Evidence for the involvement of muscle tropomyosin in the contractile elements of the coelom-esophagus complex in sea urchin embryos

Echinodermata

“…As the archenteron elongates, secondary mesenchyme cells delaminate from its tip and disperse within the blastocoel, where they proliferate to form four types of non-skeletogenic mesoderm (NSM) cells (Ettensohn and Ruffi ns 1993 ): pigment cells (Gibson andBurke 1985 , 1987 ), blastocoelar cells (Tamboline and Burke 1992 ), coelomic pouch cells, and circumesophageal muscle cells (Ishimoda-Takagi et al 1984 ;Burke and Alvarez 1988 ;Andrikou et al 2013 ). These cell types are specifi ed long before delaminating from the tip of the archenteron where they are arranged spatially to occupy different positions along the animal/ vegetal and oral/aboral axis (see different color cells in Fig.…”

A homologue of snail is expressed transiently in subsets of mesenchyme cells in the sea urchin embryo and is down‐regulated in axis‐deficient embryos

“…SMC derivatives include pigment cells, which ingress at various times during gastrulation in different species (Gibson and Burke, 1985;Takata and Kominami, 2004), blastocoelar cells (Tamboline and Burke, 1992), esophageal muscle precursors (Ishimoda-Takagi et al, 1984;Wessel et al, 1990;Venuti et al, 1993), and cells expressing the 5-hydroxytryptamine receptor (Katow et al, 2004) At least some of the SMC derivatives that express Lv-snail mRNA and protein are likely to be pigment cells, because some Lv-snailexpressing cells are embedded in the ectoderm, and because in nickeltreated embryos, which largely lack pigment (Hardin et al, 1990;Takata and Kominami, 2004), Lv-snail is down-regulated. The small number of SMCs that express Lv-snail compared with other more general markers for SMCs, such as Frizzled5/8 (Croce et al, 2006) and most SMC markers identified using macroarray approaches (Calestani et al, 2003) suggests that Lv-snail is only expressed in a subset of SMCs.…”

A myogenic factor from sea urchin embryos capable of programming muscle differentiation in mammalian cells.

“…Initially, these secondary mesenchyme cells differentiate into pigment cells that migrate to the ectoderm, but as elongation proceeds, they also form the two coelomic pouches on opposite sides of the gut (18,19). Subsequently, 8-12 cells from the coelomic epithelia on each side delaminate, differentiate into myocytes, and form the circumesophageal musculature of the larva (18)(19)(20). In sea urchins, as in vertebrates, pluripotent mesenchyme cells become committed myoblasts in a specific region of the embryo and then differentiate into muscle cells.…”