We investigated the X-ray scattering signal of highly aligned multilayers of the zwitterionic lipid 1,2-dilauroyl-sn-glycero-3-phosphatidylcholine containing pores formed by the antimicrobial peptide gramicidin as a function of the peptide/lipid ratio. We are able to obtain information on the structure factor of the pore fluid, which then yields the interaction potential between pores in the pl...

The symmetric core of the nuclear pore complex can be considered schematically as a series of concentric cylinders. A peripheral cylinder coating the pore membrane contains the previously characterized, elongated heptamer that harbors Sec13-Nup145C in its middle section. Strikingly, Sec13-Nup145C crystallizes as a hetero-octamer in two space groups. Oligomerization of Sec13-Nup145C was confirme...

We investigate the dynamics of DNA translocation through a nanopore using 2D Langevin dynamics simulations, focusing on the dependence of the translocation dynamics on the details of DNA sequences. The DNA molecules studied in this work are built from two types of bases A and C, which have been shown previously to have different interactions with the pore. We study DNA with repeating blocks A(n...

The modular architecture of voltage-gated K(+) (Kv) channels suggests that they resulted from the fusion of a voltage-sensing domain (VSD) to a pore module. Here, we show that the VSD of Ciona intestinalis phosphatase (Ci-VSP) fused to the viral channel Kcv creates Kv(Synth1), a functional voltage-gated, outwardly rectifying K(+) channel. Kv(Synth1) displays the summed features of its individua...

Advances in imaging and reductionist approaches have provided a high-resolution understanding of nuclear pore complex structure and transport, revealing unexpected mechanistic complexities based on nucleoporin functions and specialized import and export pathways.

Structural determination of the nuclear pore complex has been limited by the complexity and size of this cellular megalith. By taking advantage of exceptionally stable nucleoporins from the thermophilic fungus Chaetomium thermophilum, Amlacher et al. (2011) provide new insight into a core element of the nuclear pore scaffold.

Many natural fibrous networks with fiber diameters much smaller than the average poresize can be described as three-dimensional (3D) random line networks. We consider here a ‘Mikado’ model for such systems, consisting of straight line segments of equal length, distributed homogeneously and isotropically in space. First, we derive analytically the probability density distribution p(rno) for the ...

In the sieve elements (SEs) of the phloem, carbohydrates are transported throughout the whole plant from their site of production to sites of consumption or storage. SE structure, especially of the pore-rich end walls, has a direct effect on translocation efficiency. Differences in pore size and other features were interpreted as an evolutionary trend towards reduced hydraulic resistance. Howev...

A comparative study using small-angle x-ray scattering ~SAXS! and nitrogen adsorption has been carried out in the structural characterization of silica xerogels and aerogels, obtained from tetraethoxysilane sonohydrolysis. The specific surface and the mean pore size as measured by both the techniques were found to be in notable agreement in all cases for aerogels and xerogels. According to the ...

A nematode collected from Diaprepes abbreviatus is identified and described as a new species, Steinernema diaprepesi n. sp. The new species is closely related to S. feltiae, S. glaseri, and S. oregonense and can be distinguished from these species by the following characteristics: Males: Spicule averaging 79 (71-90) microm and spicule shape; D% (distance from anterior end to excretory pore/ eso...