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Expansion microscopy (ExM) enables imaging of cells and their components with a spatial resolution far below 200 nanometers. To this end, the proteins of the test sample are cross-linked into a swellable polymer. Once the interactions between the molecules have been destroyed, the samples can be expanded many times with water. This allows for a detailed view of their structures.
“This method was previously limited to proteins. In the journal Nature Communications we are now presenting a way to expand lipids and thus cell membranes, “says Professor Markus Sauer, expert in super-resolution microscopy at the Biocentre of Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany. JMU professors Thomas Rudel (microbiology) and Jürgen Seibel (chemistry) are also involved in the publication.
Synthetic lipids are labeled and expanded
Jürgen Seibel’s team synthesized functionalized sphingolipids, which are an important component of cell membranes. If these lipids are added to cell cultures, they are incorporated into cell membranes. They can then be marked with a dye and expanded four to ten times into a swellable polymer.
JMU researchers show that this method – in combination with structured illumination microscopy (SIM) – makes it possible for the first time to image different membranes and their interactions with proteins with a resolution of 10 to 20 nanometers. : cell membranes, the outer membranes and the nuclear membrane of the inner cell and also the membranes of intracellular organelles such as mitochondria.
Focusing on bacteria and viruses
Sphingolipids also integrate highly efficiently into the membranes of bacteria. This means that, for the first time, pathogens such as Neisseria gonorrhoeae, Chlamydia trachomatis is Flammeovirgaceae negevensis it can now be visualized in infected cells with a resolution that was previously only achieved by electron microscopy. The inner and outer membranes of Gram-negative bacteria can also be distinguished from each other.
“With new super-resolution microscopic methods, we now want to investigate the mechanisms of bacterial infection and the causes of antibiotic resistance. What we learn in the process could be used for better therapies,” says bacterial infection expert Professor Thomas Rudel.
Sphingolipids could also integrate into the virus membrane. If this is successful, the interactions of corona viruses with cells could be studied for the first time with high-resolution light microscopy.
Source of the story:
Materials provided by University of Würzburg. Original written by Robert Emmerich. Note: The content can be changed by style and length.
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