Michael R. Gretz
, Professor


Biotechnology Research Center
Department of Biological Sciences



Dow Environmental Sciences and Engineering Building, Rm. 730
Michigan Technological University
1400 Townsend Drive
Houghton, Michigan 49931
Phone: (906) 487-3175
Fax: (906) 487-3167
email:  mrgretz@mtu.edu




*This work is funded in part by the National Science Foundation. In keeping with NSF policy, we note that "any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."


Research Interests

Our work is centered on the cell wall and associated extracellular polymers of algae. We are interested in what these algal extracellular matrices can tell us about: 1) the evolution of the land plant cell wall, 2) the unique characteristics that allow for life in aquatic habitats, 3) the interactions within complex biofilms, including the heterotropic utilization of complex macromolecules, and 4) the biomineralization processes (ex. silica and calcium carbonate) associated with these extracellular polymers.

What is the broader significance of our work? The characteristics of plant cell walls determine the properties of innumerable products we consume every day. Our work has potential impact on the pulping properties of wood, the mechanical properties of textile fibers, the health effects of dietary fiber, the efficiency of energy extraction from biofuels, among others.   In aquatic ecosystems, algal extracellular polymers play a pivotal role in maintaining the integrity of biofilms. These biofilm consortia have high primary productivity and play a crucial role in many processes including regulating nutrient fluxes between terrestrial and aquatic ecosystems, flood mitigation, storm abatement, reduction of sediment from the water column, ground water recharge/purification, and maintaining stability of intertidal mudflats.


Our current projects our outlined below:

The charophycean green algae (CGA) are the closest algal relatives to the land plants and exhibit many of the same cell wall characters, suggesting that many of the key morphogenetic events and associated cell wall polymers found in modern land plants arose in their ancestors before emergence onto land approximately 470 million years ago. Our lab is part of an international team of researchers attempting to understand the functions of CGA wall characters critical to the success of land plants, and determine the evolutionary sequence that led to this result.


In our quest to discover the key cell wall components necessary for adaptation to land, we have recently reached beyond the algae to a model moss system Physcomitrella patens. Our collaborators have knock-in transformants with several cellulose synthase-like genes expressed.  We are evaluating the effects of these additions on cell wall characters in hopes of further defining the functions of CslB, E G and H.
 
One of our favorite groups of algae, the diatoms, have provided unique insights into the involvement of extracellular polymers in nano-patterning of silica (window glass) by these unique single celled organisms.

Diatoms are abundant in complex biofilms that are critical components of both marine and freshwater systems. Our studies of Everglades and Colne Estuary, UK, diatom doninated biofilms have yielded critical insights into the physiological ecology of freshwater periphyton and metaphyton and intiertidal mudflat biofilms. 

The "diatom gone wild" Didymosphenia geminata (Didymo) is unique in that, in this organism, a switch for exo-polymer production has been turned on with the result that thick (up to 30 cm) mats of diatom extracellular polymer "rock snot" covers vast reaches (kilometers) of streams worldwide.

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July 2008
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