To detect a small amount of Period1 (Per1) expression, we developed a micro-photomultiplier tube (μPMT) system which can be used both in vivo and in vitro. Using this system, we succeeded in detecting Per1 gene expression in the skin of freely moving mice over 240 times higher compared with that of the tissue contact optical sensor (TCS) as previously reported. For in vitro studies, we succeeded in detecting elevated Per1 expression by streptozotocin (STZ) treatment in the scalp hairs at an early stage of diabetes, when glucose content in the blood was still normal. In addition, we could detect elevated Per1 expression in a single whisker hair at the time of diabetes onset. These results show that our μPMT system responds to minute changes in gene expression in freely moving mice in vivo and in mice hair follicles in vitro. Furthermore, Per1 in the hair can be used for a marker of diabetic aggravation.

为了检测少量PERIOD1（PER1）的表达，我们开发了可同时采用的微光电倍增管（μPMT）系统在体内和体外。使用该系统，我们成功地检测到自由移动小鼠皮肤中Per1基因的表达，与之前报道的组织接触光学传感器 (TCS) 相比，该表达高出 240 多倍。对于体外研究，我们成功地检测升高PER1通过在糖尿病的早期阶段，在菌素头皮毛发（STZ）治疗时的血糖含量仍为正常表达。此外，我们可以检测到升高的Per1在糖尿病发病时在一根胡须中表达。这些结果表明，我们的 μPMT 系统可以响应体内自由移动的小鼠和体外小鼠毛囊中基因表达的微小变化。此外，头发中的Per1可用作糖尿病恶化的标志物。