Circadian Rhythms - Van D. Gooch
Circadian rhythms
are biological processes that oscillate with an approximate 24 hour
periodicity
when there are no external timing cues. Basically, a circadian rhythm
is an
internal daily biological clock. Time lapse video
of
Neurospora Circadian Conidiation Rhythms by Van Gooch and Jason Thoen.
Optimized
Firefly Luciferase Gene Expressed in Neurospora:
We have synthesized the firefly
luciferase gene to match the codon bias of Neurospora. That
gene can be placed behind any
promoter or gene (to make a fusion protein) and the luciferase is
robustly
expressed. We have been following Neurospora circadian rhythms via
bioluminescence. For
some fun circadian bioluminescent Neurospora
videos,
look at the
supplemental material of the first paper resulting from this work:
Van
D. Gooch, Arun Mehra, Luis F. Larrondo, Julie Fox, Melissa
Touroutoutoudis,
Jennifer J. Loros, and Jay C. Dunlap
Fully
Codon-Optimized luciferase Uncovers Novel Temperature Characteristics
of the
Neurospora Clock
Eukaryotic
Cell 2008 7: 28-37. [Abstract] [Full Text] [PDF] [Supplemental
material]
The
pictures below were taken totally by illumination from
Neurospora: Van Gooch on the
left and Julie Fox on the right:
Watch
bioluminescent movies in the supplemental materail in the Eukaryotic
Cell reference mentioned above.
Also watch a movie of the bioluminescent rhythm in a large finger bowl by clicking here.
Neurospora
Growth rate is Dramatically Circadian:
Van
D. Gooch, Laura Freeman, and Patricia L. Lakin-Thomas
Time-Lapse
Analysis of the Circadian Rhythms of Conidiation and Growth Rate in Neurospora
J
Biol Rhythms 2004 19: 493-503.
[Abstract]
[PDF] [References]
MOVIES
Phase
Response Experiments: First
consider a control where an
organism is demonstrating a cycling (appx 24 hours) of some
physiological
feature under constant conditions. For example a sleep wake cycle of a
mouse in
constant dark and with constant temperature; or the leaf movement of a
plant in
constant dim light and constant temperature. Now ask what happens if
during
those constant conditions an experimenter applies some perturbation
that one
suspects might influence the circadian clock. For example turning on
the lights
for five minutes, or raising the temperature 10C for 2 hours, or
applying a
drug for three hours. When one applies such a perturbation, it is
common to
observe that the time at which an event occurs (i.e. the phase)
is often
now different than a control that did not receive the perturbation.
This is
called a phase shift and is usually measured in hours from the
control
(or in degrees from a 360 cycle or in circadian time). One usually
finds that
the magnitude of the phase shift usually depends on the time in the
cycle at
which the perturbation was applied.
A
Phase Response Curve (PRC) is a plot of
the magnitude of phase
shifting due to a pulse versus the time at which the pulse was applied.
Experimenters have determined phase response curves for many organisms,
many
oscillating types of physiology, and using many forms of perturbation.
Carl
Johnson of Vanderbilt University has compiled the data for most of the
published phase response curves and has termed the compilation the PRC
Atlas.
With my help, that data has been put into computer format and is
available for
the asking. The best way to view the data is via the PRC Atlas that can be downloaded from
Carl Johnson's web site.
You
can get the text format of the data by downloading one of the formats
below. In
this case you will have to put the data into your own plotting program
to see
the actual plots. The data are fairly well structured so that it should
be easy
to insert into your favorite data spreadsheet program.
Download of text file
of PRC Atlas data.
Download
of Limit Cycle Displacement Model of Circadian Rhythms by Van Gooch:
Some Circadian Rhythms Web Sites:
- Society for Research on Biological Rhythms
- Jay Dunlap Lab Neurospora frq gene
- Circadian.com shiftwork
- Johnson Lab Home Page (cyanobacteria, mechanisms, transduction pathways)
- Woody Hasting's Home Page (Gonyaulax, bioluminescence)
- Peter Ruoff's Home Page (chemical oscillators, modeling)
- ClockWorks Laboratory at the University of Illinois at Urbana-Champaign
Woody
Hastings group in 1975 at Harvard Biological Laboratories
If you have comments or suggestions, email me at goochv@morris.umn.edu
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Last updated January 13 2010