Carmichael, Stephen W.

Abstract There are many transmission electron microscopes (TEMs) that have provided years of reliable service and good images, but they lack the positioning systems that are standard on the newest microscopes. A precise digital positioning capability is essential for many quantitative stereological studies and relocating specific features on a grid. For many of the older TEMs, retrofitting them with a digital positioning system is not an option, or at least a very expensive upgrade. Now Martin Hohmann-Marriott, William Sharp, Robert Roberson, and Robert Blankenship have described the hardware and software that offer a second life to these older microscopes.

Abstract Gene expression has been visualized for a few decades, but in static forms such as blots and gene chips. Susan Janicki, Toshiro Tsukamoto, Sim one Salghetti, William Tansey, Ravi Sachidanandam, Kannanganattu Prasanth, Thomas Ried, Yaron Shav-Tal, Edouard Bertrand, Robert Singer, and David Spector have recently designed a cell line in which gene expression can be observed with stunningly accurate spatial and temporal resolution. Gene expression is a cascade of events beginning with transcription of RNA from the DNA template and ending with translation into a protein sequence. Janicki et al. were able to visualize the entire process at the levels of DNA, RNA, and proteins in living cells!

Abstract In a clever application of time-lapse fluorescence microscopy, Li Wang, Scott Seeley, William Wickner, and Alexey Merz looked to see if there was membrane left over after vacuoles fused within a cell. Specifically, It is not known what happens when two vacuoles come together (this is referred to as “docking” ) and join together as one larger vacuole (“fusion“). For reference, the surfaces of the vacuoJes where they have joined is the “boundary” membrane, the membranes on the outside are the “outside” membranes, and the circular junction of the boundary and outside membranes is the “vertex.“

Abstract Green fluorescent protein (GFP) and related molecules have been important signal molecules for cell biologists because they emit a bright signal to mark the position of tagged structures as well as changes in calcium and proton concentrations. Related molecules even emit in different colors. Now Hendrik Dietz and Matthias Rief from the Technical University of Munich have given us a detailed look at the "energy landscape" of GFP with the promise that it may also be useful indicator for forces.2 In this context, energy landscape refers to a three-dimensional map of the energy levels of the molecule as it is transitioned from its native state to an unfolded state.

Abstract 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.

Abstract Clathrin-coated vesicles are the shuttle containers within cells. The vesicles carry lipids and proteins between membrane-bound compartments. Clathrin forms a cage-like structure around the membrane-bound vesicle that is pinched off from the plasma membrane (in endocytosis) or a membranous component of the cytoplasm. Clathrin recruits cargo that is within a vesicle through intermediary proteins known as adaptors that help select membrane-anchored protein and form an interface between the clathrin cage and the membrane bilayer.

Abstract Since the beginning of human civilization, people have apparently been fascinated with the reflection of light from surfaces. The creation of shiny surfaces extends from 4,000 B.C., when Neolithic farmers in ancient China polished jade objects, to the present day where modern polishing techniques are key to creating flat surfaces in the fabrication of electronic microcomponents. The question we are posing here is how does one determine when high technology was introduced in the process of polishing? Recently, Peter Lu, Nan Yao, Jenny So, George Harlow, Jianfang Lu, Genfu Wang, and Paul Chaikin offered an answer to this question. Interestingly, microscopes were used to provide the answer.

Abstract They're right at your fingertips, but how often do you consider the microscopic anatomy of your fingernails? How is their form fitted to function? Primates, including humans, use fingernails to maintain the anatomic integrity at the distal end of our phalanges, which often serves as the leading edge of our physical sensory apparatus. The nails serve as a stiff backing to the soft pads of our fingers, helping to improve the grip and sensitivity by allowing the pad to “push back” on the object we are touching. Nails also serve specific functions in maneuvering within cracks, scratching, and fighting. The gross structure of nails helps to resist upward bending forces that are encountered in these functions. The convex curvature contributes, just like a curved piece of paper has more stiffness than a flat sheet. The composition of nails is also suitable. As with the outer layer of skin, and the structure of hair, nails are also composed of keratin.

Abstract The general consensus has been that the shells of mollusks form outside of cells. Akin to bone formation in vertebrates, an organic matrix is secreted by cells and the inorganic material is deposited within this matrix in an organized way. Andrew Mount, A.P. (Hap) Wheeler, Rajesh Paradkar, and Dennis Snider have now found convincing evidence that blood cells (specifically a class of granulocytic hemocytes) may be directly involved in shell crystal production for oysters.

Abstract Many people dread the visit to their dentist when they have their teeth drilled, but how long has this been going on? The most ancient evidence to date was recently described by Alfredo Coppa, Luca Bondioli, Andrea Cucian, David Frayer, Catherine Jarrige, Jean-François Jarrige, Guivron Quivron, Massimo Rossi, Massimo Vidale, and Roberto Macchiarelli and microscopy provided the convincing proof. The specimens were recovered from Mehrgarh, Pakistan, an area known to be occupied by farmers as long as 9,000 years ago. They identified four females, two males, and three individuals of undetermined gender who had a total of eleven drilled permanent teeth, all from adults. No drilled teeth from children were found. Four of the teeth were from the maxilla and seven from the mandible. All the drilling had been in the first or second molars. This led Coppa et al. to conclude that the drilling was not done for decorative purposes because on these teeth the holes, with or without decorative material inserted into them, would have been hardly visible.