Crustacean cardiac ganglion model reveals constraints on morphology and conductances

The crustacean cardiac ganglion (CG) network coordinates the rhythmic contractions of the heart muscle to control the circulation of blood. The network consists of 9 cells, 5 large motor cells (LC1-5) and 4 small endogenous pacemaker cells (SCs). We report a new three-compartmental biophysical model of an LC that is morphologically realistic and includes provision for inputs from the SCs via a gap-junction coupled spike-initiation-zone (SIZ) compartments. To determine physiologically viable LC models in this realistic configuration, maximal conductances in three compartments of an LC are determined by random sampling from a biologically-characterized 9D-parameter space, followed by a three stage rejection protocol that checks for conformity with electrophysiological features from single cell traces. LC models that pass the single cell rejection protocol are then incorporated into a network model which is then used in a final rejection protocol stage. Using disparate experimental data, the study provides hitherto unknown structure-function insights related to the crustacean cardiac ganglion large cell, including predictions about morphology including the role of its SIZ, and the differential roles of active conductances in the three compartments. Further, we extend analyses of emergent conductance relationships and correlations in model neurons relative to their biological counterparts, allowing us to make inferences both with respect to the biological system as well as the implications of the ability to detect such relationships in populations of model neurons going forward.

Prof. Goldscheider und D-r Flatau. Normale und pathologische Anatomie der Nervenzellen auf Grund der neueren Forschungen. Berlin, 1898. (Mit 8 Abbildungen im Text und 7 Tafeln)

The question of the normal and pathological histology of nerve cells is increasingly occupying the minds of specialists-researchers of different countries. Despite the fact that the results obtained do not yet make it possible to talk about them, as about the last word in this area of ​​knowledge, the work on combining the accumulated material is not the same. So Nissl gives in his work about hypotheses of the functions of nerve cells; In such a form, a particular question appears about the recovery of sick motor cells (after cutting the nerve fiber, in case of poisoning with poison), etc. Some authors ask themselves the question of facilitating further work, carefully collecting the existing literature. The last one includes, by the way, the work of Dr. Muravyov (Russian Archives of Pathology, etc. 1897. December), as well as the work written out above by Prof. Goldscheider and Dr. Flatau.

Mechanical Signaling in the Sensitive Plant Mimosa pudica L.

As sessile organisms, plants do not possess the nerves and muscles that facilitate movement in most animals. However, several plant species can move quickly in response to various stimuli (e.g., touch). One such plant species, Mimosa pudica L., possesses the motor organ pulvinus at the junction of the leaflet-rachilla, rachilla-petiole, and petiole-stem, and upon mechanical stimulation, this organ immediately closes the leaflets and moves the petiole. Previous electrophysiological studies have demonstrated that a long-distance and rapid electrical signal propagates through M. pudica in response to mechanical stimulation. Furthermore, the spatial and temporal patterns of the action potential in the pulvinar motor cells were found to be closely correlated with rapid movements. In this review, we summarize findings from past research and discuss the mechanisms underlying long-distance signal transduction in M. pudica. We also propose a model in which the action potential, followed by water flux (i.e., a loss of turgor pressure) in the pulvinar motor cells is a critical step to enable rapid movement.

Motile traps

We review the biomechanics, functional morphology, and physiology of motile traps. The movements of snap traps in Aldrovanda and Dionaea, motile adhesive traps in Drosera and Pinguicula, and suction traps in Utricularia are driven by active water displacement processes leading to reversible turgor changes of motor cells, irreversible growth, or mechanical pre-stressing of tissues. In some cases, the motion is amplified by the release of elastic energy stored in these tissues. The only known case of a passive motile trapping movement is the ‘springboard’ trapping mechanism of Nepenthes gracilis, in which a rapid vibration of the pitcher lid is actuated by the impact force of raindrops. Open research questions are summarized and future studies are suggested.

Structure, Design, and Modeling of an Origami-Inspired Pneumatic Solar Tracking System for the NPU-Phonesat

Various plants have the ability to follow the sun with their flowers or leaves via a mechanism known as heliotropism, which is powered by pressure gradients between neighboring motor cells. Adapting this bio-inspired mechanism, in this paper we present a novel origami-inspired pneumatic solar tracking system for a picosatellite named NPU-PhoneSat that is capable of solar tracking without altering the attitude of the NPU-PhoneSat. We give an overview of the system design and address the theoretical problem of modeling the origami-inspired pneumatic solar tracking system. The theoretical results are compared with the experimental data, demonstrating the validity of the proposed analytical model. Such understanding of soft solar trackers will allow their performance to be predicted, thus enabling their wide utilization in enhancing energy supply.