Genetically identical cells may be far more different than previously believed. Published this week in linkurl:Science,;http://www.sciencemag.org/ researchers find striking variation in levels of gene expression among individual, genetically identical E. coli, seemingly the result of simple chance. "The paper is quite rich," said linkurl:Sanjay Tyagi,;http://www.phri.org/research/res_pityagi.asp a molecular biologist at New Jersey Medical School who was not involved in the research. "People thi

LIGHTING THEIR LOCATIONS:© 2002 Cold Spring Harbor PressImmunolocalization of epitope-tagged proteins. (A-E) represent cells containing HAT-tagged proteins stained with the DNA dye, DAPI, and a monoclonal antibody against hemagluttinin, α-HA. At right the images are merged. (F-J) indicates cells carrying V5 tagged proteins. The bar equals 2 μm.Aliens sifting through the remains of a lost human civilization might puzzle over the function of a ladle. But if found in a room associate

By Jeffrey M. Perkel Surpassing the Law of Averages How to expose the behaviors of genes, RNA, proteins, and metabolites in single cells. By necessity or convenience, almost everything we know about biochemistry and molecular biology derives from bulk behavior: From gene regulation to Michaelis-Menten kinetics, we understand biology in terms of what the “average” cell in a population does. But, as Jonathan Weissman of the University of Califo

A COMPLICATED UNION:Image redrawn from Ann Rev Biochem, 72:717–42, 2003Antigens bound by major histocompatibility complex (MHC) molecules interact with T-cell receptors (TCRs) at the heart of the interface for T-cell recognition. But, many other players are involved. Massive polyvalency within this confined space may compensate for low-affinity receptors, giving added sensitivity.In some ways, science resembles gold mining: Eager practitioners congregate around rich veins of discovery whil

Date: April 13, 1998PCR Based Cloning Kits Table The End Table (PDF Format) PCR has found applications in almost every imaginable facet of molecular biology, and for many applications, looking at a band on a gel is not enough. Sequencing, expressing, mutating--all require cloning. And as it happens, cloning strategies that work for other types of DNA fragments don't work at all well, or require inordinate effort, with PCR fragments. For example, the most commonly used cloning strategy requires

Suppliers of Whole-organism cDNA Libraries Suppliers of Tissue-specific cDNA Libraries The questions of gene function, interaction, and regulation are central to the science of molecular biology. Despite the myriad of new technologies, products, and techniques produced by the genomics revolution, some old standards remain just as useful as ever. One such technology is the cDNA (complementary DNA) library. The sheer number of companies offering premade and custom cDNA libraries and products th

Researchers report in two separate papers in Science this week on novel methods used by bacteria to avoid being killed by antibiotics. In one study, scientists at the Rockefeller University report that the bacterial cells known as persisters, which tolerate but do not become resistant to antibiotics, preexist in a population and that their random switching between normal and slow-growing persister states enables them to escape antibiotic killing. And in an accompanying paper, Stanford University

Two-Hybrid Systems Studying a biological phenomenon? Which field? Well, it really doesn't matter. Whatever the area of interest, rest assured that protein-protein interactions are somehow, somewhere involved--if not directly, then as part of a structural or regulatory apparatus. Two-hybrid systems, pioneered by Fields and Song,1 are powerful systems for detecting interactions between and among macromolecules. The first systems described were for protein-protein interactions; later, the basic

Microbes, traditionally thought to lack organelles, get a metabolic boost from geometric compartments that act as cauldrons for chemical reactions. Bioengineers are eager to harness the compartments for their own purposes.

Suppliers of Reporter Assay Screening Systems Courtesy of Applied BiosystemsTarget practice: Researchers can employ reporter assays to study a variety of cellular processes. Rarely is the product of a gene readily distinguishable from the myriad mRNA and protein complements that exist in a cell at any point in time. But researchers can skirt this obstacle by placing a "reporter gene" under the same controls as the gene of interest. Reporter genes have easily measurable phenotypes that form th