Previous Editions__________________________________________________________________________SSRL Headlines Vol. 10, No. 6 December, 2009__________________________________________________________________________
Contents of this Issue:
A team of researchers led by Joy Andrews of SSRL studied mercury uptake and
methylation in the rhizospheres of two common plant species in the San
Francisco Bay. They used a combination of experiments to piece together the
story of methylmercury formation. Using data collected at SSRL Beam Lines 9-3
and 10-2, they used Hg L3 x-ray absorption edge spectroscopy
(XANES) to determine what species of mercury were present in the root systems.
They used Beam Line 2-3 to perform scanning x-ray fluorescence (XRF) and
micro-XANES experiments to map the location of mercury species within the roots
of the plants. Additionally, they performed transmission x-ray microscopy (TXM)
experiments using Beam Line 6-2c, which showed that the mercury seen in the
roots was most concentrated on the outside of microorganisms.
The researchers conclude that much of the mercury is binding to sulfur in the
plant roots and microbes' cell walls, and about 10% of the total mercury is
likely to be methylated. Because these plants dominate the San Francisco Bay
environment, their rhizospheres could be a significant source of methylated
mercury in this estuary ecosystem. This work was published in the September
issue of Environmental Science & Technology.
To learn more about this research see the full scientific highlight
The synthetase that charges alanine tRNA has a structural domain that places
the amino acid, a domain that removes the wrong amino acid, and a third domain
with a previously unknown role. A group led by Professors Paul Schimmel and
Xiang-Lei Yang at The Scripps Research Institute solved the crystal structure
of this third domain of the alanine tRNA synthetase. They used SSRL Beam Line
11-1 to collect data and determined the structure at 1.85 angstroms using
single anomalous diffraction. The structure revealed a known nucleic acid
binding fold. This domain was shown through biochemical experiments to contact
the elbow region of the tRNA.
The researchers propose that this domain promotes the coupling of the
activities of the aminoacylation and the editing domains of alanine tRNA
synthetase. Because phylogenic data shows that this domain has an ancient
origin, it could have been the first bridge between these activities, ensuring
that the tRNA bears the correct amino acid. This work was published in the
August 7 issue of Science.
To learn more about this research see the full scientific highlight
Now, scientists at The Scripps Research Institute have discovered the chemical
basis for why these extraordinary efforts are necessary. The work was published
in the December 10, 2009 issue of the prestigious journal Nature.
Several data sets from SSRL are included in the paper.
"What is shown here with the 'serine paradox' is just the tip of the iceberg,"
said senior author Paul Schimmel, who is the Ernest and Jean Hahn Professor and
Chair of Molecular Biology and Chemistry and a member of The Skaggs Institute
for Chemical Biology at Scripps Research. "In the coming years, there will be
an increasing awareness of the role of mistranslation in human diseases and of
how nature has struggled to find solutions to attenuate mistranslation and its
consequences." Read more at: http://www.scripps.edu/newsandviews/e_20091214/guo.html
It's that time of year again, with another successful year of innovative
science, operations, and outstanding customer service winding down. We ended
the 2008-09 user run year with a record average uptime of 99%. In the past
year, we ran SPEAR3 routinely at 200 mA, added several new beam lines and
experienced an almost 19% increase in the number of users that we serve (1,361
on-site and remote access users). Users and staff have published over 9,000
scientific papers, books, and theses since SSRL began in 1974, with 2009
marking SSRL's 35th anniversary!
As I look forward to 2010, I see a many exciting developments on the horizon
including continuing on our path to 500 mA and the bringing of two new beam
lines into operation. I also look forward to working with all of you to develop
both short- and long-term plans for SSRL that will keep our capabilities at the
forefront for a long time to come.
Over the upcoming holiday shutdown, I encourage you all to take time out to
breathe, to appreciate how much we have accomplished as a team, and to relax
with family and friends. We look forward to coming back in 2010 ready and eager
to begin again. Best wishes for a wonderful holiday filled with joy, peace and
prosperity in the New Year.
"The contributions made by these researchers to advance the national, economic
and energy security of the United States are wide-ranging and meaningful," said
Secretary of Energy Steven Chu. "I congratulate the winners and look forward to
their discoveries still to come."
One of the highest scientific honors that is bestowed by the U.S. Government,
recipients of the E.O. Lawrence Award receive citations signed by the
Secretary, a gold medal bearing the likeness of the award's namesake, Ernest
Orlando Lawrence, and a $50,000 honorarium.
Shen's citation reads, "For his ground breaking discoveries and pioneering use
of high resolution angle-resolved photoemission to advance understanding of
strongly correlated electron systems including high-transition temperature
superconductors and other complex oxides."
"Z.-X.'s accomplishments truly fit the spirit of this award," said SLAC
Director Persis Drell. "In addition to providing leadership in the fields of
materials and energy research, Z.-X. is also tirelessly dedicated to the
encouragement of young scientists. We are privileged to have him on our
faculty." Read more at:
We are continuing to build on this existing site to provide more sophisticated
search and database capabilities and scheduling features; your input in the
development of this website is greatly appreciated. Please feel free to contact
Cynthia Patty (cpatty@slac.stanford.edu) and Nik Stojanovic
(stojanik@slac.stanford.edu) with any comments or suggestions.
For access to the full SSRL User Resources page, see:
System upgrades are scheduled December 21-23, and sporadic outages or
difficulty connecting to our website and/or user portal are likely during this
time. Please note that SLAC operations are shut down from December 19-January
3. We hope you have a great holiday! Please check back with us after January 4.
As you prepare for your upcoming beam time, please check the SPEAR operating
schedule to note holidays, accelerator physics and maintenance days.
It is extremely important that users not only inform us whenever work conducted
at SSRL results in a publication, but also acknowledge SSRL and our funding
agencies in each publication. User help is needed to keep current records on
publications including refereed journal papers, conference proceedings, book
chapters and theses, invited lectures and major awards and patents based at
least in part on work conducted at SSRL. This information allows SSRL to
demonstrate scientific achievements and productivity when responding to
requests sent out by the Department of Energy and the National Institutes of
Health.
This information can be submitted anytime via email message to Lisa Dunn or
Cathy Knotts or via the reference submission form at:
For recent publications lists and the proper acknowledgement statements see:
__________________________________________________________________________
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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