Philosophical Society of Washington

Minutes of the 2348th Meeting

President Larry Millstein called the 2348th meeting of the Society to order on May 8, 2015 at 8:02 p.m.  He announced the order of business and welcomed new members to the Society.  As the evening’s lecture was the 84th Joseph Henry Lecture, President Millstein said a few words about Joseph Henry and his contributions to the Society and he, then introduced the speaker, Pamela Silver of Harvard Medical School.  The lecture was entitled “Synthetic Biology:  The Technology Engine of the 21st Century.”


Dr. Silver stated that synthetic biology is the technology of the century.  Biology is the best chemist there is, she said, pointing out that biological structures are very sensitive, can send and receive signals, can be easily duplicated, and are modular.  We will begin to harness biology in profound ways in the 21st century.

The Synthetic Biology Working Group at MIT has been working to make biological techniques easier, more predictable, and faster to engineer.  One way to think about this is that engineering life is like programming computers.  Scientists edit DNA “code” to program cells to perform specific functions.  Current processes for doing this are tedious.  One goal of synthetic biology is to build standardized biological circuits and techniques to do the programming efficiently.

Scientists have more DNA material to work with than ever before.  The price of sequencing DNA has fallen rapidly.  It is now possible to find genes from humans and non-humans that encode proteins with desired functions. And high-throughput analytical techniques provide fast feedback in the development process.

Some critics think synthetic biology is dangerous.  But Dr. Silver said scientists have a responsibility to develop it.  She discussed the safety concerns that arose when recombinant DNA techniques were first developed.  She noted that effective rules were developed to ensure safety and that fears about the technology turned out to be unfounded.  As synthetic biology moves forward, she believes that ethical and social concerns can be addressed to the satisfaction of scientists and the public.

An early success for synthetic biology was synthetic insulin.  Today scientists are working on much more complicated problems.  She discussed one research program that took a gene pathway from a rare plant and put it in bacteria to make a drug to treat malaria.  The work took eight years and cost several hundred million dollars.  A goal of synthetic biology is to speed the process and lower the costs so that it can be readily applied to real-world problems.

She then discussed some additional problems and synthetic biology solutions.  One was energy sustainability.  Solar power is sustainable, she said, but we are able to use only a very small fraction of power from the sun.  Plants and microbes do better.  But photosynthesis evolved about 3.5 billion years ago when atmospheric O2 levels were lower and CO2 levels were higher.  It is very inefficient in sequestering carbon.  Research is focusing on photosynthetic microbes that do better at current levels of oxygen, such as cyanobacteria, responsible for about 50% of oceanic photosynthesis.  Scientists have reprogrammed cyanobacteria to produce sugar, a high-value commodity.  The process is more efficient than growing sugar cane.  The same approach could be used to make fuel and other commodities.

Dr. Silver then discussed the “Bionic Leaf.”  Her colleague Dan Nocera developed an inexpensive, inert catalyst for splitting water in the presence of sunlight.  Together they developed bacteria that can capture energy by consuming the hydrogen.  The system’s efficiency is about 5%, as good as algae and better than corn.

There are many therapeutic and diagnostic uses of synthetic biology, she said.  One project is to develop cells that remember the response to a pathogen, and that then can destroy it if further exposure occurs.  In a sense, these will be biological computers, responding to an input signal based on a programmed memory.  Other projects are to engineer bacteria to detect exposure of mice to antibiotics and to count the number of times a cell has divided (a biological counter).

Finally, she discussed a more recent project, joining fashion to biology:  clothing embedded with living, photosynthetic cyanobacteria.

In closing, Dr. Silver said the possibilities are enormous, and she asked the audience:  What do you want to build?

After the question and answer period, President Millstein thanked the speaker, made the usual housekeeping announcements, and invited guests to join the Society.  At 9:28 p.m., President Millstein adjourned the 2348th meeting of the Society to the social hour.


Attendance: 118
The weather: Partly Cloudy
The temperature: 24.7°C

Respectfully submitted,

Zeynep Dilli
External Communications Director & Recording Secretary


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