Cortical ultrastructure and chemoreception in ciliated protists (ciliophora)

Abstract

The ciliated protists (ciliates) offer a unique opportunity to explore the relationship between chemoreception and cell structure. Ciliates resemble chemosensory neurons in their responses to stimuli and presence of cilia. Ciliates have highly patterned surfaces that should permit precise localization of chemoreceptors in relation to effector organelles. Furthermore, ciliates are easy to grow and to manipulate genetically; they can also be readily studied biochemically and by electrophysiological techniques. This review contains a comparative description of the ultrastructural features of the ciliate cell surface relevant to chemoreception, examines the structural features of putative chemoreceptive cilia, and provides a summary of the electron microscopic information available so far bearing on chemoreceptive aspects of swimming, feeding, excretion, endocytosis, and sexual responses of ciliates. The electron microscopic identification and localization of specific chemoreceptive macromolecules and organelles at the molecular level have not yet been achieved in ciliates. These await the development of specific probes for chemoreceptor and transduction macromolecules. Nevertheless, the electron microscope has provided a wealth of information about the surface features of ciliates where chemoreception is believed to take place. Such morphological information will prove essential to a complete understanding of reception and transduction at the molecular level. In the ciliates, major questions to be answered relate to the apportionment of chemoreceptive functions between the cilia and cell soma, the global distribution of receptors in relation to the anterior-posterior, dorsal-ventral, and left-right axes of the cell, and the relationship of receptors to ultrastructural components of the cell coat, cell membrane, and cytoskeleton.

Toward an empirical framework for interpreting plastid evolution

“…When weighing plastid gain versus loss in evolutionary modeling, one additional point frequently is overlooked; proposed returns to heterotrophy via plastid loss, themselves, involve other dramatic gains in cellular complexity. For example, active hunters like ciliates must have invented novel and complex feeding structures, chemoreception, and elaborate new behavioral adaptations (Hufnagel ). Without separate plastid gains, mixotrophic algae like dinoflagellates and haptophytes also must have experienced independent and de novo origins of complicated hunting and feeding adaptations (Tillmann , Lukes et al.…”

Connecting alveolate cell biology with trophic ecology in the marine plankton using the ciliateFavellaas a model

“…G-protein-coupled receptor (GPCR) signal transduction pathways, in particular, are critical for chemo-and mechano-sensation of predators and prey (Yang et al, 1997;Marino et al, 2001;Ramoino et al, 2003;Rosner et al, 2003;Kissmehl et al, 2006;Walerczyk et al, 2006;Bartholomew et al, 2008). Additionally, freshwater ciliates have been proposed as model systems for studying the relationship between sensory mechanisms and cell structure (Hufnagel, 1992). Although these conserved signaling mechanisms are likely to be common to freshwater and marine ciliates, freshwater ciliates have less complex morphologies and different ecological functions.…”

Climacostol inhibits Tetrahymena motility and mitochondrial respiration

“…They possess highly evolved cytoarchitecture as well as an intracellular messenger system regulating various cell functions [9,10]. Its ultrastructure, cell physiology, development, biochemistry, genetics and molecular biology have been extensively studied [11][12][13][14][15].…”