Cilia - the prodigal organelle

UCL Institute of Child Health, London WC1N 1EH, UK. .
Cilia 04/2012; 1(1):1. DOI: 10.1186/2046-2530-1-1
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Available from: Peter Kent Jackson
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    • "This is perhaps an appropriate denotation for a biological appendage found on the surface of a variety of eukaryotic cells, with a fascinating and still not fully understood relationship between internal structure and biological function [2]. Cilia not only have the capacity to transport surrounding fluids by means of periodic movements but they also play important sensory roles [1] [3]. Remarkably, their basic morphology and internal structure (the so-called axoneme), which is the same as in all eukaryotic flagella, has been conserved throughout evolution [4]. "
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    ABSTRACT: Cilia and flagella are hair-like appendages that protrude from the surface of a variety of eukaryotic cells and deform in a wavelike fashion to transport fluids and propel cells. Motivated by the ubiquity of non-Newtonian fluids in biology, we address mathematically the role of shear-dependent viscosities on both the waving flagellar locomotion and ciliary transport by metachronal waves. Using a two-dimensional waving sheet as model for the kinematics of a flagellum or an array of cilia, and allowing for both normal and tangential deformation of the sheet, we calculate the flow field induced by a small-amplitude deformation of the sheet in a generalized Newtonian Carreau fluid up to order four in the dimensionless waving amplitude. Shear-thinning and shear-thickening fluids are seen to always induce opposite effects. When the fluid is shear-thinning, the rate of working of the sheet against the fluid is always smaller than in the Newtonian fluid, and the largest gain is obtained for antiplectic metachronal waves. Considering a variety of deformation kinematics for the sheet, we further show that in all cases transport by the sheet is more efficiency in a shear-thinning fluid, and in most cases the transport speed in the fluid is also increased. Comparing the order of magnitude of the shear-thinning contributions with past work on elastic effects as well as the magnitude of the Newtonian contributions, our theoretical results suggest that the impact of shear-dependent viscosities on transport could play a major biological role.
    Full-text · Article · Mar 2014 · Journal of Non-Newtonian Fluid Mechanics
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    • "The field of ciliopathies has been of great interest in the last few years . A variety of links between cilia and morphogen pathways have been published and the number of publications covering the field of cilia biology and ciliopathies is increasing dramatically ( Beales & Jackson , 2012 ) . The studies mentioned here show that the application of modern proteomic methods to detect and quantitatively compare protein complexes is a powerful tool to investigate disease , as well as basic biological mechanisms within this organelle . "
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    ABSTRACT: Interest in the field of cilia biology and cilia-associated diseases - ciliopathies - has strongly increased over the last few years. Proteomic technologies, especially protein complex analysis by affinity purification-based methods, have been used to decipher various basic but also disease-associated mechanisms. This review focusses on some selected recent studies using affinity purification-based protein complex analysis, thereby exemplifying the great possibilities this technology offers.
    Full-text · Article · Sep 2012 · Vision research
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    ABSTRACT: Ciliopathies lead to multiorgan pathologies that include renal cysts, deafness, obesity and retinal degeneration. Retinal photoreceptors have connecting cilia joining the inner and outer segment that are responsible for transport of molecules to develop and maintain the outer segment process. The present study evaluated meckelin (MKS3) expression during outer segment genesis and determined the consequences of mutant meckelin on photoreceptor development and survival in Wistar polycystic kidney disease Wpk/Wpk rat using immunohistochemistry, analysis of cell death and electron microscopy. MKS3 was ubiquitously expressed throughout the retina at postnatal day 10 (P10) and P21. However, in the mature retina, MKS3 expression was restricted to photoreceptors and the retinal ganglion cell layer. At P10, both the wild type and homozygous Wpk mutant retina had all retinal cell types. In contrast, by P21, cells expressing rod- and cone-specific markers were fewer in number and expression of opsins appeared to be abnormally localized to the cell body. Cell death analyses were consistent with the disappearance of photoreceptor-specific markers and showed that the cells were undergoing caspase-dependent cell death. By electron microscopy, P10 photoreceptors showed rudimentary outer segments with an axoneme, but did not develop outer segment discs that were clearly present in the wild type counterpart. At p21 the mutant outer segments appeared much the same as the P10 mutant outer segments with only a short axoneme, while the wild-type controls had developed outer segments with many well-organized discs. We conclude that MKS3 is not important for formation of connecting cilium and rudimentary outer segments, but is critical for the maturation of outer segment processes.
    Full-text · Article · Mar 2013 · PLoS ONE
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