Award Abstract #0406999
SGER: Developing Metal-Tagged DNA Probes for High Resolution Imaging of Microbial Phylotype Distributions and Nanoscale Mineral/Microbe Associations in Environmental Samples

NSF Org:	MCB Division of Molecular and Cellular Biosciences
Initial Amendment Date:	July 19, 2004
Latest Amendment Date:	August 26, 2005
Award Number:	0406999
Award Instrument:	Standard Grant
Program Manager:	Matthew Kane MCB Division of Molecular and Cellular Biosciences BIO Directorate for Biological Sciences
Start Date:	August 1, 2004
Expires:	January 31, 2006 (Estimated)
Awarded Amount to Date:	$101302
Investigator(s):	Rachel Haymon haymon@geol.ucsb.edu (Principal Investigator) Patricia Holden (Co-Principal Investigator)
Sponsor:	University of California-Santa Barbara Office of Research SANTA BARBARA, CA 93106 805/893-4188
NSF Program(s):	MICRO OBS & MICRO INTER & PRO
Field Application(s):
Program Reference Code(s):	BIOT, 9237, 9104, 7465
Program Element Code(s):	1089

ABSTRACT



ABSTRACT

High-resolution electron microscope (EM) images greatly magnify microbes and their microhabitats, and reveal minute features of microbial cells and their material surroundings. EM images potentially are of great use in studying how microbes interact with natural and man-made materials. However, the many types of microorganisms co-existing in natural samples typically cannot be distinguished from one another based on appearance alone. Furthermore, when "zoomed out" it is not possible to see the overall distribution of microbes in EM-mounted samples. A means of visually distinguishing specific genetic types of microbes in EM images must be invented to fully exploit the potential of electron microscopy for learning about in situ microbial distribution and activity in the environment. A grant has been awarded to Profs. Rachel M. Haymon and Patricia Holden at University of California, Santa Barbara, and to Dr. Stefan Sievert at Woods Hole Oceanographic Institution, for development of metallic "tags" that will attach to DNA sequences of selected microbes. When the metals are excited by electron beams used to generate EM images, the metals will emit X-rays and permit unambiguous visual identification of the targeted organisms at both high and low magnifications. This method will solve the existing problems in distinguishing spatial distributions and identities of microbes imaged with electron beams, and will make it possible to understand associations of microbes and minerals at small scales that are relevant to microbial life.

Applications of the proposed metal-tagged DNA probes to understanding how microbes interact with the environment are vast. It is expected that the proposed method will become a standard tool for studying the function, ecology, and environmental impact of microbial activities in natural environments. For example, Drs. Haymon, Holden, and Sievert hope to apply this new technique to studies of microbes in soils, where microbes are important to biodegradation of toxic anthropogenic compounds, and in hydrothermal systems, where microbes interact with geologic materials under extreme thermal and chemical conditions.

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