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线剂量计，测量波长为300至340 nm的紫外线强度。太阳紫外线，特别是UVB（290 ~ 320nm）在细胞DNA中诱导环丁烷嘧啶二聚体（CPD）和（6-4）光产物（64P）。此外，在300 ~ 340 nm的太阳光线下，已知紫外波长可以有效地将64P光异构为杜瓦异构体（DwP）。后者据说是高度诱变的。因此，我们需要建立一种测量DNA中DwP积累的剂量计，用于太阳紫外线的风险评估。然而，迄今为止还没有建立起测量300至340纳米波长的剂量计。为了建立一种新的紫外线剂量计，我们进行了以下实验：1)我们将100 J/m^2紫外线照射的DNA印迹在尼龙膜上。然后将膜暴露在来自冈崎大摄谱仪的不同剂量的单色紫外线下。暴露后，对膜进行DEM-1抗体免疫组织化学处理，并测定其颜色强度（免疫点印迹：IDB）。2)采用相同的方法（IDB），我们测量了从mylar过滤的UVB灯（Toshiba FL-20SE）发出的300 ~ 340 nm的紫外线剂量。随着UVB剂量的增加，尼龙膜上印迹DNA的颜色强度增加。因此，我们成功地制造了一种新的太阳紫外线剂量计，测量波长从300到340纳米。

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.