Browsing Department of Biological Sciences by Issue Date
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- ItemOpen AccessIndividual timing consistency across purple martin (Progne subis) migrations(2023-03) Bridges, Colin; Garroway, Colin (Biological Sciences); Davoren, Gail (Biological Sciences); Fraser, KevinMigration timing in long-distance migratory birds plays an essential role in individual survival and fitness. Migration schedules determine when individual birds depart and arrive seasonally between their overwintering and breeding sites. Bird migration timing may be largely driven by internal routines with some plasticity to environmental conditions, but individual timing across migrations has been little explored. To investigate the consistency of individual timing across migrations, I examined the individual order of migration timing in purple martins (Progne subis), a neotropical migratory songbird that travels between breeding sites throughout eastern North America and winter sites in Brazil. Migration timing data were collected for 295 different individual purple martins spanning over nine years by using light-level geolocators deployed during the breeding season at sites across the range and collected at the same sites the following year. I used a linear mixed-effect model (LMM) to examine the influence of the rank order of departure dates in one season on the rank order of four subsequent migration events while controlling for the effects of breeding latitude, sex, and age. Overall, I found that the individual rank order of migration timing in purple martins was conserved across migrations. Rank order timing was consistent between fall departure date from the breeding site and spring arrival dates in the following year (0.28 0.03, 95% CI 0.21-0.34), as well as the finer scale across fall migration departure and arrival dates (0.33 0.05, 95% CI 0.23-0.42), over the wintering period (0.39 0.04, 95% CI 0.30-0.48), and across spring migration (0.03 0.001, 95% CI 0.026-0.033). These results demonstrate that purple martin exhibit consistency in individual migration timing throughout the annual cycle. Migration distance also played a significant role, as the consistency of rank order timing lessened with distance traveled. Understanding how individual birds time migrations and if individuals are consistent between events can provide insight into how shifts in the environment with climate change could lead to a mismatch if migratory birds are unable to adapt. Future studies should examine if purple martins are able to adjust their migration timing and how long these changes persist in response to environmental alterations.
- ItemOpen AccessLipids in Anadromous Northern Dolly Varden (Salvelinus malma malma)(2023-03) Kulchycki, Lisa; Loseto, Lisa; Davoren, GailAnadromous Arctic fish species have adapted to a particular environment by evolving unique lipid cycling strategies such as storing large amounts of lipid during times of high productivity in order to survive long migrations, spawning events, and seasonal variation in food availability. Research on lipid content and storage location in the body is very limited, especially regarding the northern Dolly Varden, a fish species important culturally and for sustenance to the Indigenous Peoples in the western Canadian Arctic that is listed as ‘Special Concern’ under Species at Risk legislation. Lipid content in anadromous Dolly Varden obtained from two marine (coastal) (summer) and two freshwater (fall) locations were examined and compared to test for differences in percent lipid between locations/seasons. Percent lipid was compared between the muscle and homogenized whole-body of individuals caught in freshwater. Muscle lipid content was significantly different between freshwater locations and one of the marine locations (~34% higher from the marine location). One marine location contained fish with unexpectedly high muscle lipid percent. A weak/moderate linear relationship was found between lipid percent in the muscle tissue and whole-body tissue of the same individuals (r2= 0.2013 when sex was an added variable; r2= 0.4204 when reproductive status was an added variable), and reproductive status influenced this relationship. Sex of the individual did not affect lipid content in the muscle nor on the relationship between percent lipids in muscle and whole-body. Changing environmental factors due to climate change such as the timing of the ice melt and phytoplankton blooms can affect energy exchange through the food web, and thus research on the nature of fluctuating energy and lipid levels is needed to aid in conservation efforts of Arctic species.
- ItemOpen AccessThe importance of discs large homolog 5 and microRNA-34 expression to the development of the mosquito Aedes aegypti(2023-04) Carroll, Lara; Wilkins, Olivia (Biological Sciences); Whyard, SteveUnderstanding how the expression of particular genes and regulation of genes affects development in different organisms is key to advancing our knowledge in developmental biology. The epithelial-mesenchymal transition (EMT) process is commonly observed during the growth and development of various animal tissues. One gene involved in EMT regulation and directly related to development in humans is discs large homolog 5 (dlg5). If the role of this gene is conserved across species, it opens many medical application possibilities to help treat a multitude of medical issues, such as cancer. microRNAs are short, single-stranded non-coding RNAs that regulate gene expression by binding to the 3’UTR of complementary target mRNAs. microRNA-34 (miR-34) is a microRNA of interest with relation to dlg5 as it is predicted to bind with dlg transcripts. miR-34 has also shown clinical potential in the past with regulating cell proliferation. This study looks at the dlg5 gene and miR-34 in the mosquito Aedes aegypti to see if the expression of this gene and microRNA is evolutionarily conserved to that of Drosophila melanogaster. A developmental expression qRT-PCR analysis, analyzing the relative dlg and miR-34 transcript levels in different temporal stages of A. aegypti development, was conducted to compare the relative transcript levels of A. aegypti throughout development. Then, a dlgdsRNA RNAi-mediated knockdown by bacterial feeding was performed to see if knocking down dlg has an effect on development. The results of the qRT-PCR analysis and RNAi experiment were not significant enough to come to a justified conclusion. Therefore, further testing is required to produce meaningful conclusions regarding the developmental expression of dlg and miR-34.
- ItemOpen AccessAlternative BNIP3 splicing in alveolar rhabdomyosarcomal cells(2023-04) Fernando, Amy; Whyard, Steve (Biological Sciences); Ghavami, Saeid (Human Anatomy and Cell Science); Gordon, Joseph; Wilkins, OliviaSeveral cellular phenotypes drive tumorigenesis in alveolar rhabdomyosarcoma. These phenotypes may be attenuated via treatment with non-steroidal antiinflammatory drugs, like aspirin, tolfenamic acid, and indomethacin, which interfere with intracellular prostaglandin synthesis and induce cell death. Recent data suggest that this mechanism may be mediated by differential splicing of the cell death gene BNIP3, such that full-length BNIP3 could promote cell death, while short BNIP3 could inhibit it. Additional data indicate that oncogenic cytokines from the TGF-β family may also be involved in this mechanism. This honours thesis examines whether indomethacin alters cell death, BNIP3 splicing, and other alveolar rhabdomyosarcoma phenotypes. To assess this, RT-PCR and fluorescent imaging assays were performed on the RH30 cell line. Results of these experiments indicate that a 2.0 μM concentration of indomethacin alters the cell death phenotype. However, they also provide preliminary evidence that the expression levels of full-length and short BNIP3 are unchanged. Accordingly, drug treatments did not change calcium signalling pathways. Furthermore, this text examined the role of TGF-β cytokines in this molecular pathway. To help establish the role of TGF-β in alveolar rhabdomyosarcoma, a statistical analysis of a previously generated secretome dataset was performed. It determined that the three TGF-β isoforms are differentially secreted in alveolar and embryonal rhabdomyosarcoma. However, qRT-PCR results indicate that indomethacin exposure does not change TGF- β1 expression. Collectively, this thesis provides preliminary evidence that indomethacin exposure induces cell death in RH30s independently of alternative BNIP3 splicing.
- ItemOpen AccessComparing the Rates of Adaptive Change in Species Across Biogeographic Gradients(2023-04) Bourrier-Vince, Ava; Fraser, Kevin (Biological Sciences); Jeffries, Kenneth (Biological Sciences); Garroway, ColinThe process of adaptive evolution allows a species to persist with specific traits tailored to their environment. The rate at which a population adapts can change based on the varying environmental abiotic and biotic factors of their location. Environmental characteristics such as the amount of available energy, elevation, temperature and degree of human disturbance thus affect the rates of adaptive evolution across biogeographic gradients. In this study, I used data on adaptive rates for terrestrial species and aimed to determine if the rates of adaptive evolution showed patterns related to spatial biogeographic patterns and environmental factors such as elevation, evapotranspiration, precipitation and temperature. Additionally, I tested whether the rates of adaption changed based on these specific environmental factors and a human density. The results of my data analysis detected that the rates of adaptation showed good variation in relation to spatial scale patterning but no significant correlation patterns between the tested environmental variables and the rates of adaptive evolution were detected. This result did not support my hypothesis that the rates of adaptive change would vary through space with environmental gradients. Many potential factors may have caused this inconclusive result. Further research into this topic would be useful to understand and predict the adaptive evolution of species’ in varying environmental gradients. I propose that studies on this data should aim to utilize more of the available samples within this public dataset such as the aquatic species. Additionally, further research may benefit from narrowing the study size based on location or taxa for significant relationships to be accurately detected.
- ItemOpen AccessImproving mosquito (Aedes aegypti) sex-sorting methods for sterile insect technique using RNAi gene knockdowns(2023-04) Rempel, KadriDoublesex (dsx) is an alternatively spliced mosquito (Aedes aegypti) gene that controls sex development by producing male (DSXM) or female (DSXF) transcription factors that regulate gene expression in a sex-specific manner. As both DSXF and DSXM bind the same DNA sequence, their ability to regulate differential gene expression is predicted to be modulated by other proteins that interact with DSX. A previously conducted protein-protein interaction study identified several proteins that bind to DSXF and their role in altering female development was explored in this study by knocking down their corresponding transcripts using RNA interference during the larval stages of development. Knockdowns of the genes nop-14, wdr-48, and rnmt was achieved by feeding mosquito larvae HT115 strain E. coli transformed with a pl4440 plasmid containing a dsRNA template specific to each of three target genes. The knockdowns were carried out at their normal rearing temperature, 28oC, and at 22oC to slow mosquito development. Knockdown of one of the genes, wdr-48, at either temperature, significantly increased the time to pupation of females compared to males. This delayed development of females could prove useful in the sex sorting of males and females during the pupal stage by providing a method to select only males for a sterile male insect (SIT) population control program for Ae aegypti. Of note, the 22oC growth conditions provided a larger difference in the pupation times between the sexes than the 28oC conditions did, and thus may provide even better sex-sorting for mosquito SIT.
- ItemOpen AccessSize matters: Host body mass overshadows climate change in parasite prevalence among semi-arid ground squirrels (Xerus inauris)(2023-04) Guarino, Andrea; Davoren, Gail (Biological Sciences); Garroway, Colin (Biological Sciences); Waterman, JaneClimate change is a phenomenon in which global temperatures are rising, and animals respond by undergoing thermal stress, which may be linked to increased susceptibility to ectoparasites. Environmental temperature greatly influences ectoparasites as they rely on external heat sources to regulate their body temperature. This study investigated the effects of increasing maximum and minimum temperatures on ectoparasites abundance (number of parasites on an individual) and prevalence (number of infected individuals) of adult female African Cape ground squirrels (Xerus inauris). This study also investigated the effects of host body mass and host body condition on ectoparasite abundance and prevalence. We did not find a relationship between rising temperatures and ectoparasite loads (abundance and prevalence), nor did we find a relationship between body condition and ectoparasite loads. We speculate that the thermoregulatory behaviours of Cape ground squirrels mitigate ectoparasite loads. We did not find evidence for a relationship between host body mass and abundance; however, we found a significant negative relationship between host body mass and parasite prevalence. Our results show that a higher proportion of individuals are infected with fleas compared to lice. It remains uncertain whether the inverse relationship between host body mass and prevalence is due to increased skin strength or other traits in larger individuals. The different life history traits of the parasites could explain why fleas are more prevalent than lice. Fleas, being facultative parasites, can avoid the grooming behaviour of hosts. In contrast, lice, being obligate parasites, are bound to remain on their host, thus, are more vulnerable to being removed. As climate change persists, the host-parasite relationship between Cape ground squirrels and ectoparasites may be worth revisiting.
- ItemOpen AccessSex-sorting Aedes aegypti for sterile insect technique (SIT) by knocking down four different gene targets, expressed in the guts of female larvae(2023-04) Felix, SharonMosquitoes are vectors for diseases that affect approximately 0.7 billion people globally. Most of these diseases have a high incidence in tropical often developing countries, where they prove either fatal or severely debilitating. Despite huge investments of time and money to find solutions, we have been unable to control this disease vector. Additionally, some of the techniques previously and currently in use to prevent these diseases, have serious drawbacks such as detrimental effects on non-target species, humans and the environment. We need eco-friendly alternatives to these harmful chemicals, that are just as efficient while also being species-specific to avoid harmful effects on other beneficial insect species. Sterile insect technique (SIT) is a creative technology that does just that. It involves the mass release of sterile males of a species to outcompete wild males and mate with wild females, eventually resulting in the decline of a targeted insect population. However, before these sterile males are released, they must be separated from females. An efficient way to sex-sort males from females can use RNA interference (RNAi). RNAi is a natural defence mechanism that exists in eukaryotic cells, that can be used to knock down female-biased or female-specific genes. Targeted females will develop slower than their male counterparts due to this knockdown and this will enable their separation from a pool of male individuals. For my honours thesis, I targeted four such female-biased genes - AAEL014604, AAEL014797, AAEL009313 and AAEL005884 and measured development (in days), survival and pupal size for each of these treatments for both male and female mosquitoes. None of my treatments resulted in significant results but one of these (AAEL014797) showed great promise for an improved SIT.
- ItemOpen AccessEvaluating different double-stranded RNA structures for their ability to control pest flea beetles(2023-04) Verhaeghe, Lauren; Belmonte, Mark (Biological Sciences); Whyard, SteveCanola is an economically important Canadian crop that suffers significant annual losses by damage from feeding flea beetles (Phyllotreta cruciferae and P. striolata). Increasing incidences of resistance and concerns about off-target effects with current insecticides demands new methods of control. Recently, environmentally safer approaches to pest control have been investigated using RNA interference (RNAi), a sequence-specific gene silencing mechanism triggered by exogenous double-stranded RNA (dsRNA), to selectively induce the mortality of targeted species. This study examined three different dsRNA structures for their ability to kill P. striolata flea beetles and thereby reduce feeding damage on canola leaves. Long linear dsRNAs (212-214 bp), short hairpin RNAs (hpRNAs) (21-24 bp), and short paperclip RNAs (pcRNAs) (21-24 bp) targeting mRNAs of three essential genes, Ras opposite (Rop), Sec23, and Snf7 in P. striolata were investigated. P. striolata adults were fed dsRNA-treated canola leaf disks, and impacts on insect survivorship and leaf material consumption were recorded over an eight-day period. pcRNAs targeting Sec23 and Snf7, and long dsRNAs targeting Sec23 and Rop effectively killed flea beetles, resulting in the reduced consumption of treated canola leaf tissues. Consumption of both the Sec23-specific long dsRNA and pcRNAs caused similar levels of flea beetle mortality (68% and 76%, respectively), whereas only the Rop-specific long dsRNA and the Snf7 pcRNA were effective at killing the beetles (76% and 84%, respectively). hpRNAs proved the least effective across all gene targets, killing at most, between 40-52% of flea beetles, depending on the gene target, and in general, these values were not significantly different relative to the negative controls. While this study examined dsRNAs specific for only three target genes, it provides evidence that RNAi-based pesticides have the potential to control these economically important pests and that short pcRNAs can be as effective as conventional long linear dsRNAs.
- ItemOpen AccessExploring the role of ammonia transporters (AMTs) in the branchial tissue of the horseshoe crab, Limulus polyphemus(2023-05) Whiting, Holly; Campbell, Kevin (Biological Sciences); Treberg, Jason (Biological Sciences); Weihrauch, DirkAll organisms must manage ammonia as it is highly toxic and a product of many essential biochemical processes. One group of proteins that facilitates the movement of ammonia across cell membranes is the Ammonia Transport Protein family which are generally sorted into three groups—ammonia transporters (AMTs), Rhesus glycoproteins (Rh proteins), and methylamine permeases (MEPs)—expressed in plants, animals, and fungi, respectively. Recently, transcripts of AMTs have also been found in invertebrates, where experimental evidence suggest that they play a role in both ammonia excretion and ammonia sensing. The American horseshoe crab, Limulus polyphemus, expresses at least two AMT and two Rh proteins within the epithelia of their book gills which is the primary surface for ammonia excretion. Each gill lamellae have a ventral ammonia permeable side and a dorsal ammonia impermeable side. mRNA transcripts for both proteins LpAMT-1 and LpAMT-3 were found on the dorsal and ventral surfaces, bringing into question their function in direct ammonia excretion. In oocyte expression trials both AMTs failed to mediate the transport of radiolabeled methylamine, while transport was detected for both a coral and a human Rh protein. Direct evidence of ammonia transport by invertebrate AMTs has not been previously found and further research should be conducted into the function of these proteins in invertebrates.