ALSNews is a biweekly electronic newsletter to keep users and other interested parties informed about developments at the Advanced Light Source, a national user facility located at Lawrence Berkeley National Laboratory, University of California. To be placed on the mailing list, send your name and complete internet address to ALSNews@lbl.gov. We welcome suggestions for topics and content.

Previous Issues are available.


ALSNews           Vol. 28           June 6, 1995

Table of Contents


    1. THANK YOU!
    2. OPERATIONS UPDATE
    3. ALS NEWSLETTER ON ITS WAY
    4. X-RAY MICROSCOPE CONFIRMS CHROMATIN OBSERVATIONS
    5. NEW USER ADVISORIES

1. THANK YOU!

We, the editors, admit to being surprised, somewhat overwhelmed, and definitely pleased at the large number of responses we have received to last week's ALSNews survey (nearly 150 so far). It's nice to know most of you are reading ALSNews on a regular basis and that we have achieved a high level of customer satisfaction. For those of you who didn't read or respond to last week's issue, please do so and let us know why you aren't reading ALSNews on a regular basis if that is the case. This information is important for us as we will be analyzing the survey results in the next few weeks to incorporate your suggestions and opinions about how ALSNews can best serve you.

2. OPERATIONS UPDATE
(contact: rmmiller@lbl.gov)

For the next three weeks, the accelerator group will relinquish its Wednesday evening shift to ALS users, increasing user shifts from nine to ten per week. This arrangement will become the normal schedule once testing of the longitudinal and transverse feedback systems is concluded. Final tests await the delivery of the feedback electronics required for full multi-bunch operation; when these arrive, the accelerator group will reclaim its shift for the period required to finish tests and commissioning, and then give up the shift to users permanently.

Beam availability last week was 92.1% overall and 91.3% during user shifts. Causes of outages included storage ring sector 6 vacuum interlock trip, Beamline 6.3 photon stop micro switch adjustment, and Beamline 3.1 ion gauge trip.

Operations summary for June 6 - June 25
1.9-GeV, 250-mA, 320-bunch operations for users:
    June 7-11, 08:00-23:15
    June 14-18, 08:00-23:15
1.0-GeV, 400-mA, 320-bunch operations for users:
    June 21-25, 08:00-23:15
Maintenance: 
    June 12 & 19, 08:00-16:00, with startup 16:00-23:15
Accelerator Physics:
    June 6, 13, & 20, 08:00-23:15

3. ALS NEWSLETTER ON ITS WAY
(contact: alsnews@lbl.gov)

A new issue of the semiannual ALS Newsletter (the printed one with photos!) is hot off the presses and on its way to readers' mailboxes now. The Recent Research Results section features several experiments performed in the last six months, including one article excerpted below. Other newsletter topics include the Protein Crystallography Facility, beamline updates, progress in operations including machine performance, and recent workshops. Veteran readers of the newsletter will notice this issue's new look, created by Paula Laguna of LBL's Technical and Electronic Information Department, Illustration Group.

4. X-RAY MICROSCOPE CONFIRMS CHROMATIN OBSERVATIONS
(contact: w_meyer-ilse@lbl.gov)

Some of the more striking images coming out of the ALS research program are being produced by the x-ray microscope (XM-1) on Beamline 6.1. X-ray microscopy provides the ability to image thick (up to 10 microns) samples under conditions approximating their natural environments: no staining or thin-sectioning is necessary, and samples can be imaged in aqueous solutions. These abilities make it a useful complement to electron microscopy, which gives excellent resolution but requires extensive sample preparation, and to visible light microscopy, which is relatively non-destructive of samples but has lower resolution than x-ray microscopy.

X-ray microscopy's success in imaging unstained samples proved valuable in a recent investigation of the distribution of chromatin in the heads of sperm cells from marsupial mice (Sminthopsis). Chromatin consists of long, thin strands of DNA complexed with organizing proteins into thicker strands. Researchers have characterized the first few levels of DNA's organization into chromatin by a number of methods providing atomic-scale resolution. Because of the limitations of these methods and of existing microscopies, however, they have not successfully analyzed the subsequent levels of chromatin organization that lead to larger structures, allowing billions of DNA base pairs to fit inside a cell nucleus about 5 microns in diameter.

Researchers from Lawrence Livermore National Laboratory and from the University of Adelaide in Australia were investigating chromatin distribution on these intermediate scales, using transmission electron microscopy (TEM) to image the marsupial sperm cells. They observed an inhomogeneity in the appearance of the chromatin near the cell tip, but there was some question whether this graininess actually represented the distribution of chromatin mass or was an artifact of the staining process required in their sample preparation.

At these researchers' request, Werner Meyer-Ilse and Hector Medecki of LBL's Center for X-Ray Optics examined a similar cell without staining. They first used the beamline's visible-light microscope (VLM) to find the relevant sample location and focus without using x rays (which could damage the sample in extended exposures). Then they stored this information in the XM-1 control computer and transferred the sample to the XM-1 stage, where a system of kinematic mounts under computer control placed the chosen sample location in position for a short x-ray exposure. The same inhomogeneity in the cell's chromatin emerged in the x-ray image, confirming that the grainy pattern is primarily related to chromatin mass distribution. Biologists can now work to explain the causes and consequences of this arrangement of chromatin, with the confidence that they are investigating an actual biological phenomenon rather than an experimental artifact.

5. NEW USER ADVISORIES
(contact: alsuser@lbl.gov)

The ALS has recently issued three new User Advisories: Receiving and Sending Shipments from the ALS, ALS Chemistry Laboratory - Facilities and Safety Requirements, and User Accounts at the ALS. Copies of the advisories are available in the User Services Area near Beamline 9 and from the ALS User Office [Tel: (510) 486-7745; Fax: (510) 486-4773, Email: alsuser@lbl.gov].

"Receiving and Sending Shipments from the ALS (ALS Advisory 7)" describes a new, improved procedure for sending materials and equipment (both large and small shipments) by regular mail and expedited delivery services (UPS and FedEx) to the ALS, and how to send shipments from the ALS. To make the shipping and receiving logistics much easier for ALS users, the ALS has set up a receiving area for user shipments on the first floor of Building 7 (near the ALS building), adjacent to the storage area for user equipment. Arrangements have been made for small packages sent by regular mail and for expedited mail sent via UPS and FedEx to be delivered to this location, and users will now be notified when packages arrive addressed to them. The advisory contains all you need to know including how to address shipments, packaging instructions, contact information, etc.

"ALS Chemistry Laboratory - Facilities and Safety Requirements (ALS Advisory 11)" describes the facilities and safety rules of the Chemistry Laboratory in Building 10, Room 102. Users should note that, in addition to being used for chemistry work, the laboratory is the recommended site for cleaning small UHV parts. A biodegradable cleaning solution (MICRO) and an ultrasonic cleaner are available for this purpose. "User Accounts at the ALS (ALS Advisory 12)" explains how users can order weekly and monthly statements for their user account so they can track charges for supplies, services, telephones, etc. The advisory also includes a table of hourly rates for ALS Technicians and other crafts persons which can be used as a general guideline for estimating labor costs associated with beamline installation, vacuum, repair work, etc.