Abstract: A method for modifying nucleic acid bases by a chemical means, which enables the discrimination of every base species in plural species of bases in a nucleic acid comprising plural nucleotide units, while retaining the base sequence information of the nucleic acid. A nucleic acid base-modified product provided by the method. The nucleic acid base-modified product is essentially a single strand. In accordance with the invention, a novel means for sequencing a nucleic acid by a microscopic means is provided.

Abstract: A phase plate for an electron microscope in which a portion of a magnetic thin-wire ring or a magnetic thin-wire rod spans an opening of a support member having the opening, the magnetic thin-wire ring or magnetic thin-wire rod generates a vector potential, and a phase difference is formed between electron beams that pass through left and right sides of a spanning portion of the magnetic thin-wire ring or the magnetic thin-wire rod. The phase plate prevents the electron beam loss more effectively, can be applied at an accelerating voltage within a wide rage from a low voltage to a high voltage, causes no difficulties in production, has good utility, and makes it possible to obtain a high-contrast image.

Abstract: A method of printing an image of a three-dimensional object includes printing multiple dots of a colored ink to form an image of the object and printing dots of a transparent ink having a refractive index greater than 1 within the image. The dots of transparent ink local alter the path length of light that shines through the image to create phase variations on the image.

Abstract: A method for determining the sequence of at least a portion of a single-stranded nucleic acid molecule by base-specifically labeling the exposed bases of the nucleic acid molecule using heavy element-substituted nucleotide bases which form Watson-Crick type base-pairs with the exposed bases of the nucleic acid molecule and then imaging the labeled single-stranded nucleic acid molecule using electron microscopy, e.g., transmission electron microscopy (TEM), or some other method that permits discrimination of the heavy element substituted nucleotide bases is described. The image is analyzed to determine the base sequence of at least a portion of the nucleic acid molecule.

Abstract: Novel DNA sequence determination method and DNA sequencer system providing a sequencing speed 103 to 104 times faster than the current DNA sequencing speed (105 bases per day with a lane at maximum) of the existing DNA sequencer based on electrophoresis. The method includes the step of discriminating base-specific labels of heavy elements using a magnified image of elongated single-chain DNA or RNA produced by a transmission electron microscope (TEM). The DNA sequencer system uses this method. The invention provides a DNA sequencing speed that is higher than the existing speed by 3 or 4 orders of magnitude.