University of Calgary PRISM: University of Calgary's Digital Repository Graduate Studies The Vault: Electronic Theses and Dissertations 2016 Morphology and Dental Function in a BMP7 Rodent Knockout Model and Implications for Mammalian Tooth Evolution Zurowski, Chelsey Zurowski, C. (2016). Morphology and Dental Function in a BMP7 Rodent Knockout Model and Implications for Mammalian Tooth Evolution (Unpublished master's thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/27008 http://hdl.handle.net/11023/3264 master thesis University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission. Downloaded from PRISM: https://prism.ucalgary.ca UNIVERSITY OF CALGARY Morphology and Dental Function in a BMP7 Rodent Knockout Model and Implications for Mammalian Tooth Evolution by Chelsey Jade Zurowski A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE GRADUATE PROGRAM IN BIOLOGICAL SCIENCES CALGARY, ALBERTA SEPTEMBER, 2016 © Chelsey Jade Zurowski 2016 Abstract Tooth morphology is the result of tissue interactions, many of which involve families of regulatory genes that pattern development. Determining and quantifying the effect of regulatory genes has implications for understanding the mechanisms driving the degree of diversity observed in mammalian dentition. Bone morphogenetic protein 7 (BMP7) is one regulatory gene that is active in the developing tooth. I characterized the morphology and assessed the function of the dentition in BMP7 conditional knockout mice. Mutant molars had short, broad cusps, and extra cusps on the M1 and m1. Wear facets in the mutant mice were different in shape and in the direction that they faced on the tooth. This shows that changes in the expression of BMP7 lead to changes in the morphology and function of the dentition, suggesting that BMP7 could have acted in structuring the amount of dental diversity that is apparent in extinct and extant mammals. ii Acknowledgements I am immensely grateful to my supervisors (a.k.a. Science Moms): Heather Jamniczky and Jessica Theodor. You have both provided me with endless opportunities to learn and grow. Thank you for your guidance, patience, inspiration, feedback and support. You are role models to me for so much more than academia. I would also like to thank my committee members, Daniel Graf and Sean Rogers for their thoughtful feedback and guidance, and thank you to Daniel Graf for use of the specimens in this study. Additional thanks go to Warren Fitch for assistance tracking down ravenous beetles and taming undergrads. I lucked out with the best science siblings a graduate student could ask for. You are all endless sources of knowledge and friendship and have added balance to my life. Thank you to: Alexandra Pistore, Tegan Barry, Sarah Anderson, Jolene McLeod, Delyle Polet, Brian Rankin, Christian Barrón-Ortiz, Amie Le, and Tasha Cammidge. Through the course of this degree I have met many other extraordinary graduate students that have been a source of support and fun endeavours: Emma Carroll, Riley Waytes, Megan Goulding, Matt Szostakiwskyj, Steph Mogensen, Brandon Allen, Ramon Nagesan, Sarah Smith, Jori Harrison, Laura Kaupas, Stephanie Findlay, Jason Pardo and Stevi Vanderzwan. Finally I could never have gotten this far without the love and support of my friends and family, especially Ian Langill, Stella, my sister, granny and my parents. This research was partially supported by NSERC and the QEII scholarship fund. iii Table of Contents Abstract ............................................................................................................................... ii Acknowledgements ............................................................................................................ iii Table of Contents ............................................................................................................... iv List of Tables ..................................................................................................................... vi List of Figures and Illustrations ........................................................................................ vii List of Symbols, Abbreviations and Nomenclature .............................................................x Epigraph ............................................................................................................................. xi CHAPTER ONE: GENERAL INTRODUCTION ..............................................................1 CHAPTER TWO: MORPHOLOGY AND DENTAL FUNCTION IN A BMP7 RODENT KNOCKOUT MODEL AND IMPLICATIONS FOR MAMMALIAN TOOTH EVOLUTION .............................................................................................................4 2.1 Introduction ................................................................................................................4 2.2 Methods .....................................................................................................................9 2.2.1 Specimens ..........................................................................................................9 2.2.2 Scanning ..........................................................................................................10 2.2.3 Landmarking ....................................................................................................10 2.2.4 Statistical Analysis ..........................................................................................12 2.2.5 Wear Facet Quantification ...............................................................................13 2.2.5.1 Occlusal Fingerprint Analyzer ...............................................................13 2.2.5.2 Skeletonizing Specimens .......................................................................15 2.3 Results ......................................................................................................................16 2.3.1 General Craniofacial Description ....................................................................16 2.3.2 General Dentition Description .........................................................................17 2.3.3 Mutant Lower Molars ......................................................................................17 2.3.3.1 Mutant First Molar (m1) ........................................................................17 2.3.3.2 Mutant Second Molar (m2) ....................................................................18 2.3.3.3 Mutant Third Molar (m3) ......................................................................18 2.3.4 Mutant Upper Molars ......................................................................................19 2.3.4.1 Mutant First molar (M1) ........................................................................19 2.3.4.2 Mutant Second Molar (M2) ...................................................................20 2.3.4.3 Mutant Third Molar (M3) ......................................................................20 2.3.5 Alternate Morphology .....................................................................................20 2.3.6 Muscle Scars ....................................................................................................21 2.3.7 Geometric Morphometric Analysis .................................................................23 2.3.7.1 Replicates ...............................................................................................23 2.3.7.2 Lower Cusp Landmarks .........................................................................23 2.3.7.3 Upper Cusp Landmarks .........................................................................25 2.3.7.4 Lower Outline Landmarks .....................................................................26 2.3.7.5 Upper Outline Landmarks .....................................................................27 2.3.8 Occlusal Fingerprint Analyzer ........................................................................29 2.3.9 Wear Facets .....................................................................................................30 2.4 Discussion ................................................................................................................31 2.4.1 Overview of BMP7 Expression and Influence on Tooth Development ..........31 iv 2.4.2 Morphological Differences in Mutant Molars .................................................32 2.4.3 Cellular and Molecular Means of Producing Morphology Change ................33 2.4.4 Linking Morphology to Evolutionary Trends in Murine Dentition ................33 2.4.5 Alignment with the Inhibitory Cascade Model ...............................................35 2.4.6 Landmark Set: Scope and Challenges .............................................................35 2.4.7 Functional Consequences of Morphology Changes ........................................36 2.4.8 Conclusions .....................................................................................................39 2.4.9 Future Directions for Investigation Into Morphology and Functional Changes with Alteration in Regulatory Gene Expression ..............................................39 CHAPTER THREE: GENERAL CONCLUSIONS