Plasmids are extra-chromosomal elements that are normally found in most bacteria. A recombinant plasmid, pGLO™, is used in Escherichia coli for many student experiments, especially as part of the Advanced Placement Biology curriculum. This plasmid contains the green fluorescent protein (GFP) gene under control of the arabinose promoter and regulatory protein, the beta lactamase gene, an origin of replication, and a multiple cloning site. The plasmid is retained in cells due to selective pressure of medium containing ampicillin. Evolutionary fitness is typically considered the reproductive success of a particular genotype/phenotype with emphasis on the particular genetic background of the individual and, hence, plasmid maintenance would seem to be under tight control. Little experimentation has been done on the rate of plasmid loss in bacteria in the absence of selective pressure. In this study, plasmid loss was explored under different selective pressures, especially related to the cost of expression of GFP. This study found strong selective pressure against GFP gene expression in both DH5α and DH10B strains of E. coli, with significantly faster plasmid loss observed in DH10B than in DH5α. There was surprisingly little selective pressure for pGLO plasmid loss when GFP was not actively expressed. Gain of function mutations that allow for positive selection for their occurrence have been well characterized in the scientific literature, however loss of function mutations and subsequent use of negative selection for their retrieval provide a unique opportunity to study another facet of the evolutionary process. This research provides such an example.

Full spectrum CBD oil is widely available and touted as a safe and effective way to lower anxiety, promote restful sleep, and reduce inflammation. Given the anecdotal evidence that full spectrum CBD oil can also be used as an adjuvant to chemotherapy, an over-the-counter CBD oil product was tested to determine if it possessed cell cytotoxic properties. A “triple negative” breast cancer cell line was chosen as it represents a breast cancer subset which lacks targeted therapies and correlates with poor clinical outcomes. Cancer cells exposed to CBD oil had reduced cell viability, broad changes in gene expression, and reduced expression of a key growth factor receptor compared to control cells. Together, these data suggest that CBD oil is effective at reducing breast cancer cell viability in vitro. Future studies will focus on determining the range of cancer cell types similarly affected and on confirming mechanistic details.

During development of the inner ear, the movement and fate of progenitor cells must be carefully regulated for the adult organism to hear properly. Neuroblast delamination is the migration of neural progenitor cells from the developing otic epithelium and towards the hindbrain to create the vestibulocochlear nerve. The purpose of this research is to investigate the expression of the transcription factor Goosecoid (GSC) during neuroblast delamination in chickens. GSC is an evolutionarily conserved transcription factor that regulates changes in cell movement in several different contexts. Given this conserved function, GSC may be promoting neuroblast delamination in the chicken otocyst. Immunofluorescence was used to track the expression of GSC within migrating neuroblasts. Interestingly, the pattern of GSC localization varies among cells, with nuclear localization of GSC being positively associated with neuroblast cell identity.

Pesticide use can impact not only cultivated land, but also protected ecosystems that receive pesticide inputs due to aquatic connectivity or atmospheric transport from agricultural regions. In Costa Rica's Caribbean lowlands, pesticides applied to banana and pineapple plantations are a potential source of pollution to ecological reserves. Macroinvertebrates and fish are both potentially useful bioindicators of agrochemical pollution in aquatic systems, and our goal was to determine whether three common stream consumer species (one fish and two aquatic insect species) could serve as bioindicators for the organophosphate pesticide ethoprophos. We identified thresholds at which ethoprophos impacts the survival (LC₅₀) and observed behavior (LOEC – lowest observed effect concentration) for each species. The LC₅₀ of the guppy Priapichthys annectens was 1530 µg/L, with observable behavioral changes occurring at 1000 µg/L. Insects were more sensitive: the mayfly Traverella holzenthali had an LC₅₀ of 15 µg/L and an LOEC of 2.5 µg/L, and the caddisfly Leptonema sp. had an LC₅₀ of approximately 30 µg/L and an LOEC of 5 µg/L. The LC₅₀ values are notably higher than ambient concentrations recorded from polluted Costa Rican streams and suggest that these taxa are not ideal indicator species. However, the lower LOEC values (in the same order of magnitude as ambient concentrations) highlight the potential ecological importance of behavioral modification due to pesticides. Quantifying the thresholds at which common pesticides impact ecosystems is a key step in identifying bioindicator species and protecting tropical biodiversity.

Polyvinyl alcohol (PVA) is a bioplastic touted as an environmentally friendly solution due to its water solubility and potential to reduce plastic waste compared to the traditional polyethylene terephthalate (PET). However, few studies have characterized how PVA may impact the developmental dynamics of model organisms and biochemical processes in the environment. The objective of this study was to evaluate the impacts of PVA and PET on the growth and development of an Allium cepa plant model system. We used a controlled experimental design to evaluate plant growth in aquaponic mesocosms with dissolved PVA and suspended microplastics. We hypothesized that, relative to control plants, PVA would have fewer negative impacts than PET in terms of plant development, water chemistry, bacterial richness, and plant cell density. In both PVA and PET treatments, we detected a restricted rate of number of roots, mean root length, and mean shoot length, as well as an increased rate of change in water chemistry toward a more basic and saline environment. The lowest bacterial richness was detected in PVA, while the lowest cell density in the bulb- and root-tissues was detected in PET. Our study shows that both PVA and PET pollution similarly impacted the dynamics of the living system. We discuss bioplastics in the framework of a short-term solution to curb physical plastic-pollution and the need for long-term study of their effects on both abiotic and biotic interactions within the environment. We further propose future studies characterize the broader sustainability implications to urban green infrastructure.

Chagas disease, also known as American trypanosomiasis, is caused by the parasite Trypanosoma cruzi and is transmitted in the feces of insect-vector species in the taxonomic sub-family Triatominae. As a neglected tropical disease, the disease is endemic to the tropical Americas, has no cure, and disproportionately afflicts rural and impoverished communities throughout Latin America. The objective of our study was to evaluate biological factors contributing to the spread of Chagas disease in eastern El Salvador by using PCR techniques to identify blood-feeding preferences of Triatoma dimidiata inside and outside of housing environments. We hypothesized that T. dimidiata blood-feeding preferences would differ with respect to habitat (domiciliary or peridomiciliary), development stage (instars or adults), T. dimidiata infection-status with the T. cruzi parasite (positive or negative), and the sex of T. dimidiata. We found that T. dimidiata in peridomiciliary environments preferred feeding on birds, dogs, and rats, but were more likely to be at the adult-stage when positive for T. cruzi infection. In contrast, T. dimidiata in domiciliary environments preferred feeding on pigs, humans, and mice, but were more likely to be at instar-stages when positive for T. cruzi infection. Additionally, female T. dimidiata preferred feeding on birds and dogs, while males preferred feeding on pigs, humans, and rats. We discuss differences between our findings and those reported from western El Salvador and highlight the importance of understanding the vector ecology of T. dimidiata as part of a broader EcoHealth strategy to mitigate the transmission of Chagas disease.

This essay represents a path toward integrating an interest in a healthcare profession, dentistry, with an interest in environmental sustainability. As an undergraduate student studying biology with an interest in becoming a dentist, I focused on courses required for health care professions. At my college, my academic major department implemented curricular changes that served to diversify environmental, ecological, and evolutionary course offerings beyond the traditional evolution lecture and ecology lab. As a result, I had the opportunity to enroll in an Urban Evolutionary Biology lecture course that explored the novel role cities play as evolutionary agents of change in natural populations over time (i.e., natural selection, migration, genetic drift, and mutation). The ability to interact with a professor of evolutionary ecology provided a space to cultivate new ideas of my own by integrating concepts from environment sustainability, specifically community-engaged research in biological science disciplines. Herein, I showcase the importance of learning outside one's comfort zone, contrast operational versus environmental explorations in sustainability, and share how metadata (data about data) in green dentistry can empower sustainable communities.