Distribution and structural diversity of cilia in tadpole larvae of the ascidian Ciona intestinalis

Abstract

Accumulating evidence demonstrates that cilia play important roles in a variety of processes in embryogenesis. For functional survey of larval cilia at the cellular level, we exploited the simple cell organization of tadpole larvae in the ascidian Ciona intestinalis. Immunofluorescent microscopy showed distribution of cilia not only in previously described tissues but also in a subpopulation of ependymal cells in the sensory vesicle, gut primordium, papillae, apical trunk epidermal neurons, and the endodermal strand. Transmission electron microscopy revealed a variety of axonemal structures, including a 9+0 structure similar to vertebrate primary cilia, a 9+0 structure with electron-dense materials in the center, a 9+2 structure with no dynein arms, and an axoneme with a disorganized structure at the distal end. Extensive description of cilia in the present study gives important insights into the evolution of the ciliary structure and provides a basis for analysis of ciliary functions in establishment of chordate body plan.

Immunohistochemical study of the nervous system of the tunicate Thalia democratica (Forsskal, 1775)

“…This type of antibody has been widely used in ascidian larvae, mainly to stain the cilia. 9,10 We observed very long and numerous projections crossing the tunic of the animals all around the body. Although TEM observations are necessary to define the structure of these projections, they were reminiscent of the long cilia of epidermal sensory cells of the trunk and tail of ascidian larvae.…”

Ciliary and Flagellar Structure and Function—Their Regulations by Posttranslational Modifications of Axonemal Tubulin

“…Although primary cilia are found in invertebrates (Gardiner and Rieger, 1980;Konno et al, 2010), their functions are poorly understood. Once regarded as rudimentary organelles, primary cilia, protruding from nonsensory cells, are now also known to be important for cells to transmit various exogenous cues into the intracellular signaling pathways involved in morphogenesis, maintenance of organs, or behavior, at least in vertebrates.…”

A calaxin Gene in the Pacific Oyster Crassostrea gigas and Its Potential Roles in Cilia

“…A comprehensive knowledge of widely distributed cilia is therefore essential to understanding animal biology. Because animal cilia have differentiated during the course of evolution, they are structurally and functionally diverse among different tissues and animals (Silverman and Leroux, 2009;Konno et al, 2010;Vincensini et al, 2011). Despite extensive studies, there are still many open questions to be addressed on animal cilia.…”