February 27, 2012 - IMM@BUCT

C&EN TALKS WITH
PENNY CHISHOLM
MIT BIOLOGIST discusses the benefits of public outreach
CRAIG BETTENHAUSEN , C&EN WASHINGTON
PROCHLOROCOCCUS is the smallest
cell on the planet that can harvest
energy directly from the sun. This tiny
marine cyanobacterium, less than
1 µm across, represents a huge portion
of the ocean biomass; an estimated
10 27 of them roam the oceans. Yet scientists
were unaware of Prochlorococcus
until 1985, when Massachusetts Institute
of Technology biologist Sallie
W. (Penny) Chisholm and colleagues
from Woods Hole Oceanographic
Institution spotted a chlorophyll
fluorescence coming from a tiny cell
careening through the capillary tube
of their flow cytometry apparatus. The discovery begat a sea change
in the understanding of the ocean’s food web.
In addition to its outsized role in the ecosystem, Prochlorococcus
also has the smallest genome of any O 2 -evolving organism, at around
2,000 genes. The portion that codes for the photosynthetic machinery—1,200
genes that are conserved across the many different
strains—composes the most succinct genetic picture of photosynthesis
available. But even 26 years after the discovery of Prochlorococcus
, though the organisms “contribute a significant fraction of global
photosynthesis,” Chisholm laments, “nobody knows about them.”
Chisholm perceives a gap in the public’s scientific literacy surrounding
photosynthesis, which frustrates her because the process
is so central to life. She points to a 1997 video produced by the Harvard-Smithsonian
Center for Astrophysics, in which freshly minted
Harvard University and MIT graduates are handed a seed and a log
and asked where the mass of a tree comes from. The students offer
water and nutrients drawn from the soil as candidates and are incredulous
when presented with the idea that the vast majority of the
mass is derived from CO 2 in the air.
The general public “doesn’t understand photosynthesis, and
they should,” Chisholm recalls venting to her friend Molly Bang, a
children’s book author, in 2001. A few years later, Bang was looking
for another science topic to follow up on her 2004 book “ My Light ,”
which teaches children about electricity and introduces the idea
that it ultimately comes from the sun. In 2005 Chisholm and Bang
began work on what would become their 2009 collaboration “ Living
Sunlight: How Plants Bring the Earth to Life .” It
is solidly a children’s book, but kids are far from the
only targeted audience. “Most adults aren’t going to
buy a book about photosynthesis for themselves,”
Chisholm tells C&EN, “but they might buy one for
their children and read it to them.”
In “Living Sunlight” Chisholm and Bang focus
on photosynthesis on land, writing at a kindergarten
to fifth-grade reading level about how plants
absorb the sun’s rays and use that energy to convert
water and CO 2 into glucose, which then feeds the
JAMES M. LONG
“Most adults
aren’t going to
buy a book about
photosynthesis for
themselves, but
they might buy one
for their children
and read it to them.”
WWW.CEN-ONLINE.ORG 56 FEBRUARY 27, 2012
rest of the food web. The colorful illustrations
and simple text are supplemented
with an appendix that is more
substantial than those found in most
children’s books. The pair teamed up
for another book, titled “ Ocean Sunlight:
How Tiny Plants Feed the Seas ,”
that is slated to come out in May.
The upcoming work opens by reminding
readers about land plants
and then asks: If life on land depends
on plants and there’s all this life in the
sea, where are the plants of the sea?
“ ‘Ocean Sunlight’ has been the hardest
thing I’ve ever done,” Chisholm
says. The hardest bit was boiling her life’s work down to its essence
and not letting other details sneak in. But given Chisholm’s enthusiasm
for the research, she found it hard to leave the details out.
In “Ocean Sunlight,” for example, Chisholm and Bang talk about
bottom-up population control, the idea that the availabilities of nitrogen
and phosphorus limit the growth of phytoplankton like Prochloroccus
. However, top-down control, wherein predation limits
populations, is mentioned only in passing. It’s complex, Chisholm
says. “We’re trying to teach systems dynamics to six year olds.”
WRITING CHILDREN’S BOOKS has forced Chisholm to set priorities
and think holistically about how her work fits in a larger context.
In much the same way, teaching undergraduate classes has helped
Chisholm develop a vision for her research and a compelling way to
explain its importance to scientists and laypeople alike.
That broader perspective has an impact in the lab. “Thinking
about the big picture,” Chisholm argues, “has become a great asset
for my research. It helps me identify the fundamentally important
questions—it provides a compass for our work.” Communicating
with the general public pays dividends in that process, she says, and
collaborating with Bang on “Living Sunlight” and “Ocean Sunlight”
has been an extension of that.
Because of the books, she is invited to speak at a wide range of
events. For example, she gives regular talks on the MIT alumni
lecture circuit, and she speaks to MIT’s Knight Science Journalism
program each year. “Anytime you’re invited to do a talk for a general
audience, go for it; there is no better way” to get
down to the core of a scientific problem, she says.
“At most universities, there are more opportunities
for outreach than there is faculty interest or
time,” Chisholm notes. To her, however, outreach to
the general public should be a priority for scientists,
right alongside the demands of research, funding,
and management. “I’ve been enjoying the taxpayers’
dollars for 35 years, having all this fun in the lab, so
I feel it’s really important that I make every effort I
can for them to understand what we learn.” ◾