Can Molecular Motors Drive Distance Measurements in Injured Neurons?

Injury to nerve axons induces diverse responses in neuronal cell bodies, some of which are influenced by the distance from the site of injury. This suggests that neurons have the capacity to estimate the distance of the injury site from their cell body. Recent work has shown that the molecular motor dynein transports importin-mediated retrograde signaling complexes from axonal lesion sites to cell bodies, raising the question whether dynein-based mechanisms enable axonal distance estimations in injured neurons? We used computer simulations to examine mechanisms that may provide nerve cells with dynein-dependent distance assessment capabilities. A multiple-signals model was postulated based on the time delay between the arrival of two or more signals produced at the site of injury–a rapid signal carried by action potentials or similar mechanisms and slower signals carried by dynein. The time delay between the arrivals of these two types of signals should reflect the distance traversed, and simulations of this model show that it can indeed provide a basis for distance measurements in the context of nerve injuries. The analyses indicate that the suggested mechanism can allow nerve cells to discriminate between distances differing by 10% or more of their total axon length, and suggest that dynein-based retrograde signaling in neurons can be utilized for this purpose over different scales of nerves and organisms. Moreover, such a mechanism might also function in synapse to nucleus signaling in uninjured neurons. This could potentially allow a neuron to dynamically sense the relative lengths of its processes on an ongoing basis, enabling appropriate metabolic output from cell body to processes

Instrumental Food Analysis

The instrumental analysis of foods is an important step in food processing and manufacturing companies because of the presence and interactions of various compounds in foods during storage and processing. While traditional methods are still used, most analysis involves the use of different instruments. This chapter is structured to provide a description of the information each technique can provide, a simple explanation of how it works and examples of its application, and facilitates comparison of techniques. The focus of this chapter is on spectroscopic, chromatographic and electrophoretic methods, including specific examples of instruments such as capillary electrophoresis, high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), atomic absorption, emission and inductively coupled plasma, fluorescence spectroscopies, gel electrophoresis, etc., among many others. © Springer-Verlag Berlin Heidelberg 2015