Intracellular communication is imperative for multicellular organisms. Such devices as synapses and gap junctions have been recognized for decades. Now Amin Rustom, Raiser Saffrich, Ivanka Markovic, Paul Walther, and Hans-Hermann Gerdes have described a new model of cell-to-cell communication.

While looking at PC12 (rat pheochromocytoma) cells in the presence of fluorescently labeled wheat germ agglutinin, Rustom et al. observed relatively long connections extending between cells. These structures were 50 to 200 nm in diameter and up to several cell diameters in length and were named tunneling nanotubes (TNTs). TNTs were subsequently found connecting cultured cells from other lines. They were consistently positioned along the smallest distance between the cells, did not contact the substrate, and occasionally were branched. TNTs immunostained positive for actin, but did not contain microtubules. Scanning and transmission electron microscopy definitively established that a TNT represented a seamless continuity of the plasma membrane from one cell to another.

The Materials Science Program of NASA's Office of Biological and Physical Research (OB PR) has attacked futidamental problems of materials science as defined by an external advisory group, known as the Discipline Working Group (DWG). These have been:

1. • Nucleation and Metastable States

2. • Prediction and Gontrol of Micrestructures

3. • Crystal Growth and Detect Generation

4. • Phase Separation and Interfacial Phenomena

5. • Thermophysical Properties and Process Modeling.

While the program's primary objectives are science-based and despite the fact that 90% of these programs concentrate on pre-cursor and theoretical research on the ground, NASA demands that there be a microgravity rationale driving the research.

The invention of scanning tunneling microscopy (STM) in 1982 revolutionized surface analysis by providing atomic-scale surface imaging of conducting and semiconducting materials. Shortly after that, atomic force microscopy (AFM) was introduced as an accessory of STM for high-resolution imaging of surfaces independent of their conductivity. Mechanical force interactions between a sharp tip placed at one end of a micro fabricated cantilever and a sample surface were employed for imaging in this method. In the past decade, AFM has developed into a leading scanning probe technique applied in many fields of fundamental and industrial research. The progress of AFM has been made possible by implementation of an optical level detection scheme, which allows precise measuring of the cantilever deflection caused by the tip-sample forces, by mass microfabrication of probes consisting of cantilevers, and by developments of oscillatory imaging modes, particularly, Tapping ModeTM.

The recent article in this journal by O'Keefe et al provides an excellent introduction to the complexities that must be considered when embarking on the installation of a high-resolution electron microscope. It should not pass one's notice, however, that the advent of nanoscience has placed ever stricter attention on the control of vibration not just for analytical instrumentation but also for fabrication facilities. In addition to the thick isolated concrete slab-ongratie described in the above article, designs are coming into use (Fig. 1) that incorporate rigid “waffle” floor structures on closely spaced building columns and pneumatically isolated inertia slabs as are used, for example, in the subterranean portion of the NIST Advanced Metrology Laboratory. Each of these approaches might with time also find applications in the design of electron microscopy laboratories. However, each has the problem of rather high expense of construction.

It is a common practice to use microscopic images to describe the differences observed between plant tissues. The images illustrate the taxonomic characteristics of the studied species. In this work we introduce a quantitative method for conducting these analyses utilizing digitized images obtained via scanning electron microscopy (SEM) of barley leaf surfaces. The topography of the leaf surfaces of a narrow-leaf mutant and its wild type mother line was characterized, see figure 1, using the Rotated Image with Maximum Average Power Spectrum (RIMAPS) technique and the Variogram method. Spectra resulting from RIMAPS analysis allow us to identify the specimens and to distinguish between the adaxial or the abaxial side of the leaf. These results are complemented by obtaining the typical scale lengths that characterize the abaxial surfaces of both the mutant and the mother line barley leaves.

The technique of embedding TEM specimens in polymer resins for subsequent ultra-thin sectioning is well established. For geological materials, this protocol prevents specimen damage introduced by ion beam thinning, and is often used for preparing friable or porous materials. However, traditional polymer-based embedding resins may introduce organic carbon contaminants, producing artifacts in carbon analyses. Thus, a carbon-free substitute for traditional embedding media is required to ensure accurate carbon analyses of embedded and ultramicrotomed TEM specimens.

A suitable technique that was first reported by Bradley is to embed specimens in pure sultur. In this technique, the specimen is immersed in liquid sulfur, the liquid is solidified, and the resulting block is ultramicrotomed as with traditional resins. Since sulfur has a high vapor pressure at room temperature, the ultra-thin sections are then placed in a separate vacuum chamber to sublimate the sulfur, yielding TEM specimens free of any embedding medium.

The use of microwave energy to assist in the processing of biological tissues for microscopy has generated significant interest in recent years. Microwave (MW) processing has been used to prepare tissues for light microscopy (Carranza et al. 1990 [using parasite tissues]; van Dorp et al. 1995; Davis et al. 1997; Izumi et al 2000; and Rohr et al. 2001), as well as for electron microscopy (Kasa et al. 1982; Hopwood et al. 1984; Leong et al. 1985; Kang et al, 1991 [using parasite tissues]; Heumann 1992; Wagenaar et al. 1993; Login and Dvorak 1993; Giberson and Demaree 1995; Madden and Miriam 1997; Giberson et al. 1997; Morin et al. 1997; Petrali and Mills 1999; Massa and Arana-Chavez 2000; Hernandez and Guillen 2000 [using parasite tissues]; Demaree 2001; Giberson 2001).

Most reports, particularly those published by manufacturers of microwave ovens, have shown positive results regarding tissue ultrastructure, however discussion continues on possible mechanisms of preservation by the use of MW technology.

Principal components analysis of multivariate data sets is a standard statistical method that was developed in the early halt or the 20th century. It provides researchers with a method for transforming their source data axes into a set of orthogonal principal axes and ranks. The rank for each axis in the principal set represents the significance of that axis as defined by the variance in the data along that axis. Thus, the first principal axis is the one with the greatest amount of scatter in the data and consequently the greatest amount of contrast and information, while the last principal axis represents the least amount of information.

The cell is the fundamental unit of all living organisms, ranging from the unicellular archaea and bacteria (prokaryotes) to higher multicellular plants and animals (eukaryotes). All cells are bounded by a complex and dynamic plasma membrane, which functions principally to maintain cellular and organismal steady state by performing complex energy transformations and regulating the flow of information for the cell. The cell membrane also performs a number of vital housekeeping functions, which include control of the transport of substances between extracellular and intracellular environments, participation in cell signaling cascades by hosting receptors of extracellular ligands, and facilitating critical cell-to-cell communications in multicellular organisms (Karp, 2005).

Considerable research over the last fifty years has significantly increased our understanding of cell membranes and their structural organization. Every membrane is fundamentally comprised of a dynamic lipid bilayer that supports a variety of transmembrane and membraneassociated proteins.

Flicker stereo alternates two pictures (∼ 1 frame/sec.) of the same structure with views tilted 6° ± 1° about a vertical axis—Natural appearing stereo visualization results. A flicker stereo program to be used for viewing with a personal computer (PC) was developed by the authors. The two images are installed, adjusted for superposition and then alternated on the computer monitor or computer projection system. Flicker stereo can be applied to micrographs from the optical microscope, SEM, TEM, pictures or line drawings. Flicker stereo provides simultaneous three dimensional viewing for several individuals without special viewers, projection systems and/or glasses. Different flicker images may be retrieved and viewed on a PC in rapid succession. Flicker stereo facilitates technical discussion between collaborators and provides a convenient approach for 3D visualization by audiences using a digital LCD projection. The program is available to readers.