21) Shanon Hankin, Simon Landhäusser and Justine Karst, MSc, poster OR oral presentation
Abstract Title: Impact of capping material selection on the recovery of ectomycorrhizal fungi and seedling growth of forest reclamation sites
The application of successful forest reclamation techniques will require an understanding of above and below-ground environments, as the two habitats form a dynamic relationship that drives forest processes. In the Canadian boreal forest, accessibility of organic nutrients by plants is facilitated by ectomycorrhizal (EM) fungal root symbionts who receive carbon from the plant in exchange. EM fungi are diverse and important for the vitality of trees and for belowground carbon and nutrient cycling. In the Canadian oil sands region, where the mutualistic relationship between trees and EM fungi has been destroyed, it is poorly understood how this symbiosis re-establishes with reclamation efforts. This research project investigates the recovery of EM fungi in three capping materials from the Aurora Soils Capping Study. In a growth chamber and field study, Pinus banksiana, Picea glauca, and Populus tremuloides grown in forest floor, peat, and subsoil were analyzed for EM fungal colonization and growth. This project will inform the understanding of how species diversity of EM fungi is partitioned between capping materials and host species, and how EM fungi influence seedling growth during the first growing season after reclamation.
22) Tara Stach, Andrew Waskiewicz, Ph.D., oral presentation preference
Abstract Title: Identification of the Superior Ocular Fissure & Characterization of its Molecular Genetics
We have identified seven patients with superior ocular colobomata, a novel birth defect associated with eye morphogenesis. Morphological and immunohistochemical examination of zebrafish eye development have revealed the presence of a transient fissure within the dorsal retina, indicating the presence of an evolutionarily conserved structure. We investigated the mechanisms that specify the position of the superior fissure. The expression boundaries of the forkhead box transcription factors foxg1 (nasal retina) and foxd1 (temporal retina) precisely align with the locations of the superior fissure. We find that knock-down of Foxd1 or Foxg1 results in aberrant superior fissure formation. Our goal is to understand the molecular causality of superior colobomata disorders. Sequence analysis of a patient with unilateral superior coloboma revealed biallelic CYP1B1 mutations. Restricted expression of zebrafish cyp1b1 to the dorsal retina, and prior research demonstrating enzymatic activity in synthesizing retinoic acid (RA) led us to suspect a role for RA in the closure of the superior ocular fissure. Knockdown of zebrafish cyp1b1 results in a loss of RA-dependent signaling and an increase in the duration of ocular fissure opening. The dorsal retinal expression of cyp1b1 is dependent on the Bone Morphogenetic Protein (BMP), Gdf6a. Consistent with this finding, zebrafish gdf6a mutants fail to close their superior fissures with such phenotypes rescued by cyp1b1 overexpression or RA supplementation. Taken together, our reseach highlights the existence of a novel fissure in the developing vertebrate eye, a structure conserved from fish to humans.
23) Nicole Webster, Dr. A. Richard Palmer, Ph.D, oral
Abstract Title: Growth and arrangement of varices – How do snails control shell ornamentation?
Snails (Gastropoda) produce some of the most beautiful skeletons of any animal, often with complex ornamentation. This ornamentation on the shell is mainly thought to reduce vulnerability to predators. How snails control the growth and spacing of shell ornamentation remains a significant unsolved puzzle of gastropod biology. Here we studied the growth of varices: periodic, blade-like extensions of the aperture in Ceratostoma foliatum (Muricidae), which has regular, synchronized varices spaced 120° apart. Each new varix is positioned by a varix from the previous whorl. This coordinated positioning suggests that encountering a previous varix during growth stimulates the formation of new, synchronizing varix. To test this hypothesis, body whorl varices and/or the apertural varix were removed, or extra varices glued on, to determine how their absence affected future varix growth. Where varices were removed, the new varix was formed at the appropriate location. In contrast, the addition of a varix in a foreign location stimulated new varix production at that position, and could disrupt placement of future varices. The presence of previous varices is not necessary for the growth of new varices in the correct position, but can affect varix placement. This suggests an internal regulatory mechanism is partly responsible for signaling varix growth and positioning.
24) Lindsey March, Molecular Biology and Genetics, Andrew Waskiewicz, MSc, Poster
Abstract Title: Studies of crx-dependent photoreceptor differentiation in zebrafish
Photoreceptors are central in our ability to convert an image into the neural messages that result in our visual experience. Patients with photoreceptor-degeneration disorders such as Leber’s congenital amarousis (LCA), retinitis pigmentosa (RP) and cone-rod dystrophy (CRD), experience ongoing sight deterioration, often resulting in blindness. All neuronal retinal cells are derived from a population of common multi-potent retinal progenitor cells. One major contributor to photoreceptor differentiation from retinal progenitors is the transcription factor cone-rod homeobox (crx). crx is a member of the highly conserved orthodenticle-related (otx) gene family of transcription factors, and has been associated with LCA, RP and CRD. Zebrafish have five otx-family genes: crx, otx1a, otx1b, otx2, and otx5. We used zinc-finger technology to produce a zebrafish crx mutant line. These fish have a 7 bp deletion in exon 1, resulting in a premature stop codon at the 10th amino acid residue. Surprisingly, these mutants do not present phenotypes expected of crx mutants, and look wild-type. Zebrafish crx and otx5 have similar expression in patterns in the retina. To test the model that Otx5 and Crx have overlapping functions in photoreceptor specification, we injected otx5 morpholino into maternal-zygotic crx-/- mutants. These morpho-mutants have reduced blue opsin (opn1sw2) mRNA expression, and lack zpr-1 immuno-labeled double-cones, providing evidence that Crx and Otx5 cooperatively specify photoreceptor identity.
25) Matt Gilbert, Physiology, Cell and Developmental Biology/ Tierney, MSc, Oral if available on Thursday
Abstract Title: Alternative migratory strategies of Arctic char in a highly variable and changing environment
In the summers of 2012 and 2013 we began monitoring the migratory patterns and physical environment of Arctic char in Nulahugyuk Creek (NC), the site of a traditional Inuit fishery. During the migration we recorded large daily fluctuations in water temperature (>10°C) and low flows that decreased through the summer, which made the stream impassable by early August. Adult arctic char began their upstream (return) migration far earlier (late June) in NC than in the surrounding area. At the same time, large numbers of juvenile char were migrating downstream. Fish 30 to 55 cm in length were absent from the migratory population. The timing of the juvenile migration relative to the navigability of the creek suggests that nearly all of the juvenile char that leave NC cannot return within the same year like char usually would. Furthermore, based on the large gap in size within the population, it is likely that these fish do not return for a number of years afterward. Moving forward, we will determine the population age distribution and migratory frequency by analyzing otoliths. Our findings will inform the local restoration and maintenance of a culturally valuable arctic char population and will assist in regional fisheries management.
26) Rachel Kinsella, M.Sc., Poster
Abstract Title: Investigating Acinetobacter baumannii pathogenicity
Gram-negative bacterium Acinetobacter baumannii is a nosocomial pathogen of increasing significance due to its expanding antibiotic resistance and ability to survive in the hospital environment. A. baumannii ATCC 17978 O-glycosylates 7 glycoproteins in an O-oligosaccharyltransferase (O-OTase) dependent manner. O-OTases facilitate the transfer of a lipid-linked glycan from undecaprenylpyrophosphate to hydroxylated amino acids. O-glycosylation in ATCC 17978 is required for biofilm formation and full virulence in insect and animal infection models. Acinetobacter strains consistently glycosylate the same 7 unique proteins, however with different glycans. Conservation of these proteins and their glycosylation suggests an important biological role; however, lack of homology to characterized proteins makes it difficult to predict their function. Comparison of wild-type and the O-OTase mutant through general carbohydrate staining (Periodic Acid Schiff) and anti-glycan Western blot analysis revealed one main 35kDa glycoprotein. Based on molecular weight, we predict this dominant glycoprotein to be A1S_3626. High abundance of this glycoprotein suggests it largely contributes to biofilm formation. Future work will explore the role of A1S_3626 in biofilm formation and pathogenicity by comparing the isogenic A1S_3626 mutant with wild-type ATCC 17978. Additionally Transmission Electron Microscopy will be used to visualize A1S_3626 on the cell surface, providing information on its putative function.
7) Kendal Prill and Dr. Dave Pilgrim, M.Sc and oral presentation <firstname.lastname@example.org>
Abstract Title: Still heart mutation reveals a novel role of SMYD1b in Sarcomere formation
The muscle sarcomere is one of the most highly patterned cellular structures yet the establishment of that pattern is poorly understood. Striated muscle development depends upon higher-order folding and assembly of contractile and attachment components, requiring muscle-specific chaperone proteins. The two types of vertebrate striated muscles, cardiac and skeletal, generally have unique structural contractile components (myosins, titins etc). I am interested in components that act early in development and are shared between the muscle types, as they may represent a basic shared pathway of sarcomere establishment and patterning. A mutant in zebrafish, still heart, has defects in heart function and trunk muscle structure. I have characterized the cellular defect and identified that while sarcomere formation is initiated there is an absence of mature contractile structures in fast muscle fibers due to absence of fast myosin incorporation, while myosin expression remains normal. Still heart mutant hearts lack the required chamber definition to circulate blood and expression boundaries between chambers are also missing. Using genetically polymorphic strains, I mapped the mutation to the smyd1b gene. Despite protein features suggesting a gene regulatory role, SMYD1b is an assembly/maintenance protein responsible for aiding in the folding and incorporation of fast myosin into the sarcomere.
28) Justin Duma, Dr. Christine Szymanski, B.Sc, poster
Abstract Title: Role of bacteriophage glucosylation operon in N-linked protein glycosylation in Campylobacter fetus species.
The Campylobacter fetus (Cf) protein N-glycosylation pathway (Pgl) is necessary for the synthesis of two unique hexasaccharides in a 4:1 ratio. These sugars are synthesized in the cytoplasm and then transferred onto the sequon D/E-X-N-X-S/T of several proteins by the oligosaccharyltransferase, PglB. In silico analysis of the Cf genome identified gtr genes homologous to the bacteriophage glucosylation operon involved in bacterial O-antigen modification. Previous attempts at generating both Cf hexasaccharide structures in vivo using only the pgl operon resulted in pentasaccharides with no Glc or GlcNAc branch. We hypothesize that the Cf gtr operon encodes enzymes for the addition of Glc or GlcNAc to the pentasaccharide backbone in Cf. The gtr operon encodes three putative enzymes, GtrA a flippase for the UndP-Glc precursor, GtrB a bactoprenyl glucosyltransferase, and GtrC a serotype-specific glucosyltransferase. All three Cf Gtr enzymes have been cloned into Escherichia coli along with the Cf pgl operon and a glycoprotein acceptor and the products are being characterized. In vitro enzymatic assays with purified Cf GtrB and several UDP-linked sugar donors demonstrates that the enzyme preferentially transfers GlcNAc over Glc, consistent with the hexasaccharide ratio observed. We are currently constructing Cf gtr mutants to examine their phenotypes in vivo.
29) Emmanuel Pila, School of Public Health/Dr. Patrick Hanington, Ph.D student, Poster
Abstract Title: Characterization of Fibrinogen-related protein (FREP) 3 in the snail immune response against trematodes
Fibrinogen-related proteins (FREPs) are unique molluscan immune factors composed of a conserved C-terminal fibrinogen domain joined to one or two, more variable N-terminal immunoglobulin (Ig) superfamily domains. These secretory molecules exist in various forms, some of which have been shown to undergo somatic diversification from limited germline sequences. FREPs are capable of precipitating trematode secretory/excretory products and siRNA-mediated knockdown studies have implicated FREP3 in susceptibility of the snail Biomphalaria glabrata to various trematode challenges, including those responsible for causing schistosomiasis a disease that affects about 207 million people worldwide. However, not much is known about the specific mechanisms through which FREPs elicit an immune response. Here, we discuss FREP3 function and ongoing in situ hybridization and immunohistochemistry approaches that are being used to determine the role that FREPs play in trematode recognition and clearance.
30) Michael Burns, Systematics and Evolution/Philip Currie, Ph.D., oral presentation
Abstract Title: How did armoured dinosaurs grow? Histology informs development and ontogeny of ankylosaurs (Dinosauria; Ornithischia)
Bone histology has emerged as a powerful tool for examining the biology, growth dynamics, physiology, and reproductive strategies of extinct organisms. This technique, however, has not been extensively applied to the armored dinosaurs. Because ankylosaurs generally form a rare component in most dinosaurian faunas, especially with respect to confidently identifiable juvenile material, their ontogenetic variation is not well understood. Here we apply paleohistological techniques to juvenile ankylosaur material for the first time to examine the ontogeny of their postcrania.
Juveniles show zonation in some cases as LAGs; however, some are azonal. Primary vascular orientation is variable among and within elements with an average vascularity of 7%. Subadults show highly zonal fibrolamellar bone with LAGs and annuli. Adults show some of the most heavily-remodelled bone known for dinosaurs, preserving several generations of secondary osteons and no primary tissue.