Nature Biotechnology pp 47 - 51

Quantum dots are tiny light-emitting crystals that hold great promise as a tool for imaging cells and biological molecules. In the January issue of Nature Biotechnology, two teams of scientists show that quantum dots can be used effectively to visualize cells and even specific structures inside of cells.

Currently, the standard method for imaging cells or cellular components is to tag them with a fluorescent organic dye. But these dyes are available in only a few colors. Quantum dots, on the other hand, can be made in virtually any color. This feature should allow many more objects to be tracked at the same time. In addition, quantum dots light up more brightly, and for a longer time, than organic dyes do.

In the first paper, Wu and colleagues show that quantum dots can be used to label proteins located in three different parts of the cell--the cell surface, the nucleus, and the region between the two. In the second paper, Simon and coworkers use quantum dots to follow the growth of an organism (the soil-living amoeba Dictyostelium discoideum) for up to 12 days.

Nature Biotechnology pp 52 - 56

Scientists in Japan have engineered silkworms that can accumulate foreign proteins within the fabric of their cocoons. In the January issue of Nature Biotechnology, Katsutoshi Yoshizato and colleagues describe a new technology that prompts silkworms to produce a foreign protein, in this case collagen, together with their own silk fiber and weave it into cocoons. Collagen, a protein of great interest to the pharmaceutical industry for its applications in tissue engineering and in the production of cosmetics, was efficiently extracted from the cocoons and separated from the silk. This new approach holds promise for the large-scale manufacture of proteins for therapeutic and other purposes.

Large-scale production of proteins is often limited by the rate at which we can rear the host systems, i.e., the organisms whose production capabilities we exploit. Silkworms are currently used in sericulture (the art of silk production), which is an important agro-industry in many parts of the world, including Japan, China, India and several European countries. The existing capability of large-scale silk production should allow the rapid and efficient implementation of this technology to produce protein in silkworms.

Nature Biotechnology pp 57 - 63

Researchers have pinpointed a potential tumor marker for prostate cancer using a novel antibody screening approach. Reasoning that cancer patients often produce specific antibodies against specific tumors antigens that could be of diagnostic importance, scientists at the University of Texas M. D. Anderson Cancer Center report in the January issue of Nature Biotechnology a means of identifying tumor-specific antigens by screening for their corresponding antibodies in the serum of cancer patients. Their scheme consists of four main steps: first, eliminating ubiquitous antibodies that are found in all serum samples; second, iterative purification of cancer-specific antibodies from the serum of cancer patients; third, identification of synthetic antigens that bind these cancer-specific antibodies; and lastly, identifying the natural antigens that elicited the cancer-specific antibodies in the first place.

To demonstrate the approach, Wadih Arap and colleagues obtained serum from patients with advanced prostate cancer and used it to identify tumor-specific immune activity. They then went on to characterize the antigens targeted by the antibodies and discovered a particular antigen specific to prostate cancer. The authors believe that their approach could be adopted widely as a means of rapidly identifying cancer-specific proteins for use in diagnosis and treatment.