Investigating the Function of the Mold Specific Gene <I>M46</I>
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The University of Southern Mississippi The Aquila Digital Community Dissertations Spring 5-2013 Investigating the Function of the Mold Specific Gene M46, in the Pathogenic Dimorphic Fungus Histoplasma capsulatum Davida LaShaundra Crossley University of Southern Mississippi Follow this and additional works at: https://aquila.usm.edu/dissertations Part of the Biology Commons, and the Ornithology Commons Recommended Citation Crossley, Davida LaShaundra, "Investigating the Function of the Mold Specific Gene M46, in the Pathogenic Dimorphic Fungus Histoplasma capsulatum" (2013). Dissertations. 741. https://aquila.usm.edu/dissertations/741 This Dissertation is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Dissertations by an authorized administrator of The Aquila Digital Community. For more information, please contact [email protected]. The University of Southern Mississippi INVESTIGATING THE FUNCTION OF THE MOLD SPECIFIC GENE M46, IN THE PATHOGENIC DIMORPHIC FUNGUS HISTOPLASMA CAPSULATUM by Davida LaShaundra Crossley Abstract of a Dissertation Submitted to the Graduate School of The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy May 2013 ABSTRACT INVESTIGATING THE FUNCTION OF THE MOLD SPECIFIC GENE M46, IN THE PATHOGENIC DIMORPHIC FUNGUS HISTOPLASMA CAPSULATUM by Davida LaShaundra Crossley May 2013 Histoplasma capsulatum (Hc) is a dimorphic fungus that is the etiologic agent for the respiratory infection histoplasmosis. The fungus is found in the environment in contaminated soils of birds and bat excreta as a multi-cellular saprophytic mold. Once the soil is disturbed, spores are released and are inhaled into the lungs. In the lungs, the fungus converts to uni-cellular parasitic yeast (Maresca & Kobayashi, 1989). The conversion from mold to yeast is a requirement for pathogenesis. Previously, several mold specific genes have been isolated by our laboratory from a subtracted cDNA library. One such gene, is M46. M46 is a single copy gene and has a predicted protein size of 8.5 kDa. Northern blot analysis of M46 in four major Hc strains, revealed that M46 is not expressed in yeast. The gene is expressed in mold for strains G186AS and Downs, but is silent in strains G184AS and G217B. These findings suggest that M46 may not be involved in dimorphism. According to NCBI Genbank, M46 does not have a homolog, and therefore the function is unknown. Several experiments were conducted to gather more information about possible functions of M46. Over expression of M46 in the yeast did not induce filamentous growth. Examination of a M46 knock out mutant constructed by allelic replacement, with confocal microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), did not reveal any ii significant structural changes. Therefore, M46 may not be involved in maintaining the mold and yeast morphology. Growth curve studies of the M46 knockout and wild type strains, revealed that M46 is not involved in maintaining the normal growth rate in mold and yeast. Parallel comparison of gene expression of the M46 knockout and wild type strain via RNA sequencing, suggest that the function of M46 may be correlated with drug resistance and iron and sugar transport. iii COPYRIGHT BY DAVIDA LASHAUNDRA CROSSLEY 2013 The University of Southern Mississippi INVESTIGATING THE FUNCTION OF THE MOLD SPECIFIC GENE M46 IN THE PATHOGENIC DIMORPHIC FUNGUS HISTOPLASMA CAPSULATUM by Davida LaShaundra Crossley A Dissertation Submitted to the Graduate School of The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Approved: Glenmore Shearer, Jr. Director Mohamed Elasri Anthony Bell Yan Lin Guo Susan A. Siltanen Dean of the Graduate School May 2013 ACKNOWLEDGMENT This has been such an amazing long adventure. “Exploring where no man has ever gone before,” as Dr. Shearer would say. I am blessed to be able to have the opportunity to broaden my knowledge by exploring science. This has laid the foundation for the beginning of a new life for me, in which I may broaden and increase the knowledge of many others. To Dr. Shearer, I would like to give many thanks for allowing me to be a student in your lab and for the many conversations that has challenged my way of thinking. I would also like to thank my lab colleagues, Melissa Adams, Lacey Howard, and Logan Blancett for the countless advice and mental support for when our projects were just not moving for us. Big thanks to Hana Ali, Rupesh Patel, Danielle Williamson, and Erin Smith for the tremendous hours of help and support throughout the years. Dr. Gordon Cannon, Dr. Mohamed Elasri, Dr.Yan Lin Guo, and Dr. Anthony Bell, you were all great committee members and your advice was of such tremendous help. I would also like to thank Dr. Shahid Karim and his lab for advice and for emergency supplies throughout the day, and Dr. Kenneth Curry and his lab for advice and help with experiments. To my family, I would like to thank my dad Michael Crossley, Sr, and my mother Barbara Crossley, for many years of support mentally and financially. You were always there for me, and there is no way that I could possibly pay you back for all your love. I hope in exchange that I have made you proud. I would like to dedicate this iv dissertation to my mother and father, as well as the late Mrs. Idell Smith. To Idell, I know that you will not be able to see me graduate, but I know that you are watching me from above, and you will be there in spirit. Thank you so much and I love you all. v TABLE OF CONTENTS ABSTRACT……………………………………………………………………………..ii ACKNOWLEDGMENTS……………………………………………………….……...iv LIST OF TABLES…………………………...……...……………………...…….…...viii LIST OF ILLUSTRATIONS……………...………………………...……..……..….....ix CHAPTER I. INTRODUCTION…………………………………….……………….…1 II. BACKGROUND AND LITERATURE REVIEW..…………………….4 Histoplasma capsulatum (Hc) History HistoplasmosisTreatment and Diagnosis Mold and Yeast Morphotype Virulence in Hc Strains and Varients Molecular Challenges Approaches to Identify Phase Specific Genes Examples of Phase Specific Genes III. GENERAL MATERIAL AND METHODOLOGY……………...….…16 Experimental Strains and Growth Conditions RNA and DNA Purifications Transformations Genetic Manipulation Procedures Blotting Techniques Microscopy Preparations RNA Sequencing IV. CHARACTERIZATION OF M46………………………………………27 M46 Sequence Analysis Genomic Copy Number of M46 Northern Blot Analysis of M46 in Four Major Hc Strains NCBI GENBANK M46 Homologs vi V. OVER EXPRESION OF M46 IN YEAST…………………………….…32 Northern Blot Confirmation of M46 Over Expression Phenotype of M46 Over Expression in Yeast VI. GENOMIC DISRUPTION OF M46……………………………….....….36 Construction of Genomic Replacement Plasmid M46 Genomic Replacement Map Confirmation of M46 Knock out Phenotype Observation Growth Curve Analysis VIII. VII. RNA SEQUENCING……………...…………...…………………..…….49 FPKM Scatter Plot of M46 Knock out vs Wild type Northern Blot Confirmation of DGE Results Celelsu Gene Ontology Analysis of M46 Knock out Strain VIII. DISCUSSION………………………..…………………………….....….59 Confirmation of General Characterization of M46 Rapid Methods for Determining the Function of M46 M46 Knock out Confirmation Morphological and Growth Studies RNA Sequencing APPENDIX…………………………………………...……………………..…………74 REFERENCES….…………………….…………………………......…………...….....77 vii LIST OF TABLES Table 1. NCBI Blast Homologs of M46………….……………………..……………....31 2. RNA Sequencing Analysis of Genes with Undetectable Read………………..54 viii LIST OF ILLUSTRATIONS Figure 1. M46 Genomic and Putative Protein Sequence. ………..…………….……..….28 2. Genomic Copy Number of M46……………………………..…………………29 3. Northern blot Analysis of M46 in Four Major Hc strains………………...……30 4. Over Expression Plasmid of M46………….…………………………………...33 5. Northern Blot of M46 Over Expression in the Yeast Phase…………....………34 6. M46 Over Expression in Yeast Grown in Liquid HMM Media…......................35 7. M46 Over Expression in Yeast Grown on HMM Solid Media…….…..……....35 8. Construction of Replacement Plasmid pUDCg::hph……………………….......37 9. The Genomic Replacement Map of M46…………………..………..………....39 10. Confirmation of M46 Knock out via PCR………………………………….…..40 11. Confirmation of M46 Knock out via Southern Blot Analysis………………….41 12. Confirmation of M46 Knock out via Northern Blot Analysis………….………41 13. Phenotype of M46 Knock out and Wild type in Liquid Media.……….....…… 43 14. Phenotype of M46 Knock out and Wild type on Solid Media…………………44 22. Phe 15. Phenotype of M46 Knockout and Wild type Yeast using SEM…………..……45 16. Phenotype of M46 Knockout and Wild type Mold using SEM……………..….45 17. Phenotype of M46 Knockout and Wild type Yeast using TEM…......................46 25. Phenotype of M46 knockout vs Wild type mold transmission e 18. Phenotype of M46 Knock out and Wild type Mold using TEM...……………. 46 19. Growth Curve of M46 Knock out and Wild type Yeast………….….................47 20. Growth Curve of M46 Knock out and Wild type Mold…..................................48 ix 21. RPKM 1,000 Scatter Plot of M46 Knock out and Wild type…………...…..….50 22. RPKM 5,000 Scatter Plot of M46 Knock out and Wild type ……..…..……….51 23. RPKM 10,000 Scatter Plot of M46 Knock out and Wild type …………….......52 24. RPKM 20,000 Scatter Plot of M46 Knock out and Wild type………….….......53 25. Northern blot Analysis of RNA seq Confirmation……………….………...….54 26. M46 Knock out Cellular Component Ontology Report………………..............56