pore size exclusion
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2015 ◽  
Vol 26 (9) ◽  
pp. 1752-1763 ◽  
Author(s):  
Michael J. W. VanGompel ◽  
Ken C. Q. Nguyen ◽  
David H. Hall ◽  
William T. Dauer ◽  
Lesilee S. Rose

Torsin proteins are AAA+ ATPases that localize to the endoplasmic reticular/nuclear envelope (ER/NE) lumen. A mutation that markedly impairs torsinA function causes the CNS disorder DYT1 dystonia. Abnormalities of NE membranes have been linked to torsinA loss of function and the pathogenesis of DYT1 dystonia, leading us to investigate the role of the Caenorhabditis elegans torsinA homologue OOC-5 at the NE. We report a novel role for torsin in nuclear pore biology. In ooc-5–mutant germ cell nuclei, nucleoporins (Nups) were mislocalized in large plaques beginning at meiotic entry and persisted throughout meiosis. Moreover, the KASH protein ZYG-12 was mislocalized in ooc-5 gonads. Nups were mislocalized in adult intestinal nuclei and in embryos from mutant mothers. EM analysis revealed vesicle-like structures in the perinuclear space of intestinal and germ cell nuclei, similar to defects reported in torsin-mutant flies and mice. Consistent with a functional disruption of Nups, ooc-5–mutant embryos displayed impaired nuclear import kinetics, although the nuclear pore-size exclusion barrier was maintained. Our data are the first to demonstrate a requirement for a torsin for normal Nup localization and function and suggest that these functions are likely conserved.


Soil Research ◽  
2005 ◽  
Vol 43 (6) ◽  
pp. 695 ◽  
Author(s):  
Guangming Jiang ◽  
Mike J. Noonan ◽  
Graeme D. Buchan ◽  
Neil Smith

Bacterial transport in unsaturated soils is much less well understood than in saturated conditions, especially for intact soils. This paper aims to investigate the fate and transport of bacteria in intact soils with different water saturations, and particularly the effect of low suction (and hence removal of water flow in the largest macropores). An intact soil column (0.50 m diameter by 0.70 m depth) with a tension infiltrometer was used to investigate the transport and deposition of Bacillus subtilis endospores (i.e. dormant and persistent bacteria) during saturated and unsaturated flows. Soil porosity and pore size distribution were measured. Porosity decreased with depth and macropores were concentrated in the topsoil. Three tensiometers and a temperature sensor were installed along the soil column to monitor matric suction and temperature. Breakthrough curves for bacteria and chemical tracer Br– at 0 and 0.5 kPa suction were obtained during the 3-month leaching experiment. Bacterial breakthrough occurred earlier than the inert chemical tracer, which is consistent with effects of pore size exclusion. Also, saturated flow gave a significantly higher concentration and recovery ratio of leached bacteria, i.e. 51% v. 0.88%. Recovery of Br– in leachate at both suctions reached >85%. The column was destructively sampled for deposited endospores at the completion of leaching. Bacterial deposition was concentrated in the top 0.10 m, then decreased abruptly and was relatively constant with column depth, although showing some irregularity at the bottom of the column.


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