The MAP kinase p38 is part of Drosophila melanogaster's circadian clock.

All organisms have to adapt to acute as well as to regularly occurring changes in the environment. To deal with these major challenges organisms evolved two fundamental mechanisms: the p38 mitogen-activated protein kinase (MAPK) pathway, a major stress pathway for signaling stressful events, and circadian clocks to prepare for the daily environmental changes. Both systems respond sensitively to light.

Drosophila clock neurons under natural conditions.

The circadian clock modulates the adaptive daily patterns of physiology and behavior and adjusts these rhythms to seasonal changes. Recent studies of seasonal locomotor activity patterns of wild-type and clock mutant fruit flies in quasi-natural conditions have revealed that these behavioral patterns differ considerably from those observed under standard laboratory conditions. To unravel the molecular features accompanying seasonal adaptation of the clock, we investigated Drosophila's neuronal expression of the canonical clock proteins PERIOD (PER) and TIMELESS (TIM) in nature.

The ability to entrain to long photoperiods differs between 3 Drosophila melanogaster wild-type strains and is modified by twilight simulation.

The ability to adapt to different environmental conditions including seasonal changes is a key feature of the circadian clock. Here, we compared the ability of 3 Drosophila melanogaster wild-type strains to adapt rhythmic activity to long photoperiods simulated in the laboratory. Fruit flies are predominantly crepuscular with activity bouts in the morning (M) and evening (E).

Neuropeptide F immunoreactive clock neurons modify evening locomotor activity and free-running period in Drosophila melanogaster.

Different subsets of Drosophila melanogaster's clock neurons are characterized by their specific functions in daily locomotor rhythms and the differences in their neurotransmitter composition. We investigated the function of the neuropeptide F (NPF) immunoreactive clock neurons in the rhythmic locomotor behavior of adult flies. We newly identified the fifth s-LN(v) and a subset of the l-LN(v)s as NPF-positive in addition to the three LN(d)s that have been described previously.