Phylogenetic analysis and developmental expression of thymosin-β4 gene in amphioxus

Developmental expression of amphioxus RACK1

Vertebrate RACK1 plays a key role in embryonic development. This paper described the cloning, phylogenetic analysis and developmental expression of AmphiRACK1, the RACK1 homologous gene in amphioxus. Phylogenetic analysis indicated that amphioxus RACK1 was located at the base of vertebrate clade. AmphiRACK1 expression in lithium-treated embryos was also examined. During embryonic development, AmphiRACK1 was expressed strongly in cerebral vesicles, neural tubes and somites. In lithium-treated embryos, the segmental expression of AmphiRACK1 in somites became blurry and decreased. Its expression in cerebral vesicles and neural tubes was also weaker or disappeared. In the adult animal, AmphiRACK1 transcripts were detected in the epithelium of midgut diverticulus and gut, wheel organ, gill blood vessels and testis.

Ciliary band gene expression patterns in the embryo and trochophore larva of an indirectly developing polychaete

The trochophore larvae of indirectly developing spiralians have ciliary bands with motor and feeding functions. The preoral prototroch ciliary band is the first differentiating organ in annelid and mollusk embryos. Here we report the expression of several ciliary band markers during embryogenesis and early larval stages of the indirectly developing polychaete Hydroides elegans. Genes with similarity to caveolin, beta-tubulin, alpha-tubulin, and tektin are expressed in the eight primary prototroch precursors, 1q(221) and 1q(212). Blastomeres 1q(221) and 1q(212) locate at the same equatorial latitude after the complementary asymmetric division of their 1q(22) and 1q(21) precursors. In addition, caveolin and alpha-tubulin are expressed in the metatroch and adoral ciliary zone. Caveolin is expressed in foregut ciliated cells, and alpha-tubulin is expressed in apical tuft ciliated cells. The expression of a beta-thymosin homolog is restricted to 1q(122) and 1q(121) blastomeres, which locate just above and in close association with the eight primary prototroch cells 1q(221) and 1q(212). In addition, the beta-thymosin homolog has a transient expression in the hindgut and apical zone. The expression of all these genes provides a landmark for the early specification of ciliary bands and other ciliated organs.