Zhu Rong discovers that water also exists on Mars recently | Global scientific news

? COVID-19 epidemic?

China's cancellation of zero clearance policy may trigger a wave of O'Micron infection.

China's dynamic zeroing policy, designed to cut off the chain of transmission and quickly fight the epidemic, has been used to deal with the more contagious mutant novel coronavirus since August 2021. Recently, researchers from Fudan University predicted COVID-19 's disease burden after China abolished the dynamic zero clearance policy. The results show that if the current dynamic zero clearance policy is abolished, it may lead to a large number of O'Micron infection. The study is published in Nature Medicine.

The researchers developed a mathematical model to simulate the spread of novel coronavirus and corrected it according to the early stage of the development of the O'Micron epidemic in Shanghai in 2022. The baseline scenario set in the model was that the population received enhanced injections and did not take more stringent non-drug interventions (NPI), such as large-scale nucleic acid testing and travel restrictions, and did not use anti-novel coronavirus drugs. The final model results show that the Omicron mutant may cause 5.1 million hospitalizations, 2.7 million ICU and 1.55 million deaths from March to September 2022. The researchers also said that a combination of three strategies to ease COVID-19 's disease burden-continuing to promote vaccination, the use of anti-novel coronavirus drugs and stricter NPI---could reduce mortality and prevent a run on medical resources.

? Planetary science?

Zhurong found that water also exists on Mars recently.

Martian climate is cold and dry, so it is difficult to find liquid water on Mars. It is generally believed that Mars was wet about 3 billion years ago, after which it lost a lot of water. But the research team of the National Space Science Center of the Chinese Academy of Sciences used data collected by Zurong on the Martian utopian plain to find traces of liquid water activity on the Martian surface 700 million years ago. The research is published in the journal Progress of Science.

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Using the data collected by the "Zhurong" short-wave infrared spectrometer and other equipment, the research team found some brightly colored hydrated sulfate and hydrated silicon dioxide near the landing site. Their existence indicates that there was a large amount of liquid water activity near the landing site of the Zhu Rong. This liquid water may come from rising groundwater or melting underground ice. Based on the timing of the crater near the landing site, the team estimated the age of the area at about 700 million years. This shows that the recent water activity on Mars is more active than previously estimated.

? Virology?

Offspring of seasonal H1N1 influenza virus or influenza 1918 strain

A recent study published in Nature Communications found that the seasonal H1N1 flu virus may be a direct descendant of the 1918 strain that caused the global influenza pandemic. The researchers analyzed 13 lung samples collected in the historical archives of German and Austrian museums from different individuals from 1901 to 1931, six of which were collected in 1918 and 1919. Based on these samples, they sequenced two incomplete genomes collected in Berlin in June 1918 and a complete genome collected in Munich in 1918.

By comparing genomes before and after the pandemic flu peak (1918), the researchers found differences in nucleoprotein genes-differences associated with resistance to the antiviral response that may have helped the virus adapt to the human body. They also used molecular clock modeling to estimate the time scale of evolution and found that all segments of the genome of the seasonal H1N1 influenza virus may be direct descendants of the original strain of the 1918 pandemic. This refutes other previous hypotheses that the seasonal virus comes from genetic recombination, in which segments of the genomes of different viruses are swapped. However, the researchers also stressed that their sample size is still extremely limited.

? Medicine?

After 20 years of freezing, the testicular tissue can still produce active sperm.

The survival rate of childhood cancer has increased significantly in recent decades, but a serious side effect is reduced fertility. One response is to collect, freeze and reimplant testicular tissue containing stem cells, after scientists have shown in rhesus monkeys that short-term frozen testicular tissue can help animals regain fertility. But what if it needs to be preserved for a long time? Rat testicular tissue can still be reimplanted into animals to produce viable sperm after more than 20 years of cryopreservation, according to a new study published in PLoS Biology (PLoS Biology).

The researchers thawed rat spermatogonial stem cells (SSC) that had been cryopreserved for more than 23 years, implanted them into nude mice (mice lacking immune response), and compared the sperm capacity of these spermatogonial stem cells with those frozen for only a few months and normal spermatogonial stem cells. It was found that long-frozen stem cells could colonize in mouse testis, and these stem cells could differentiate into all the cell types needed to produce sperm. However, long-term frozen spermatogonial stem cells produce fewer elongating sperm cells (which will continue to grow into swimming sperm cells) than short-term thawed and freshly collected spermatogonial stem cells. Even so, scientists believe that the findings play an important role in preserving the fertility of boys with cancer.

? Physiology?

Cerebrospinal fluid of young mice can improve memory of old mice.

With the aging of the brain, the risk of neurodegenerative diseases gradually increases, and people's cognitive ability will decline. Understanding the aging mechanism of the brain will help scientists to find ways to slow down brain aging. Recently, in a study published in Nature, scientists focused on the role of cerebrospinal fluid in brain aging. They found that memory improvements occurred in older mice after they were infused with cerebrospinal fluid from young mice.

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Cerebrospinal fluid (CSF) is part of the direct environment of the brain, which is responsible for delivering nutrients to brain cells and transducing signals of various molecules and growth factors. The team infused cerebrospinal fluid from young mice (10 weeks old) into the brains of old mice (18 months old) and reported an improvement in memory function. Studies have shown that the cerebrospinal fluid of young mice can enhance the stimulation of oligodendrocyte precursor cells in the hippocampus and has the potential to regenerate oligodendrocytes (a class of nerve cells) and myelin (the fatty substance that protects nerve cells). To clarify the mechanism, scientists studied signal transduction pathways activated by cerebrospinal fluid (CSF) in young mice. The results showed that transcription factor SRF could mediate the effect of cerebrospinal fluid of young mice on oligodendrocyte progenitor cells, and the expression of this transcription factor decreased in the hippocampus of old mice. It was also found that growth factor Fgf17 is a candidate molecule to induce SRF signal transduction. The expression level of Fgf17 in aging mice decreased, and the effect of injecting Fgf17 into old mice was similar to that of infusing cerebrospinal fluid of young mice. The scientists say the study shows that the FGF17 gene has the potential to be a therapeutic target and that this route of administration of drugs directly into the cerebrospinal fluid may be helpful in the treatment of dementia.

? Virology?

Influenza virus can directly invade cardiomyocytes

Patients with influenza are often accompanied by heart disease. Previously, the researchers found that mice without the IFITM3 gene had a weaker ability to clear the virus and had a higher risk of heart disease after infection, while 20 per cent of Chinese and 4 per cent of Europeans also had IF