51ÁÔÆæ

The hyphal wall is the cell structure most responsible for mediating the varied interactions between the fungal cell and its environment. The architectural relationships between the numerous polysaccharides and glycoproteins of the wall are little known, as are the steps by which the complex fabric of the wall is assembled and modified. We have isolated 52 strains from an Aspergillus nidulans mutant collection that are deficient in cell wall assembly, determined by hypersensitivity to the chitin synthase inhibitor Calcofluor White at concentrations having little effect on wildtype strains. The phenotype appears as reduced hyphal growth rate, blocked or delayed conidium germination, and aberrant hyphae. The screening strategy is based upon the premise that mutants with already-weakened walls will be less able to endure an additional disturbance from a sublethal concentration of the inhibitor. We have identified 6 single-gene mutations, assigned them to 6 complementation groups and determined cellular and colonial morphologies.

Recent Grants:

National Science Foundation (C-RUI)
Description: Identification of genes regulating cell wall integrity in Aspergillus nidulans, January 2003- January 2006; Awardees: Drs. Hill & Loprete

Merck/AAAS
Description: An interdisciplinary project that involves undergraduates. February 2002-February 2005; Awardees: Drs. Hill, Loprete, Viano and Redfearn

Links to Collaborators:

Dr. Terry Hill 
Dr. Loretta Jackson-Hayes

SELECTED PUBLICATIONS

Rhodes student co-authors are in bold.

Loprete, D.M. and Hartman, K.A. "Conditions for the Stability of the B, C and Z Structural Forms of Poly(dG-dC) in the Presence of Lithium, Potassium, Magnesium, Calcium, and Zinc Cations."Biochemistry, 1993, 32, 4077-4082.

Loprete, D.M. and Hartman, K.A. "Structure of Poly(dG-dC) and Poly(dA-dT) Stabilized by Anions." J. Biomol. Struct. Dyn. 1995, 13, 57-68.

Coffman, J.A., Rai, R., Loprete, D.M., Cunningham, T., Svetlov, V. and Cooper, T.C. "Cross Regulation of Four GATA Factors That Control Nitrogen Catabolic Gene Expression in Saccharomyces cerevisiae." J. Bacteriol. 1997, 179, 3416-3429.

Hill, T. W. and Loprete, D. M. "Isolation and Characterization of a Branching-Related Endo-(1,4)- ß -Glucanase Secreted from Achlya ambisexualis". Mycological Society of America. June, 1998. San Juan, Puerto Rico.

Hill, T. W., D. M. Loprete, M. Momany, Y. Ha, L. M. Harsch, J. A. Livesay, A. Mirchandani, J. J. Murdock, M. J. Vaughan, and M. B. Watt. 2006. "Isolation of cell wall mutants in Aspergillus nidulans by screening for hypersensitivity to Calcofluor White". Mycologia 98: 400-410.

T. W. Hill, Loprete, D. M., K. N. Vu, S. P. Bayat Mokhtari, and L. V. Hardin. Proteolytic release of membrane-bound endo-(1,4)-ß-glucanase activity associated with cell wall softening in Achlya ambisexualis. Can. J. Microbiol. 48: 93-98 (2002).

Loprete, D. M., and Hill, T. W. Isolation and Characterization of a Branching-Related Endo-(1,4)-ß-Glucanase Secreted from Achlya ambisexualis. Mycologia 94 (6): 903-911(2002).

Terry W. Hill, Darlene M. Loprete, Jared A. Castagna, and Samuel O. Weems. Efficient high-volume cleaning of Aspergillus nidulans cleistothecia using bare fingers. Fungal Genet. Newsl. 50:4-5 (2003).