Introduction to Chlamydomonas:
a model organism for active material
Dr. Cynthia Barber
Nicastro Lab, Brandeis University
Active Matter Workshop
Feb 20th, 2013
Thursday, March 7, 13
Chlamydo-what?
Chlamydomonas-singled celled algae
Thursday, March 7, 13
Characteristics of Chlamydomonas
~10um in diameter
two ~12um flagella
Thursday, March 7, 13
Characteristics of Chlamydomonas
Colored eye spots
Dieckmann (2003)
Thursday, March 7, 13
Characteristics of Chlamydomonas
cell wall- resist osmotic pressure
chloroplasts- photosynthesis
pyrenoid- carbon fixation
Figure 2.1 The Chlamydomonas Sourcebook, 2nd ed.
Thursday, March 7, 13
Chlamydomonas lifecycle
The Chlamydomonas Sourcebook, 2nd ed.
Thursday, March 7, 13
Chlamydomonas lifecycle
The Chlamydomonas Sourcebook, 2nd ed.
Thursday, March 7, 13
Chlamydomonas in the lab
no flagella while on plates
Thursday, March 7, 13
Chlamydomonas in the lab
grow flagella in ~1hr in liquid cultures
Thursday, March 7, 13
Hundreds of species
living in:
soil, fresh water,
salt water, snow,
ice, etc.
Proschold et al. (2001)
Thursday, March 7, 13
Hundreds of species
living in:
soil, fresh water,
salt water, snow,
ice, etc.
Chlamydomonas reinhardtii
Proschold et al. (2001)
Thursday, March 7, 13
Hundreds of species
living in:
soil, fresh water,
salt water, snow,
ice, etc.
Chlamydomonas reinhardtii
Isolated from a potato field in
Amherst, MA in 1947
Proschold et al. (2001)
Thursday, March 7, 13
Chlamydomonas as active matter
Thursday, March 7, 13
Chlamydomonas as active matter
swimming
phototaxis
photoshock
Thursday, March 7, 13
Chlamydomonas as active matter
swimming
phototaxis
photoshock
Flagella function/regulation
Thursday, March 7, 13
Chlamydomonas Behavior- Forward Swimming
Power Stroke
Weibel D B et al. PNAS 2005;102:11963-11967
Thursday, March 7, 13
Recovery Stroke
Chlamydomonas Behavior- Forward Swimming
Power Stroke
Recovery Stroke
~150um/s
~50Hz
Weibel D B et al. PNAS 2005;102:11963-11967
Thursday, March 7, 13
Chlamydomonas Behavior- Forward Swimming
Power Stroke
Recovery Stroke
~150um/s
~50Hz
Weibel D B et al. PNAS 2005;102:11963-11967
helical path rotating at a frequency of 2Hz
Thursday, March 7, 13
Chlamydomonas Behavior- Forward Swimming
Power Stroke
Recovery Stroke
~150um/s
~50Hz
Weibel D B et al. PNAS 2005;102:11963-11967
helical path rotating at a frequency of 2Hz
Daniel Chen in Dogic Lab
Thursday, March 7, 13
Chlamydomonas Behavior- Phototaxis
Dieckmann (2003)
Thursday, March 7, 13
Chlamydomonas Behavior- Phototaxis
Exact behavior depends on:
Wavelength
Intensity
State of the cell
Dieckmann (2003)
Thursday, March 7, 13
Chlamydomonas Behavior- Phototaxis
Two types of photoreceptors:
470nm (blue) Ridge (2002)
510nm (green)
Dieckmann (2003)
Thursday, March 7, 13
Chlamydomonas Behavior- Phototaxis
Two types of photoreceptors:
470nm (blue) Ridge (2002)
510nm (green)
Cannot detect red!
Dieckmann (2003)
Thursday, March 7, 13
Chlamydomonas Behavior- Phototaxis
The Chlamydomonas Sourcebook, 2nd ed.
Thursday, March 7, 13
Chlamydomonas Behavior- Photoshock
Thursday, March 7, 13
Chlamydomonas Behavior- Photoshock
Forward
Swimming
Thursday, March 7, 13
Chlamydomonas Behavior- Photoshock
Forward
Swimming
Photoshock
escape
symmetrical, undulating waveform
Brokaw et al. 1982
Thursday, March 7, 13
Creating mutants
Thursday, March 7, 13
Creating mutants
UV
X-rays
nitrosoguanidine (MNNG)
methyl methanesulfonate (MMS)
ethylmethanesulfonate (EMS)
5-fluorodeoxyuridine (thymidine analog)
Thursday, March 7, 13
Creating mutants
UV
X-rays
nitrosoguanidine (MNNG)
methyl methanesulfonate (MMS)
ethylmethanesulfonate (EMS)
5-fluorodeoxyuridine (thymidine analog)
Can’t specifically mutate a gene of interest
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
non-symmetrical forward stroke
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
non-symmetrical forward stroke
symmetrical backward stroke
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
non-symmetrical forward stroke
symmetrical backward stroke
phototaxis toward medium intensity blue/green light
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
non-symmetrical forward stroke
symmetrical backward stroke
phototaxis toward blue/green light
photoshock/escape from high intensity blue/green light
Thursday, March 7, 13
Chlamydomonas reinhardtii
Single celled algae
used to study flagella dynamics
non-symmetrical forward stroke
symmetrical backward stroke
phototaxis toward blue/green light
photoshock/escape from high intensity blue/green light
cannot detect red light
Thursday, March 7, 13
Questions???
Thursday, March 7, 13