Biological complexity: circadian clock feedback loop (Introduction)

by David Turell , Tuesday, January 16, 2018, 19:23 (2503 days ago) @ David Turell

Another molecular mechanism to control circadian rhythm is found in the honeybee:

https://www.sciencedaily.com/releases/2018/01/180116095503.htm

"Circadian clocks regulate the behaviour of all living things. Scientists from the University of Würzburg have now taken a closer look at the clock's anatomical structures and molecular processes in the honeybee.

"How does the honeybee manage to visit the flowers that bloom exactly at the right time? How do bees find their way back to the hive even when the sun, which they use as reference point, has changed its position in the sky? How do they communicate this information to other bees? And which molecular processes control this behaviour and in which anatomical structures do they take place?

***

"'In our current study, we focused on the concentration of a specific peptide in the bee's central nervous system," Charlotte Helfrich-Förster explains. This peptide is called "pigment-dispersing factor" or short PDF in scientific language. It has been known to play a central role in the circadian clocks of insects for some time. Previous measurements also revealed that special nerve cells, the so-called clock neurons, produce PDF.

***

"Charlotte Helfrich-Förster sums up the central findings of these experiments as follows: "Our analyses show that PDF neurons head for brain areas that are essential for learning, memory and orientation to the sun. The concentration of the PDF proteins is subject to considerable fluctuations throughout the day with an absolute low early in the morning. When the bees were given artificial PDF, their typical behavioural pattern was postponed by some time."

"For the scientists this is the clue that PDF clock neurons form an anatomical bridge between the different pacemaker cells in the clock network of insects. What is more, they transfer day-night information from the circadian clock to such brain areas that control complex behaviours such as orientation to the sun, temporal memory and organizing the work throughout the day."

Comment: Again communication of information by molecular messanger. How did evolution decide on this particular protein to use? For the honeybee, when it evolved this messenger molecule had to be in place to help them in their hunt for pollen and nector. Evidence of dsign is everywhere.