HR: 1340h
AN: B13A-1053    [Abstracts]
TI: The Rise of Complexity: Do the Pavilion Lake Microbialites Suggest a Way to Build a Macroorganism?
AU: * Schulze-Makuch, D
EM: dirksm@wsu.edu
AF: Dept. of Geology, Washington State University, Webster Hall, Pullman, WA 99164 United States
AU: Laval, B
EM: blaval@civil.ubc.ca
AF: Dept. of Civil Engineering, University of British Columbia, 2324 Main Mall, Vancouver, BC V6T1Z4 Canada
AU: Lim, D S
EM: dlim@mail.arc.nasa.gov
AF: Space Science and Astrobiology Division, NASA Ames Research Center, Mail Stop 245-3, Moffett Field, CA 94035 United States
AU: Irwin, L N
EM: lirwin@utep.edu
AF: Dept. of Biological Sciences, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79912 United States
AB: The distinctive assemblage of freshwater calcite microbialites discovered at Pavilion Lake, BC, has been associated with organisms such as Epiphyton and Girvanella, fossils from just before the Cambrian explosion about 550 million years ago (Laval et al., 2000). The presence of the microbialite structures in a dimictic mid-latitude lake and their establishment after the last ice age about 10,000 years ago is puzzling. Their distinctive morphologies include cone-shaped seepage structures 2 m or more in height with hollow internal conduits that open at the top of the cones, and dense artichoke-like structures with calcite "leaves" greater than 1 m in height. These structures are astounding as they imply functional properties. In principle, this is not unlike the interaction of individual cells in a macroorganism, in which many different types of specialized cells interact with each other to the benefit of the whole organism (e.g. interaction of blood, integument, and organ cells within animals). Certainly, the complex interaction of these microbial cells is not equivalent to the collaboration of cells within an individual multicellular organism, where each cell has the same genetic information but differential gene expression provides well-defined cellular specializations. However, the microbialites raise the question of how much complexity and structure can be achieved by a high degree of communication within a multitude of microbial cells. Our findings indicate a complex and interacting microbial consortium associated with the structures at Pavilion Lake, and revealed biomarkers for proteobacteria, sulphur reducing bacteria, and firmicutes (possibly photosynthetic heliobacteria), among others. Types of genetic exchange among these microbial cells may include lateral gene transfer via conjugation, transformation, and transduction, or other mechanisms. This finding may have significant implications for the evolution of life on Earth and possible life on other planets. References: Laval, B., Cady, S.L., Pollack, J.C., McKay, C.P., Bird, J.S., Grotzinger, J.P., Ford, D.C., and Bohm, H.R. (2000) Modern freshwater microbialite analogues for ancient dendritic reef structures. Nature 407, 626-629.
UR: http://supercritical.civil.ubc.ca/~pavilion/information/science.htm
DE: 0406 Astrobiology and extraterrestrial materials
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0444 Evolutionary geobiology
DE: 1813 Eco-hydrology
DE: 5200 PLANETARY SCIENCES: ASTROBIOLOGY
SC: Biogeosciences [B]
MN: Fall Meeting 2005