Microscopy has long been an area of development and innovation, from early beginnings of the light microscope to the advent of electron microscopes, cutting-edge techniques, and beyond. This growth has included the implementation of microscopy technologies into devices suitable for microplate tissue and cell imaging, high-throughput analysis, and a variety of other applications. Now, several recent developments have pushed the microscopy and imaging fields into new realms of space and time.
We previously reported on ground breaking developments that were forging the path of the imaging resolution evolution. We spoke about imaging resolution and the fact that earlier technologies were incapable of breaking the limits necessary to achieve atomic level structural details of biological molecules and complexes. Several studies and a host of new technologies demonstrated that indeed science was well on its way towards this new super-resolution goal.
Fast forward to more recent developments, where we reported on innovations in ultra-high resolution optical microscopy and single-cell (and single-molecule) microscopy. Several key developments included:
What do all of these developments mean for the life sciences?
Fast forward to the present, and a new dimension for exploration. Researchers at the ImmunoSensation2 Cluster of Excellence at the University of Bonn have developed techniques that use multi-focal images to reconstruct the movement of fast biological processes in 3 dimensions. This work titled “Multifocal imaging for precise, label-free tracking of fast biological processes in 3D” has been published in Nature Communications.
Many biological processes are rapid, happening on the millisecond time scale. Image acquisition at high frame rates has been used in the past to record fast biological processes. In order to keep track of targets, however, a large field of view and bright fluorescent labels were required. Challenges in maintaining accuracy and precision of watched targets have made previous work tenuous.
The investigators in the present study, focused on the dynamics of flagellar beating in connection with the swimming action of sperm. Using a 3D reconstruction algorithm and multi-focal images, they tracked the movement of non-labeled spherical and filamentous structures quickly and easily, over long time periods and distances. The also charted the fluid flow in the medium surrounding the sperm. How fast and precise were these measurements? The investigators characterized fluid flow and flagellar beating with a z-precision of 0.15 µm, in a volume of 250x260x21 µm, and at high speed of 500 Hz - 2.5 faster sampling speeds than previous work.
As the authors state, “Life happens in three dimensions”. Nearly all biological materials (cells, organelles, molecular structures) undergo some form of 3D movement. Many of these events occur on the micrometer scale within milliseconds. State-of-the-art microscopy and imaging technologies have made significant impacts on the components of 3D space. Now, as evidenced by this study, the fourth dimension - time - is being explored in even greater accuracy and detail than before.
Tracking rapid biological 3D movements in time will provide the opportunity to better understand biological processes, how they happen and what happens when they go awry. Beyond that, better clarity of these processes may contribute to biomechanical engineering efforts and the development of artificial mechanical systems.
In the current study, the investigators go on to apply their techniques to the actions of insect wings (Drosophila melanogaster), foraging Hydra vulgaris, and crawling Amoeba proteus, to demonstrate the applicability of the approach to a wide variety of movement processes. Such work on an expanding set of subjects may yield valuable insights into how to influence biological processes or replicate these motions for use in our world.