Biology

Permanent URI for this collection

https://hdl.handle.net/10315/27613

Browse

Now showing 1 - 20 of 276

Open Access
A Chironomid-Based Paleolimnological Assessment of Long-Term Cumulative Effects Of Multiple Anthropogenic Stressors on Hypolimnetic Oxygen Dynamics in Lake Erie
(2018-08-27) Perlov, Dmitri; Quinlan, Roberto
The central basin of Lake Erie is annually subjected to hypoxia, which has implications for fish communities and nutrient recycling. As limnological monitoring data for Lake Erie does not extend beyond the 1970s, paleolimnological techniques can be used to reconstruct long-term water quality trends. Chironomidae (Diptera) remains preserved in dated sediment cores from the western, central, and eastern basins in Lake Erie were used to assess the long-term cumulative effects of multiple anthropogenic stressors on hypolimnetic dissolved oxygen. Results from analyses of subfossil chironomid remains indicated that the central basin has exhibited mesotrophic to eutrophic conditions since 1850. However, a transition in chironomid communities further towards anoxic-type taxa between 1930-1950 suggests that the severity and duration of hypolimnetic anoxia has increased in recent decades. Variance partitioning analysis (VPA) indicated that the effects of land use and climate had significant implications in driving changes in chironomid assemblages in the central basin.
Open Access
A Revision of Chilicola (Heteroediscelis), A Subgenus Endemic to Chile
(2015-12-16) Monckton, Spencer Kelvin; Packer, Laurence
The bee subgenus Chilicola (Heteroediscelis) Toro & Moldenke, 1979 (Colletidae: Xeromelissinae) is revised. Seven new species are described: Chilicola (Heteroediscelis) charizard Monckton sp. nov., Chilicola (Heteroediscelis) curvapeligrosa Monckton sp. nov., Chilicola (Heteroediscelis) guanicoe Monckton sp. nov., Chilicola (Heteroediscelis) lickana Monckton sp. nov., Chilicola (Heteroediscelis) mayu Monckton sp. nov., Chilicola (Heteroediscelis) packeri Monckton sp. nov., and Chilicola (Heteroediscelis) randolphi Monckton sp. nov. Nine of the ten existing species are redescribed and Chilicola (Heteroediscelis) valparaiso Toro & Moldenke, 1979 syn. nov. is treated as a junior synonym of Chilicola (Heteroediscelis) mantagua Toro & Moldenke, 1979. Keys to species for males and females are provided, along with habitus images, images of male terminalia, and distribution maps for each species. Results of phylogenetic analyses are presented, based upon 61 morphological characters and CO1 barcode sequences. Monophyly of the subgenus is supported, and groupings within it are briefly discussed in the context of geographic distributions.
Open Access
A Role for Fenugreek in Altering the Osmoregulatory Capacity in Rainbow Trout (Oncorhynchus Mykiss)
(2015-12-16) Mckee, Sean Dylan; Kelly, Scott Phillip
Fenugreek (Trigonella foenum-graecum) is a botanical galactogogue that has been shown to increase milk production and serum prolactin in mammals. Prolactin is classically considered to be a freshwater-adapting hormone in teleost fishes. If fenugreek promotes prolactin synthesis, then it has the potential to decrease perturbations associated with exposure to hypoosmotic conditions in fishes. To test this, rainbow trout (Onchorhynchus mykiss) were fed doses of fenugreek, and endpoints of ionoregulatory ability were assessed. A single dose was used in a hypoosmotic stress experiment. Fenugreek did not disrupt systemic endpoints of salt-and-water balance. Transcript abundance of prolactin receptor in the gill and hypothalamus, and corticosteroid receptors in the gill decreased. Fenugreek resulted in an increase in claudin-7 and -30, and a decrease in claudin-33b. While it was demonstrated that fenugreek can impact salt-water balance, and affect changes similar to freshwater acclimation, it is unlikely that these changes were brought about via prolactin.
Open Access
A Taxonomic Revision of Canadian Non-Osmia Osmiini (Hymenoptera Megachilidae)
(2018-03-01) Rowe, Genevieve Lauren; Packer, Laurence D. M.
The Osmiini (Hymenoptera: Megachilidae) is a tribe whose species encompass much of the biological diversity seen among bees (Michener 2007), and is one that contains many polytypic species in several genera. I use a molecular approach to taxonomy to test current morphological assessments of species-level diversity in the group, and herein examine all polytypic Canadian non-Osmia osmiine species. The analyses resulted in several taxonomic considerations in both the Ashmeadiella and Atoposmia groups. In addition, I present an up-to-date revision of Canadian non-Osmia Osmiini (Hymenoptera: Megachilidae). A key to the seven genera of Canadian Osmiini is provided and the 29 species of Canadian non-Osmia Osmiini are keyed, in dichotomous format for each genus, with all key features illustrated and full redescriptions of all species provided. Summaries of biogeographic distributions and life histories are included for each genus and its Canadian species.
Open Access
Abnormal Brain Connectivity in the Primary Visual Pathway in Human Albinism
(2016-09-20) Grigorian, Anahit; Schneider, Keith A.
In albinism, the ipsilateral projection of retinal axons is significantly reduced, and most fibres project contralaterally. The retina and optic chiasm have been proposed as sites for misrouting. The number of lateral geniculate nucleus (LGN) relay neurons has been linked to LGN volume, suggesting a correlation between LGN size and the number of tracts traveling through the optic radiation (OR) to the primary visual cortex (V1). Using diffusion data and both deterministic and probabilistic tractography, we studied differences in OR between albinism and controls. Statistical analyses measured white matter integrity in areas corresponding to the OR, as well as LGN to V1 connectivity. Results revealed reduced white matter integrity and connectivity in the OR region in albinism compared to controls, suggesting altered structural development. Previous reports of smaller LGN and the altered thalamo-cortical connectivity reported here demonstrate the effect of misrouting on structural organization of the visual pathway in albinism.
Open Access
Abnormal Lipid Signalling in the Developing Mouse Brain: Implications in Autism Spectrum Disorder
(2021-11-15) Rai, Ravneet; Crawford, Dorota Anna
Autism spectrum disorder (ASD) is a neurodevelopmental disorder, currently characterized by difficulties in social communication, delayed speech and language, and appearance of restricted and repetitive sensory-motor behaviours. Currently, there are many etiological factors, both genetic and environmental, that have been involved in its manifestation, including the lipid signaling pathway. The brain is rich in lipids, and the plasma membrane acts as a reservoir of bioactive molecules such as Prostaglandin E2 (PGE2), a lipid signaling molecule important for normal brain development and function. PGE2 is converted by cyclooxygenase-1 and -2 (COX-1 and -2) enzymes, a downstream action following release of arachidonic acid from the plasma membrane. Various genetic and environmental factors can influence the level of PGE2 and have been identified for their involvement in increased ASD-risk. However, the exact mechanisms behind this relationship are not well known, and thus the current dissertation aims to contribute to this gap in knowledge with four studies in vivo in the mouse brain. Using mouse models, we investigated the effects of maternal PGE2 administration (PGE2-injected) and gene knockdown of COX-1 and COX-2 enzymes (COX-1-/- and COX-2-/-) at E16 and E19, on sex- and age-dependent expression of developmental genes and proteins, global analyses of biological pathways, and characterization and analysis of dendritic spines morphology at P25. These studies established that aberrations in the COX/PGE2 signalling pathway result in differential expression of many genes and pathways involved in neurodevelopment and ASD etiology. We found abnormal age- (i.e. Mmp7 and Wnt2, Spn, Actb) and sex-dependent (i.e. Spn, Actb) gene and protein expression of developmental and synaptic functions, sex-specific enlargement of mushroom spines in cerebellar neurons, and ASD genes that are dysregulated throughout development (i.e. Glo1, Gabra2, Grm5). Interestingly, novel in vivo findings in mouse models of PGE2-administration and COX-2-/- (high and low levels) both confirmed an interaction between COX-2/PGE2 and Wnt pathway particularly at the E16 stage of development. The current findings strengthen the involvement of abnormal COX/PGE2 signalling during early brain development, and thus, many genes and environmental exposures during gestation can act on different constituents of the COX/PGE2 pathway, and result in neurological conditions such as ASD.
Open Access
Analysis of Double-Crested Cormorant Nest Spatial Patterns in Single and Mixed -Species Colonies and their Effect on Cormorant Behaviour and on Black-Crowned Night Heron Spatial Patterns
(2016-09-20) Rosenberger, Lisa Charlotte; Fraser, Gail
Double-crested cormorants (Phlacrocorax auritus) are managed because they eat fish, transform habitat and can affect other waterbirds. Conversely, cormorants have been highly successful in North America since the 1970s due to increased food supply and their adaptability, although other factors may be important. I researched cormorants at Tommy Thompson Park, Ontario, and tested 1) whether tree-nesting cormorants nesting with black-crowned night herons (Nycticorax nycticorax) decreased heron population through direct or indirect effects and 2) whether ground-nesting cormorants changed their behaviours due to nest density or position and whether there was a behavioural trade-off that affected fledging success. Cormorant variables were correlated with heron declines due to indirect effects in some areas. Increased density was related to lower aggression, but there were no trade-offs between the behaviours. My research illustrates the different behaviour and spatial patterns for cormorants in single and mixed-species colonies and in ground versus tree nesting colonies.
Open Access
Analysis of Properties of Heterochromatin Relative to Meiotic Recombination and Heterochromatic Gene Expression
(2015-12-16) Taylor, Rhodri Wyndham; Hilliker, Arthur
To better understand the genetic properties of heterochromatin, I have pursued two avenues: meiotic recombination around the border of euchromatin and heterochromatin, and position effects at the heterochromatic light locus. Heterochromatin lacks recombination, and using meiotic recombination frequencies, I show that the recombination inhibition border concurs with the previously defined molecular border based on changes in histone proteins, specifically histone 3 methylation, characteristic of heterochromatin. I also show that the heterochromatic gene light behaves in a similar fashion to a previously studied heterochromatic gene, in that its function is impaired when moved out of the heterochromatic environment, but can be restored when brought near to large blocks of heterochromatin. These findings support the idea that gene function and recombination can be tightly controlled by the molecular environment of heterochromatin.
Open Access
Analysis of Spatial Learning in Honeybee Foragers Using the Food Search Box Assay
(2020-11-13) Morrison, Bandele Mojoyinola Abike; Zayed, Amro
Given the under-representation of genetic analyses of spatial learning in honeybee literature, I designed an experiment to investigate gene expression profiles associated with spatial learning. The experimental design involved using the Food Search Box (FSB) assay to assess learning in Single Drone-Inseminated (SDI) foragers, then collecting the bees for RNA-seq analysis to generate and compare full-transcriptome gene expression profiles for five different stages of learning. From the first to the third learning trial, the SDI foragers did not decrease the number of mistakes they made in a significant way: they did not switch from chance to non-chance searching behaviour. In addition, during the memory recall stage, the bees made significantly more errors than chance, suggesting they did not remember their focal flower. Landmarks cues, inter-trial interval, motivation level for sucrose and genetics may each play a role in the ability of SDI foragers to learn vs. foragers from naturally mated queens.
Open Access
Anterior Cingulate Cortex Cells Identify Errors of Attentional Control Prior to Prefrontal Disengagement
(2014-07-09) Shen, Chen; Womelsdorf, Thilo
The anterior cingulate cortex (ACC) is implicated in the detection of errors and the allocation of correctional adjustments. However, error detection alone is not sufficient to resolve and prevent future mistakes since errors can occur in various ways, subsequently requiring different adjustments. I therefore investigated whether the ACC tracks specific processing states that give rise to errors in order to identify which specific processing aspects need readjustment. To do this, my lab recorded from cells in the prefrontal cortex (PFC) of macaques while they were performing a selective-attention task that elicited three types of error. My study provides support for the functional role of the ACC in performance monitoring and specifying correctional adjustments through the tracking of specific sources of erroneous task outcomes.
Open Access
AP-1 Proteins Regulate Autophagy in Skeletal Muscle Progenitor Cells
(2019-11-22) Edwards, Tracey Anne; McDermott, John Charles
Autophagy has been observed to be a key regulator in myogenesis, maintenance of quiescence in satellite cells (SC) and regenerative capacity of skeletal muscle. Activator protein-1 (AP-1) transcription factors have been proteins of interest in autophagy regulation in various cancers due to the established roles of AP-1 in cellular proliferation, death and survival. However, AP-1 involvement in the regulation autophagy in skeletal muscle progenitor cells has not been extensively assessed. AP-1 protein c-Jun is expressed in paired box gene 7 (Pax7) positive satellite cells. AP-1 proteins c-Jun and JunB regulate autophagy. Changes to c-Jun expression lead to changed autophagosome content in C2C12 cells in both growth conditions and induced autophagy conditions. Additionally, c-Jun knockdown altered autophagosome content in cultures containing Pax7+ and Pax7- cells. AP-1 protein c-Jun appeared to be regulated by mTor. AP-1 proteins act as autophagy regulators dependent on cell type and autophagy induction method.
Open Access
Aquaporin AaAQP2 protein abundance in the anal papillae of Aedes aegypti is modified by salinity
(2021-11-15) Guardian, Elia Edith Grieco; Donini, Andrew
The Aedes aegypti mosquito, a viral disease vector, can complete its life cycle in breeding sites that range in salinity from ion-poor to fresh and brackish water. Fluctuations in salinity provide different challenges to larval regulation of ion and water transport. Western blots of proposed water channel A. aegypti aquaporin 2 (AaAQP2) revealed this protein is found in the osmoregulatory organs, including gastric caecae, Malpighian tubules (MTs), hindgut, and anal papillae (AP) of larvae reared in varying salinity. AaAQP2 immunolocalization in MTs shifted from apical to intracellular as salinity increased, and could imply AaAQP2 is trafficked from the cell membrane to potentially decrease MT water secretion. Protein abundance of the presumed AaAQP2 monomer in AP increased as salinity increased, however, larval survival increased when larvae with knockdown AaAQP2 in the AP were transferred to higher salinity. Results suggest AaAQP2 protein levels impact larval physiology when changes in environmental salinity occur.
Open Access
Aromatic Rich Natural Organic Matter Increases Growth and Reduces Nickel Toxicity in a Wild Daphnia Hybrid
(2015-08-28) Geiger, Christine Simone; Yan, Norman; Arts, Michael
Natural organic matter (NOM) is on the rise across the Shield. Its heterogeneous, amalgamate nature makes each NOM source potentially unique. Relatively little is known about the direct effects distinct NOM sources have on daphniids, or the varying protection NOM provides against metal toxicity –specifically Ni. I show that NOM from different natural sources increases growth rates and decreases time to maturation of Daphnia to various degrees. These changes relate to aromatic content of NOM isolates, the mechanism most likely being a hormonal effect or mild oxidative stress. Aromatic content (representing phenolic groups) is also positively related to Ni mitigation for those isolates with specific UV absorbance below 19.3 cm2mg-1. Incorporating NOM aromatic content into a predictive model improves the relationship between predicted and measured LC50s by 5%. I demonstrate that structural differences between NOM isolates relating to aromatic content play a major role in their effects on Daphnia.
Open Access
Assessing the Benefits of Extra-pair Mating for Female Purple Martins (Progne subis)
(2015-12-16) Kramer, Patrick Michael; Stutchbury, Bridget J.
Approximately 75% of socially monogamous passerines pursue extra-pair mating with the frequency of extra-pair paternity varying among and within taxonomic groups. Despite the ubiquity of extra-pair mating systems, substantial research into the subject has produced mixed results and the benefits to females remain elusive. Two genetic benefits hypotheses, the good genes hypothesis and heterozygosity theory, predict that extra-pair offspring (EPO) should generally be more fit than within-pair offspring (WPO). This study aims to test for genetic-based benefits to extra-pair mating in purple martins (Progne subis) by comparing EPO and WPO. Specifically, I compare the first year survival estimates of EPO and WPO and of those offspring that are recruited into the breeding population, I compare the reproductive success of EPO and WPO. I found no differences in first-year survival probability nor did I find any differences in reproductive success between EPO and WPO. I conclude that female purple martins are not benefiting from extra-pair mating through the improved survival or reproductive success of their offspring. Such benefits may be context-dependent or historical contexts in which the benefits of extra-pair mating for females may no longer exist for this semi-domesticated species.
Open Access
Assessing the Effects of Temperature, Feeding Status, and the Microbiome on the Maximal Activities of Several Enzymes Important to Energy Production and Ammonia Detoxification in the Intestines of Teleost Fish
(2020-11-13) Turner, Leah Anne; Bucking, Carol
This thesis examined the effects of temperature, feeding status, and the microbiome on the maximal activities of several enzymes important to energy production and ammonia (NH3) detoxification in the intestines of three species of teleosts: the goldfish, rainbow darter and central stoneroller. In warm-acclimated goldfish, intestinal and branchial tissues were more responsive to feeding, while renal tissues were not affected by digestion or thermal acclimation. This was reflected in the maximal enzyme activities of Na+, K+-ATPase (NKA), citrate synthase, pyruvate kinase, and glutamine synthetase (GS). Increased NKA activity following a meal suggested an increase in ATP demand, and amplified GS activity likely assists in enhanced NH3-detoxification processes in the intestinal tract. There was a strong effect of host species on intestinal tract bacteria composition and on enzyme activities in the rainbow darter and central stoneroller, and sampling location was a significant determinant of the central stoneroller intestinal microbiome.
Open Access
Barrier Properties and Molecular Physiology of Fish Gill Epithelia and Gill Epithelium Models
(2020-11-13) Chen, Chun Chih; Kelly, Scott Phillip
The fish gill epithelium interfaces directly with surrounding water and participates in numerous physiological processes. However, the barrier properties of the fish gill epithelium have been largely overlooked until recent studies have suggested that a dynamic repertoire of tight junction (TJ) associated elements control gill epithelium paracellular permeability and dictate barrier function of this tissue. Primary cultured gill epithelium models have become valuable tools to examine gill epithelium permeability, but models have been developed using few species. Furthermore, continued refinement of existing models provides enhanced insight. My thesis work focused on refining an existing primary cultured gill epithelium model derived from a freshwater (FW) bony fish (rainbow trout) by considering how epithelium TJs and permeability might be influenced by native serum as a growth supplement and heparin (an anti-coagulant used to collect extracellular fluid). A FW trout gill model was also used to examine the effect of the thyroid hormone 3,5,3-triiodo-L-thyronine (T3) on gill epithelium TJs and barrier function. Data indicate that (1) native serum enhances the barrier properties of the trout gill model; (2) heparin compromises epithelium integrity; and (3) T3 may induce changes that prepare a diadromous fish for seawater (SW) entry. In addition, I examined a role for putative pore-forming claudin-10 TJ proteins in the mummichog gill and opercular epithelium and provide data supporting an integral role for Cldn-10c in Na+ secretion across the SW fish gill. Finally, I examined the molecular physiology of the lamprey gill epithelium TJ complex through metamorphosis and I developed the first primary cultured gill epithelium model for this basal vertebrate. Peri-metamorphic observations of the lamprey gill TJ complex indicate that SW entry has a much greater impact on TJs than metamorphosis alone, and a cultured lamprey gill epithelium model, derived from FW residing larval lamprey, reveals a comparatively tight epithelium with a TJ profile that mimics the intact gill epithelium. Together, data provide new insight into the barrier function of fish gill epithelia as well as new and improved tools to study this function.
Open Access
Behavioral Endocrinology of Male Dispersal in Vervet Monkeys at Lake Nabugabo, Uganda
(2021-03-08) L'Allier, Simon; Schoof, Valerie
Dispersal between social groups reduces risks of inbreeding and may provide individuals with reproductive opportunities. However, this movement may come with socio-ecological costs, such as risks of predation and starvation, loss of allies, kin support, and increased conspecific aggression. Dispersal strategies, such as the timing of movement and decisions on whether to transfer alone or in parallel with a peer may be associated with different costs and benefits between individuals. This research uses long-term demographic, behavioral, hormone, and ecological data to examine the triggers and consequences of 36 dispersal events from 29 male vervet monkeys (Chlorocebus pygerythrus) at Lake Nabugabo, Uganda. Dispersing adult males timed their transfer with the conception seasonality and improved their potential access to females by moving to a group with higher female-to-male sex ratio or by increasing their dominance rank. However, we argue that each transfer is unique to each individual and their own socio-ecological context.
Open Access
Behavioural Genetics and Social Environment in the Small Carpenter Bee, Ceratina Calcarata
(2022-03-03) Huisken, Jesse Leon; Rehan, Sandra
Most bees are solitary but the eastern small carpenter bee, Ceratina calcarata, are both subsocial and facultatively social. Females form associations of parents and a single generation of offspring, often including a smaller under provisioned dwarf eldest daughter (DED) who feeds her adult siblings. To study the influence of social environment on this species, firstly, observation nests were constructed, and secondly, I conducted an experiment in the field to compare gene expression profiles among ages and phenotypes of foraging females. Observation nests were treated by removing either only mothers, or both mothers and DEDs. In the absence of mothers offspring were more tolerant, and aggression was significantly greater in the absence of both mother and DED. Here I also present brain gene expression profiles of foraging mothers, DEDs in the presence and absence of mothers, and regular daughters. I found significant differences in gene expression associated with age, size and social environment.
Open Access
Binding Determinants of HIV-1 REV RNA to the Pokeweed Antiviral Protein
(2015-08-28) Jobst, Kass Alvin; Hudak, Katalin A.
The pokeweed antiviral protein (PAP) is an N-glycosidase that removes an adenine residue from the sarcin/ricin loop (SRL) of rRNA through a process called depurination. PAP has also been shown to depurinate the ORF of Rev RNA of HIV-1 in vivo without causing toxicity. The sequence and structure of Rev RNA that PAP interacts is identified and compared to the sarcin/ricin loop in order to describe the importance of RNA structure for PAP specificity. My results show that PAP binds to a short GGGAA sequence at the site of depurination of Rev RNA. Structural analysis reveals that the binding site is within a 15 nt hairpin pentaloop. The pentaloop contains a pseudo GNRA loop structure that swings G and A residues out of the hairpin, allowing PAP access to these purines for binding and depurination. These data provide new insight into the specificity of PAP to target an RNA.
Open Access
Biochemical Studies of EA22, A Protein Involved in The Bacteriophage Lysogenic-Lytic Decision and the Virulence of Clinically Relevant Serotypes of E. Coli
(2022-12-14) Tong, Jinge; Donaldson, Logan
Enterohemorrhagic Escherichia coli (EHEC) infections are associated with short term gastrointestinal problems, but in some cases, it can lead to more life-threatening conditions. The pathogenicity of EHEC Is supported by an endogenous, dormant bacteriophage that persists in the bacterium as a lysogen until it is activated by a stress-related event. While the lysogenic-lytic development decision has been characterized for decades, there are still genes that are unknown in every way, from structure to function. These genes are found in a region between exo and xis in the l bacteriophage genome which may serve as a model for understanding other related phages in EHEC. This thesis focuses on the protein encoded by the ea22 gene, the largest conserved gene in the exo-xis region. The most significant finding of my research was the expression and characterization of several Ea22 proteins and protein fragments from l and two phages associated with EHEC. Structural differences in the C-terminal domains of these proteins may help explain the broad range of effects the Ea22 proteins mediate during infection.