UCLA physics professor ‘loves viruses’

 

By Emily Khaykin

UCLA physics professor Robjin Bruinsma discussed the reasons “why physicists love viruses” in an optional assembly that was given in Ahmanson Lecture Hall on Dec. 3.

About 60 students and teachers attended the event which was during a special break period.

Professor Bruinsma came to speak as a favor to his friend, science teacher Antonio Nassar.

Bruinsma explained the similarities between physics and biology and how they have collaborated over the years in research on different viruses.

He described viruses as “part of a gray, intermediate world between living and dead matter.”

Bruinsma said that many of the tools that biologists use were first developed by physicists. For example, the electron microscope, developed in Germany, was made by physicists.

“When you look at the shape of a virus, you can tell how close we are to the world of atomic physics,” Bruinsma said.

Bruinsma stressed physicists’ interest in the symmetry of a virus. Bruinsma explained that physicists use a method called X-Ray crystallography to determine the geometry of the atoms within a virus.

Bruinsma cited several examples of physicists who conducted experiments on viruses and found some astonishing results.

For example, by taking the tobacco mosaic virus’ protein and combining it with water, salt and capsids in a test tube, two physicists, Heinz Fraenkel-Conrat and Robley Williams, discovered in 1955 that viruses were examples of “complex systems that spontaneously assemble to make working systems.”

Another example Bruinsma gave was based on Sir Aaron Klug’s work.

Klug was the first to “show the mechanical way of how viruses assemble,” using a phase-diagram, a common graph to describe a change in motion in physics.

Klug’s discovery also showed that spherical viruses have icosahedra symmetry, making them “exactly the same shape as a soccer ball,” Bruinsma said.

Bruinsma also talked about important discoveries by Sir Francis Crick, a physicist who helped discover the structure of DNA.

Bruinsma said that Crick was one of the first scientists to ask the question “Why are viruses icosahedra?”

This question, along with many others related to it, is what Bruinsma’s team of physicists at UCLA are currently working on.

“Using simple physics principles, we figured that viruses, like many other things in nature, want a low surface to volume ratio,” Bruinsma said. “Right now we are trying to push the idea that virus capsids are like miniature elastic shells.”

“That would mean that from the physics of elasticity, we know that the harmonic spring of the shell would determine the radius or the thickness of the shell,” Bruinsma said.

“Virus shells are like plastic, they have properties similar to plastic, but at the same time, a virus, unlike plastic, can be assembled and disassembled,” Bruinsma said.

“This is what initiated the love affair between physics and biology,” Bruinsma said.

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