The research team with Shuya Bongard, a professor of computer science at the University of Vermont, as the corresponding author, recently published the latest research results online in the proceedings of the American Academy of Sciences, proposing that a programmable creature can be created, which is named xenobot (heteromorphic robot), also known as biological robot.

After the research of Bongard and others was published, it aroused a lot of doubts. So what exactly is their job?

American scientists have created a biological robot called xenobot

1. How was xenobot made?

Bongard defined this artificial life: “they are neither traditional robots nor known animal species. It is a living, programmable organism.”

It is not a traditional robot, that is, a robot that is not a mechanical device, but a biological robot less than 1mm, that is, a micro biological robot, which is much larger than microorganisms and larger than some parasites. It’s just that it’s man-made. Other microorganisms, such as bacteria, viruses, chlamydia and mycoplasma, as well as animals, plants and people, are all organisms that naturally evolve and exist on the earth.

Xenobot’s synthesis first obtained two kinds of cells: heart cells and epidermal cells of African claw frog, but both of them were differentiated from embryonic stem cells of African claw frog.

The researchers cut the embryonic cells under the microscope. The two parts of the cells were cut and cultured separately. Then the two kinds of cells are pieced together, using the natural inclination of cells to adhere to each other. The researchers then looked at how their unique structures, including the arrangement of cells and the overall shape of spots, corresponded to behavior.

The relevant data were sent to the team of computer scientists at the University of Vermont, who built a simulated environment using the digital version of the special-shaped robot by the supercomputer cluster deep green, and took advantage of the natural selection process of life evolution. According to this model, xenobot that completes specific tasks in simulation is considered “appropriate”, so as to create a new generation of “evolutionary” xenobot. The researchers also used tweezers and electrodes to “carve” the remodeled cell according to the design simulated by the supercomputer. The remolded cells have different shapes, some wedge-shaped and some arch shaped.

Xenobot is composed of African claw frog heart cells (contractile cells) and epidermal cells (passive cells), so it has a variety of life characteristics of natural life, such as moving in aqueous medium, self-healing ability and self biodegradation. The most powerful thing is that even if the biological robot is cut in half, it can not only sew itself up, but also continue to move, a bit like the self-healing function of salamanders. Moreover, they can not only travel in a straight line, but also turn in circles. If the robot is turned over, it will lose its ability to move like a turtle with its back down.

At present, this kind of biological robot can be used to clean up the micro plastic pollution in the ocean, as a biodegradable drug delivery robot, and its future role will be unlimited, for example, as a surgical assistant to dredge blood vessels.

2. There are many artificial life in the world

However, xenobot is not the first man-made living life in the world. Before that, there had been pure biosynthetic man-made life.

As early as 1995, Craig Venter of the United States and another biologist Hamilton Smith created the first bacteria with an artificial genome (chromosome set), which is not only a living organism that does not rely on the previous generation, but also the prototype of artificial life.

On May 20, 2010, a team of 46 scientists from Venter private research institute developed the first artificial cell on earth, a goat mycoplasma cell. The genetic material in the cell was synthesized according to the genome of another species Mycoplasma fungoides. The artificial cell showed the life characteristics of the latter, named Cynthia (Synthia, meaning “synthesis”).

Cynthia, a microorganism composed of blue cells, can grow and reproduce. The cells have divided more than 1 billion times and can produce artificial life generation after generation. The implanted DNA fragment contains about 850 genes, while the human genome contains about 20000 genes.

The genes in the chromosome constructed by the researcher are composed of 1.08 million pairs of “letters” and leave a “watermark” on the synthetic genes, including the names of 46 scientists and researchers, the website of the Institute, and the famous sentence “survive, make mistakes, fall, overcome, and create life with life” by Irish writer James Joyce. The study was published in the journal Science on May 21, 2010.

Venter et al. Selected a bacterium called Mycoplasma filamentosum and decoded its chromosome. Then rearrange the DNA bit by bit using chemical methods. After that, the recombinant DNA fragments were put into the yeast solution and slowly re polymerized. Then put the artificial DNA into another receptor bacterium. Through growth and isolation, the recipient bacteria produce two cells, one with artificial DNA and the other with natural DNA. Antibiotics are added to the Petri dish to kill the cells with natural DNA, leaving only artificial DNA proliferating. Within a few hours, all traces of the original DNA in the recipient bacteria disappeared, artificial cells continued to reproduce and new life was born.

What is the use of synthesizing such artificial life? Venter’s answer is to synthesize the minimum number of genes available for life, and then make up for other genes to create a series of new microorganisms, such as bacteria that can produce biofuels, useful drugs, bacteria that can absorb carbon dioxide and other pollutants from the air, or proteins needed to make synthetic vaccines.

Since then, on August 2, 2018, nature published two papers by American and Chinese researchers online at the same time, both of which were the results of yeast chromosome fusion. Chinese researchers have created a new synthetic yeast strain sy14, which contains only one huge linear chromosome, which is different from the wild-type yeast with 16 chromosomes.

The synthetic yeast is eukaryote. Animals, plants and fungi belong to eukaryotes. Their genomes are rich and complex. They usually contain hundreds of millions to billions of base pairs, which is not easy to synthesize. However, the genomes of bacteria, viruses and other prokaryotes are relatively simple and easy to synthesize. Therefore, the synthesis of eukaryotic genome has reached a new level and played a greater role in technology.

Saccharomyces cerevisiae is the first eukaryote sequenced by the whole genome. The large-scale design and reconstruction of yeast genome is a direct test of the authenticity, integrity and accuracy of the knowledge reserve in the yeast field. Synthetic yeast, on the one hand, can help human beings understand some basic biological problems more deeply. On the other hand, through genome rearrangement system, yeast can realize rapid evolution and obtain strains with important application potential in medicine, energy, environment, agriculture, industry and other fields.

3. Advantages and disadvantages of synthetic artificial organisms

Xenobot, Cynthia and artificial yeast are synthetic living life, but Cynthia is simpler and is synthesized based on prokaryotes, while artificial yeast is synthetic eukaryotes. Xenobot is also synthesized using eukaryotic model, and uses the combination of life evolution model and computer programming function. Xenobot’s volume is much larger than the artificial life created in the past, close to 1mm, while mycoplasma is only 0.1-0.3 microns and yeast is 2-10 microns. Therefore, xenobot can complete far more work and functions than mycoplasma and yeast.

However, will they pose a threat to human society and become biological weapons? This may be why people are afraid. As early as 2010, when Venter and others created Cynthia, the United States held hearings in many fields and departments, asking Venter and others to fully explain the positive and negative significance and application of artificial life. The hearing raised 13 questions about the synthesis of new life, including why to synthesize artificial cells (life); What are the potential uses of artificial life; What are the risks of synthetic organisms; What are the prepared protection and control measures to prevent the accidental release of artificial life to the environment.

For the safety of synthetic new life, Venter et al. Said that synthetic biology, like many genomic technologies, can not only produce beneficial bioengineering microorganisms, but also create microorganisms harmful to humans and the environment. Of course, such technologies may be used by evil people with extensive resources.

However, nature itself is an existing expert, and it is also creating microorganisms that can cause great harm to human beings. Synthetic new life does not necessarily lead humans to a path closer to harm than existing technology or nature itself. In this regard, what is needed is strict management.

In fact, after the current xenobot is designed, we can not only see its great use, but also see that it may cause harm to people and the natural environment in its application. The key is the need for legislative management to ensure that there must be supporting regulatory constraints in the application of xenobot.

Various forms of life

The biggest difference between artificial life and natural life is that the former is “life as it can be”, while the latter is “life as we know it”. As I know, life is all kinds of animals, plants and microorganisms that people already know today; The life it can include digital life, virtual life and man-made life (things) that may exist on other planets but have not been discovered.

Amosif, a famous American scientific writer and biochemist, has several divisions of natural life. One is fluorinated silicone biological with fluorinated silicone as medium; The second is sulfur fluoride biological with sulfur as the medium; The third is nucleic acid / protein (oxygen based) biology with water as medium; Fourth, nucleic acid / protein (nitrogen based) biology with ammonia as medium; Fifthly, lipid biological compounds with methane as medium; The sixth is the biological of lipid compounds with hydrogen as the medium.

Although xenobot created by American scientists is a micro biological robot, most of it is created according to the fourth principle of natural life, that is, nucleic acid / protein (nitrogen based) life with ammonia as the medium. So it has similarities with natural life.

Responsible editor; zl

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