Seeking To Restart Evolution
Seeking to Restart Evolution With Life’s Simplest Ingredients
By William Booth
Washington Post Staff Writer
BOSTONJack Szostak is no Dr. Frankenstein, but if he succeeds in his work, the soft-spoken biologist may be the first to create life in the laboratory.
Szostak and his colleagues at Massachusetts General Hospital here plan to manufacture not a hulking monster with electrodes in his neck, but nature’s most elemental unit of life: a cell.
Their cell, to be built almost from scratch in the next year or so, will not be very sophisticated. Little more than a fat bubble containing bits of genetic material, Szostak’s creations will be so simple and primitive that some rival researchers say it would be almost hyperbolic to call them life.
“I think it’s a perfectly neat thing to do, but really, calling them cells?” said Norman Pace of Indiana University. “It’s probably more tongue-in-cheek than anything else.”
But Szostak is not kidding, and he is not alone. There are at least three major scientific groups around the country trying to create life in the laboratory. Szostak himself is convinced that his cells will be technically alive, at least by his definition. They will replicate. And as important, they will be playthings for the forces of natural selection. As such, Szostak believes his little cells could evolve into more complex beings.
The work of Szostak and his colleagues is designed to address some of the looming questions of how life originated: How simple can life be? And what might the first forms have looked like as they began their long journey toward complexity and variety?
Most people think life as we know it today is quite complicated. But Szostak and his colleagues are attempting to reduce biology to its simplest ingredients. In essence, Szostak’s recipe is as follows:
LIFE
Fat
Water
Spermidine (a ubiquitous but somewhat mysterious compound of carbon, hydrogen and nitrogen first detected in human sperm)
A special segment of RNA from a protozoan called Tetrahymena thermophilia.
Modify the RNA slightly. Set aside. In a separate bowl, mix the other ingredients. Slowly add RNA to broth of fat, water and spermidine.
Allow soup to sit while fats self-assemble into membranes that curl up into cell-like bubbles, encapsulating bits of RNA, water and spermidine. These are the cells.
Replenish periodically with small bits of RNA, which serve as food for the new cells. Shake vigorously to make cells divide.
Repeat feeding and shaking indefinitely. Check occasionally for evolution.
The central ingredient in Szostak’s cells is the RNA, for ribonucleic acid, which many scientists believe was the first master molecule of life, contained in the original cells that arose from the primordial soup about 4 billion years ago. Today, the master molecule is the similar but more complex deoxyribonucleic acid, DNA. But in the beginning, DNA’s more primitive and unstable ancestor may have reigned supreme, in a realm molecular biologists call the “RNA World.”
Why wasn’t DNA the first molecule of life? All cells living today rely on DNA to act as their genes, carrying the instructions for making various specific kinds of proteins, the workhorses of life. But there is