Types Of Signaling Systems Research Articles

The Features and Functions of Neuronal Assemblies: Possible Dependency on Mechanisms beyond Synaptic Transmission.

“Neuronal assemblies” are defined here as coalitions within the brain of millions of neurons extending in space up to 1–2 mm, and lasting for hundreds of milliseconds: as such they could potentially link bottom-up, micro-scale with top-down, macro-scale events. The perspective first compares the features in vitro versus in vivo of this underappreciated “meso-scale” level of brain processing, secondly considers the various diverse functions in which assemblies may play a pivotal part, and thirdly analyses whether the surprisingly spatially extensive and prolonged temporal properties of assemblies can be described exclusively in terms of classic synaptic transmission or whether additional, different types of signaling systems are likely to operate. Based on our own voltage-sensitive dye imaging (VSDI) data acquired in vitro we show how restriction to only one signaling process, i.e., synaptic transmission, is unlikely to be adequate for modeling the full profile of assemblies. Based on observations from VSDI with its protracted spatio-temporal scales, we suggest that two other, distinct processes are likely to play a significant role in assembly dynamics: “volume” transmission (the passive diffusion of diverse bioactive transmitters, hormones, and modulators), as well as electrotonic spread via gap junctions. We hypothesize that a combination of all three processes has the greatest potential for deriving a realistic model of assemblies and hence elucidating the various complex brain functions that they may mediate.

Possibilities of RutasOptiRed Package

Planning the operations of Renfe Operadora trains on Adif's (Spanish) railway network is very complex. The reasons are the coexistence of two track gauges, two kinds of electrification systems and five types of signaling systems; together with fixed and variable gauge rolling stock, sometimes able to run under different types of electrification and signaling systems. There is even a multiple unit hybrid series (730). The authors have developed a microscopic simulation computer package that calculates timings and minimal paths, and estimates costs, consumptions and emissions. The package is topology-independent and can perform computations for any type of trains. We shall focus here on its use, the structure of its input files and its possibilities.

Contribution of lipoxygenase metabolism to the brassinosteroid signaling pathway.

Brassinosteroids (BSs) are phytohormones, the chemical structure of which is closest to the chemical structure of animal steroid hormones. It was shown by a number of researchers that BSs contributed to plant growth and development [1]. It was also demonstrated that BS caused an increase in the plant resistance to pathogens [2] and adverse climatic factors [3]. Receptors of BS were found to be located in plasmalemma [4]. Phosphorylation of certain proteins was demonstrated to be an early BS-induced response [5]. These findings suggest that BSs are incorporated into the signaling systems of plant cells. However, it is still unclear which types of signaling systems may incorporate BSs. It was also suggested that BSs constituted a previously unknown signaling system [2]. Because it is well known that the lipoxygenase signaling system is involved in cell response to various pathogens, mechanical injuries, elicitors, and some other primary signals [6], the goal of this work was to study the possibility of the brassinosteroid-induced activation of this signaling system. Effects of 24-epibrassinosteroid (EPB), the most active form of BS, on concentrations of oxygenated derivatives of linoleic acid (indicators of lipoxygenase activity) and on the level of phosphorylation of soluble proteins of pea leaves (it is well known that reactions of protein phosphorylation/dephosphorylation are a very important component of signaling systems) were studied. It was suggested that the analysis of lipoxygenase activity and the use of phospholipase A 2 (PLA 2 ) inhibitor provided an opportunity to elucidate the contribution of the lipoxygenase metabolism to the initial phase of the EPB-induced response of the cells. Bromphenylacyl bromide (BPB) was used as a phospholipase A 2 inhibitor decreasing the rate of release of unsaturated fatty acids (lipoxygenase substrate). The lipoxygenase activity level was assessed using the methodological approach based on the appearance of two conjugated bonds and absorption maximum at 232 nm during the reaction of formation of oxygenated derivatives of linoleic acid.

Ligands of steroid/thyroid receptors induce cone photoreceptors in vertebrate retina.

The mechanisms by which multipotent progenitor cells are directed to alternative cell identities during the histogenesis of the vertebrate central nervous system are likely to involve several different types of signaling systems. Recent evidence indicates that 9-cis retinoic acid, which acts through members of the steroid/thyroid superfamily of receptors, directs progenitor cells to the rod photoreceptor cell fate. We now report that another effector of this family of receptors, thyroid hormone, induces an increase in the number of cone photoreceptors that develop in embryonic rat retinal cultures, and that combinations of 9-cis retinoic acid and triiodothyronine cause isolated progenitor cells to differentiate as either rods or cones, depending on the relative concentrations of the ligands. These results implicate thyroid hormone in CNS cell fate determination, and suggest that different photoreceptor phenotypes may be modulated through the formation of thyroid/retinoid receptor heterodimers.

Vibrating reed selectors for mobile radio use

A new type of signaling system <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> has been developed for mobile radiotelephone service in the Bell System. The basic selection of this system is performed by the use of vibrating reed selectors as described in this article.