation between physical activity patterns and depression severity, particularly during the periods around sleep. However, no significant associations were observed in the group with low emotional regulation. Surprisingly, the overall magnitude of daytime physical activity did not correlate with depression levels, suggesting that specific patterns of activity rather than overall activity levels may be more relevant to understanding depression in the context of emotional regulation. This study highlights the potential of cognitive behavioral therapy that incorporates differences in physical activity patterns and emotional regulation among individuals
Troubling Waters: Anthropocene Marine Gothic in the 19th-Century Anglo-American Fiction
No full textThe 19th century witnessed intensifying marine ecological disruptions by colonial, industrial, and imperial activities. Meanwhile, current scholarship acknowledges the significance of the 19th century in tracing the emergence of the “Anthropocene” – a loose shorthand for ecological damages that are planetary in scale. This thesis aims to analyze how gothic imagination of the marine space unravels the linkages between the two temporally intersecting phenomena. Drawing on ocean studies, ecocriticism, new materialism, and gothic studies, I theorize what I call “Anthropocene marine Gothic discourse” to understand how 19th-century Anglo-American writers attend to the marine space to grapple with planetary ecological concerns that resonate with current theories about Anthropocene anxiety. Through the case studies of Edgar Allan Poe’s “The Narrative of Arthur Gordon Pym of Nantucket” (1838), Herman Melville’s “The Encantadas” (1854), and William Hope Hodgson’s “The Voice in the Night” (1907),I argue that these writers repurpose traditional marine gothic tropes to incorporate both the representations of gothic marine ecologies and the evocation of a specific type of Anthropocene horror. In so doing, their works recognize the marine space as a crucial site documenting the multidimensional human-environmental relationalities beyond the presumed human/nature binary, taking into account the planetary entanglements of beings involving different temporospatial scales. Moreover, by capturing how such entanglements speak to the extensive marine ecological disruptions, their imagination of a unified “Anthropocene marine Gothic discourse,” whether consciously or not, challenges the colonial, industrial, and imperial logics of treating the more-than-human marked by resource extraction and the manipulation of the nonhuman world
Geotransformación and Overcoming Underdevelopment in Socialist Cuba
No full textThe term geotransformación, coined and theorized by Cuban geographer and revolutionary Antonio Núñez Jiménez in his 1968 book Geotransformación de Cuba, is an analytic frame which emphasizes the interconnectedness of social and natural transformation. As such, geotransformación functions as a conceptual weapon against not only theories of geographic determinism attempting to depoliticize history, but also grand historical narratives which center the human by overstating its independence from the forces of nature. Taking geotransformación as a conceptual compass for a return to the Cuban Revolution’s decisive early years, I engage in close readings of primary texts including geographic treatises, legal documents, and poetry. Drawing on key passages from Geotransformación de Cuba, I argue that agrarian reform cannot be separated from the social transformations of the revolution. Then, I theorize the plantation as an engine of underdevelopment and show how overcoming the structure of the colonial plantation formed the central task of agrarian reform. An analysis of Hurricane Flora and Cuba’s response to its devastation highlights the importance of geotransformación’s conceptual frame for understanding the interconnections between social and natural transformations in Cuba, and how these transformations relate to overcoming the long history of Cuba’s underdevelopment. I conclude by arguing geotransformación forms an important contribution to the wave of ecological thought which emerged in Marxist theory beginning the 1960s