Ultrarapid Cooling Enables Molecular Patterns of Life To Be Observed

Original from: Technology Network

Fluorescence light microscopy has the unique ability to observe cellular processes over a scale that bridges four orders of magnitude. Yet, its application to living cells is fundamentally limited by the very rapid and unceasing movement of molecules that define its living state. What is more, the interaction of light with fluorescent probes that enables the observation of molecular processes causes their very destruction. Ultrarapid cryo-arrest of cells during live observation on a microscope, as developed in the Department of Systemic Cell Biology at the Max Planck Institute of Molecular Physiology in Dortmund, now circumvents these fundamental problems. The heart of the approach is the cooling of living cells with enormous speeds up to 200,000 °C per second to -196 °C. This enables an unprecedented preservation of cellular biomolecules in their natural arrangement at the moment of arrest. In this low temperature state, molecular movement and light-induced destruction is stopped, enabling the observation of molecular patterns of life that are otherwise invisible.

The almost 100 trillion cells of our body are alive because they maintain themselves in a permanently active state by continuous energy consumption. The microscopic patterns that constitute a cell thereby originate from the ever-dynamic behavior of billions of nanometer-sized biomolecules, like proteins, lipids, nucleic acids and other molecules, that bustle around in a seemingly unorganized way. To observe how higher scale organization emerges from this incessant activity, biomolecular species can be selectively equipped with fluorescent probes. These fluorescent molecules are photon catalysts: they absorb high energy photons (e.g. blue light) and subsequently emit lower energy (red-shifted) photons. These photons can be imaged through a microscope to not only precisely localize the labeled biomolecules, but also report on local molecular reactions. However, light-induced destruction of the probes and blurring through the very vital molecular motion are two fundamental problems that hamper observations of how the molecular processes of life generate structure at the cellular scale. 

An uncertainty principle to fluorescence microscopy

The solution is literally very cool

Making the invisible visible

Ultrarapid cryo-arrest allowed the use of normally destructive high laser powers to analyze native molecular patterns at tens-of-nanometer resolutions that were otherwise invisible. What is more, because of the absence of photodestruction at -196 °C, the same arrested cells could be observed by different microscopy modalities to measure patterns from the molecular to the cellular scale. This new technology thereby led to the discovery of nanoscopic co-organization of an oncoprotein and a tumor suppressor protein that safeguards cells from exhibiting malignant behavior. “This is an enabling step for fluorescence microscopy, especially the combination of super-resolution microscopy and microspectroscopy that allow the mapping of molecular reactions in cells at multiple scales. It will change the way we observe molecular organization and reaction patterns in cells and therefore provide more insight in the self-organizing capabilities of living matter”, says Philippe Bastiaens.

Source: Ultrarapid Cooling Enables Molecular Patterns of Life To Be Observed