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

我们建立了一台太阳紫外线剂量计，测量了300-340 nm波长范围内的紫外线干涉系数。太阳紫外线，特别是UVB(290-320 nm)诱导了细胞DNA中的环丁烷嘧啶二聚体(CPD)和(6-4)光产物(64P)。此外，在太阳光中，从300到340 nm的紫外光波长可以有效地将64P光异构化为其杜瓦异构体(DWP)。后者据说具有很强的诱变性。因此，我们需要建立一种测量DWP在DNA中积累的剂量计，以用于太阳紫外线的风险评估。然而，到目前为止，还没有建立起测量波长从300到340 nm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)在尼龙膜上印迹经100J/m~2紫外线照射的DNA。然后将薄膜暴露在冈崎大型光谱仪提供的不同剂量的单色紫外光下。染毒后，用DEM-1抗体进行免疫组织化学处理，并测定染色强度(免疫斑点杂交：IDB)。到目前为止所获得的结果表明，从64P到DWP的光异构化在320 nm处发生。2)用同样的方法(IDB)，我们测量了Mylar滤光式UVB灯(Toshiba FL-20SE)从300 nm到340 nm的紫外剂量。随着UVB剂量的增加，印迹DNA在尼龙膜上的颜色强度略有增加。因此，我们成功地研制出了一种新的太阳紫外线剂量计，测量波长从300到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.