LOW-DOSE ENERGY-SLECTED ELECTRON MICROSCOPY WITH AN OMEGA FILTER

带 OMEGA 滤光片的低剂量能量选择电子显微镜

• 批准号: 5204141
• 负责人: R LEAPMAN
• 金额: --
• 依托单位: NATIONAL CENTER FOR RESEARCH RESOURCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/5204141
• 关键词: Alphaherpesvirinae; biomedical equipment development; capsid; charge coupled device camera; cryopreservation; digital imaging; image processing; transmission electron microscopy; virus DNA

We have investigated the potential of using an in-column omega filter in a conventional transmission electron microscope for elemental mapping of biological structures at low dose. Digital images were collected at a beam energy of 100 keV by means of a 1024 x 1024-pixel, phosphor-coupled, cooled slow-scan CCD camera on a Zeiss 912 electron microscope. Frozen-hydrated specimens of herpes simplex virus (vitrified by plunging into liquid ethane) were cryotransferred and freeze-dried before imaging in the region of the phosphorus L-edge at energy losses of around 130 eV. These digital micrographs were recorded from large numbers of viruses at a dose of less than 1000 electrons per square nanometer. Resulting noisy images were corrected for read-out noise and pixel-gain variations before cross-correlating, summing, and removing the noncharacteristic background image extrapolated from the pre-edge region of the EELS spectrum into the post-edge region. In this way, it was possible to build up an averaged projected distribution of phosphorus, i.e., nucleic acid, in the core of the herpes simplex capsid.

我们已经研究了使用柱内omega过滤器的可能性 在元素的常规透射电子显微镜中 在低剂量下绘制生物结构图。数字图像被 通过1024×1024像素在100keV的束能量下收集， 蔡司912电子上的荧光粉耦合制冷慢扫描CCD相机 显微镜。单纯疱疹病毒冰冻水合标本 (通过插入液态乙烷进行玻璃化)被冷冻转移和 冷冻干燥前成像的区域的磷L-边缘在 能量损失约130 eV。这些数字显微照片是 从剂量小于1000的大量病毒中记录 每平方纳米的电子数。对产生的噪声图像进行了校正 对于在互相关之前的读出噪声和像素增益变化， 对非特征背景图像进行求和和去除 从鳗鱼光谱的前缘区域外推到 后边缘区域。这样，就有可能建立起一种 年平均预测的磷分布，即核酸 单纯疱疹病毒衣壳的核心。