Biology Commons^™

Microscopic Analysis Of Dna And Dna-Protein Assembly By Transmission Electron Microscopy, Scanning Tunneling Microscopy And Scanning Force Microscopy, T. Müller-Reichhert, H. Gross

Scanning Microscopy

To investigate DNA and DNA-protein assembly, nucleic acids were adsorbed to freshly cleaved mica in the presence of magnesium ions. The efficiency of DNA adhesion and the distribution of the molecules on the mica surface were checked by transmission electron microscopy. In addition, various kinds of DNA-protein interactions including DNA wrapping and DNA super-coiling were analyzed using electron microscopy. In parallel, this Mg²⁺/mica method can be applied (1) to analyze embedded DNA by scanning tunneling microscopy, (2) to visualize freeze-dried, metal coated DNA-protein complexes by tunneling microscopy, and (3) to image DNA or DNA-protein interaction in air or …

Deposition Of Supercoiled Dna On Mica For Scanning Force Microscopy Imaging, B. Samori, I. Muzzalupo, G. Zuccheri

Scanning Microscopy

The deposition of DNA molecules on mica is driven and controlled by the ionic densities around DNA and close to the surface of the substrate. Dramatic improvements in the efficiency and reproducibility of DNA depositions were due to the introduction of divalent cations in the deposition solutions. The ionic distributions on DNA and on mica determine the mobility of adsorbed DNA molecules, thus letting them assume thermodynamically equilibrated conformations, or alternatively trapping them in non-equilibrated conformations upon adsorption.

With these prerequisites, mica does not seem like an inert substrate for DNA deposition for microscopy, and its properties greatly affect the …

Imaging Molecular Structure Of Channels And Receptors With An Atomic Force Microscope, Ratneshwar Lal

Scanning Microscopy

Biological membranes contain specialized protein macromolecules such as channels, pumps and receptors. Physiologically, membranes and their constituent macromolecules are the interface surfaces toward which most of the regulatory biochemical and other signals are directed. Yet very little is known about these surfaces. The structure of biological membranes has been analyzed primarily using imaging techniques that are limited in their resolution of surface topology. An atomic force microscope (AFM) developed by Binnig, Quate and Gerber, can image molecular structures on specimen surfaces with subnanometer resolution, under diverse environmental conditions. Also, AFM can manipulate surfaces with molecular precision: it can nanodissect, translocate, …