Section 36
Chapter 35,972

Transducin binding in bovine rod outer segment disk membranes of different age/spatial location

Young, J.E.; Albert, A.D.

Experimental Eye Research 70(6): 809-812


ISSN/ISBN: 0014-4835
PMID: 10843786
DOI: 10.1006/exer.2000.0821
Accession: 035971899

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Activity of serotonin N -acetyltransferase (NAT), a key regulatory enzyme in melatonin biosynthesis, was detected in the rat lens. NAT activity in the lens showed significant diurnal variation in vivo and in vitro, peaking during the period of darkness, when the lenses were maintained under 14 hr light/10 hr dark cycle. Cultured lenses exhibited a circadian rhythm of NAT activity when maintained under constant darkness. However, the rhythm in vitro was not entrained when the light/dark cycle was delayed 8 hr from the cycle in intact animals. These data strongly suggest that the rat lens contains a circadian clock that controls NAT activity, although the circadian clock appears to lack a photic entrainment mechanism.

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