M. Menaker et Ma. Vogelbaum, MUTANT CIRCADIAN PERIOD AS A MARKER OF SUPRACHIASMATIC NUCLEUS FUNCTION, Journal of biological rhythms, 8, 1993, pp. 190000093-190000098
Fetal suprachiasmatic nucleus (SCN) tissue transplanted into the third
ventricle of hamsters bearing complete SCN lesions restores the circa
dian locomotor rhythm with a period that depends exclusively on the ge
netically determined period of the tissue donor. If the host is only p
artially lesioned and thus retains rhythmicity with its own geneticall
y determined period, an implant from an animal of a different genotype
can induce a second rhythm with a period determined by the donor geno
type. Both rhythms can be present simultaneously in the record of such
a ''temporal chimera,'' interacting only superficially (i.e., not at
the level of the pacemaker). Our data support the interpretation that
under such circumstances the graft is able to capture part of the loco
motor output of the circadian system, but does not make functional con
nections with the host SCN pacemaking system.