Techniques for Visualizing Cells

Kotaro Oka (Professor, Department of Biosciences and Informatics)

Even if you look at cells, the "stage" for various life phenomena, under an ordinary microscope, you cannot know what is happening inside them. To understand what is happening in the cells you are observing, "visualization" techniques are necessary. In the field of cell biology, based on the principle that "seeing is believing," there have been widespread attempts to capture life phenomena occurring within cells as real-time images. The "green fluorescent protein," which was awarded the Nobel Prize in Chemistry in 2008, is also used for such "visualization."

In our laboratory, we are conducting research using various fluorescent dyes and proteins in collaboration with laboratories both inside and outside the university to "visualize" cells. For example, in collaboration with the laboratory of Professor Koji Suzuki of the Department of Applied Chemistry, we have succeeded in "visualizing" Mg ions within cells. Although Mg ions are important ions responsible for various physiological functions, the basic cellular physiological mechanisms, such as when and under what conditions their intracellular concentration changes, were previously unknown. We expect that this new fluorescent dye will clarify the relationship between Mg and various diseases, including Parkinson's disease.

Recently, we have also been developing techniques to visualize intracellular signaling molecules. Within cells, various signaling substances called second messengers weave complex temporal and spatial patterns, controlling complex and diverse life phenomena. Our laboratory has developed a novel method for visualizing multiple intracellular second messengers and has succeeded, for the first time in the world, in simultaneously "visualizing" the different responses of cyclic nucleotides and calcium ions in beating cardiomyocytes.

Using these "visualization" techniques, we are excitedly investigating what is happening inside cells. We hope to clarify important issues in biology and medical sciences, such as how the tip of a growing nerve cell is steered to connect with its target nerve cell.

In cardiomyocytes, the intracellular calcium concentration (Ca) increases during systole, but the cyclic adenosine monophosphate (cAMP) concentration does not change (the four figures on the left; stronger red indicates higher concentration). On the other hand, when a stimulus that increases the intracellular cAMP concentration is applied, the Ca concentration during contraction increases along with the rise in cAMP concentration (the four figures on the right). Modified from Niino Y, Hotta K, Oka K (2009) PLoS ONE 4(6): e6036.