Microdissection and Measurement of Polytene Chromosomes Using the Atomic Force Microscope

A method to isolate specific regions of the Drosophila polytene chromosome using an atomic force microscope (AFM) was explored. The AFM was used for the microdissection of the locus of interest with much greater precision than standard microdissection techniques. The amplification of DNA isolated in this fashion by the polymerase chain reaction (PCR) is discussed. A study of the effect of hydration level on gross chromosome structure was carried out. It was shown that chromosome swelling is dependent upon humidity or the buffered medium. The significance of this swelling with respect to studies of chromosome structure under physiological conditions is considered

Visualization of circular DNA molecules labeled with colloidal gold spheres using atomic force microscopy

We have imaged gold‐labeled DNA molecules with the atomic force microscope(AFM). Circular plasmid DNA was labeled at internal positions by nick‐translation using biotinylated dUTP. For visualization, the biotinylated DNA was linked to streptavidin‐coated colloidal gold spheres (nominally 5 nm diam) prior to AFM imaging. Reproducible images of the labeled DNA were obtained both in dry air and under propanol. Height measurements of the DNA and colloidal gold made under both conditions are presented. The stability of the DNA‐streptavidin colloidal gold complexes observed even under propanol suggests that this labeling procedure could be exploited to map regions of interest in chromosomal DNA

Analyzing Chromosomes, Ion Channels and Novel Nucleic Acid Structures by AFM

The atomic force microscope (AFM) is proving to be a powerful tool for analysis of biological samples. We provide three examples of the application of AFM to the study of biological questions. First, polytene chromosomes from Drosophila are imaged and manipulated by the AFM. Second, the localization of calcium channels on the release face of a nerve terminal is described. Finally, analyses of a new form of DNA, the G-wire, is presented. These examples illustrate the wide variety of biological questions to which AFM can contribute

Imaging Biological Samples with the Atomic-Force Microscope

The application of atomic force microscopy (AFM) to biological investigation is attractive for a number of reasons. Foremost among these is the ability of the AFM to image samples, even living cells, under near native conditions and at resolution equal to, or exceeding, that possible by the best light microscopes. Moreover, the ability of the AFM to manipulate samples it images provides a novel and far reaching application of this technology

Visualization of circular DNA molecules labeled with colloidal gold spheres using atomic force microscopy

We have imaged gold‐labeled DNA molecules with the atomic force microscope(AFM). Circular plasmid DNA was labeled at internal positions by nick‐translation using biotinylated dUTP. For visualization, the biotinylated DNA was linked to streptavidin‐coated colloidal gold spheres (nominally 5 nm diam) prior to AFM imaging. Reproducible images of the labeled DNA were obtained both in dry air and under propanol. Height measurements of the DNA and colloidal gold made under both conditions are presented. The stability of the DNA‐streptavidin colloidal gold complexes observed even under propanol suggests that this labeling procedure could be exploited to map regions of interest in chromosomal DNA.This article is from Journal of Vacuum Science & Technology A 11 (1993): 820, doi: 10.1116/1.578311. Posted with permission.</p

Analyzing Chromosomes, Ion Channels and Novel Nucleic Acid Structures by AFM

The atomic force microscope (AFM) is proving to be a powerful tool for analysis of biological samples. We provide three examples of the application of AFM to the study of biological questions. First, polytene chromosomes from Drosophila are imaged and manipulated by the AFM. Second, the localization of calcium channels on the release face of a nerve terminal is described. Finally, analyses of a new form of DNA, the G-wire, is presented. These examples illustrate the wide variety of biological questions to which AFM can contribute.This is a proceeding from NATO Advanced Research Workshop: "Scanning Probe Microscopies and Molecular Materials" (1994): 1. </p

Imaging Biological Samples with the Atomic-Force Microscope

The application of atomic force microscopy (AFM) to biological investigation is attractive for a number of reasons. Foremost among these is the ability of the AFM to image samples, even living cells, under near native conditions and at resolution equal to, or exceeding, that possible by the best light microscopes. Moreover, the ability of the AFM to manipulate samples it images provides a novel and far reaching application of this technology.This is a proceeding from 51st Annual Meeting of the Microscopy Society of America (1993): 512.</p

Reconstruction of ribosomal subunits and rDNA chromatin imaged by scanning force microscopy

Scanning force microscopy (SFM) reveals surface topography by scanning a sharp tip in close proximity to the sample. Due to tip–sample interaction, artificial broadening of the real surface structure with the tip geometry occurs. One approach for image reconstruction is the use of calibration standards, preferably in the size range of the samples. In the present study, an image reconstruction method based on colloidal gold as a geometric standard was used to reconstruct SFM images of biomolecules. Sample and calibration standard size were in the nanometer range, and the standards were coadsorbed with the specimen. Raw and reconstructed images of the biomolecules were compared, and the reconstruction was characterized by difference images as well as determination of the difference volume. The application of image reconstruction based on colloidal gold as a calibration standard for SFM of biomolecules is discussed.This article is from Journal of Vacuum Science & Technology B 14 (1996): 1405, doi: 10.1116/1.589108. Posted with permission.</p