John Brown is a cell biologist at Berkeley Lab's Center for X-Ray Optics (CXRO). His job at the ALS is to run the XM-1 x-ray microscope, an extremely powerful microscope that permits analysis of the subcellular components of a human or bacterial cell. The XM-1 (see photo at right) works like a light microscope except that it uses x rays instead of visible light and has a camera and monitor to project images of the specimen. Unlike the more widely used electron microscope, the x-ray microscope can image thick specimens-- a capability that allows researchers to view unsliced cells. When a cell is sliced, it undergoes pressure and temperature changes that can alter its structure and dry it out. Therefore, the ability to image unsliced cells gives scientists a clearer representation of what the original cell structures looked like. Because the x-ray microscope is a unique research tool, people from around the world travel to Berkeley Lab and the ALS to use it. An important part of John's job is to assist visiting researchers in conducting experiments and interpreting the video images they get from the x-ray microscope. His job involves understanding cell biology, physics, and computers.
Because John's job at the CXRO is to work with whichever group reserved time on the x-ray microscope, he is involved in many projects. Some examples of the research he has worked on are studying the chemistry of concrete, following the germination process of bacterial spores, and looking at changes to the "sludge" at the bottom of San Francisco Bay. One of his major projects is studying the parasite that causes malaria. At present, Berkeley Lab researchers are analyzing malaria's effects on red blood cells. They are trying to find out exactly how the malaria parasite interacts with a red blood cell and what changes occur to the cell after infection. With this knowledge they hope to come up with new treatments for this crippling disease. As with most of the projects he is working on, this research is the only one of its kind taking place in the world. To find out more about how malaria is studied with an x-ray microscope and to see some of the images taken with XM-1, see CXRO's Soft X-Ray Microscopy site. To follow a malaria experiment from start to finish, see "From Mosquito to Microscope: Research on Malaria at the ALS" in the eXperiment Files.
John says that there are relatively few lows to his job. The only low he could think of was that he often works long hours because research teams have only a limited amount of time to use the x-ray microscope, so when they come to the ALS, they come prepared to use every second possible. That means that he sometimes puts in over 100 hours in a week at the microscope! He says, "You just have to work until you're done."
John says that there are many highs associated with his job. One big high is using the x-ray microscope and seeing images of structures on a microscopic level that have never been seen before--a result that also delights the participating research team. His goal is to help scientists use the XM-1 to achieve the best results, and his reward is that his work is interesting and entertaining. There's always something to do.
John begins his day at the ALS by performing some simple preparations on the x-ray microscope, such as aligning the x-ray beam going into the microscope and filling the cooling system with liquid nitrogen to keep the optical system clean. After he has turned on the microscope and everything is in working order, he waits for the scientists to arrive with the specimens or samples they are going to study. When the scientists get there, John shows them how to load their specimens on the special plates that hold the slides for the x-ray microscope (see photo at right). They first view the slide with a light microscope to mark the positions of cells they want to look at with the x-ray microscope. Then they put the slide on the x-ray microscope and take notes about the images of cells that appear on the video monitor. They work either until they finish or until the light coming into the beamline is shut off.