Manipulation of μm-sized particle is one of the important techniques in bioengineering. Recently, the techniques have been applied to conduct DNA manipulation. DNA molecule can be attached on latex particle and the particle can be easily manipulated by laser tweezers. In this paper, the latex-DNA complex was manipulated inside a capillary (inner diameter 1-35μm). Micromanipulation inside the capillary has some advantages, because diffusion of DNA is restricted in one-dimension and the DNA can be easily stretched by suspension flow. Even through these advantages, it is some difficulties because laser focal spot is distorted by the capillary wall, and the distortion reduces trapping force inside the capillary. We designed an optical system to trap the DNA-bead complex inside the capillary and investigated the characteristics of laser trapping inside the capillary. The DNA molecule was also stretched by electric field and/or suspension flow.
The conventional DNA sequencing of a long DNA molecule requires a reorganization process. This process is time consuming and requires tremendous efforts, because the long DNA is cut into smaller fragments, which lose information on their order. Utilizing the manipulation techniques of single DNA molecule, we experimentally demonstrated the sample preparation to obtain the fragments with order information. These manipulation techniques will contribute DNA sequencing of the long DNA molecule.

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The impedances of the dielectric cell containing a seed and deionized water were measured to clarify the changes of a seed in germination process. The impedance of the seed was calculated and a symplasmic resistance, an apoplastmic resistance and a capacitance of plasma membranes were calculated on the basis of a linear equivalent electrical circuit for plants. At the same time, the interior of a seed was directly observed and compared with the impedances.
When the absorption of water began, the relative dielectric constant of the tissue increased in the requency range of 5kHz to 700kHz and the conductivity of the tissue increased in the frequency range of 40kHz to 10MHz. The apoplastmic resistance decreased and the symplasmic resistance increased. After those changes the relative dielectric constant increased and the conductivity increased abruptly in the fequency range of 1MHz to 10MHz. The apoplastmic resistance increased and the symplasmic resistance decreased down to approximately zero. The capacitance of plasma membranes increased with increasing time in germination process.

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Two types of microelectroporation capillaries (two-electrode and three-electrode poration capillaries) for injection of genes or drugs into single cells were fabricated and their performance was investigated using Fe(CN)₆^3- as a model substance. The two-electrode poration capillary consisted of a glass capillary with a sputtered Pt film at the outside and a Pt microwire at the inside. The three-electrode poration capillary possesses another Ag/AgCl microelectrode in the capillary. When an electric pulse was applied between the Pt film and Pt wire of the two-electrode capillary (Pt film positive, Pt wire negative), Fe(CN)₆^3- dissolved in the solution inside the capillary was released by electromigration. The amount of the released Fe(CN)₆^3- can be controlled by adjusting the magnitude and period of the pulse. We applied the two-electrode poration capillary to inject Fe(CN)₆^3- into a single protoplast. The application of a electric pulse brought about a reversible membrane breakdown to form small pores in the membrane and simultaneously repelled Fe(CN)₆^3- from the capillary by electromigration. The injection of Fe(CN)₆^3- into the protoplast was confirmed by detecting the reduction current of Fe(CN)₆^3- at an ultramicrodisk electrode inserted into the cell. In the three-electrode poration system, we applied two consecutive pulses for reversible membrane breakdown and for electromigration. The three-poration capillary was found to be effective for injection of charged substances.

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Microgrooves (equivalent diameter 4-6μm; length 8-100μm (one size per chip); number 1300 or 2600 in parallel) formed in the surface of a single-crystal silicon substrate were converted to leak-proof microchannels by tightly covering them with an optically flat glass plate. Flow characteristics of blood cells and yeast through the microchannels were studied under constant suction.
Erythrocytes suspended in autologous plasma, prepared from fresh heparinized blood obtained from healthy subjects, showed an extremely quick transit through the microchannels under suction of 20cmH₂O; their mean transit time through 20μm long channels was estimated to be 0.7msec. Erythrocytes treated with 0.14% glutaraldehyde could not pass through the channels even under 200cmH₂O suction.
Leukocytes in whole blood took more than one hundred times longer than erythrocytes to pass through the microchannels. Their transit time was further increased by more than ten times when they were activated by 2nM of the chemotactic peptide FMLP (formy 1-methiony 1-leucy 1-phenylalanine).
Yeast cells could not pass through the microchannels even under 200cmH₂O but became passable under 20cm H₂O when exposed to 60% ethanol. Protoplasts prepared from vegetative cells showed an easy transit through the microchannels.
These results suggested the possibility of cell sorting by differences in cellular physiological state or activity using the microchannel arrays or other microchannel networks.

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This paper proposes, and experimentally demonstrates, a novel method of 'molecular surgery' of DNA, where a enzyme-labeled particle or probe is pressed against DNA, which is immobilized on the substrate with known conformation and orientation, to make chemical modifications at arbitrary positions of the DNA molecule. In the method presented in this paper, DNA is subjected to high-intensity high-frequency electric field (≥1MV/m, ≈1MHz) created in micro-fabricated electrodes, so that it is 1) stretched to a straight conformation parallel to the field by the electrostatic orientation effect, and 2) positioned onto a substrate by the dielectrophoresis. Once DNA is thus stretch-and-positioned, one has access to arbitrary position of any one of aligned molecules. A latex particle, 2.8μm in diameter, is labeled with DNA-cutting enzyme, DNaseII, and is laser-manipulated and contacted with DNA. It is observed that DNA is instantaneously cut at the contact point. This result is considered to be the first demonstration of space-resolved biochemical modification.

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