Biological Sciences Undergraduate Works
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- ItemOpen AccessCircadian Patterns of Flight in a Long-Distance Migratory Songbird(2024-07-05) White, Trina; Davoren, Gail (Biological Sciences); Fraser, KevinMigration is a common strategy in many different animal taxa, including birds. Most migratory songbirds migrate mainly at night (i.e., nocturnal migrants), with some species migrating primarily during daytime (i.e., diurnal migrants). Some birds can even combine nocturnal and diurnal flights, but these tend to be associated with barrier crossings (e.g., long overwater flights). Whether diurnally migrating songbirds also incorporate night flights into other periods of their spring migrations despite a lack of migration barriers has not been investigated. Further, we lack a precise understanding of the influence of specific environmental conditions on day or night flight behaviour. We investigated circadian patterns of flight in purple martins (Progne subis), a long-distance migratory songbird that journeys between nonbreeding areas in South America and breeding sites in eastern North America. We used direct-tracking (GPS loggers) of individual spring migrations to quantify the daily timing of flights, flight speed, flight distance, and altitude as well as whether these factors were associated with temperature. Birds were tagged with GPS loggers in Winnipeg, Canada, which collected location and altitude every two hours during spring migration. We used Movebank to align location data with average local temperature. We found that martins migrated mainly during daylight, but surprisingly, 15% of flights overland occurred during the night. The average speed for daytime and nighttime flights was similar. We found that neither temperature nor timing of flights influenced flight speed and distance travelled, but flights at higher altitudes were associated with longer flight distance and faster speeds. Our results suggest that a species classified as a diurnal migrant routinely makes night flights overland that are not associated with crossing known migratory barriers. Further studies could increase the sample size of birds and the number of usable GPS fixes, which would allow us to track birds as close to their breeding grounds in temperate areas as possible.
- ItemOpen AccessEnergy Density of Capelin (Mallotus villosus) and Sand lance (Ammodytes americanus and Ammodytes dubius) during the summer in Coastal Newfoundland(2024-07-05) Vonderbank, Kate; Stacey, Joy (Biological Sciences); Treberg, Jason (Biological Sciences); Davoren, GailSpawning capelin (Mallotus villosus) and non-spawning Atlantic sand lance (Ammodytes americanus, A. dubius) adults and juveniles are important forage fish species in coastal Newfoundland during July and August when high abundances of top predators rely on them as critical energy sources. To determine whether these prey types differ in their energy content, and interannual changes in quality, samples of each prey type were collected during July-August 2020 and 2023. Bomb calorimetry was used to measure whole-body dry energy density (kJ/dry g) and calculate wet energy density (kJ/wet g) and water content. Although sand lance are at the peak of their annual lipid cycle and capelin are at their minimum during the summer, adult female sand lance had lower dry energy density (mean of both years ± SE, 20.7 ± 0.11 kJ/dry g) than all capelin sex and maturity categories, and wet energy densities (4.4 ± 0.09 kJ/g) did not differ from capelin. Within capelin, wet and dry energy densities did not differ among gravid females, spent females and males, which contrasts previous findings from before the capelin population in Newfoundland collapsed. Within sand lance, juvenile dry energy density (20.8 ± 0.14 kJ/g) did not differ from adult females. Juvenile sand lance wet energy density was the only prey type that varied interannually, where energy density in 2020 was higher (5.3 ± 0.15 kJ/g), but this is thought to be because the samples were more dried out before collection. Overall, our findings indicate that although sand lance adults and juveniles are similar in wet energy densities to capelin, their lower wet mass per fish would result in a higher number of sand lance needed to reach a fixed energy content per meal. Other factors, including abundance and distribution of each species, also impact foraging costs and must be paired with energy densities to estimate prey type quality.
- ItemOpen AccessIRE1 Activation in Spinal Cord Development and Repair in the Zebrafish Model(2024-07-05) Talabis, Kayla; Jeffries, Kenneth (Biological Sciences); Stacey, Joy (Biological Sciences); Whyard, Steve (Biological Sciences); Lindsey, BenjaminThe Unfolded Protein Response (UPR) is a cellular pathway that functions in the maintenance of proteostasis in response to endoplasmic reticulum (ER) stress. Recent studies implicate the IRE1 branch of the UPR in the development of the central nervous system (CNS) and in response to spinal cord injury (SCI). To date, studies have focused mainly on mammalian models and thus we know little about the role of the UPR in the CNS of other vertebrates. In this study, we take advantage of the many attributes of the zebrafish model, including its capacity for neurorepair, to investigate the activation of IRE1 during spinal cord development and following SCI. Using the Tg(xbp1s:eGFP) transgenic reporter fish that expresses GFP upon IRE1 activation, we show that IRE1 is strongly upregulated in early larvae compared to juveniles and adults. High levels of IRE1 expression are displayed at 4-days post fertilization (dpf) and drop off into adulthood. Interestingly, when exposed to the ER stress inducing drug Dithiothreitol (DTT), larvae at 4-dpf also show slight elevated levels of IRE1 activation compared to later stages of development, suggesting IRE1 is less inducible with age. We next established a larval SCI model to ask whether IRE1 expression was upregulated after SCI. We demonstrate that, in contrast to mammalian models, spinal cord IRE1 activity remains the same or slightly decreases following SCI.
- ItemOpen AccessDetermining the influence of migratory stopover timing and movement on plant seed dispersal by a short-distance migratory songbird, the American robin, Turdus migratorius(2024-07-05) Sturch, Tamara; Fraser, KevinAnimals disperse approximately 50% of seeds worldwide and could assist plants in shifting their distribution in the face of climate change. However, seed dispersal by animals is understudied particularly in temperate areas. American robins (Turdus migratorius) are migratory thrushes which have a frugivorous diet in the fall and may be important seed dispersers. Nineteen American robins were fitted with GPS tracking units at Assiniboine Park, Winnipeg, Manitoba during their fall migration in 2022. The GPS units provided live location data for the birds every 6 hours. This data was used to investigate the seed dispersal potential of American robins during their fall migration by examining the time spent and distance travelled while at stopover, as well as the use of urban versus rural habitats. Fecal samples collected at capture were used to identify the seeds of plant species these robins had consumed and therefore may disperse. I found that individual robins spent 15 to 33 days at fall migratory stopovers (an average of 26.64 days ± 4.95) and travelled extensively at stopovers (29-320 km; average 101.68 km ± 84.95) before continuing migration. Birds made use of both urban and rural habitats while at stopovers. I also found that fecal samples contained both native and non-native seed types, with Malus sp. making up most (62.71%) of the seeds in the samples. Overall, my results show that American robins have the potential to be important dispersers of native and non-native seeds across both rural and urban habitats, due to the large amount of time and distance travelled at fall migratory stopovers. Future studies should evaluate the viability and recruitment of seeds that have been dispersed by robins and examine the movements of American robins during fall stopovers originating from both urban and rural populations.
- ItemOpen AccessInvestigating the Roles of Homeobox Proteins and TEAD in Small Cell Lung Cancer(2024-07-05) Ricarte, Bea; Pearson, JoelLung cancer remains a significant global health concern, responsible for a substantial number of cancer-related deaths annually. Small cell lung cancer (SCLC), one of its subtypes, is particularly aggressive and resistant to treatment, leading to a poor prognosis for patients. Unfortunately, treatment options for SCLC remain limited and have not been advanced for decades. This highlights the urgent need for a deeper understanding of the molecular mechanisms underlying the pathogenesis of SCLC in order to identify novel therapeutic strategies for this disease. DNA-bind proteins, TEADs, play a crucial role in promoting SCLC survival. TEADs are best recognized for their role in interacting with transcriptional activators, YAP and TAZ, however, it was found that the function of TEADs in SCLC is completely independent of YAP and TAZ. Beyond this however, the mechanisms underlying the critical function of TEAD in SCLC is unknown. Preliminary data gathered by the Pearson lab identified the presence of homeobox proteins PROX1, NKX2-1 and NKX2-2 with the TEAD complex in SCLC, prompting the hypothesis that TEAD interacts with these proteins to silence TEAD target genes in SCLC, promoting the cancerous state. Using co-immunoprecipiation, the association of TEAD with PROX1 and NKX2-1 were confirmed. Additionally, CRISPR interference was used to knockdown PROX1, NKX2-1 and NKX2-2 in SCLC cells, to assess their role in TEAD-mediated gene regulation. This resulted in an increase in controlled cell regulation and differentiation genes, and a decrease in SCLC biomarkers, consistent with the hypothesis. However, contrasting the hypothesis, protein knockdowns showed a decrease of cell adhesion genes. Nevertheless, these findings bring light to a novel pathway in SCLC pathogenesis. Understanding the exact mechanisms behind these homeobox proteins and their interaction with TEADs could lead to the development of more effective treatment for SCLC.