We have used the giant ciliary comb plates of ctenophores to record electrical activity directly from cilia. A compound action potential was recorded extracellularly over most of the length of the comb plate cilia in response to electrical stimulation of the ectodermal nerve net. The ciliary action potential was correlated with intracellularly recorded action potentials, selectively blocked by ...

Defects in cilia are associated with diseases and developmental abnormalities. Proper cilia function is required for sonic hedgehog and PDGFRalpha signaling in mammals and for insulin-like growth factor (IGF) signaling in Caenorhabditis elegans. However, the role of cilia in these pathways remains unknown. To begin addressing this issue, we are characterizing putative cilia proteins in C. elega...

Microscopic hair-like structures, such as cilia, exist ubiquitously in nature and are used by various organisms for transportation purposes. Many efforts have been made to mimic the fluid pumping function of cilia, but most of the fabrication processes of these ‘‘artificial cilia’’ are tedious and expensive, hindering their practical applications. In this paper, an attractive and potentially co...

Eukaryotic cilia/flagella are ancient organelles with motility and sensory functions. Cilia display significant ultrastructural conservation where present across the eukaryotic phylogeny; however, diversity in ciliary biology exists and the ability to produce cilia has been lost independently on a number of occasions. Land plants provide an excellent system for the investigation of cilia evolut...

Cilia and flagella are microtubule-based appendages extending from the basal body of most eukaryotic cells, and are classified as either motile or primary. Motile cilia or flagella can be found on many cells such as Chlamydomonas, sperm, and respiratory tract epithelial cells. This type of cilia is responsible for movement of the cell itself or generation of fluid flow. In contrast, primary cil...

The response of glycerinated cilia from Tetrahymena to the addition of adenosine triphosphate (ATP) can be assayed by measuring the size of the ciliary pellet obtained after brief, low-speed centrifugation in hematocrit tubes (1) . Upon the addition of ATP, cilia swell, resulting in pellets up to threefold larger than pellets of control cilia . There are two interdependent hydrodynamic factors ...

Primary cilia play critical roles in many aspects of biology. Specialized versions of primary cilia are involved in many aspects of sensation. The single photoreceptor sensory cilium (PSC) or outer segment elaborated by each rod and cone photoreceptor cell of the retina is a classic example. Mutations in genes that encode cilia components are common causes of disease, including retinal degenera...

Fibers keep cilia regular A ctin fi bers and microtubules help cilia coordinate the direction and sequence of their beating, Werner et al. show. At fi rst, the multiple cilia on an embryonic cell are a bit like the musicians in a garage band, each doing its own thing. But over time the fi laments turn so that they all beat in the same direction. They also coordinate their timing, so that the ci...

Specification of the mammalian left–right (L–R) axis is controlled by fluid flows in the embryonic node, a ciliated pit like structure located at the distal tip of the mouse embryo. Nodal cilia rotate so as to cause a leftward fluid flow-this has been experimentally demonstrated to control embryonic sidedness. How the embryo interprets this flow remains the subject of debate. The two cilia hypo...

The cilium serves as a cellular antenna by coordinating upstream environmental cues with numerous downstream signaling processes that are indispensable for the function of the cell. This role is supported by the revelation that defects of the cilium underlie an emerging class of human disorders, termed "ciliopathies." Although mounting interest in the cilium has demonstrated the essential role ...