Olfaction enables most mammalian species to detect and discriminate vast numbers of chemical structures called odorants and pheromones. The perception of such chemical compounds is mediated via two major olfactory systems, the main olfactory system and the vomeronasal system, as well as minor systems, such as the septal organ and the Grueneberg ganglion. Distinct differences exist not only among species but also among individuals in terms of their olfactory sensitivity; however, little is known about the mechanisms that determine these differences. In research on the olfactory sensitivity of mammals, scientists thus depend in most cases on behavioral testing. In this article, we reviewed scientific studies performed on various mammalian species using different methodologies and target chemical substances. Human and non-human primates as well as rodents and dogs are the most frequently studied species. Olfactory threshold studies on other species do not exist with the exception of domestic pigs. Olfactory testing performed on seals, elephants, and bats focused more on discriminative abilities than on sensitivity. An overview of olfactory sensitivity studies as well as olfactory detection ability in most studied mammalian species is presented here, focusing on comparable olfactory detection thresholds. The basics of olfactory perception and olfactory sensitivity factors are also described., M. Wackermannová, L. Pinc, L. Jebavý., and Obsahuje bibliografii
The distance between the ß-subunits of Na + /K + -ATPase isolated from pig dark red kidney medulla was determined by Forster energy transfer. First, oligosaccharides of the ß-subunit were shown to be labelled with three fluorophores: Lucifer yellow (LY), Lissamine rhodamine B sulfonyl hydrazine (LRSH) and Cascade blue (CB). Further, LY and LRSFI were used as the donor and the acceptor, respectively, for Forster energy transfer studies to determine the localization of the ß-subunit in the native enzyme which is known to be formed as a tetramer (aß)2. It was found that the ß-subunits in the functional enzyme complex in the membrane are not localized next to each other but are spatially separated. The distance between fluorophores covalently attached to the ß-subunits was found to be 5.1 nm. This conclusion was confirmed by measurements with another donor- acceptor pair CB-LY. The results also support the idea of a direct interaction of the ß-subunit with the extracellular part of the a-subunit. These interactions were modified in the presence of millimolar concentrations of magnesium ions. This indicates a crucial role of magnesium in extracellular interactions between the alpha and beta subunits.