Caught the world's largest freshwater fish in the Mekong River, weighing 300 kg; South Korea's successful launch of a self-developed rocket | global scientific highlights

· Zoology ·

The largest freshwater fish found in the Mekong, weighing 300 kg

300 kg stingray. Image credit: Wonders of the Mekong

Recently, fishermen on Cambodia's Mekong River caught a 300 kg Urogymnus polyepis. The U.S.-funded Wonders of the Mekong Research Project claims that the stingray broke the previous record for the largest freshwater fish, following the 293 kilograms of Giant Mekong Catfish caught in Thailand in 2005. The stingray was eventually released, and before being released into the river, the researchers attached an acoustic tag to it in an attempt to understand the mysterious creature's elusive behavior.

· Aerospace ·

South Korea successfully launched a fully self-developed launch vehicle

At 16:00 local time on June 21, South Korea's self-developed carrier rocket "Soyok" was launched for the second time, and the launch site was located at the Roroo Aerospace Center in Koxing County, Jeolla Nam Province, South Korea. The rocket carried a 162.5 kg performance verification satellite, a 1.3-ton satellite model and four miniature cubesats, all in predetermined orbit. After the performance verification satellite entered orbit, it successfully contacted the Sejong Science Base in Antarctica, South Korea, and confirmed the position of the satellite.

The World is a three-stage carrier rocket with a total length of 47.2 meters and a total weight of 200 tons, which can send 1.5-ton satellites into an orbit of 600 to 800 kilometers above the ground. The World was first launched on October 21, 2021, but was unable to send the rocket's model satellite into a predetermined orbit due to the early depletion of fuel for the third stage engine. With this launch, South Korea became the 11th country after North Korea to have the capability to launch launch launch vehicles autonomously. (Xinhua News Agency)

· Molecular biology ·

A new mechanism of blood formation

The conventional wisdom is that blood cells are differentiated from hematopoietic cells. Recently, a study published in Nature broke with this traditional belief and proposed that blood cells actually come from two types of mother cells. In 2020, the team reported on a cell lineage tracking technique they developed in The Cell magazine. The technique "barcodes" individual cells, specifically, by using transposase or CRISPR gene-editing tools, they can insert unique gene sequences into mouse embryonic cells, which allows all cells that differentiate from those embryonic cells to carry the sequence.

In the new study, the researchers used "barcodes" attached to embryonic cells to track the different types of blood cells and their mother cells that appeared in mice at different ages. They found that the transformation of skin cells into hematopoietic cells during the embryonic period was accompanied by another type of mother cell, embryonic pluripotent progenitor cells (eMPPs). The researchers said that most of the blood from embryonic to early adulthood comes from eMPP, after which the number of blood cells differentiated from eMPP gradually decreases. In addition, compared to hematopoietic cells, eMPP is also the main source of immune cells such as B cells and T cells. In the future, researchers will use the newly discovered mother cells to treat blood-related diseases.

· Aerospace ·

NASA's space launch system passes fuel refueling tests

According to NASA, the Large Lunar Rocket Space Launch System (SLS) Artemis I completed a wet suit test on June 20, local time. Wet-loading testing includes fuel refueling and a countdown to rocket launches, but no ignition launches. During the refueling, the rocket team noticed a hydrogen leak in the connecting pipe between the mobile tower and the rocket, and they tried unsuccessfully to repair it, and then decided to continue testing. Such a leak could delay the launch program during a real launch, but the rocket team ignored these warnings in order to complete the full-process test. According to the plan, the rocket wet loading test should continue until 9 seconds before the countdown to the rocket launch, but eventually because of the hydrogen leak, it can only be stopped at 29 seconds after the launch countdown.

Artemis 1 will then be moved from Launch Pad 39B to the assembly building, where technicians will further analyze the results of the test. On April 14 this year, Artemis 1 also suspended testing due to a leak in the connecting pipe between the mobile launch tower and the rocket.

· Health ·

Whether to take vitamins

The Journal of the American Medical Association recently published an editorial saying that for unpregnant and healthy Americans, buying and taking vitamins is just a waste of money because there is not enough evidence that vitamins help prevent cardiovascular disease or cancer. Previously, the U.S. Preventive Services Task Force (USPSTF) had reached the same conclusion based on 84 systematic reviews. Also, the USPSTF recommends against taking β-carotene supplements because they may increase the risk of lung cancer. In contrast, fruits and vegetables contain a mixture of vitamins, phytochemicals, fiber, and other nutrients, and the synergy between these substances may be the reason why fruits and vegetables are good for good health. However, for some individuals who are deficient in vitamins, dietary supplements such as calcium and vitamin D can also benefit their health, such as preventing fractures. In addition, the recommendations made by the USPSTF do not apply to pregnant women because some vitamins, such as folic acid, are essential for fetal development. More data is needed in the future to understand the possible effects of vitamin supplements during pregnancy.

· Medicine ·

"Softening" the ovaries helps restore fertility

Fertility in women usually declines from the 30s, and the decline is severe with age until menopause. As for why fertility declines, a new study published in the journal Science Advances points out that during age, mouse ovaries accumulate some "stiff" tissue; Reducing such tissue, or "softening" the ovaries, helps animals regain their fertility.

For women, the number of oocytes in the ovaries is limited, and as they age, ovulation gradually becomes sporadic and disordered, eventually leading to loss of fertility. Researchers suspect that one of the main causes is fibrosis, an abnormal proliferation of connective tissue, a process that hardens the ovaries and can cause ovulation disorders. The scientists administered the fibrosis-reducing drug pirfenidone to 15-month-old female mice (about the equivalent of humans in their early 50s), and more than half of them ovulate, while the unmedicated control group of females did not. The eggs produced by these elderly female mice are fertilized and healthy embryos are developed. In addition, the scientists also administered the same drug to female mice that were 12 months old (equivalent to about 35-year-old humans), and as a result, their ovulation rate was almost double that of unmedicated female mice of the same age, and the fertilization rate and embryonic development rate were normal. Young mice ovulated without being significantly affected by the drug. When the researchers looked at the ovaries in the microscope, they found that the degree of fibrosis in middle-aged and elderly mice was indeed significantly lower than that of the control group. Scientists believe that ovarian fibrosis associated with aging can be reversed, thereby improving ovulation function and prolonging the reproductive period.

· COVID-19 ·

As of 10:00 Beijing time on June 22, according to the latest statistics of Johns Hopkins University, the global cumulative number of confirmed COVID-19 cases is 540,535,654, and the number of deaths is 6,321,976.

According to the data of the official website of the National Health Commission, at 0-24:00 on June 21, 31 provinces (autonomous regions and municipalities directly under the Central Government) and the Xinjiang Production and Construction Corps reported 31 new confirmed cases. Among them, there were 21 imported cases (7 cases in Guangdong, 4 cases in Tianjin, 4 cases in Fujian, 3 cases in Shaanxi, 1 case in Beijing, 1 case in Inner Mongolia, 1 case in Zhejiang), including 5 cases converted from asymptomatic infected people to confirmed cases (2 cases in Tianjin, 1 case in Zhejiang, 1 case in Fujian, 1 case in Guangdong); There are 10 local cases (4 in Beijing, 4 in Shanghai, 1 in Inner Mongolia and 1 in Guangdong). There were no new deaths. There were no new suspected cases.

31 provinces (autonomous regions and municipalities directly under the Central Government) and the Xinjiang Production and Construction Corps reported 95 new cases of asymptomatic infection, of which 83 cases were imported from abroad and 12 cases were local (4 cases in Liaoning, 4 cases in Shanghai, 2 cases in Beijing, and 2 cases in Guangxi).

As of June 20, 2022, 31 provinces (autonomous regions and municipalities directly under the Central Government) and the Xinjiang Production and Construction Corps have reported a cumulative total of 3,395.704 million doses of COVID-19 vaccine.