Kainz P M, Neitz J, Neitz M
Department of Cellular Biology, Medical College of Wisconsin, Milwaukee 53226, USA.
Vision Res. 1998 Nov;38(21):3315-20. doi: 10.1016/s0042-6989(98)00078-9.
Until recently, New World primates were found to have a single M/L photopigment gene on the X-chromosome. This arrangement limits males to dichromatic, or monochromatic color vision. Only females who were heterozygous for the M/L gene were trichromatic. Recently, an exception has been discovered. Male howler monkeys appear to have more than one M/L pigment gene, and both genders are uniformly trichromatic. We characterized promoter regions corresponding to two M/L pigment genes in howlers. Comparison of DNA sequences with those of humans and three species of New World primate suggest a recent and independent acquisition of a second M/L gene locus in the howler.
