Steven L. Coon

TL;DR: The variety of mechanisms that have evolved among vertebrates to achieve the same goal-a rhythm in melatonin-underlines the important role melatonin plays as the hormonal signal of environmental lighting in vertebrates.

TL;DR: The pineal serotonin N-acetyltransferase generates the large circadian rhythm in melatonin, the hormone that coordinates daily and seasonal physiology in some mammals, and AA-NAT represents a family within a large superfamily of acetyltransferases.

TL;DR: It is discovered that expression of the AA-NAT gene in the rat pineal gland is essentially turned off during the day and turned on at night, resulting in a more than 150-fold rhythm.

TL;DR: This chapter describes the mammalian AANAT regulatory system, which includes the retina, neural structures, transsynaptic processes, and molecular events, and special attention is paid to the functional characteristics of the systems which insure that the nocturnal increase in melatonin is an accurate and reliable indicator of the duration of the night.

TL;DR: It is shown that the evolutionary history of most genes encoding enzymes involved in the metabolism of these messengers is best described by scenarios that include horizontal gene transfer (HGT) from bacteria, with some transfers occurring after the divergence of animals from fungi.