E.I. Ekwue 2 The design, construction and testing of a soil dry sieving apparatus, which could be used to effectively determine the particle size distribution curves of dry soil samples is described. The design required that a means be developed to agitate soil samples placed on two stacks of sieves, each arranged in decreasing sizes. The apparatus was designed to utilize a horizontal and verti...

Open-channel blockers such as tetraethylammonium (TEA) have a long history as probes of the permeation pathway of ion channels. High affinity blockade by extracellular TEA requires the presence of an aromatic amino acid at a position that sits at the external entrance of the permeation pathway (residue 449 in the eukaryotic voltage-gated potassium channel Shaker). We investigated whether a cati...

A photoactivatable derivative of the inactivating peptide of the Shaker B potassium channel (ShB peptide) has been synthesized from ShB peptide containing an added cysteine residue at the peptide carboxy-terminus and 1-(p-azidosalicylamido)-4-(iodoacetamido)butane. The peptide derivative restores rapid inactivation in the deletion mutant Shaker Bdelta6-46 potassium channel in a manner indisting...

The patterned activity generated by the pyloric circuit in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus, results not only from the synaptic connectivity between the 14 component neurons but also from differences in the intrinsic properties of the neurons. Presumably, differences in the complement and distribution of expressed ion channels endow these neurons with many...

High-performance muscles such as the shaker muscles in the tails of western diamond-backed rattlesnakes (Crotalus atrox) are excellent systems for studying the relationship between contractile performance and metabolic capacity. We observed that shaker muscle contraction frequency increases dramatically with growth in small individuals but then declines gradually in large individuals. We tested...

Peptide neurotoxins are powerful tools for research, diagnosis, and treatment of disease. Limiting broader use, most receptors lack an identified toxin that binds with high affinity and specificity. This paper describes isolation of toxins for one such orphan target, KcsA, a potassium channel that has been fundamental to delineating the structural basis for ion channel function. A phage-display...

The voltage-dependent gating mechanism of single A-type potassium channels coded for by the Shaker locus of Drosophila was studied by single-channel recording. A-type channels expressed in Xenopus oocytes injected with Shaker B and Shaker D mRNA exhibited gating and voltage dependence that were qualitatively similar to those of the native Shaker A-types channels from embryonic myotubes. In all ...

While there are a great variety of digital musical interfaces available to the working musician, few offer the level of immediate, nuanced and instinctive interaction that one finds in an acoustic shaker. bEADS is a prototype of a digital musical instrument that utilises the gestural vocabulary associated with shaken idiophones and expands on the techniques and sonic possibilities associated wi...