Figure 3

Raman spectra of Drosophila chemosensory wing hairs under 514 nm and 785 nm laser excitation.

Each chemosensory wing hair shows a diameter little changed from the base to the extremity, where a unique pore is located. The Raman beam was focused on three places: at the base of the bristle (A), at 2/3^rd of the length (B) and at 9/10^th of the length (near the extremity) (C). On the left, microphotographs represent one hair of a wing with the impact of the laser beam. Excitation lengths were 514 nm (middle) and 785 nm (right). The three corresponding spectra are represented on each graph. We noted a large main peak between 1,500 and 1,650 cm⁻¹. Each individual line in the three categories (A–C) was obtained with different individual wings. Strong differences in the intensity of Raman signals are shown among the three locations of the laser beam.