Mutations in S-cone pigment genes and the absence of colour vision in two species of nocturnal primate.
Most primates have short-wavelength sensitive (S) cones and one or more types of cone maximally sensitive in the middle to long wavelengths (M/L cones). These multiple cone types provide the basis for colour vision. Earlier experiments established that two species of noctural primate, the owl monkey (Aotus trivirgatus) and the bushbaby (Otolemur crassicaudatus), lack a viable population of S cones. Because the retinas of these species have only a single type of M/L cone, they lack colour vision. Both of these species have an S-cone pigment gene that is highly homologous to the human S-cone pigment gene. Examination of the nucleotide sequences of the S-cone pigment genes reveals that each species has deleterious mutational changes: in comparison to the sequence for the corresponding region of the human gene, exon 4 of the bushbaby S-cone pigment gene has a two nucleotide deletion and a single nucleotide insertion that produces a frame shift and results in the introduction of a stop codon. Exon 1 of the owl monkey S-cone pigment gene likewise contains deletions and insertions that produce a stop codon. The absence of colour vision in both of these nocturnal primates can thus be traced to defects in their S-cone pigment genes.
Jacobs
G H
GH
Department of Psychology, University of California, Santa Barbara 93106, USA.
Neitz
M
M
Neitz
J
J
D000595:Amino Acid Sequence; D000818:Animals; D016645:Aotidae / Q000235:genetics* / Q000502:physiology*; D001483:Base Sequence; D003118:Color Perception / Q000235:genetics* / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005701:Galago / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D012168:Retinal Pigments / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D017931:DNA Primers; D012168:Retinal Pigments