Establishment of a solar UV dosimeter based on the photoisomerization of (6-4)photoproducts to the Dewar isomers.

我们建立了一个太阳紫外辐射剂量计，测量波长范围为300 - 340 nm的紫外辐射强度，太阳紫外辐射，特别是UVB（290- 320 nm），诱导细胞DNA中的环丁烷嘧啶二聚体（CPD）和（6-4）光产物（64 P）。此外，已知太阳光中300至340 nm范围内的UV波长可有效地将64 P光异构化成其杜瓦异构体（DwP）。后者据说是高度致突变的。因此，我们需要建立一个剂量计测量积累的DNA的DwP的太阳紫外线的风险评估。然而，迄今为止还没有建立测量300至340 nm波长的剂量计。为了建立一种新的紫外线剂量计，我们进行了以下实验：1）将100 J/m^2的UVC照射的DNA印迹在尼龙膜上。然后将膜暴露于来自冈崎大型光谱仪的各种剂量的单色UV光。暴露后，用DEM-1抗体免疫组织化学处理膜并测定颜色强度（免疫斑点印迹：IDB）。到目前为止所获得的结果表明，从64 P的DwP的光异构化有效地发生在320 nm处。2）通过使用相同的方法（IDB），我们测量了从Mylar过滤的UVB灯（Toshiba FL-20 SE）发射的300至340 nm的UV剂量。尼龙膜上DNA印迹的颜色强度随UVB剂量的增加而增加。因此，我们成功地生产了一种新的太阳紫外线剂量计测量波长从300至340 nm。

We established a solar UV dosimeter measuring the UV inteiasiiy of wavelengths ranging from 300 to 340 nm.The solar UV, especially UVB(290-320nm)induces cyclobutane pyrimidine dimers(CPD)and(6-4)photoproduct(64P) in cellular DNA. Furthemore, the UV wavelengths ranging from 300 to 340 nm in solar light are known to efficiently photoisomerize 64P to its Dewar isomer(DwP). The latter is said to be highly mutagenic. Thus, we need to establish a dosimeter measuring the accumulation of the DwP in DNA for the risk assessment of solar UV. However, none of dosimeters measuring the wavelengths from 300 to 340 nm has been established so far. To establish a new UV dosimeter, we carried out the experiments nmentioned below,1) We blotted the DNA irradiated with 100 J/m^2 of UVC on a nylon membrane. The membrane was then exposed to various doses of monochromatic UV light from the Okazaki Large Spectrograph. After exposure, the membrane was treated with DEM-1 antibody immnohisitochemically and the color intensity was assayed (immuno-dot-blot : IDB). The results obtained so far revealed the photoisomerization of DwP from 64P efficiently occurs at 320 nm.2) By using the same method (IDB), we measured the UV doses from 300 to 340 nm emitted from the Mylar-filtered UVB lamp (Toshiba FL-20SE). The color intensity of the blotted DNA on the nylon membrane increased lmearly with increasing dosed of UVB. Thus, we succeeded to produce a new solar UV dosimeter measuring the wavelengths from 300 to 340 nm.