Why is the panda Qizai brown and white? Scientists have written a family tree for it丨Bolan Daily

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From pregnancy to childbirth,

The volume of the female uterus increases 1,000 times

The size of the uterus can be in two states. One is the normal state, that is, the state when not pregnant.

When not pregnant, the uterus is smaller than our fist, about the same size as a rose or lotus.

In terms of volume, the volume of the uterus when it is not pregnant is only 5 ml. As the fertilized egg embryo grows, this volume will gradually expand and grow to the level required by the fetus.

Therefore, each of us is embraced by maternal love from the day the fertilized egg is born.

At the moment before delivery, the size or capacity of the uterus (together with the fetus, placenta, and amniotic fluid) can reach 5000 ml.

From 5 ml to 5000 ml, the volume increased 1000 times.

About 6 weeks after the birth of the child, the expanded uterus will shrink back to its pre-pregnancy size. These 6 weeks are called "confinement" in China, and the scientific term is "puerperium", which is the process by which the female reproductive system, except for the breasts, returns to its pre-pregnancy size.

Why is the panda Qizai brown and white?

Scientists have written a family tree for it

Giant pandas are traditionally black and white, but Qizai, a panda deep in the Qinling Mountains, has a mixture of brown and white fur. It is also the only brown giant panda in the world. Recently, a team led by Wei Fuwen, an academician of the Chinese Academy of Sciences, published a study in the Proceedings of the National Academy of Sciences of the United States, revealing the genetic secrets behind Qizai's brown and white fur.

By analyzing the genetic data of 157 giant pandas in Foping Nature Reserve and its surrounding areas, scientists constructed two pedigrees of Qizai and found that Qizai's parents and offspring were all black and white. Combining Qizai with the known pedigree of Dandan (Dandan was the first brown giant panda discovered in China in the 1980s and died in 2000), it was inferred that the brown phenotype was controlled by an autosomal recessive inheritance mode.

Further gene sequencing revealed a key genetic variation: the first exon of the BACE2 gene of the brown giant panda was missing 25 base pairs. This deletion is the genetic basis for the coat color variation of Qizi and other brown giant pandas.

Brown giant panda Qizai. Photo by Xinhua News Agency reporter Zhang Bowen

In addition to the findings at the genetic level, the study also observed that the number of melanosomes in the brown panda's fur was smaller and smaller. These melanosomes are organelles responsible for hair and skin pigmentation, and their reduction and shrinkage may be the key to the formation of brown fur color. The research team used gene editing technology to construct a homologous segment knockout model in mice, which also verified this finding.

Breakthrough in hydrogen production from seawater without relying on fresh water!

Hydrogen has the advantages of high calorific value, cleanliness and renewability. Compared with the traditional hydrogen production method based on fossil energy, the electrochemical technology driven by renewable energy (such as solar energy, wind energy, etc.) to directly decompose water to produce hydrogen is considered to be one of the best ways to the "green hydrogen economy" in the future.

Direct seawater electrolysis has become one of the ideal green hydrogen production methods because it does not rely on freshwater resources, but the high cost and catalyst deactivation caused by seawater corrosion have become the main bottlenecks restricting its development.

Recently, the team led by Chen Yong, a researcher at the Photochemical Conversion and Synthesis Center of the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, proposed a strategy for electrochemical reforming of waste PET plastics coupled with seawater to produce hydrogen. By designing a Pd-CuCo2O4 composite electrocatalyst, they can highly selectively reform waste PET into high-value-added glycolic acid.

The results of the mechanism study show that enhancing the adsorption of OH- species on the catalyst surface can improve the catalytic activity, and can form an anion layer on the catalyst surface to repel chloride ions and improve the catalyst stability. In a simulated seawater environment, the system can operate stably for more than 100 hours at an industrial current of 1.6A.

It is estimated that by 2030, China's green hydrogen production will reach 5 million tons to 10 million tons. Do you think the hydrogen energy era is really coming?

Why does the body shake suddenly when sleeping?

If you search online, you may get a variety of answers. Some say it's calcium deficiency, some say it's still growing, and some say it's the nervous system that's sending you a pop-up window. If you open some irregular medical websites, then...

In fact, this is a normal physiological phenomenon, medically known as hypnic myoclonus. This may be difficult to understand, so what is a more understandable explanation?

If you want to move, you have to rely on the brain and nerves to control the muscles. The brain sends out commands, which are received by the nerves, and then the nerves pass the commands to the muscles. It's like a big boss conveying a task to your leader and then conveying it to you...

For example, if you have a holiday tomorrow and your boss forgets to tell your supervisor, your supervisor asks you to arrive on time tomorrow. When you arrive, you look at the empty office and fall into deep thought. When the brain forgets to send the signal that it has "slept", the nerves will continue to command the muscles to work.

The result is that you are sleeping and suddenly shaken because of the wrong instruction. Minors have incomplete neurological development, just like encountering an unreliable "middle-level leader". The brain has weak control over the nerves, so this phenomenon occurs frequently.

The content is compiled from China Science Popularization Expo Weibo, Gezhi Lundao Forum, Institute of Zoology, Chinese Academy of Sciences, Institute of Physical and Chemical Technology, Chinese Academy of Sciences, and Brief History

This article was first published in China Science Expo (kepubolan)