Mr. Molina et Rm. Cripps, Ostia, the inflow tracts of the Drosophila heart, develop from a genetically distinct subset of cardial cells, MECH DEVEL, 109(1), 2001, pp. 51-59
The homeobox gene tinmun and the nuclear receptor gene seven-up are express
ed in mutually exclusive dorsal vessel cells in Drosophila, however, the ph
ysiological reason for this distinction is not known. We demonstrate that t
in and svp-lacZ expression persists through the larval stage to the adult s
tage in the same pattern of cells expressing these genes in the embryo. In
the larva, six pairs of Svp-expressing cells form muscular ostia. which per
mit hemolymph to enter the heart for circulation, however, more anterior Sv
p-expressing cells form the wall of the dorsal vessel. During pupation, the
adult heart forms from a chimera of larval and imaginal muscle fibers. The
portion of the dorsal vessel containing the larval ostia is histolyzed and
the anterior Svp-expressing cells metamorphose into imaginal ostia. This i
s the first demonstration that the significant molecular diversity of cardi
al cells identified in the embryonic heart correlates with the formation of
physiologically and functionally distinct muscle cells in the animal. Furt
hermore, our experiments define the cellular changes that occur as the larv
al heart is remodeled into an imaginal structure in an important model orga
nism. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.