Biophysical Society Newsletter - July 2015

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BIOPHYSICAL SOCIETY NEWSLETTER 14 JULY 2015
Subgroups
BIV
An interview with Arnold Boersma, a research
fellow at the University of Groningen and co-cor-
responding author on the paper, A Sensor for Mac-
romolecular Crowding in Living Cells, A.J. Boersma,
I.S. Zuhorn, and B. Poolman; Nat Methods, 2015,
12: 227-229.
Arnold, could you describe the molecular
components of your sensor? The crowding sensor
consists of three parts, two fluorescent proteins
connected by a flexible linker that includes two
stable helices. The fluorescent proteins form a
FRET pair, allowing one to monitor the size (com-
pactness) of the molecule in response to crowding
effects.
What experiment convinced you that the sensor
is responding to changes in excluded volume?
The FRET signal increases with increasing size or
amount of added polymers like Ficoll, but the cor-
responding monomers (e.g. sucrose) do not change
the signal, ruling out direct chemical interactions.
How were the measurements obtained with
living cells? The intensities of the emission of the
FRET donor and acceptor were determined by
confocal microscopy. Taking into account auto-
fluorescence from the cells, the ratio of the two
fluorophores was determined after splitting the
emission into two channels.
How did you alter the extent of crowding, and
what was the result? We increased the osmolar-
ity of the medium which leads to dehydration of
the cells and an increase in crowding. When we
tested the sensor under these conditions, we indeed
observed an increase in the FRET signal, which
diminished when we allowed the cells to adapt to
the osmotic stress.
What next? This research was done as part of a
grant aimed at developing an independent line
of research, hosted in Bert Poolman’s laboratory.
Next, I’m planning to continue on this path and
further improve our understanding of the physi-
cochemical environment in the cell – there is still
much to learn about the cell interior which cannot
be extracted from the genome but is crucial for life!
BIV Subgroup Store
Need to commemorate the achievement of a lab
group member or colleague? Consider buying a
unique gift from the BIV Subgroup Store! (http://
—Daryl K. Eggers , Subgroup Secretary-Treasurer
Grants and Opportunities
East Asia and Pacific Summer Institutes for
U.S. Graduate Students (EAPSI)
Objective: To provide U.S. graduate students in
science, engineering, and education first-hand
research experiences in Australia, China, Japan,
Korea, New Zealand, Singapore, or Taiwan; an
introduction to the science, science policy, and
scientific infrastructure of the respective location;
and an orientation to the society, culture, and
language.
Deadline: November 12, 2015
Website: www.nsf.gov/funding/pgm_summ.
jsp?pims_id=5284
The Sunnybrook Research Prize
Objective: Student should be in third or fourth
year of study at a Canadian university by Fall
2015 and have completed a research project with
a focus on biomedical research.
Deadline: October 29, 2015
Website:
content/?page=sri-ed-undergrad-prize
Arnold Boersma