Transcript Sieracki_July 5_Colloquium - C-MORE

Should We Study Microbes at
Microbial Scales, and If We
Should, How Can We?
Michael Sieracki
Bigelow Laboratory for
Ocean Sciences
Philosophy
• Scientists try to be rational, objective, and unbiased.
Philosophy
• Scientists try to be rational, objective, and unbiased.
• But scientists are human, and humans are irrational,
subjective, and biased.
Philosophy
• Scientists try to be rational, objective, and unbiased.
• But scientists are human, and humans are irrational,
subjective, and biased.
• Human minds are visual, and we like stories.
Philosophy
• Scientists try to be rational, objective, and unbiased.
• But scientists are human, and humans are irrational,
subjective, and biased.
• Human minds are visual, and we like stories.
• So much of what we “know” about nature is based on
good stories that hold together and are pleasing to us.
Evidence and observations fit into these stories, so they
are believable. But that does not make the stories true.
Wolpert, Lewis (1993, reprinted 2000)
The unnatural nature of science: why
science does not make (common) sense.
Harvard University Press.
Advice
• Learn everything you can about your subject, from
lectures, literature.
• Know it, but do not believe it (this is not religion).
• You must know the subject to judge when an idea or
observation is new.
• Be skeptical of experts, do not believe what we tell you
or what you read.
• Trust your own eyes, your own observations, over what
someone else says or has written (especially experts).
• Question your instructors, make them uncomfortable,
find out what they don’t know.
Plankton Orders of Magnitude
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
“Micro-liter-sphere”
1 cm
Number of organisms in 1
microliter of open ocean water
10,000
Viruses
1,000
Bacteria
10
Picophytoplankton
1
Flagellates
1 microliter (µL)
= 1 cubic millimeter
(mm3)
Ciliates
Diatoms
0.02
.
0.02
Microbial Food Web
Flagellates
Ciliates
Small phytoplankton
Dissolved Organic
Matter
All forms produce dissolved organic matter
Bacteria
“Microliter-sphere”
In every microliter of
seawater there are all
the organisms for a
complete, functional
ecosystem.
These organisms form the
fabric of life in the sea
- the other organisms
are embroidery on this
fabric.
“Microlitersphere”
• Nice story, but….
“Microlitersphere”
• Nice story, but….
• Is it true??
“Microlitersphere”
• Nice story, but….
• Is it true??
• What could be wrong with this picture?
“Microlitersphere”
• Nice story, but….
• Is it true??
• What could be wrong with this picture?
• Hint: what are the assumptions?
DAPI stained bacteria
Polymer Gels
Tanaka 1993
Polymer gels are naturally produced and
dispersed in seawater
1 nm
1 um
Ca2+
Ca2+
Ca2+
assembly
Ca2+
Ca2+
Ca2+
annealing
Ca2+
Ca2+
Ca2+
Ca2+ Ca2+ Ca2+
Ca2+
dispersion
Ca2+ fragmentation Ca2+
Ca2+
Ca2+
Ca2+
Ca2+
Ca2+
Ca2+
MacroCa2+
Ca2+
molecules
Nanogel
Microgel
Orellana and Verdugo 2003
Azam Impressionist View
1998 Science 280:694-696
• “Organic matter
continuum”
• Dissolved to
particulate
Bacterial clustering around protists
• Darkfield
microscopy
Blackburn et al. 1998
Science 282:2254-2256
Should we study microbes at microbial scales?
……… if so ……. how?