Many intracellular proteins are catalysts that regulate cellular functions. These catalysts can be assayed to determine their functional state, but untii now it was not possible to simultaneously obtain a functional analysis and spatial data. Tony Ng, Anthony Squire, and others, working in the laboratories of Phillippe Bastiaens and Peter Parker, have combined Fluorescence Lifetime Imaging Microscopy (FLIM) with Fluorescence Resonance Energy Transfer (FRET) to spatially resolve the activation of a protein catalyst within living cells. Their technique was also applied to fixed cells.

There are many techniques available that enable us to know what is happening at the surface of a living cell. These techniques have allowed us to characterize many aspects of the process of exocytosis, the fnal cellular event in secretion. Patch clamping has given us quantitative measurements of the capacitance changes as the membrane of the secretory vesicle is added to the surface of the cell during exocytosis, and the change in the opposite direction as membrane is retrieved back into the cell during endocytosis. Tiny probes have measured electrochemical changes just outside the surface of the cell as reactive molecules are released into their surroundings. Differential interference contrast microscopy has given us high resolution pictures of the cell surface during exocytosis; real-time images are suggestive of bubbles breaking the surface of a boiling pot of water. However, exocytosis is known to be proceeded by an ordered series of events that occur below the surface of the cell.

Many important discoveries in cell biology have been made by introducing specific compounds into a certain cell and observing the effect. Several methods have been used for the introduction of the compounds. For example, permeabilizing the cell by electroporation (an electric shock that has been demonstrated to poke holes in the plasma membrane), the use of biologic molecules (such as streptolysin 0) to create channels in the plasma membrane, or detergents to dissolve hoies in the plasma membrane. Several laboratories have shown these methods to be effective, but one questions the physiologic state of a holey cell. Liposomes or similar vehicles can be packed with compounds and fused with the cells of interest, but this method of introduction has drawbacks as well.

In a movie I saw recently, a young Will Shakespeare was seen to repeatedly dip the nib of a quill into a reservoir of ink and scrawl on pieces of paper until, finally, what we know as "Romeo and Juliet" was penned. As pointed out by Richard Piner, Jin Zhu, Feng Xu, Seunghun Hong, and Chad Mirkin, this technology is much older than Shakespeare, dating back about 4000 years. But even technology this old can change.

As you are well aware, making devices on a smaller and smaller scale (nanofabrication) is certain to change our future way of life, Nanofabrication frequently relies on lithographic methods where a pattern is superimposed on a resistive film and the film is chemically etched to create a structure that conforms to the pattern.

Ever since the first embryo was put under a microscope, scientists have been trying to determine which embryonic cells form which structures in the mature organism. Classic methods were to kill (ablate) certain cells and see what structures were malformed or missing when the animal developed. More recently, cells have been labeled with visible tags and the tagged cells traced through development. One problem is that the tag gets diluted by half each time a labeled cell divides. A new labeling method that shows a lot of promise has been demonstrated by David Piston, Robert Summers, Susan Knobel, and John Morrill.

Old embryos are now being looked at in a new way. About a hundred years ago, an embryologist by the name of FranMyn Paine Mall devoted his career to collecting human embryos and fetuses (an embryo becomes a fetus after 2 months of gestation) from miscarriages and abortions. These specimens form the core of what is known today as the Carnegie Collection of Human Embryos, housed in the National Museum of Health and Medicine of the Armed Forces Institute of Pathology in Washington, D.C. Whereas this is a priceless national educational resource, how do we extract the information about our embryonic development from these specimens? Classic techniques involve slicing a specimen as thinly as possible on a microtome, then reconstructing the slices in a model large enough to study. The problem is the specimen is effectively destroyed in the process. What is needed is a technique that allows whole embryos to be examined, but not destroyed.

Although the Charge-Coupled Device (CCD) imaging chip is the standard in today's video and digital cameras, things may change during the coming year. The CCD chip is being challenged by a competing device, the CMOS ("C-moss") chip.

CMOS is the most widely used type of integrated circuit for memory and digital processing, virtually everything in computers is CMOS based. The economies of scale and production of CMOS devices are the main reasons why computer prices have continued to drop during the past few years. If a device or an instrument has a microprocessor in it, chances are it includes CMOS technology..

The requirements for such a medium are that it won't deposit crystals when it evaporates and that it won't be incapable of evaporating. The second condition probably excludes anything containing glycerol. The first is more difficult. A polymer such as gum, polyvinylpyrollidone or gelatin might fiil the bill, especially in the presence of a sugar that can form a syrup that1 s almost solid. Fructose (levulose) has this reputation, and is a good aqueous mountant. Very cheap, but for some reason somewhat too acidic for basic dyes, but can be buffered. Its not 100% predictable. l've had fructose crystallize under coverslips, but you can quickly remove ail the mess with water and then try again.

An old and certain way to make a solid and perhaps permanent aqueous mount is to use a smaller-than-usual coverslip and as little aqueous mountant as possible.

Today's clinical laboratory has a diversity of reagents and protocols from which to choose: a variety of clinical chemistry reagents, antibodies, and molecular probes, among others. These materials facilitate serum and urine analysis, histology, hematology, cytology, and a host of additional sensitive and specific assays

Regardless of the application, labs may see an array of labeling statements indicating a reagent's general use: "For Laboratory Use Only" [LUO]; "For Research Use Only" [RUO]; "For Investigational Use Only" [IUO]; "For In Vitro Diagnostic Use" [IVD]; and "Analyte Specific Reagent" [ASR]. These preparations are often employed without realizing the course manufacturer's must follow in order to provide reagents, and the reasons for these designations.

Most electron microscopists appreciate that proper operation of the source is vital to the operation of the entire instrument. But because the gun involves a complex interplay of phenomena, few of which can be directly observed, some common misconceptions have gained currency — typically these "myths" contain a kernel of truth, but they can also mislead when accepted uncritically. In this series of articles, we explore three areas of common misunderstanding relative to operation of the thermionic {tungsten filament or LaB6) gun. (Field emitters are subject to very different considerations.)

Scanning probe microscopes (SPMs) are a family of instruments used for studying the surface properties of materials on a dimensional scale ranging from the atomic to the micrometer level. As depicted in Figure 1, all SPMs work by scanning a finely tipped probe in a raster pattern over the sample surface while measuring and mapping some interaction between the probe and the surface as a function of x-y position. The piezoelectric scanners used to provide the scanning motion offer very fine positional control but have certain inherent errors that, uncorrected, can distort images, introduce artifacts, and degrade measurement accuracy.

Three-dimensional images, or anaglyphs, can provide useful information as to height relationships between components of an image. They can also enliven presentations before diverse groups. Imagine a boardroom full of executives having their 5th straight meeting of the day. You are there to present preliminary research information that could lead to a major contract. After requesting that everyone to put on red/blue glasses (not exactly the height of fashion), you proceed to show stereo images of hair samples with obviously different degrees of roughness. Correlation is drawn between the different samples and the nutritional components of the dietary supplement being tested. A picture not only saves a lot of words. It also leaves a lasting image in the minds of the observers that could easily translate into $$$. Besides, it's fun to look at neat 3-D images!