Office of Biological and Environmental Research Weekly Report

June 16, 2008

Journal of Structural Biology Cover Article on X-ray Imaging of Cells at Advanced Light Source (ALS). X-ray tomography has determined the structure of organelles in yeast cells during different stages of the cell cycle, providing for the first time three-dimensional images that show how the cells change during the cycle. The research is reported in the June issue of the Journal of Structural Biology, with selected images shown on the cover. The authors show that use of the soft X-rays at the ALS enables imaging of cellular components without having to expose the cells to potentially damaging staining reagents. They were able to determine how the yeast responds to changes in its environment. They note that the new X-ray microscope being commissioned at the ALS for biological studies will enable further improvements in spatial resolution that should reveal fine structure of microtubules and other components of the cell. This new imaging technique is ideally suited to imaging bioenergy-relevant organisms. The research was led by Dr Carolyn A. Larabell of the Lawrence Berkeley National Laboratory and the University of California-San Francisco.

Media Interest: No

Contact: Roland F. Hirsch, SC-23.2, (301) 903-9009

SC Investigator’s New Approach to Capturing Multiprotein Complexes Highlighted in Journal of Proteome Research: A LBNL project led by Dr. Mark Biggin has developed an enhanced approach to rapidly separate intact multiprotein complexes from cells. These multiprotein complexes, often called molecular machines, play critical roles in every aspect of the biochemistry of the cell but are often difficult to isolate and study intact. Traditionally, these complexes are captured using biological tags that are genetically and laboriously inserted into different proteins in the complex one at a time. The new approach eliminates the need for these tags. The “tagless” approach involves removing the cell’s soluble content followed by several gentle chromatographic steps that leave the complexes intact. The complexes are separated from one another based on properties such as electric charge and molecular weight. At the end of the process there is a high probability that only one complex is clustered in one or a small number of related fractions.  Mass spectrometry is used to confirm the identity of the proteins. The separation approach is being automated providing researchers with a new tool to rapidly determine how these complexes and their associated biological processes change in a microbe or a plant exposed to different environmental conditions or genetic modifications. This work was highlighted in the Journal of Proteome Research.

Media Interest: No

Contact: Arthur Katz, SC-23.2, (301) 903-4932

Practical Gas Sampling Method Enables Rapid Evaluation of all Major Dissolved Gases in Groundwater. Researchers at the Oak Ridge National Laboratory recently developed a practical method to sample all major dissolved gases present in groundwater without the need for pumping groundwater to the surface or the need for multiple analytical methods to measure gas concentrations. Traditional dissolved gas sampling techniques in the field are labor intensive, time consuming efforts. This new passive sampling technique requires little sampling effort allowing researchers to quickly deploy, retrieve and analyze gas samples from multiple locations. Concentrations of dissolved gases such as oxygen, hydrogen, nitrogen, carbon dioxide, methane, nitrous oxide, and carbon monoxide yield important information on microbial and chemical processes occurring in the subsurface. Microorganisms profoundly affect the transport of contaminants in the subsurface and these methods can help identify which microbial processes are active in the subsurface. The sampling device is suspended in a well until it equilibrates with ambient conditions, and then it is removed for analysis in the laboratory. The technique is highly sensitive to trace levels of gases and can provide researchers and modelers with information on active microbial processes in the subsurface. Understanding which microbial processes are active at a specific field site will help in refining simulations of contaminant transport, understanding bioremediation, monitoring natural attenuation processes and devising new techniques to intercept and immobilize contaminants.

Reference: Environmental Science & Technology, 2008, vol 42(10):3766-3772.

Media Interest: No

Contact: Robert T. Anderson, SC-23.4, (301) 903-5549