Sperm It has attracted the attention of scientists since the Dutch Anthony van Leeuwenhoek It occurred to him that he had witnessed the process of ejaculation under a microscope about 343 years ago.
Recent research has accused male reproductive cells of “Very cheeky creatures“Because his tail It does not swing in a zigzag manner Like a snake or eel, but it slithers in a spiral while moving its tail to one side only.
But in a study published in October 2023, it goes further and suggests sperm is the culprit Challenges Newton’s third law of motionThis is done by distorting his body while swimming in a way that does not provoke any reaction from his environment.
Kenta Ishimoto, mathematician at Kyoto UniversityHe and his colleagues investigated the movement of human germ cells and found that they slide through materials that should theoretically resist their movement.
Newton’s third law, also known as “Law of action and reaction”It says that every action has an equal and opposite reaction. This means that if you push something forward with a certain force (action), that object will push you back with the same force but in the opposite direction (reaction).
but This universal law does not apply to some biological swimmers, such as sperm.
In the new study, scientists analyzed Chlamydomonas algae and human sperm and identified non-reciprocal mechanical interactions, which they called “strange elasticity” and which did not conform to Newton’s third law.
Both Chlamydomonas and spermatozoa use hair-like appendages called flagella which they use to move. These appendages protrude from the cell, almost like a tail, in order to propel it forward. So They change shape To the extent that it interacts with the fluid surrounding it.
🚨 It’s amazing that human sperm are able to defy one of the fundamental laws of physics.
This is suggested by a study published in PRX Life, which shows how these microorganisms move through viscous fluids without generating an equal reaction and… pic.twitter.com/bZZLRuqAEV
— Biological Community (@Bio_comunidad) October 26, 2023
Scientists explain that the flagella move in a non-reciprocal manner, that is, they do not elicit an equal and opposite response in the environment, thus violating an important law of physics.
So-called non-reciprocal interactions appear in rogue systems composed of flocks of birds, fluid molecules, and swimming sperm.
When birds and cells generate their own energy, which is added to the system with every flap of their wings or every movement of their tail, The system moves away from equilibrium The same rules do not apply.
Very viscous fluids would dissipate flagellar energy and impede the movement of sperm or single-celled algae. But somehow those flexible flagella managed to move.
Sperm and algae are not the only ones that contain flagella. Many microorganisms have one, which means there are likely other cells that violate Newton’s laws that science has yet to discover.
The researchers believe that the results could be very useful because they can help in designing Small, stretchable robots They also have the ability to break the laws of physics.
While mathematicians in Kyoto are studying the properties of the movement of human male reproductive cells, a team of mathematicians in Kyoto is studying the properties of the movement of human male reproductive cells Stockholm University Deciphering how sperm comes out of existence Passive spectators for dynamic swimmers To start the path towards fertilization.
To explain this finding colloquially, we must imagine that sperm are little explorers seeking to reach the holy grail: the human egg. They don’t have maps or GPS but they are used Chemical instrument more effective.
The egg releases chemical signals that activate and attract Sperm because it has receptors on its surface capable of detecting it.
David DrewThe professor of biochemistry at Stockholm University explained that the protein known as SLC9C1 It is found exclusively in sperm and is generally inactive.
But the story changes when chemical signals interact with the sperm’s surface.
“SLC9C1 functions as a highly sophisticated exchange system. It exchanges protons from inside the cell for sodium ions from the outside, creating a temporarily less acidic environment inside the sperm. This changes the internal environment It causes an increase in sperm motilityDrew said.
Christina Polinoa structural biologist at the Center for Biochemistry in Heidelberg University In Germany, he also studied the properties of a protein essential for sperm motility and male fertility.
Scientists are interested in the potential role of SLC9C1 in male infertility, Paulino said.
Since the protein is only found in sperm, it can be used for this Development of contraceptives for men Because this medicine will not change other cells in the body.
But the researcher Benjamin CobbHe is a biophysical chemist at the University of Bonn and the Max Planck Institute for Interdisciplinary Sciences. He was not involved in the study. He warned that there is a big gap Between understanding the basic function of SLC9C1 and being able to use that knowledge for pharmacological birth control in men.
The truth is that there are dozens of researchers around the world trying to uncover the mysteries that sperm still hide to advance the fields of genetics, biotechnology, and human reproduction.
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