Conjugative plasmids are extrachromosomal genetic elements commonly found in bacteria and are capable of being shuttled between different bacterial cells via a process called conjugation. The Luria-Delbruck Method (LDM) is a stochastic based modeling framework used to estimate the conjugation rate of a particular plasmid between bacterial strains. In my experiment, I am probing the theoretical experimental assumptions made by the LDM; in particular, I am testing that when there is variation in the precision of the selection assay, the application of a theoretical correction can result in accurate quantification of the conjugation rate. In the early phases of the experiment, I performed experimental assays in liquid medium to determine antibiotic concentrations in which donors (strains hosting a conjugative plasmid) and recipients (strains able to receive plasmids from donors via conjugation) die and transconjugants (recipient cells that have received plasmid from donor) grow. To test the theoretical correction, I chose two antibiotic concentrations that differ in the amounts of extinction occurring in the transconjugant population. I executed the LDM conjugation assay with these two conditions which produced equivalent conjugation rate estimates, as would be predicted if the correction factor is effective at mitigating the bias produced from variable amounts of transconjugant extinction in the selective conditions. My experiments demonstrate that the LDM continues to be robust in the face of violations to experimental assumptions which affirms the viability of applying the method to a wider range of bacterial populations with variable selective conditions and thereby broadens our ability to understand the dynamic movement of conjugative plasmids.

The drug rapamycin can increase lifespan in a variety of model organisms by repressing the activity of the mTOR complex, a cellular component required for growth and development. Other than one small study that looked at genetic variation in the effect of rapamycin on lifespan in fruit flies (Rohde et al., 2021), little is known about how natural genetic variation affects the response to rapamycin. Previous work by the Promislow lab, utilizing developmental time to indicate rapamycin’s affect, has shown that some strains of fruit flies are completely resistant to rapamycin while others are sensitive. These genotypic differences are also reflected in the metabolome, the complete set of small molecules and metabolites present within cells. Metabolome analysis of these strains revealed significant differences in metabolite concentrations between resistant and sensitive lines. Interestingly, when we treated sensitive strains with rapamycin, their metabolome profiles were like those of starved larvae. I hypothesize that rapamycin is affecting larval ability to take up nutrients and that the starved metabolome is a result of actual starvation. To test my hypothesis, I am designing a starvation assay to compare the death rate of sensitive and resistant larvae. Measurement of resistance to starvation is taken two days after rapamycin treatment by transferring larvae to nutrient deficient food. The duration of time for individual larvae to die is recorded, and the death rates between the two populations are compared. If my hypothesis is true, the sensitive larvae will have a higher death rate than the resistant larva. If death rates are similar however, that could mean that rapamycin does not cause a nutrient deficit and there is another explanation for its effects on the metabolome. This study will provide insights to the underlying mechanisms of sensitivity to rapamycin, and why it might differ between individuals.

It is well-established that mutations have impacts on an organism’s fitness; however, the fitness effects of mutations are not static, and can vary depending on environmental contexts, such as the species in which a mutation is found. Evolution of the same gene in different species could thus lead to the evolution of different phenotypes, as different species would favour different sets of mutations. If that gene could be exchanged between species, it could lead to increased evolutionary possibilities, as high-fitness genotypes that require a prerequisite deleterious mutation in one species could become accessible if the mutation is not deleterious in another. Our research examines how the presence of two bacterial hosts, Escherichia coli and Klebsiella pneumoniae, could affect the evolution of an antibiotic resistance-conferring TEM-1 β-lactamase gene located on a conjugative plasmid. If different hosts confer different mutational effects to TEM-1, the process of horizontal gene transfer (HGT) that allows mutations to be shared between species could open up more mutational possibilities than those accessible in either single-species population alone. We tested this hypothesis through three rounds of experimental evolution in the presence of the antibiotic cefotaxime, where we evolved two single-species E. coli and K. pneumoniae populations and one multi-species population where HGT was simulated with a shared plasmid pool. We are now reconstructing the genotypes found in all three populations after each round to assess how much antibiotic resistance they confer in both species, and hope to see if the genotypes acquired under HGT treatment provide higher resistance compared to the single-species populations. Our results have practical implications for the predictability and nature of antibiotic resistance development in the real world, a current global health crisis, and potentially motivate further study in predicting resistance emergence in clinically encountered multi-species populations.

Southeast Asian communities in the United States and in Asia have a preexisting notion that whiteness equates to beauty and that fair complexions are standard. The colorist mindset is implicitly taught through the media, magazines, workplaces, and most commonly the average Asian family household. Teachings of anti-Blackness are introduced from a young age by advertising the use of whitening products, avoidance of the sun, or not being allowed to wear any clothing that exposes skin because of the risk of tanning. This generational upbringing negatively impacts the way young Asian Americans view themselves, view others, and continues the cycle of internalized colorism and anti-Blackness. My research explores how cultural upbringing, generational trauma, and family dynamic influences the understanding of anti-Blackness being something ingrained into Southeast Asian communities. Through conducting interviews and surveys, I examine how colorism is represented and inherently taught within these communities and the ways it has negatively impacted younger generations in terms of self-image. Rather than presenting statistical research, my research presents in the form of a magazine consisting of stories, original art, and portraiture. By incorporating my skills as a photographer and designer, my research encourages audiences to engage on a more interpersonal level to confront the ways colorism exists in our communities and how we can begin a journey of healing and unlearning our prejudiced biases. The results of this project are displayed through a collaborative, ongoing magazine where the interviews are transcribed as articles with photography and original artwork connecting to the theme of colorism and anti-Blackness. This magazine uses the research collected from the interviews and surveys to produce a design piece that shares experiences, allows audiences and participants to be vulnerable, and explores how socio-political topics can be translated through art/design.

In the era of the internet, numerous individuals participate in fan communities on online social platforms to pursue their interests. Despite all members sharing genuine passions, these communities exhibit varying levels and types of engagement, with some attracting millions if not billions of active users daily, while others show little to no activity. Additionally, users tend to engage in discussions on certain topics more frequently in specific communities. This research aims to explore the reasons behind this difference by investigating the interaction between community size and openness. While previous works focus on the impact of either size or openness, this study develops hypotheses on how their interaction affects member engagement. A survey study is outlined to test these hypotheses, examining members' sense of belonging, level of hostility, and variation of opinions in four distinct communities representing different interactions between community size and openness: large and open, large and closed, small and open, and small and closed. The survey will be distributed among TFBoys fans on Sina Weibo in the Spring of 2023. The expected results will provide insights into how community size and openness interact to influence member engagement in online fan communities, offering recommendations for online social platforms to design features that promote member engagement and contribute to scholarly knowledge in Computer-Mediated Communication and Social Media Studies.

In a liberal and democratic society, unjust policies can be prevented by the people through voting or political action. People in a free society have a default political responsibility to prevent unjust policy in these ways. However, people under a non-democratic regime do not have the means to actively engage in political affairs and therefore do not causally contribute to unjust policy. This paper analyzes the protests against the zero-COVID policy employed by the Chinese government since the outbreak of the COVID-19 pandemic. I use three theoretical approaches to examine to what extent people have a moral responsibility to oppose unjust policy. First, people can follow the heroic example of Antigone in Sophocles' tragedy and mount heroic resistance at great personal cost. They can appeal to higher moral values and take up rebellion against the authoritarian government. Second, individuals can honor their social roles despite the state's rules. Doctors should treat the patients even though the zero-Covid policy demands them not to do so. Finally, individuals can seek to preserve truth and inner freedom. This is the approach with the least cost. People should seek truth and be aware of the lies made by the government. In the meantime, they need to protect themselves from being punished by the authoritarian government. These are three models of moral responsibility. I argue that sticking with the truth is the minimum moral requirement for individuals under authoritarian regimes.

Phonemic proficiency refers to the ability to manipulate the phonemes, or unit of sounds, in a word. Speech perception deficits has been linked to lower phonemic proficiency, as children have difficulty isolating, manipulating, and blending sounds that they cannot perceive. Autistic children commonly report difficulty perceiving speech in noisy real-world environments where many people are talking at the same time, such as a classroom or playground. Thus, in this study, we investigate the relationship between phonemic proficiency and multitalker speech perception in autistic children. We hypothesized that we would observe a stronger correlation between speech perception and phonemic proficiency in autistic children compared to the neurotypical comparison group. Moreover, we expected that autistic children will have worse multitalker speech perception thresholds overall, suggesting difficulty perceiving speech under complex conditions. We tested 19 7-to-10-year-old autistic children and a comparison group of 19 age- and biological sex-matched neurotypical children. The Phonemic Proficiency subtest of the Weschler Individual Achievement Test – Fourth Edition was administered to assess phonemic awareness. Multitalker speech perception thresholds were obtained under 2 conditions: Co-located Noise and Segregated Noise. In the Co-located Noise condition, the target speaker spoke sentences from 0° azimuth with two additional distracting talkers, referred to as maskers, co-located from the same location. In the Segregated Noise condition, the distracting talkers were spatially segregated to ±90° azimuth, while the target talker remained at 0°. Preliminary analyses suggest that a relationship between phonemic proficiency and multitalker speech perception is observed. These results will advance our understanding of the difficulty autistic children have perceiving speech and have the potential to lay the groundwork for novel assessment and intervention strategies to improve how children with and without autism listen and learn in a noisy classroom. All authors participated in data acquisition, analysis, and preparation of this presentation.

 Children are tasked with listening and learning in noisy environments where many people are talking at the same time every day. Conceptual models of listening under complex conditions posit that working memory plays a role in the ability to extract the target speech from the distracting noise. Hard-of-hearing (HoH) children, in particular, do worse listening in noisy environments. Thus, in this study we investigate the relationship between working memory and multitalker speech perception in HoH children. We hypothesized that we would observe a correlation between working memory and speech perception in both HoH and the typical hearing comparison group. Moreover, we expected that HoH children will have worse multitalker speech perception thresholds overall, suggesting difficulty perceiving speech under complex acoustic conditions. We tested 7-to-18-year-old HoH children and an age- and biological sex-matched typical hearing (TH) comparison group. Working memory was assessed in both visual and auditory domains; participants were asked to recall either a sequence of visually presented letters or auditorily presented numbers. Multitalker speech perception thresholds were obtained under 2 conditions: Collocated noise and Segregated noise. In the Collocated Noise condition, the target speaker spoke sentences from 0° azimuth with two additional distracting talkers, referred to as maskers, collocated from the same location. In the Segregated Noise condition, the distracting talkers were spatially segregated to ±90° azimuth, while the target talker remained at 0°. Preliminary analyses suggest that a relationship between working memory and multitalker speech perception is observed. These results will advance our understanding of why HoH children experience difficulty perceiving speech under noisy conditions and have the potential to lay the groundwork for novel assessment and intervention strategies to improve how TH and HoH children listen and learn in a noisy classroom. All authors participated in data acquisition, analysis, and preparation of this presentation.

CRISPR Activation (CRISPRa) is a powerful discovery-based tool to evaluate gain-of-function en masse. Applied successfully to emerging cell therapies, this technology offers tremendous promise to inform next-generation therapy design. Despite this potential, translation of CRISPRa to primary cells, including T lymphocytes, has been impeded by poor transgene expression. Based on prior reports of dCas9 genotoxicity, we suspected that CRISPRa could be exerting a toxigenic effect on CAR T cells, and thereby selecting against clones with high expression. To test this hypothesis, three separate constructs were designed with inhibited transcription and/or translation of the CRISPRa transgene. Following delivery of the constructs to donor T cells, analysis by flow cytometry revealed similar levels of cell yields and no net increase in dCas9 marker positivity across all CAR T cell subsets. Further epigenetic experiments and drug studies with anti-silencing compounds revealed that transcription of the CRISPRa transgene was severely inhibited. Collectively, these findings suggest that the CRISPRa transgene does not exert a toxigenic effect on CAR T cells; rather, low CRISPRa expression is caused by transgene silencing. Targeted efforts to mitigate silencing of the CRISPRa transgene are thus warranted to achieve adequate implementation to therapeutic cell subsets.