As long as eight genes are activated to produce gene control proteins, it is enough to directly transform mouse stem cells into egg-like cells, which can even be fertilized like egg cells after they mature.
In a study recently published by the top academic journal Nature, researchers from Kyushu University, Japan’s Institute of Physics and Chemistry (RIKEN), and other teams reported the above findings.
The research team said that these findings have further deepened our understanding of egg development and may have an impact on reproductive medicine.
Oocytes are stored in the body, and after developing into eggs through multiple stages, it means that they are ready for fertilization. This is usually considered the first step in creating a new life. There is no doubt that oocytes are very unique. They have the ability to produce more than 200 highly differentiated cells needed to create an individual.
Scientists mentioned that oocytes and their cytoplasm are unusual. Scientists in the history of life sciences believe that a typical example of their manipulation is somatic cell cloning, in which the nucleus of the somatic cell is injected into an egg from which genetic material has been removed (this process is called somatic cell nuclear transfer (SCNT)), which is activated by artificial methods and then transplanted to The surrogate mother can give birth to a new life. This is how the famous “Dolly” sheep was born.
Therefore, the research team believes that a basic understanding of oocytes and their development is important to advance reproductive medicine and to better understand how life reproduces. However, the regulatory network of genes involved in the process of oocyte development is still unclear.
Professor Katsuhiko Hayashi of the School of Medical Sciences at Kyushu University and colleagues used mouse embryonic stem cells to identify eight transcription factors (proteins that regulate gene expression) required to trigger the growth of oocytes. Then they induced the expression of these eight transcription factors in mouse pluripotent stem cells to test whether they were sufficient to drive the growth of oocytes.
The results of the study found that this led to the production of oocyte-like cells, which they named “directly induced oocyte-like cells”.
“After introducing a few factors, we saw that mouse stem cells formed oocytes so quickly and simply. I didn’t believe it at all at first, but repeated experiments proved it to be true.” On the official website of Kyushu University In a press release for the study, Nobuhiko Hamazaki, the first author of the research paper and assistant professor at Kyushu University, said, “It is quite amazing to find that 8 transcription factors can cause such a large change.”
The Kyushu University team and researchers from the Japan Institute of Physics and Chemistry (RIKEN) found that both mouse embryonic stem cells and induced pluripotent stem cells (iPS) can be transformed into oocyte-like cells using their method. They also found that in some cases only 4 transcription factors can complete this process, but the test repeatability is reduced.
Hayashi said, “Stem cells can be directly transformed into egg-like cells without following the same steps that occur naturally, which is very remarkable.”
The study also showed that when the oocyte-like cells obtained in this work are cultured and grown in vitro with other cells around the oocyte under normal conditions, the oocyte-like cells will develop into cells that are structurally similar to mature egg cells. But they did not undergo meiosis, so the number of chromosomes is abnormal from that of normal eggs.
Despite the above-mentioned situation, research still found that mature oocyte-like cells can be fertilized in vitro and show early development, and some even develop to the 8-cell stage. However, further development beyond this point will be affected.
The research team believes that although the nucleus of oocytes may be unusable in the long run, the cytoplasm of these oocytes will be very promising, such as reproductive biology research and mitochondrial replacement therapy. “The cytoplasm from oocytes is an invaluable resource in reproductive biology and medicine. This method can provide a new tool for mass production of oocytes without any invasive process.”
Hayashi commented, “Although this process may still be much more complicated for humans, these preliminary results in mice are very promising.”
Tianwen-1 completed the fourth midway correction of its orbit and returned the first image of Mars
At 20 o’clock on February 5, 2021, the engine of the first Mars exploration mission Tianwen-1 probe was ignited, and the fourth midway correction of the ground fire transfer section was successfully completed to ensure that Mars capture was carried out as planned.
Up to now, Tianwen-1 has been in orbit for about 197 days, about 184 million kilometers away from Earth, about 1.1 million kilometers away from Mars, and a flight mileage of about 465 million kilometers. The probe systems are in good condition.
Prior to this, Tianwen-1 acquired the first Martian image at a distance of about 2.2 million kilometers from Mars.
The potential mass range of dark matter is narrowed, helping to focus the search area
According to a report by the physicist organization network on the 27th, British scientists used the fact that gravity acts on dark matter to fundamentally calculate the mass range of dark matter for the first time. This range is much narrower than previously thought. The latest research has narrowed the range of potential masses of dark matter particles and also limited the search range for future dark matter “catchers”. It will also help scientists discover potential new forces in the future.
Dark matter does not emit light, emit electromagnetic waves, does not participate in electromagnetic interactions, and cannot be directly “seen” with any optical or electromagnetic wave observation equipment. Scientists have confirmed its existence through the effect of dark matter on galaxies. The result of the cosmic microwave background radiation observation experiment gives the proportion of dark matter in the total amount of cosmic matter. In the universe, ordinary matter accounts for only 4.9%, dark matter accounts for 26.8%, and dark energy accounts for 68.3%. Dark energy and dark matter are also considered to be two dark clouds in the physics sky at the beginning of the 21st century.
In the latest study, the research team led by Professor Xavier Kalmot of the School of Mathematics and Physical Sciences at the University of Sussex assumed that gravity is the only force acting on dark matter, and calculated that the mass of dark matter particles is between Between 10-3eV (electron volt) and 107eV, it is much narrower than the theoretically expected 10-24eV to 1028eV.
“This is the first time anyone has used quantum gravity to calculate the mass range of dark matter,” Carmott said. This study shows that unless there is a hitherto unknown force affecting it, dark matter cannot be like some theories. It is said to be “ultralight” or “overweight”.
The researchers believe that this research will benefit physicists in two ways: one is to focus on the search area of dark matter; the other is to help reveal whether there are mysterious unknown forces in the universe-if the mass of dark matter is found to exceed in the future The range predicted by the Sussex team indicates that dark matter is affected by other forces in addition to gravity.
The collapse of some marine species: sea surface temperatures continue to rise under multiple pressures
A zoology study published on the 28th in the British “Nature” magazine pointed out that some marine species are facing a crisis of “population collapse”-since 1970, the number of marine slatyfish in the world has decreased by 71%. Among these marine species, More than three-quarters of them are on the verge of extinction; and another study published at the same time pointed out the “climate crisis” of the ocean: global sea surface temperature has been rising for the past 12,000 years.
The ocean is facing multiple pressures. Issues such as climate change, rising sea temperature, pollution, overfishing, and ocean acidification have been affecting the health of the ocean. Scientists currently believe that the risk of marine species extinction should mainly come from overfishing. However, the reduction of individual species has always been difficult to measure. Although the reduction of marine and coastal plategill fish populations in different regions of the world has been recorded before, there has been no global development. analysis.
This time, the Simon Fraser University team in Canada estimated the relative abundance of 18 marine slaty fish species from 1970 to 2018 and assessed the extinction risk of all 31 marine slaty fish species. They found that from 1970 to 2018, the global abundance of marine slaty fish fell by 71.1%. Among these 31 species, 24 are on the verge of extinction; 3 shark species have declined especially, and are now classified as critically endangered—this is also the most threatened species in the World Conservation Union (IUCN) list The grade.
The researchers blamed the reduction of these species on fishing pressure, which increased 18 times during this period. The research team pointed out that immediate action should be taken to prevent “population collapse”, and specifically called on governments to implement fishing restrictions to help promote species recovery.
In the climate report published on the same day by the journal Nature, the Rutgers University of New Jersey team pointed out the “climate crisis” of the ocean. According to the report, the global average annual sea surface temperature has been rising for the past 12,000 years.
The researchers reinterpreted the two latest climate models this time and devised a method to assess the seasonal deviation of a single record, and then calculate the annual average sea surface temperature. They found that climate warming from 12,000 to 6,500 years ago was caused by the retreat of the ice sheet, while recent warming was caused by the increase in greenhouse gas emissions. The current temperature is the highest in the past 12,000 years. The temperature was similar during the last interglacial period about 125,000 years ago.
In addition to suggesting that emissions have caused the sea surface temperature to continue to rise, this study also fills a long-standing gap in the gap between climate models and data used to reconstruct historical climate changes in the Holocene.