Oceanview software

Experimental setup for spectroscopy is explained in more detail in Supplementary information. Briefly, light from an LED driver (Mightex Systems, USA) passes through the thread device held by a custom built PMMA holder, where the light is diffused in an integrating sphere (Newport, USA). The detector is a Flame Spectrometer (Ocean Optics, USA) and records reflectance spectra via Oceanview software (Version 1.6.3, Ocean Optics, USA).

To conduct optical tracking of magnetophoresis, a deuterium–halogen UV–VIS–NIR light source (DH2000-BAL, Ocean Optics, Orlando, FL, USA) using only halogen as the light source was passed through a quartz cuvette (CV10Q3500, Thorlabs, Newton, NJ, USA) containing the suspended nanoparticles. The transmitted light was focused onto a flame spectrometer (Ocean Optics), which was paired with OceanView software (Version 1.6.7, Ocean Optics). The probed area was a cylindrical region in the cuvette with a 5 mm diameter and a 10 mm height, centered 70 mm above a magnet (neodymium, 10 mm × 10 mm × 10 mm). The magnet’s distance-dependent magnetic flux density was measured using a gaussmeter. The extinction peak was monitored temporally, and a linear fit of the peak extinction is used to monitor magnetophoresis.

For in vivo fiber photometry, Agrp^Creor Mc4r^Cre mice were injected AAV9-FLEX-GCAMP6f into the ARC or dBNST. Animals were allowed to recover for at least 2 weeks before experiments proceeded. Optic probes were assembled and implanted following the previous protocol. The 488 nm laser was used to excite GCaMP6 through the multi-mode fiber patch cord and the QE Pro detector (Ocean optics) was used to collect the photons emitted from the tissue through the multi-mode detection fiber patch cord. The OceanView software (Ocean optics) was used to acquire the data. Spectral channel (500–543 nm) was selected for GCaMP6. The integrated photon count was used as a measure of intensity. The spectrum data were recorded continuously at 10 Hz sampling frequency. The percentage ∆F/F was calculated by 100 × (F− Fmean)/Fmean, where Fmean was the mean fluorescence intensity throughout the entire acquisition fragment. The detection threshold for a fluorescence transient was defined as µ + 3σ, where µ and σ were the mean and the standard deviation of the fluorescence baseline period. The fluorescence transients during baseline were randomly sampled (40–45 s). For the heat map the recorded data were saved as ASCII files and opened in MATLAB. And the heat map can be plotted by Matlab. All Data were analyzed offline using Excel, Matlab, and Prism.

For all subjects, reflectance spectra were captured using a custom-designed fiber-optic reflection probe (Gulf Photonics, Oldsmar, FL, USA). The fiber optic probe has a 200-μm core, 2-m long bifurcated reflection probe with a central light-emitting fiber with 6 collection fibers surrounding it to capture the light reflected from the luminal tissue. The probe was connected to a spectrometer (Ocean Optics, Orlando, FL, USA) and white light source and connected via USB to a laptop with the OceanView software (Ocean Optics, Orlando, FL, USA), as shown in Figure 1. The probe was calibrated prior to testing by collecting dark and white reference spectra. To capture the white spectrum, the white light was turned on, and the end of the probe was inserted into a white integration sphere (FIOS-1, Ocean Optics, Largo, FL, USA). The dark spectrum was collected by turning off the white light source and covering the end of the probe with sterile black fabric.

We sacrificed the fish using a −20° freezer and placed them in a Petri dish for measurement. The reflectance spectra of the body trunks from five medaka were measured by a spectrometer (FLAME-S-UV-VIS-ES, Ocean Optics, Inc. FL, US). A light source (DH-MINI) providing UV to visible light output illuminated the probe (R400-7-SR) under an angle of 45° to the fish trunk. The reflectance spectra of the fish were recorded with a resolution of 1 nm relative to a white standard (WS-1) with OCEANVIEW software (Ocean Optics, Inc. FL, US).

We measured the spectral reflectance of the eyes of A. irradians using a modified Olympus CX-31 microscope (Center Valley, PA, USA). We replaced the right eyepiece of the microscope with a custom-made adapter to which we attached a Y-shaped reflection probe (QR400-7-UV-VIS; Ocean Optics, Dunedin, FL, USA) that supplied light from a 20 W tungsten halogen lamp with an emission range of 360–2400 nm (HL-2000-HP-FHSA; Ocean Optics) and carried reflected light back to a Flame-S-VIS-NIR-ES spectrometer (Ocean Optics) that we operated using Ocean View software (Ocean Optics). We focused light onto samples using an Olympus 10X PlanC N UIS2 objective. To standardize our measurements, we used a reflectance standard made of Spectralon (WS-1-SL; Ocean Optics). Because fixing the eyes of scallops appears to alter their colour slightly, we measured the spectral reflectance of fresh, unfixed eyes. We compared our reflectance measurements from the eyes of scallops with measurements taken from the unpigmented mantle tissue immediately adjacent to the eyes.

Coloration of transparent films was measured on a UV–Vis Maya 2000 Pro spectrometer using halogen light source of DH-2000-BAL (Ocean Optics). The VIS spectra were processed in OceanView software (version 1.6.7, Ocean Optics, Dunedin, FL, USA) and expressed in CIELAB color space with a standard illuminant “D65” and an observer at “2-degrees”. The test formulations were cast on microscopic glass slides (76 × 26 × 1 mm³) using frame applicators of 120-µm gap and left under standard laboratory conditions (T = 23 °C, relative humidity = 50%) at diffuse daylight illumination. Reported data are given relative to pure microscopic slides.