Meeting Abstract

91.5  Thursday, Jan. 7  The development of mesoderm in the brachiopod Terebratalia transversa PASSAMANECK, Y.J.*; HEJNOL, A.; MARTINDALE, M.Q.; Univ. Hawaii, Kewalo Marine Lab; Univ. Hawaii, Kewalo Marine Lab; Univ. Hawaii, Kewalo Marine Lab yale@hawaii.edu

Classical observations of articulate brachiopods have presented a range of interpretations regarding the formation of the mesoderm, including coelomic spaces, although there is general agreement that endomesoderm is derived from the lateral regions of the archenteron during gastrulation. In the larva of terebellid articulate brachiopods, mesodermal derivatives constitute a complex network of muscles throughout the mantle and pedicle lobes, however little is know about the cellular or molecular origins of these structures. We have analyzed in Terebratalia transversa the expression of a number of candidate genes associated with mesoderm specification and differentiation in other bilaterians (e.g. dpp, FoxC, FoxD, mef2, msx, NK4, Pax1/9, snail, tropomyosin, twist). Consistent with the complexity of mesodermal derivatives in the Terebratalia larva, a wide variety of gene expression patterns are observed, with most genes displaying dynamic patterns of expression over the course of larval development that appear to be associated with the origins of mesodermal derivatives.