2003 Annual Science Report
Carnegie Institution of Washington Reporting | JUL 2002 – JUN 2003
A New Molecular Recognition Instrument for Astrobiological Applications
Task 1. Molecular Recognition Instruments for Astrobiological Applications (Fogel, Steele)
Fogel and Steele have been applying the Cyphergen Protein Chip reader to detect small lipid molecules in modern and fossil samples. Together with postdoctoral fellow Jake Maule, they have made an antibody to the bacterially derived lipids, hopanes, and have successfully tested this antibody using enzyme-linked immunosorbent assay (ELISA) techniques. The antibody was created in the usual manner by injecting the hopane molecule bound to a small peptide into a rabbit. The goal of the experiment was to test whether biomarkers can be concentrated from solutions with antibodies for subsequent biosignature identification as might ultimately be done on the surface of Mars. Specialized chip surfaces were used to bind IgG proteins, proteins that provide a “handle” for the antibodies. This was the first test of the protein chip reader with antibody-based chips. Using standard reagents, it was found that the instrument could selectively detect specific proteins that had been bound to antibodies. With the hopane antibody, no evidence for hopane binding could be found, but this technique is being evaluated further. In control experiments where hopane-bearing solutions were analyzed directly, the chip reader was able to detect signals from small quantities of material. In addition, lipid extracts obtained from the fossiliferous Enspel Formation in Germany were tested for the presence of bacterial lipids. For these samples hopanes and other lipid molecules were detected by the Chip reader, but their molecular weights (around 200 daltons) were nearly identical to energy-absorbing molecules needed for matrix assisted laser desorption, so that the detections may be artifacts.
Steele’s group has also begun to fabricate high-spot-density protein chips, printed at CIW, using a deoxyribonucleic acid (DNA) protein printing system and hydrogel-coated slides. Optimization of the protocols for printing and evaluating the results using fluorescence are underway. The development of further antibodies to molecules potentially relevant for Martian exploration is underway. These include oxidized polycyclic aromatic hydrocarbon (PAH) molecules, suggested as a possible organic constituent in Martian regolith. The group also initiated fabrication of a bench-top instrument to test soil extraction protocols and establish extraction efficiencies to aid in the development of remote handling systems for samples returned from future missions. The latter work is in collaboration with NASA, Johnson Space Center (JSC), Oceaneering Space Systems, Lockheed Martin Space Operations (LMSO), and Montana State University. Finally, Steele has also initiated a new collaboration with the lab-on-a-chip (LOAC) group at Marshall Space Flight Center for testing microfluidic chips. These chips will be used for the extraction, reaction, concentration, and buffering of an inoculum before being introduced to enzyme and microarray chips that are also being developed as part of the Modular Arrays for Solar System Exploration (MASSE) project.
PROJECT INVESTIGATORS:Marilyn Fogel
PROJECT MEMBERS:Mohammad Mahmood
RELATED OBJECTIVES:Objective 2.1
Sources of prebiotic materials and catalysts
Origins and evolution of functional biomolecules
Earth's early biosphere
Environment-dependent, molecular evolution in microorganisms
Adaptation and evolution of life beyond Earth
Biosignatures to be sought in Solar System materials