Evolve yeast into multicellular organisms that are 20,000 times larger and 10,000 times physically stronger
The fossil record suggests that the first multicellular organisms appeared about 1 billion years ago.
Since life was born 3.5 billion years ago, it is calculated that it took 2.5 billion years for multicellular organisms to appear.
Considering that it took only 1 billion years from the birth of the earth (4.5 billion years ago) to the birth of life (3.5 billion years ago), it is quite difficult for multicellular organisms to prosper on the earth. I can hear you.
However, recent research has revealed that the trial and error for multicellular life has been repeated constantly, and evolutionary events from single-celled organisms to multicellular organisms have occurred at various times and in various places on the earth. It is known to have occurred more than 20 times independently in
In order for living organisms to achieve multicellularity, there are many issues that must be cleared, such as cell coordination and connection strength.
However, if we succeed in becoming multicellular, we will have the great advantage of being able to divide labor among cells that specialize in specific functions such as digestion, reproduction, locomotion, and sensation.
(*Similar independent multiple evolutions also occur in “Crabification”)
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Therefore, for example, when examining the process by which animals, plants, and fungi (mushrooms, etc.) became multicellular, they were not due to a common multicellular ancestor splitting into three, but to each
“Multicellular Ancestors of Later Animals”
“Multicellular ancestors that later became plants”
“Multicellular ancestors that later became fungi (mushrooms, etc.)”
and are known to have descended from three independent (unrelated) ancestors.
Considering that the “eyes” of animals and the “placenta” of mammals originated from a one-time mutation that occurred in a common ancestor, it can be said that the evolutionary pressure (demand) to promote multicellularity was considerably high. .
butHow unicellular organisms became multicellular is largely a mysterywas surrounded by
Therefore, in recent years, “artificial evolution experiments” that evolve unicellular organisms into multicellular organisms in a laboratory environment have become popular.
for exampleA study done in 2012In , the living environment of yeasts, which are single-celled organisms, was intentionally changed to a harsh environment “for” multicellular organisms, increasing the evolutionary pressure toward multicellularity.
After about 60 days, some of the yeasts began to maintain a snowflake-like state that stuck together even after cell division, as shown in the figure above, leading to multicellularity. It was shown to start walking.
And the multicellular yeast obtained in this experiment was named “Snowflake yeast”.
Similar artificial evolution has been successful in many studies, and it turns out that it is relatively easy to make yeast and algae existing on the earth multicellular.
However, all the organisms that have become multicellular according to existing research are extremely small, with several tens to hundreds of cells.
On the other hand, the number of cells that make up existing multicellular organisms is as large as 1031 even in small animals such as nematodes, 30 billion in mice, and 60 trillion in humans.
Therefore, researchers at the Georgia Institute of Technology this time cultured the snowflake yeast created in 2015 and repeated the selection to collect as large a lump as possible over 3000 generations.
Then, as shown in the figure above, the snowflake yeast, which was just a collection of about 100 cells, promoted multicellularity,Ultimately, it was found to be 20,000 times its original size (1 mm in diameter), and its physical strength had also increased 10,000 times.
Speaking of 1 mm in diameter, it is a size comparable to Drosophila, which is known as a small fly.
In addition, the physical strength, which increased 10,000 times, is comparable to that of wood.
This result shows that yeast, which was originally a single-celled organism, can be evolved to a visible size (macroscopic size) by artificial evolution.
The question then becomes what happened to the yeast.
What kind of transformation did yeast cells that evolved to macroscopic size cause?
