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Characterization of uge and ugm genes of A. fumigatus. Undergraduate Research Project Proposal Form.

INSTRUCTIONS - PROFESSORS: Fill out Sections A & B then submit this form online. (You will receive an email copy of the form. The Office for Undergraduate Research in Science will also post the project online, indicating whether the project is open for students to apply or taken.) DONE
INSTRUCTIONS - STUDENTS: You may receive this form by email, or you may download it after it has been posted. Either way, print this form. Complete and sign Section C on the hardcopy. Ask your supervisor to sign Section D. Take it to the department corresponding to the course number in Section A (this may or may not be your own department). Do not register for a '396' course on Minerva until you receive departmental permission.
INSTRUCTIONS - DEPARTMENTS: After the unit chair/director/designate approves (or not) this project, notify student. If approved, please give student permission to register on Minerva, and fax this form (with signatures) to the Office for Undergraduate Research in Science.
QUESTIONS OR FEEDBACK? Contact Victor Chisholm by email, or phone 514-398-5964.
Name: Don Sheppard
Email: donald [dot] sheppard [at] mcgill [dot] ca
Phone: 514-398-1759
Supervisor's department: Microbiology and Immunology
Supervisor's department (if none of the above)
Course number: MIMM396 (Microbiology)
Term: Fall 2010-2011
Project start date: September 1, 2010
Project end date: December 3, 2010
Project title: Characterization of uge and ugm genes of A. fumigatus
Project description: The carbohydrate cell wall of Aspergillus fumigatus is both a rigid and dynamic structure, highly important for normal survival of this opportunistic pathogen. The ability of the organism to vary cell wall composition allows the fungus to adapt to its environment and serves as a reserve of molecules such as toxins and enzymes important during infection. The composition of A. fumigatus cell wall is poorly understood, requires more detailed characterization, as it may lead to a better understanding of this organism’s pathogenicity mechanism and to development of new drug targets to treat invasive aspergillosis. Recently, a novel cell wall polysaccharide, galactosaminogalactan (GAG) was reported, and although it only constitutes 2% of the cell wall, it was identified as a major component of the biofilm formed by A. fumigatus within in tissues of patients with aspergilloma or invasive aspergillosis. It is a polymer of galactopyranose and N-acetylgalactosamine, but the mechanism of GAG biosynthesis is unknown.

While conducting a genome wide screen of developmental transcription factors, we have identified a transcription factor, MedA, which is required for GAG synthesis. Interestingly, this mutant is hypovirulent and unable to adhere to host tissues. This defect in adherence is restored with the addition of exogenous GAG, strongly suggesting this carbohydrate plays an important role in fungal adherence and virulence.

Whole genome microarray analysis of the ∆medA mutant strain has identified a cluster of cell wall genes that are predicted to encode galactosamine synthesis. We hypothesize that genes within this cluster comprise the core biochemical pathway for the synthesis of GAG. Based on the composition of this cluster and carbohydrate synthesis in other fungi, we hypothesize that two genes; UDP-glucose epimerase, and UDP-mutase play an important role in governing the synthesis and production of GAG. Disruption of Ugm is associated with hyperproduction of GAG and increased adherence, but the function of Uge remains uninvestigated. We hypothesize that a MedA dependent expression of the Uge and Ugm genes controls the biosynthesis of GAG.

To test this hypothesis and explore the role of GAG in fungal adherence and virulence we propose the following specific aims:

1) Characterization of UGM and UGE gene expression: using qPCR, we will analyze the expression of these genes of interest and compare this expression to various mutant strains including the ∆ugm and ∆medA mutant strains.

2) Construction of a ∆uge mutant strain. The effects of Uge disruption on adherence, GAG production and Ugm expression will be examined in detail to elucidate the role of this novel gene in adherence to host tissues and virulence.

These studies are highly likely to yield key insights into the regulation of this novel virulence factor. Further, the discovery of enzymes responsible for biosynthesis of GAG can uncover potential drug targets, affecting virulence of A. fumigatus.
Prerequisite: 1 term completed at McGill + CGPA of 3.0 or higher; or permission of instructor.
Other prerequisite, if applicable:
Grading scheme (The final report must be worth at least 50% of final grade): Final grade shall be based on laboratory performance as evaluated by the research supervisor (50%) and the final written research report (minimum 10 pages) graded by the supervisor and the course coordinator or the coordinator's delegate (50%)
Other project information:
Project status - This project is: Taken. The professor has no more '396' projects this term.
How students can apply: N/A; this project is filled.
If other, please specify:
Ethics, safety, and training
Which of the following, if any, is involved? One or more of the following
Animal subjects [ ]
Human subjects [ ]
Biohazardous substances [x]
Radioactive materials [ ]
Handling chemicals [x]
Using lasers [ ]
Supervisors are responsible for the ethics and safety compliance of undergraduate students.
Do not complete this section unless/until the student is identified.
McGill ID:
Email (first [dot] last [at] mail [dot] mcgill [dot] ca):
Program (E.g., B.Sc. Maj. Chem. Min. Biol.):
Level (U0 / U1 / U2 / U3):
Student signature - I have not applied for another '396' course in this term:
Do not complete this section unless/until the student is identified.
Supervisor: I give my permission for the student identified in section C to register for this project under my supervision.
Supervisor's signature:
Unit chair/director/designate: I certify that this project conforms to departmental requirements for 396 courses.
Unit chair/director/designate's name:
Unit chair/director/designate's signature: