Motowo Tsukakoshi

A novel method of DNA transfection by laser microbeam cell surgery

A new technique is presented to incorporate exogeneous gene materials (DNA) into cells with a microbeam irradiation from an uv pulsed laser. A frequency-multiplied Nd:YAG laser, 355 m wavelength, 5 ns pulse duration, punches a self-healing hole of submicrometer aperture in cell membrane under selected irradiation conditions. It takes a fraction of a second for the aperture to close, long enough to allow the foreign DNA, contained in the medium, to slip into the cell. The method offers a clear advantage over existing methods: increases the success rate of DNA transfection as well as the efficiency of cell modification by orders of magnitude.

The elevation of the cytoplasmic calcium ions in vascular smooth muscle cells in SHR —measurement of the free calcium ions in single living cells by lasermicrofluorospectrometry

We have developed an accurate and sensitive system for the measurement of cytoplasmic free calcium concentrations ([Ca++]i) of a single cell by using UV-laser and Indo-1. By this method, we made the first successful measurement of [Ca++]i of single living vascular smooth muscle cells. [Ca++]i in spontaneously hypertensive rats was elevated and maintained after the 6th passage culture. However, [Ca++]i in Goldblatt hypertensive rats was not elevated. Thus, these results suggest that the maintenance of high [Ca++]i levels of vascular smooth muscle cells in spontaneously hypertensive rats is genetically regulated and that it is one of the mechanisms for hypertension.

Fluorescence lifetimes of no A2Σ+(ν′= 3 and 4), C2Π(ν′= 0) and D2Σ+(ν′= 0) studied by tunable VUV laser excitation

Abstract The fluorescence lifetimes of NO molecules have been investigated under collision-free conditions in a free jet expansion. Single-photon absorption of the laser-generated, tunable and monochromatic VUV radiation prepared NO molecules in the electronically excited A 2 Σ + , C 2 Π and D 2 Σ + states near the dissociation limit. The lifetimes of the C 2 Π 1 2 , 3 2 (ν′= 0)-B 2 Π 3 2 (ν′= 7) perturbed states showed a significant rotational level dependence which can be explained in terms of the known interactions between the B and C states. The measured lifetimes for the A 2 Σ + (ν′= 3 and 4) states, 163.9±3.5 and 137.1 ±2.5 ns, respectively, showed no rotational level dependence. A new dependence of the electronic transition moment on internuclear distance has been derived for the A 2 Σ + -X 2 Π transition to account for the variation of the radiative lifetimes of the A 2 Σ + (ν′= 0, 1, 2 and 3) states. The lifetimes of the A 2 Σ + (ν′= 4) and D 2 Σ + (ν′= 0) states indicated that these states are not predissociative although they are located above the dissociation limit.

Fine structure of the two-photon photoemission from benzene adsorbed on Cu(111)

Abstract Two-photonphoto emission (2PPE) spectroscopy has been applied to benzene adsorbed on a Cu(111) surface. With laser light in the 3.7 to 4.3 eV photon energy region, 2PPE occurs through benzene-induced excited states which are about 1 eV above the Fermi level. The excited state is considered to be the lowest triplet state of adsorbed benzene. The spectrum shows a progression of sharp peaks of less than 0.2 eV width, each separated by about 0.2 eV. The widths of the peaks indicate that the lifetimes of the excited and ionic states are both longer than 3 fs.

Low-frequency Raman spectra of guanosine and nucleotides in ordered states : origin of the lowest-frequency mode

Raman spectra of self‐associates of guanosine were investigated in the 5–200 cm−1 region together with crystals of guanosine⋅2H2O, Na2⋅5’–UMP⋅7H2O, Na2⋅5’–GMP⋅7H2O, Na2⋅5’–CMP⋅8H2O, Na2⋅5’–dGMP⋅4H2O, and Na2⋅ATP⋅3H2O, to clarify the origin of the lowest Raman active mode of deoxyribonucleic nucleic acid (DNA). When the bases stack well to form a column, as in guanosine self‐associates and crystals of guanosine and adenosine triphosphate (ATP), the spectral patterns are similar to that of DNA. The lowest‐frequency bands are sharp and isolated from other bands. The result suggests that the origin of the lowest‐frequency mode of DNA is assigned to the motion of bases stacked in a column. Guanosine has no phosphate groups, and ATP has no hydrogen bonds between bases in the crystal state. Therefore, neither hydrogen bonds between bases nor phosphate groups are necessary for the existence of this mode.

VUV laser spectroscopy of Xe2 in the C′ 1u state

Abstract Xe 2 molecules in a supersonic free jet have been excited to the C′ 1 u state with tunable and monochromatic VUV laser radiation generated by four-wave difference frequency mixing in Kr. From the vibrationally resolved excitation spectrum, the following spectroscopy constants are derived for the C′ 1 u state: T′ e = 77240.6, ω′ e = 16.2, ω e χ′ e = 1.1, and D′ e = 140 cm −1 . It was also found that the radiative lifetimes of the ν′ = 0 and 1 states of the C′ 1 u state were 4.3±0.5 and 3.8±0.6 ns, respectively.

Four-wave mixing in CO via the C1Σ+ (υ′=0) state

Coherent vacuum ultraviolet (VUV) radiation was generated by four-wave difference frequency mixing (ωVUV=2ω1−ω2) of pulsed dye laser radiation in carbon monoxide (CO). The frequency ω1 was tuned to the C1Σ+(υ′=0)←X1Σ+(υ″=0) two-photon transition, while the dye laser frequency ω2 was scaned around 17650 cm−1 which corresponds to the A1Π(υ=7)«C1Σ+(υ′=0) transition energy. The VUV intensity was found to be strongly wavelength dependent. The analysis of the spectrum revealed (i) that the VUV intensity was enhanced by the rotational levels of the A1Π(υ=7) state and (ii) that the off-resonance excitation in the C1Σ+(υ′=0)←X1Σ+(υ″=0) two-photon transition greatly contributed to the present four-wave mixing process. The effects of pumping laser detuning, saturation and foreign gases are briefly discussed.

VUV and uv fluorescence lifetimes of Cl2

Abstract A spectroscopic study of Cl 2 by VUV laser-induced fluorescence is reported for the first time. The free jet excitation spectrum in the region between 79000 and 80100 cm −1 revealed the contribution of some additional band systems other than the dominant 2 1 Σ u + ←X 1 Σ g + transition system. The VUV and UV fluorescence lifetimes ranging from 15 ns down to 1 ns or less depended strongly upon the excitation wavelengths, but very little on the fluorescence wavelengths. Possible assignments of the excitation bands are discussed.

Four‐wave mixing spectroscopy of NO E 2Σ+ state

The E 2Σ+ state of NO (nitric oxide) has been probed by four‐wave mixing spectroscopy via the A 2Σ+ state. In the present scheme, the pump laser frequency ω1 was fixed on the A 2Σ+ (v’=0 and 1)←X 2Π3/2(v‘=0) two‐photon transition, while the probe laser frequency ω2 was remained variable to monitor the E 2Σ+←A 2Σ+ electronic system. The intensity of the resultant coherent VUV radiation (ωVUV=2ω1+ω2) was strongly wavelength dependent. The analysis of the spectrum revealed the following two respects: (1) The intensity of VUV radiation was enhanced by the resonance of ω2 to rotational levels of the E 2Σ+ state as well as of 2ω1 to the A 2Σ+ state. (2) The spectral structure corresponding to the E 2Σ+←A 2Σ+ system was governed by different rotational selection rules from ordinary single‐photon transitions. These aspects were discussed in terms of the third order nonlinear process in isotropic media and of the two‐photon line intensities for the A 2Σ+←X 2Π system.

Saturation and Detuning Effects of Pump Waves in VUV Generation by Resonant Sum Frequency Mixing in Hg

Saturation and detuning effects on VUV generation are observed in resonance sum frequency mixing in Hg. The results demonstrate that the mechanism of VUV generation is different above and below 9p1P1 at 79964.1 cm-1 and that higher order effects in the pump and probe powers should be taken into account.