Investigation of effects of pest controlling methods including alternative fumigants of methyl bromide on DNA of museum objects.

对博物馆藏品进行灭虫处理通常是必不可少的。但这种处理方法有时会对博物馆藏品产生不利影响。当我们观察自然标本时，用于分类学研究的DNA分析已经变得越来越普遍。但一些文物保护人员开始担心，一些熏蒸剂可能会对天然标本的DNA分子产生不利影响。因此，我们在本研究中考察了博物馆藏品中使用的熏蒸剂对自然标本DNA的影响。以冻干蘑菇和冻干肌肉为材料，研究了几种灭虫处理对天然标本DNA的影响。数据清楚地表明，熏蒸剂甲基溴、甲基溴/环氧乙烷混合气体、环氧乙烷、环氧丙烷和碘化甲酯即使只熏蒸一次，也会对标本DNA造成明显的降解。用PCR（聚合酶链反应）扩增某些DNA片段的后续步骤在这些样品中是困难的。放大较大的DNA片段比放大较小的DNA片段有更多的问题。PCR效率下降的主要原因被认为是模板DNA的降解。另一方面，热方法（加热和低温）、60%的二氧化碳处理和硫酰氟熏蒸似乎对标本的DNA分子几乎没有影响，从而使后续的PCR得以成功进行。对PCR产物进行直接测序，以检查DNA序列修饰的可能性。当PCR产物扩增到足够的数量进行直接测序时，我们对少数基因区域的DNA序列进行了检查，结果正常。

Treatments for pest eradication on museum objects are often indispensable. But such treatments sometimes cause adverse effects on museum objects. When we look at natural specimens, DNA analysis for taxonomic studies have become increasing common. But some conservators had become concerned about the possibility that some fumigants may adversely affect DNA molecules of natural specimens. Thus we investigated the effects of fumigants which have been used for museum collections on DNA of especially natural specimens in this research. The effects of several treatments for pest eradication on natural specimen DNA were examined using freeze-dried mushroom and freeze-dried muscle. The data clearly showed that the fumigants methyl bromide, methyl bromide/ ethylene oxide mixed gas, ethylene oxide, propylene oxide, and methyl iodide all caused significant degradation of specimen DNA, even with a single fumigation. Subsequent steps at amplification of certain DNA fragments by PCR (polymerase chain reaction) were difficult in these samples. There were more problems in amplifying larger DNA fragments than smaller fragments. The main cause of the decreased efficiency of PCR was thought to be the degradation of template DNA. On the other hand, thermal methods (heating and low temperature), 60 percent carbon dioxide treatment, and fumigation by sulfuryl fluoride seemed scarcely to affect the DNA molecules of the specimens, allowing subsequent PCR to be successfully performed. Direct sequencing of the PCR products was also performed to check the possibility of modifications to the DNA sequences. When the PCR products were amplified to the sufficient amount for the direct sequencing, the DNA sequences were normal in our examination of the few gene regions.