X-ray microprobe unveils biostructures.Proteins play a crucial role in binding a sperm to an egg to begin fertilization. The absence of these proteins in defective sperm may contribute to infertility. Now, researchers have developed a new form of X-ray microscopy that can locate and map proteins in and on sperm cells. The technique can also probe a variety of biological structures to determine the distribution of DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. and other molecular constituents. The method involves passing intense X rays, generated by a particle accelerator (SN: 5/4/96, p. 276), through a system of mirrors and lenses that focuses the rays into an extremely narrow beam. Developed by physicist Janos Kirz and his coworkers at the State University of New York (body) State University of New York - (SUNY) The public university system of New York State, USA, with campuses throughout the state. at Stony Brook, the system generates a shaft of X rays only 50 nanometers wide at a wavelength between 2.3 and 4.4 nm. "We think this is the smallest beam of focused electromagnetic radiation electromagnetic radiation, energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an of any wavelength [anyone has yet produced]," Kirz says. He described the technique this week at an American Physical Society The American Physical Society was founded in 1899 and is the world's second largest organization of physicists. The Society publishes more than a dozen science journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than twenty science meeting in Kansas City, Mo. By tuning the X-ray wavelength, it's possible to map specific molecules. With scientists from the Lawrence Livermore (Calif.) National Laboratory, Kirz and his team used an X-ray microbeam to determine the distribution of protein and DNA in bull, mouse, stallion, and hamster hamster, Old World rodent, related to the voles, lemmings, and New World mice. There are many hamster species, classified in several genera. All are solitary, burrowing, nocturnal animals, with chunky bodies, short tails, soft, thick fur, and large external cheek sperm. Though the individual proteins vary from species to species, their arrangement proved remarkably similar. The researchers hope to develop an X-ray microscope x-ray microscope n. An instrument using x-rays to render a highly magnified image. that will enable them to image cellular structures in three dimensions without having to stain or thin-slice samples. Such a tomographic technique would require taking a large number of images, which would normally damage the sample. Recent experiments, however, show that flash-freezing to liquid-nitrogen temperatures lessens dramatically the damage inflicted by X rays, opening the way for developing nanotomography. |
|
||||||||||||||||||||

Printer friendly
Cite/link
Email
Feedback
Reader Opinion