What comes to mind when you combine the words "dyed blonde hair" and "Ph.D. advisor"? In fact, there is such a person with dyed blonde hair at the Beijing Institute of Life Sciences (hereinafter referred to as "Beijing Life Sciences Institute"), and that is Su Jun, born in 1994.

"Dyed Blonde Hair Advisor" is his nickname on Xiaohongshu. It is understood that he graduated from the Chinese University of Hong Kong with a bachelor's degree and from the University of Göttingen in Germany with a Ph.D., and completed his postdoctoral research at the Max Planck Institute in Germany. In 2022, at the age of 28, Su Jun returned to China to become the youngest researcher at the Beijing Life Sciences Institute and also serves as a doctoral advisor at Tsinghua University.

In fact, he has not only dyed his hair blonde but also other colors. Because he is only a few years older than his students, this gives him a natural affinity with them. In group photos with students, it is difficult to tell that he, wearing a pink T-shirt, is actually a doctoral advisor.

At the same time, he writes about his reading experiences and monthly team-building activities on Xiaohongshu, and patiently replies to the inquiries of netizens he has never met in the comments section.

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Although when you talk to him, he occasionally still comes out with a few words with a distinct Hong Kong accent, Su Jun's Mandarin is already relatively proficient. Coupled with his handsome appearance, he is often invited to serve as the host of conferences.After joining the Beijing Institute of Life Sciences, he received good news for two consecutive years. First, in 2022, he was selected for the "35 Innovators Under 35" China list by MIT Technology Review. Then, in 2023, he was selected for the Alibaba DAMO Academy Orange Award and became the youngest Orange Scholar of this session.

When Su Jun, wearing a color-blocked sweater and black casual pants, with dyed hair and bright decorations in the office, one might be confused whether he is a scientific researcher or a fashion blogger. Until he began to continuously speak professional terms, it was confirmed that he is indeed a scientist.

Currently, Su Jun is focused on the research of female reproduction. Oocytes and early embryonic development are his main research subjects. Before this, he had published three papers in Science and one in Cell. Although he has not published many papers, he can achieve "one is one".

The oocytes he studies are the source of life for every person on Earth. In nature, most organisms, including humans and monkeys, reproduce offspring through sexual reproduction.

When the reproductive cells of oocytes and sperm combine, a fertilized egg can be formed. Then, a new life begins. The development of oocytes is an extremely complex process, which is also called oocyte maturation.For mammals, the oocyte is the most primitive cell, which is already formed during the embryonic stage and no new oocytes are produced after a female is born. That is to say, the number of oocytes at birth determines the number of eggs that can be produced in the future.

Secondly, as the largest cell in the female body, the oocyte can store a lot of substances, which ensure the growth of the early embryo.

At the same time, oocytes are also very precious, and human females can only ovulate 1 to 2 eggs per month. In addition, the quality of eggs is closely related to the age of women, the older the age, the worse the quality of eggs.

After reaching sexual maturity during puberty, female oocytes will undergo the first meiotic division before ovulation every month, and after discarding half of the genetic material, they form eggs. When the egg meets the sperm, the egg will undergo the second meiotic division to form a fertilized egg, and then undergo countless cleavages to form a new individual. The above process is very important for female reproduction.

And Su Jun's daily work is to study the above process. In this direction, he has discovered new structures in oocytes and revealed the molecular mechanism of chromosomal abnormalities that often occur in human oocytes.Discovering the liquid spindle assembly domain, proving its role in the assembly process of the chromosome separation machinery.

In the field of female reproduction, he not only clarified the important mechanism for the assembly of spindles in mammalian oocytes but also identified the causes of chromosomal number abnormalities in human oocytes, and proposed the first prevention and treatment plan for chromosomal abnormalities in human eggs.

For mammalian embryos, they often exhibit developmental abnormalities, which subsequently lead to miscarriages or the occurrence of genetic diseases such as Down syndrome. The key reason behind this phenomenon is that oocytes inevitably make errors in chromosome separation when forming eggs.

In the process of separating chromosomes, cells need to temporarily assemble the chromosome separation machinery, the spindle. The spindle is composed of the cytoskeleton, which generally requires the assistance of centrosomes to assemble the cytoskeleton. However, centrosomes degenerate during the development of mammalian oocytes, but they can still separate chromosomes by forming acentrosomal spindles.

So, how is the acentrosomal spindle assembled? This was once a difficult problem facing Su Jun. Interestingly, although there are no centrosomes in mammalian oocytes, they still express many centrosome proteins.Based on this, Su Jun began to screen for proteins related to the meiotic spindle of oocytes. During this process, he mainly used high-resolution microscopic imaging to observe the localization of 70 spindle-related proteins in oocytes.

To his surprise, 19 of these proteins were all gathered on a previously unreported structure. Since this structure was liquid-like, it was named the liquid-like meiotic spindle domain (LISD).

This structure is very orderly, and the proteins inside it will gather at both ends of the spindle, forming many droplet-like things.

These structures also have very unique performances, and they will fuse or split like liquids. Therefore, Su Jun began to speculate whether this is related to the bio-physical phenomenon of liquid-liquid phase separation.

However, this research was carried out in 2018, and liquid-liquid phase separation was not a popular research direction at that time. Coincidentally, the scholar who discovered liquid-liquid phase separation and Su Jun, who was studying abroad at the time, both worked at the Max Planck Society in Germany.Thus, Su Jun went to Dresden to consult with him. Subsequently, he discovered that these structures were very likely produced by liquid-liquid phase separation.

After a large number of experimental verifications, Su Jun further proved that the aforementioned structural domains were indeed formed through liquid-liquid phase separation, and he used the Trim-Away technology previously developed in the laboratory to identify the core proteins that form this structural domain.

In other words, when this protein is removed, not only can this structural domain no longer be formed, but it also leads to the spindle apparatus being unable to assemble normally, indicating that this structure is crucial for the division of chromosomes in oocytes.

Revealing the molecular mechanism by which human oocytes often incorrectly separate chromosomes, and for the first time proposing prevention and treatment plans.In young women, as many as 20% to 40% of eggs have an abnormal number of chromosomes. These abnormal eggs are mainly due to the assembly of unstable spindles during the maturation process of oocytes, which leads to errors in chromosome separation.

To reveal the underlying molecular mechanisms and identify the reasons for the high instability of spindles in human oocytes, Su Jun conducted a detailed study on oocytes from different mammalian species, comparing the differences between them.

Through genetic screening, he identified a key motor protein, KIFC1 (kinesin superfamily protein C1), that regulates the stability of oocyte spindles.

In other mammalian species such as mice, pigs, and cows, the motor protein KIFC1 ensures the stability of their oocyte spindles. However, in human oocytes, the expression level of motor protein KIFC1 is very low.

So, is the absence of motor protein KIFC1 the cause of the instability of human oocyte spindles?In order to clarify this issue, Su Jun attempted to supplement the human oocyte with the motor protein KIFC1 and performed real-time imaging of spindle assembly.

The results showed that after injecting KIFC1, the accuracy of spindle assembly was greatly improved, and the risk of chromosomal separation errors was significantly reduced. On this basis, he proposed a prevention and treatment plan for chromosomal mis-separation in human eggs, which is to purify human KIFC1 and re-inject it into human oocytes.

In response to this achievement, Su Jun and his collaborators have applied for a technical patent. He stated that this technology can have a very positive effect on the development of early eggs and early embryos, improving the quality of human eggs and embryos.

Since the injection of protein is in the cytoplasm of the oocyte and does not involve the safety issues of gene editing, it is very promising for widespread application.

In detail, when using this technology, it is necessary to first extract the oocyte or egg and inject the KIFC1 protein before fertilization. And for women of childbearing age who want to undergo assisted reproduction, the process of routine treatment will inevitably go through the step of egg retrieval.Therefore, for the current in vitro fertilization (IVF) technology, Su Jun's achievements can be easily applied clinically. Thus, he hopes to improve the overall efficacy of IVF by enhancing the quality of eggs. In this way, for women undergoing assisted reproductive treatment, they may be able to say goodbye to the situation where they must go through multiple IVF cycles to become pregnant.

Currently, Su Jun's laboratory at the North Institute is a cell and developmental biology research group oriented towards clinical applications. At present, he and his team are focusing on studying the developmental mechanisms of early mammalian embryos, combining clinical samples obtained from different reproductive centers in the country to explore and optimize human assisted reproductive technology, helping to further improve fertility efficiency.