PTOs & Food Entrainment & MASCO Flashcards
What is used in circadian organization:
Between cells and tissues
Within cells
Between:
- Oscillator coupling, intercellular signalling
- Distribution of functions (e.g. light input, rhythm generation)
- Feedback of circuits from peripheral oscillators
Within:
- TTFL
- PTO
Oscillator coupling
Circadian blindness
Set of organs work together and share responsibility to produce circadian cycle
- Important to have backup if something fails
- SCN must also receive feedback from other oscillators around body (not always needed)
Must have no eyes at all to be circadian blind
- Diff from visual blind (which is reliance on photoreceptors)
How do plant clocks differ from animal clocks? Conflicts?
Use light to get both energy and sync clock w/ light
- May conflict w/ each other bcuz twilight might favour clock for photosynthesis rather than clock for sunset/sunrise
Plant negative feedback loop
Cryptochrome (Crys)
Photosynthesis (Phys)
TOC1
Crys: Phase shifting and entrainment, measures length of day
Phys: Detects light
Negative feedback loop in middle w/ TOC1
How are growth and reproduction temporally separated (don’t happen at same time) from each other in plants?
Has loop connecting day and night genes (inhibitory)
- Day for reproduction (Glutamate release is inhibited in day)
- Night for growth
** Not the negative feedback loop (TTFL)
True or false;
when we sleep, closing our eyes even in the light causes SCN activity to increase
False
- Causes SCN activity to decrease bcuz we’re reducing its responsibility
- Less signalling via melanopsin from ipRCG
Acetabularia
nucleus removal experiment
transplantation experiment
nucleus entrainment
W/out nucleus in constant light, oxygen production rhythm persists
- Cytoplasm may be creating rhythm (and can be synced w/ light and dark)
Raised them in opposite light cycles
- Nucleus transplanted into each other shows og host’s rhythm
- Transplantation of stalk showed same result
Only illuminated nucleus
- Nucleus synced to light and drove rhythm of stalk
Conclusion:
- Clocks in both stalk/cytoplasm and nucleus
- Nucleus main pacemaker, which determines phase of cytoplasmic clock
- Example of distributed system (like sparrow)
Bulla gouldiana clock
Regulation of K channels
- Similar system as acetabularia
- Light causes depolarization of BRN and calcium entry
- Input sent to clock thru calmodulin CaMK to regulate K channel
- But in periodic light and dark, clock not needed as long as eyes can detect light
Cyanobacteria quinones
Changes in quinones on membrane detect oxidation and drive KaiC movement
- When reduced, allows KaiC to move to next phase
Cellular metabolism
W/out clock
Necessity
Red blood cell example
- Involved w/ circadian clock and reflects activity of cell
- Responsibility occurs even w/out circadian clock (can continue responding to light but lose ability to anticipate)
- Metabolic processes go up and down thruout day and in response to getting nutrients
- Clock useful for making it more precise but not necessarily if always getting food
Red blood cells rhythmic even w/out nucleus (clock)
- Continue to metabolize more at one part of day than others in 24-hour nutrient cycle
Peroxiredoxin cycle (PTO cycle of metabolism)
TTFL
CLOCK genes cause ROS expulsuon and ROS buildup
- Can exist independently from TTFL
- Can sync to external factors
- Affects ability to survive (know where things are, when to recover, etc)
Bmal1/Clock more involved in cardiometabolic control
Per/Cry more involved in nutritional status
3 oscillators important in metabolism
Transcriptional-translational oscillator
- Metabolism
Redox oscillator
Membrane excitability oscillation
- Important in bulla
- Also important for cells to communicate thru membrane
True or false
Cry/Per have different jobs other than interacting w/ Clock/Bmal1
True
- Together, they interact with them for clock output
- But also separately involved in different parts of gluconeogenesis, adipocyte differentiation (Per), inflammation (Cry)
Insulin feedback loop
Insulin detected by receptor
Activates mTORC1 to translate genes
Activates PER to create clock output for diff cell types
Creates behav output
Diffs in TORC1 (yeast) and mTORC1 (mammals) in metabolism
Yeast:
- Tunicamycin and rapamycin interact w/ TORC1
- Interacts w/ Sfp1 and Mpk1
- Mpk1 important in increasing RACs, proteasome subunits, proteasome levels, cell survival
Mammals:
- Nutrient starvation and Rapamycin interact w/ mTORC1
- Interacts w/ ERK5
- Increases same things as Mpk1
