The role of MAPK signaling in patterning and establishing axial symmetry in the gastropod Haliotis asinina.

TY - JOUR

T1 - The role of MAPK signaling in patterning and establishing axial symmetry in the gastropod Haliotis asinina.

AU - Koop, Demian

AU - Richards, Gemma S

AU - Wanninger, Andreas

AU - Gunter, Helen M

AU - Degnan, Bernard M

N1 - Keywords: Animals; Body Patterning; Bone Morphogenetic Proteins; Fetal Proteins; Gastropoda; Gastrulation; MAP Kinase Signaling System; Protein Structure, Tertiary; T-Box Domain Proteins

PY - 2007

Y1 - 2007

N2 - Gastropods are members of the Spiralia, a diverse group of invertebrates that share a common early developmental program, which includes spiral cleavage and a larval trochophore stage. The spiral cleavage program results in the division of the embryo into four quadrants. Specification of the dorsal (D) quadrant is intimately linked with body plan organization and in equally cleaving gastropods occurs when one of the vegetal macromeres makes contact with overlying micromeres and receives an inductive signal that activates a MAPK signaling cascade. Following the induction of the 3D macromere, the embryo begins to gastrulate and assumes a bilateral cleavage pattern. Here we inhibit MAPK activation in 3D with U0126 and examine its effect on the formation and patterning of the trochophore, using a suite of territory-specific markers. The head (pretrochal) region appears to maintain quadri-radial symmetry in U0126-treated embryos, supporting a role for MAPK signaling in 3D in establishing dorsoventral polarity in this region. Posterior (posttrochal) structures - larval musculature, shell and foot--fail to develop in MAPK inhibited trochophores. Inhibition of 3D specification by an alternative method--monensin treatment--yields similar abnormal trochophores. However, genes that are normally expressed in the ectodermal structures (shell and foot) are detected in U0126- and monensin-perturbed larvae in patterns that suggest that this region has latent dorsoventral polarity that is manifested even in the absence of D quadrant specification.

AB - Gastropods are members of the Spiralia, a diverse group of invertebrates that share a common early developmental program, which includes spiral cleavage and a larval trochophore stage. The spiral cleavage program results in the division of the embryo into four quadrants. Specification of the dorsal (D) quadrant is intimately linked with body plan organization and in equally cleaving gastropods occurs when one of the vegetal macromeres makes contact with overlying micromeres and receives an inductive signal that activates a MAPK signaling cascade. Following the induction of the 3D macromere, the embryo begins to gastrulate and assumes a bilateral cleavage pattern. Here we inhibit MAPK activation in 3D with U0126 and examine its effect on the formation and patterning of the trochophore, using a suite of territory-specific markers. The head (pretrochal) region appears to maintain quadri-radial symmetry in U0126-treated embryos, supporting a role for MAPK signaling in 3D in establishing dorsoventral polarity in this region. Posterior (posttrochal) structures - larval musculature, shell and foot--fail to develop in MAPK inhibited trochophores. Inhibition of 3D specification by an alternative method--monensin treatment--yields similar abnormal trochophores. However, genes that are normally expressed in the ectodermal structures (shell and foot) are detected in U0126- and monensin-perturbed larvae in patterns that suggest that this region has latent dorsoventral polarity that is manifested even in the absence of D quadrant specification.

U2 - 10.1016/j.ydbio.2007.08.035

DO - 10.1016/j.ydbio.2007.08.035

M3 - Journal article

C2 - 17916345

SN - 0012-1606

VL - 311

SP - 200

EP - 212

JO - Developmental Biology

JF - Developmental Biology

IS - 1

ER -