Centres Científics i Tecnològics UB



Publication of the protocol "Cryo-transmission Electron Microscopy of Outer-inner Membrane Vesicles Naturally Secreted by Gram-negative Pathogenic Bacteria"

Phd Lidia Delgado, head of the Cryomicroscopy Unit of the CCiTUB, has published, together with professors of the Department of Health, Biology and Environment of the Faculty of Pharmacy of the UB and of the Nanoscopy Division of the University of Maastricht, the article "Cryo-transmission Electron Microscopy of Outer-Inner Membrane Vesicles Naturally Secreted by Gram-negative Pathogenic Bacteria" in the Bio-protocol protocol journal.

It was the magazine itself that invited the research group to detail the preparation protocol that is usually used for cryo-TEM due to its technical expertise and the impact that have had the articles on membrane vesicles previously published by the group of the Faculty of Pharmacy where this protocol has been used.

Bacterial membrane vesicles have implications for the secretion of proteins, lipids, RNA, DNA and other effector molecules. This ability to interact and enter the host cells has led to the development of an expanding research field that explores possible clinical and biotechnological applications.

Electronic cryomicroscopy is very useful in the structural characterization of membrane vesicles because the preservation achieved is considered the closest to how the sample would be in its environment, thus avoiding the typical artifacts of other methods of preparation for electronic microscopy of conventional transmission at room temperature. This is achieved thanks to the cryoimmobilization, which allows to transform the water from the sample directly into vitreous ice avoiding the formation of crystals, followed by the observation of the samples at cryogenic temperatures.

This publication details the entire preparation process optimized for this type of sample, which is the most critical part to obtain good results and which is not usually explained in detail in the usual articles. In this way, it could help other laboratories that need to perform electronic cryomicroscopy of bacterial membrane vesicles or other types of membranous systems, such as extracellular vesicles, released by organisms of any domain of life (Eukarya, Archea, Bacteria) and which are considered to intervene as communicasomes between cells; as well as liposomes or other lipid formulations, which are used in drug delivery systems.

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