A research group led by Assistant Professor Kenta Ishimoto of the Kyoto University Hakubi Center uses an equation (Stokes equation) that expresses the flow of water in the microscopic world to describe the movement of human sperm and the characteristic patterns that appear in the surrounding liquid. I found it.
It is generally said that the birth of life begins with the encounter of one sperm and an egg, but before that the sperm must win the "competition" with many other sperms.To what extent is the "story" of this sperm journey true? This research group approached the sperm journey from the formula that expresses the flow of liquid around the sperm swimming.
Previous studies have used the Stokes equation to investigate the mechanism of sperm swimming.In this formula, the movement of microorganisms is required only by the information on the shape of swimming.However, there was no example of verifying the swimming method obtained from the Stokes equation with an actual microscopic image of sperm.
Therefore, this research group tried to verify the effectiveness of the mathematical approach by comparing the answer to this equation with the actual sperm movement in microscopic images.
As a result of analyzing the equation of the flow that occurs around it based on the information acquired from the microscope image, we succeeded in reproducing the sperm movement on a computer.In addition, when the state of the surrounding flow was calculated from the same formula, it was found that there was a certain pattern even in the complicated flow.When we reconsider the movement of sperm based on this pattern, it became clear that the movement of sperm also has a characteristic rhythm of pushing and pulling while twisting the tail.By describing this rhythm with a flow equation, we succeeded in finding a simple mathematical formula that expresses sperm movement.
In the past, when creating a mathematical model by "coarse-graining" motion, we often relied on "physical intuition."However, since the method used this time can obtain a mathematical model that extracts the essence of sperm movement from experimental data only by mathematical operation, it is expected that it can be applied to the movement of various kinds of swimming microbes.
In addition, by further research, it will be possible to clarify the state of sperm movement, which is difficult to observe experimentally, with a mathematical eye, and it will be possible to understand the mechanical function of sperm necessary for fertilization. It is expected to contribute to the development of fertility treatment.
