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SSRL Headlines Vol. 8, No. 6  December, 2007

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Contents of this Issue:

  1. Science Highlight — Another Step Toward Understanding Autism
  2. Science Highlight — Structure of a Coated Gold Nanoparticle
  3. Holiday Greetings from the Director
  4. Photon Science Faculty Receives Honors
  5. Shipping and Receiving to Remain Open During Shutdown
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1.  Science Highlight — Another Step Toward Understanding Autism
       (contacts: D. Arac, E. Özkan, P. Strop, E. Newell and A.T. Brunger, Stanford University; A.A. Boucard and T. Südhof, University of Texas Southwestern Medical Center)

Structures of Neuroligin-1 and the Neuroligin-1/Neurexin-1 b complex. [larger image]
Establishment of neural connections is critical for proper brain function, and errors in the process are thought to be associated with autism and other disorders. Howard Hughes Medical Institute investigators Axel Brunger (Stanford University School of Medicine and Photon Science) and Thomas Südhof (University of Texas Southwestern Medical Center), working in part at SSRL, have solved the structure of the proteins that form this connection-neuroligin-1 and neurexin-1b—giving clues to how neurons forge physical connections between one another. The results are published in the December 20, 2007, issue of the journal Neuron.

Nerve impulses are triggered when a presynaptic neuron releases a chemical neurotransmitter into the synapse that is recognized by the postsynaptic neuron. Neurexin and neuroligin, respectively, are presynaptic and postsynaptic connector proteins that extend outside of the cells where they are produced and contact one another to form a physical link across the synapse. Using SSRL Beam Line 11-1 and ALS Beam Line 8.2.2, Brunger and colleagues solved the structure of neuroligin-1 by itself and in complex with neurexin-1b.

To learn more about this research see the full scientific highlight at:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/neuroligin_hires.html


2.  Science Highlight — Structure of a Coated Gold Nanoparticle
       (contacts: P.D. Jadzinsky, G. Calero, C.J. Ackerson, D.A. Bushnell and R.D. Kornberg, Stanford University)

X-ray crystal structure determination of Au102(p-MBA)44 nanoparticle. [larger image]
A team of scientists, working in part at SSRL's crystallography beam lines and led by Stanford Professor Roger Kornberg, has determined for the first time the atomic structure (at 1.1 Å resolution) of a thiol-covered gold nanoparticle, a discovery with potential for a range of applications from biosensors to nanotransistors. The results were published in the October 19 issue of Science.

Gold is an appealing metal for many uses because of its softness, optical and electrical properties, and because it does not oxidize. However, a plain gold surface may not be compatible with certain applications, so scientists are experimenting with gold clusters and surfaces coated with organic molecules, such as thiols. The organic layer, which self-assembles in a geometric array on the gold surface, changes the gold's chemistry. For example, coating gold can make it biocompatible for implantation into living organisms. Another possible application is to make self-lubricating materials.

Synthesizing well-defined thiol-coated gold nanoclusters is a challenging process. This thiol-coated structure, confirmed from the screening of 15 separate crystals derived from multiple preparations, shows homogeneous clusters of 102 gold atoms surrounded by 44 molecules of p-mercaptobenzoic acid. The central gold atoms are packed with decahedral symmetry, with additional layers of gold atoms in unexpected geometries. The cluster is coated by a thiol monolayer, with each sulfur bridging between two gold atoms, and with stabilization of the coat provided through several types of interactions between the thiol molecules. This structure will assist in the understanding of principles of nano-core assembly and the theoretical basis of gold-thiol interactions.

To learn more about this research see the full scientific highlight at:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/goldnano.html


3.   Holiday Greetings from the Director

SSRL Director Jo Stohr 
Jo Stöhr
Dear Users, Colleagues and Friends of SSRL,

As we near the end of 2007, I would like to take a moment to send you my best wishes for a happy holiday and to reflect back on many high points from the past year.

During the FY2007 run (November 2006-August 2007), SPEAR3 continued to provide very stable beam for >98% of the scheduled time, allowing >2,000 researchers to benefit from 88,882 hours of beam which were delivered on our 29 experimental stations. Also during the past three scheduling periods, >1,300 experiments were conducted on 423 different proposals. Users consistently rated their overall scientific experience at SSRL very highly (92% ranked their experience as excellent or very good).

The FY2008 run got off to a good start in November 2007, but with a total run time yet to be decided depending on the final operating budget. SSRL continues to provide valuable scientific training experience for the future workforce, indicated by the large number of on-site users who are undergraduate students, graduate students, or postdoctoral fellows (>56%).

Since SSRL began user operations in 1974, users have reported >8,000 scientific publications based on research conducted at SSRL. In the last three years alone, users published >1,100 papers including >95 student theses (reported to date). If you have not responded to my recent request, I encourage you to inform us of your SSRL-related publications, awards, and invited lectures covering 2005-2007. This information is needed for a key program review of SSRL by the DOE Office of Basic Energy Sciences which will be held in January. The current lists of publications that have been reported to SSRL to date can be found at
http://www-ssrl.slac.stanford.edu/pubs/. Please send these to Lisa Dunn, lisa@ssrl.slac.stanford.edu, or use the web form at http://smb.slac.stanford.edu/forms/reporting/form_publication.shtml. Thank you for your support.

The first joint SSRL and Linac Coherent Light Source (LCLS) Users' Meeting was a wonderful success. Approximately 320 individuals participated in various activities scheduled over the six-day event which began with a special symposium on the future of x-ray science, September 28-29; this was followed on September 30 with a joint SSRL/ALS workshop on synchrotron radiation techniques. The main Users' Meeting, on October 1-2, featured presentations on recent developments and new opportunities in structural biology, material and environmental science, ultrafast science and LCLS instrumentation. On October 2, the keynote presentation was given by Nobel Laureate Professor Roger Kornberg, who utilized SSRL's crystallography beam lines for his experiments on RNA polymerase. The event concluded on October 3, 2007, with four concurrent workshops: Imaging and X-ray Microscopy; Microfocusing; Scientific Opportunities for Studying Laser Excited Dynamics at the LCLS; and XANES Spectroscopy.
http://www-conf.slac.stanford.edu/ssrl-lcls/2007/default.htm

As part of the meeting tradition, several awards for outstanding scientific and technical achievement in synchrotron radiation-based science were presented, including prizes for Outstanding Student Scientific Posters: Brittany Nelson-Cheeseman (UC Berkeley), Origin of Anomalous Magnetic Behavior in NiMn2O4 Thin Films; Stephen Kelly (Stanford), The Effect of Cycling on Microstructure and Reaction Kinetics in Mg/MgH2; David Singer (Stanford), Using Synchrotron Radiation X-ray Techniques to Examine Uranium Speciation as a Function of Depth in Contaminated Hanford Sediments; and Samuel Wilson (Stanford), XAS Pre-edge and EXAFS Spectroscopy Reveals Mechanistic Differences between Tyrosine Hydroxylase and Other Pterin Dependent Hydroxylases. The William Spicer Young Investigator Award was presented to Hugh Harris, a lecturer at the School of Chemistry and Physics, University of Adelaide, Australia. Jessica Vey, a graduate student at MIT, received the Melvin Klein Professional Development Award. And, Cathy Knotts, Manager of SSRL User Research Administration received the Farrel Lytle Award.

I want to thank everyone who provided feedback and suggestions to us through the 2007 users' survey, the end-of-run surveys, and especially those individuals who serve on SSRL's advisory committees - the SSRL Scientific Advisory Committee (SAC), Proposal Review Panel (PRP), the SMB Advisory Committee (SMBAC) and the SSRL Users' Organization Executive Committee. Guidance from these groups is extremely important to help us plan and move forward in the wisest and most effective ways. We continue to be grateful to our funding agencies - the Department of Energy's Office of Basic Energy Sciences for providing the core operations funding and support for materials research and the DOE Office of Biological and Environmental Research and the National Institutes of Health NIGMS and NCRR Programs for support of the structural biology program. Without their effective support, we would not be able to push the scientific forefront and effectively serve our diverse and growing user community. I urge you to continue to let us know your opinions and ideas - it helps us to serve you better, to improve our operations and to plan for our future.

In closing, on behalf of SSRL and its staff, let me extend our very best wishes to all of you for this holiday season and for 2008!

—Jo Stöhr, SSRL Director

4.   Photon Science Faculty Receives Honors
       (contact: C. Knotts, knotts@slac.stanford.edu)

Christopher E. D. Chidsey, Associate Professor of the Department of Photon Science and of the Department of Chemistry, has been elected Fellow of the American Association for the Advancement of Science (AAAS) for his distinguished contributions to understanding molecular electronics and its applications to energy efficiency, and for his commitment to improving teaching and learning. Election as a fellow is an honor bestowed upon AAAS members by their peers.

Many other members of our Photon Science faculty and user community have received awards and honors over the past few years. We greatly appreciate the input that we have received in response to our recent requests for information so far. If there are still more SSRL-related awards to be reported, and you have not yet done so, please contact us.


5.   Shipping and Receiving to Remain Open During Shutdown
      —SLAC Today article by Kelen Tuttle

Do you have an important package coming in over the next two weeks? Never fear! Shipping and Receiving will remain open during the shutdown, albeit with limited hours. Shipping and Receiving will be staffed between 8:00 a.m. and 12:00 p.m. on December 26, 27 and 28 as well as January 2. During this time packages may be picked up, but will not be delivered. Regular hours and operations will resume on Thursday, January 3.

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SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical Sciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site.

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Last Updated: 20 DEC 2007
Content Owner: L. Dunn
Page Editor: L. Dunn