Pigment-dispersing factor in pea aphid clock cells may link day length to insulin-producing cells

A PDF-coding gene was identified in the pea aphid, which has significant changes in its amino acid sequence.

• The neuropeptide pigment-dispersing factor (PDF) is involved in the circadian clock and seasonal responses in photoperiodic species.
• Four neurons in each hemisphere of the pea aphid brain were stained, which co-express the clock protein Period.
• These neurons exhibit daily and seasonal plasticity, similar to PDF neurons in fruit flies.
• PDF terminals overlap with dendrites of insulin-like peptide (ILP) positive neurosecretory cells, suggesting a connection to seasonal adaptations.
• The presence of putative terminals from Cryptochrome (CRY) positive clock neurons indicates PDF may be linked to day length measurement.

Simplified