Courtesy of Qbiogene  GOT LACTOSE? 3T3 cells expressing b-galactosidase (which converts lactose into glucose and galactose) after transfection with Qbiogene's jetPEI reagent. Laboratories are loading mammalian cells and tissues with exogenous DNA more routinely and more successfully than ever before. The means available to deliver the DNA--lipofection, transduction, electroporation, and so on--seem to be increasing at a staggering rate, whether measured in terms of published protocols, c

Courtesy of Mark Jenkins  SLICED MICE: Single-cell-thick sections of adult mice expressing CD45.1 stained with nuclear dye (blue) and a monoclonal antibody specific for CD45.2 (red). The left panel shows a background level of CD45.2 staining. The center panel shows a mouse that received several million Salmonella peptide-specific CD4 T cells from a transgenic mouse expressing CD45.2. Transferred naïve T cells were found only in secondary lymphoid organs. At right, when also injected w

5-Prime | Protein Phosphorylation Cascades of signals are transduced when, for example, a hormone meets its receptor, when one cell touches another, or when a lymphocyte contacts its cognate antigen. Many steps in these pathways involve protein phosphorylation. (See related story, Monitoring Protein Phosphorylation) What are kinases and phosphatases? Kinases are enzymes that catalyze the addition of phosphate groups. Most large cellular molecules, including proteins, carbohydrates, and lip

Great Lakes Fishery Commission Just in from the Hammond Bay Biological Station on Lake Huron, Jared Fine heads to his St. Paul laboratory to perform bioassays on sea lampreys. He's looking for chemicals that may be sexually alluring to this parasitic fish. Electro-olfactograms (EOGs), which Fine uses to track the lamprey's responses to odors, "require a pretty elaborate setup," says the fisheries graduate student from the University of Minnesota. It's easier and cheaper for his advisor, Peter

© Mark Smith/Photo Researchers The slim, striped zebrafish, one of the newest and wettest members of the model organism family, has attributes that researchers look for: size, fecundity, and low maintenance costs. Toss in a couple more assets--its visible internal development, and its genetic similarity to mice and humans--and this fish's return-on-investment increases. But it arguably would not have gained its formidable reputation had it not responded so well to new techniques. Studie

One Link Found, Many To Go Researchers at the UK's Cambridge Institute of Medical Research (CIMR) and Merck & Co. reported a link between cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and autoimmunity (H. Ueda et al., "Association of the T-cell regulatory gene CTLA4 with susceptibility to autoimmune disease," Nature, e-pub ahead of print, doi:10.1038/nature01621, April 30, 2003). The researchers used positional cloning to search a 330 kb region surrounding the CTLA4 gene for polymorp

5-Prime | T-Cell Subsets: On the Immunity Warpath How do T cells recognize their targets? The acquired immune system consists of two major cell types, T and B cells, which recognize specific antigens. They differentiate from hematopoietic precursors and from each other in the bone marrow, with T cells migrating off to mature in the thymus (hence the name). The T cell is endowed with receptors (TCRs) of unique specificity, created by somatic DNA rearrangement and random chain pairing. In the

Courtesy of Michael Dustin PASS IT ON: A T cell (blue) interacts with a dendritic cell (yellow) through a molecular pattern described as an immunological synapse (red = adhesion, green = foreign antigen). This is a composite image of a scanning electron micrograph and a fluorescence image. We can do things that haven't been done before, I think, ever in cell biology," exclaims Mark Davis of Stanford University. His 3-D, fluorescence video-microscopy system allows him to count the number

Courtesy of DakoCytomation Conventional wisdom holds that flow cytometers are expensive, massive, high-maintenance instruments that require trained operators. They are plumbed into centralized facilities of large institutions, where investigators can pay to have their cells sorted, or perform the analyses themselves (provided they have the requisite skills) under the watchful eye of the center's personnel. But as so often happens, the conventional wisdom is wrong. Nowadays, flow cytometers ar

Data derived from the Science Watch/Hot Papers database and the Web of Science (ISI, Philadelphia) show that Hot Papers are cited 50 to 100 times more often than the average paper of the same type and age. M. Muramatsu et al., "Class switch recombination and hypermutation require activation-induced cytidine deaminase (AID), a potential RNA editing enzyme," Cell, 102:553-63, Sept.1, 2000. (Cited in 134 papers) P. Revy et al., "Activation-induced cytidine deaminase (AID) deficiency causes the aut

Images Courtesy of Genomic Solutions Product literature for Invitrogen's E-gels®, a precast agarose gel system, neatly summarizes the purported advantages of such products: "E-gels make agarose electrophoresis as easy as Plug & Play." The vast majority of researchers are perfectly capable of pouring their own gels, of course--the process is certainly not difficult. It may, however, be tedious. It can also be tricky; leaks are a constant bugaboo, and gel-to-gel variation can be a probl

Courtesy of Timothy Shacker  COLLAGEN COUNTS: (A) A modified trichrome stain on lymphatic tissue from an HIV- patient. Stained tissue from an HIV+ patient (B) shows a relatively intact peripheral CD4+ count with collagen at 2.2%, compared with a patient with advanced HIV-1 (C) with collagen at 18.6%. (J Clin Invest, 10:1133-9, 2002) Because HIV preferentially targets CD4+ T cells, their numbers, along with other metrics like HIV RNA levels, traditionally are used to indicate the infectio