The spectral composition of ambient light varies across both space and time. Many species of jawed vertebrates adapt to this variation by tuning the sensitivity of their photoreceptors via the expression of CYP27C1, an enzyme that converts vitamin A1 into vitamin A2, thereby shifting the ratio of vitamin A1-based rhodopsin to red-shifted vitamin A2-based porphyropsin in the eye. Here, we show that the sea lamprey (Petromyzon marinus), a jawless vertebrate that diverged from jawed vertebrates during the Cambrian period (approx. 500 Ma), dynamically shifts its photoreceptor spectral sensitivity via vitamin A1-to-A2 chromophore exchange as it transitions between photically divergent aquatic habitats. We further show that this shift correlates with high-level expression of the lamprey orthologue of CYP27C1, specifically in the retinal pigment epithelium as in jawed vertebrates. Our results suggest that the CYP27C1-mediated vitamin A1-to-A2 switch is an evolutionarily ancient mechanism of sensory plasticity that appeared not long after the origin of vertebrates.
Lamprey_CYP27C1_qPCR
Data from qPCR analysis of Cyp27c1 expression in the retinal pigment epithelia of downstream juvenile and upstream migrant adult Petromyzon marinus.
Lamprey_qPCR.csv
Figure 2A - rod responses
Mean responses of 13 rods to 20-ms 500-nm flashes given at t = 0 at the following intensities (in photons μm−2): 9, 40, 98, 366, 1055, and 2591.
Figure2A_rodresponses.dat
Figure2B - cone responses
Mean responses of 6 cones to 20-ms 600-nm flashes given at t = 0 at the following intensities (in photons μm−2): 78, 711, 2051, 5036, 1.91 × 10^4, 2.20 × 10^5, 6.71 × 10^5, and 6.96 × 10^5.
Figure2B_coneresponses.dat
Figure2C - response intensity curves
Normalized mean current response amplitudes (± SE) as a function of flash intensity for rods and cones. Data for both cell types were fitted with the Michaelis-Menton equation, r/rmax = I/(I + I½) where r/rmax is the normalized current amplitude, I is the flash intensity, and I½ is the flash intensity producing a half-maximal response. Best-fitting values of I½ were 52 photons μm−2 for rods and 3210 photons μm−2 for cones.
Figure2C_responseintensitycurves.dat
Figure3A - MSP
Microspectrophotometric determinations of mean pigment absorbance (± SE) normalized to absorbance at λmax, taken from 58 juvenile rods.
Figure3A_MSP.dat
Figure3A - SSC plus fit
Suction-electrode recordings of 9 juvenile rods and best-fitting A1 visual-pigment nomograms.
Figure3A_SSCplusfit.dat
Figure3B - MSP
Microspectrophotometric determinations of mean pigment absorbance (± SE) normalized to absorbance at λmax, taken from 9 juvenile cones.
Figure3B_MSP.dat
Figure3B - SSC plus fit
Suction-electrode recordings of 7 juvenile cones and best-fitting A1 visual-pigment nomograms.
Figure3B_SSCplusfit.dat
Figure3C - MSP
microspectrophotometric determinations of mean pigment absorbance (± SE) normalized to absorbance at λmax, taken from 70 adult rods.
Figure3C_MSP.dat
Figure3C - SSC
Suction-electrode recordings of 13 adult rods and best-fitting A1 and A2 visual-pigment nomograms.
Figure3C_SSC.dat
Figure3D - MSP
Microspectrophotometric determinations of mean pigment absorbance (± SE) normalized to absorbance at λmax, taken from 23 adult cones.
Figure3D_MSP.dat
Figure3D_SSC
Suction-electrode recordings of 14 adult cones and best-fitting A1 and A2 visual-pigment nomograms.
Nanogram fitting scripts and data
This archive contains the R scripts, functions, and data used to fit A1 and A2-based opsin visual pigment templates to miscrospectrophotometric measures of lamprey rod and cone photoreceptor absorbance spectra.
Nanogram fitting.zip