• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >The upper surface of an Escherichia coli swarm is stationary
【24h】

The upper surface of an Escherichia coli swarm is stationary

机译：大肠杆菌群的上表面是固定的

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

When grown in a rich medium on agar, many bacteria elongate, produce more flagella, and swim in a thin film of fluid over the agar surface in swirling packs. Cells that spread in this way are said to swarm. The agar is a solid gel, with pores smaller than the bacteria, so the swarm/agar interface is fixed. Here we show, in experiments with Escherichia coli, that the swarm/air interface also is fixed. We deposited MgO smoke particles on the top surface of an E. coli swarm near its advancing edge, where cells move in a single layer, and then followed the motion of the particles by dark-field microscopy and the motion of the underlying cells by phase-contrast microscopy. Remarkably, the smoke particles remained fixed (diffusing only a few micrometers) while the swarming cells streamed past underneath. The diffusion coefficients of the smoke particles were smaller over the virgin agar ahead of the swarm than over the swarm itself. Changes between these two modes of behavior were evident within 10-20 μm of the swarm edge, indicating an increase in depth of the fluid in advance of the swarm. The only plausible way that the swarm/air interface can be fixed is that it is covered by a surfactant monolayer pinned at its edges. When a swarm is exposed to air, such a monolayer can markedly reduce water loss. When cells invade tissue, the ability to move rapidly between closely opposed fixed surfaces is a useful trait.
机译：当在琼脂上的丰富培养基中生长时，许多细菌会伸长，产生更多的鞭毛，并以漩涡状包装在琼脂表面上的薄膜状流体中游动。据说以这种方式扩散的细胞会蜂拥而至。琼脂是一种固态凝胶，其毛孔小于细菌，因此群/琼脂的界面是固定的。在这里，我们展示了在大肠杆菌实验中，虫群/空气界面也被固定了。我们将MgO烟雾颗粒沉积在其前进边缘附近的大肠杆菌群体的顶表面上，在那里细胞在单层中移动，然后通过暗场显微镜观察颗粒的运动，然后依次观察底层细胞的运动对比显微镜。值得注意的是，烟团保持固定（仅扩散几微米），而蜂巢细胞则从下方流过。烟尘颗粒在群之前的原始琼脂上的扩散系数小于群本身上的扩散系数。这两种行为模式之间的变化在群体边缘的10-20μm范围内很明显，表明在群体之前流体深度增加了。可以固定群/空气界面的唯一可能的方法是，将其表面钉扎在其边缘上，然后覆盖一层表面活性剂。当一个群体暴露于空气中时，这种单层可以显着减少水的流失。当细胞侵入组织时，在紧密相对的固定表面之间快速移动的能力是有用的特性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号