Autonomous navigation system for the Marsokhod rover project

This paper presents a general overview of the Marsokhod rover mission. The autonomous navigation for a Mars exploration rover is controlled by a vision system which has been developed on the basis of two CCD cameras, stereovision and path planning algorithms. Its performances have been tested on a Mars-like experimentation site

New Method for Determining the Total Calcium Content of Tissue Applied to Whole Skeletal Muscles from Mice with and Without Calsequestrin Knocked Out

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Ryanodine receptor leak triggers fiber Ca²⁺ redistribution to preserve force and elevate basal metabolism in skeletal muscle

Muscle contraction depends on tightly regulated Ca2+ release. Aberrant Ca2+ leak through ryanodine receptor 1 (RyR1) on the sarcoplasmic reticulum (SR) membrane can lead to heatstroke and malignant hyperthermia (MH) susceptibility, as well as severe myopathy. However, the mechanism by which Ca2+ leak drives these pathologies is unknown. Here, we investigate the effects of four mouse genotypes with increasingly severe RyR1 leak in skeletal muscle fibers. We find that RyR1 Ca2+ leak initiates a cascade of events that cause precise redistribution of Ca2+ among the SR, cytoplasm, and mitochondria through altering the Ca2+ permeability of the transverse tubular system membrane. This redistribution of Ca2+ allows mice with moderate RyR1 leak to maintain normal function; however, severe RyR1 leak with RYR1 mutations reduces the capacity to generate force. Our results reveal the mechanism underlying force preservation, increased ATP metabolism, and susceptibility to MH in individuals with gain-of-function RYR1 mutations

Human skeletal muscle plasmalemma alters its structure to change its Ca2+-handling following heavy-load resistance exercise

High-force eccentric exercise results in sustained increases in cytoplasmic Ca2+ levels ([Ca2+]cyto), which can cause damage to the muscle. Here we report that a heavy-load strength training bout greatly alters the structure of the membrane network inside the fibres, the tubular (t-) system, causing the loss of its predominantly transverse organization and an increase in vacuolation of its longitudinal tubules across adjacent sarcomeres. The transverse tubules and vacuoles displayed distinct Ca2+-handling properties. Both t-system components could take up Ca2+ from the cytoplasm but only transverse tubules supported store-operated Ca2+ entry. The retention of significant amounts of Ca2+ within vacuoles provides an effective mechanism to reduce the total content of Ca2+ within the fibre cytoplasm. We propose this ability can reduce or limit resistance exercise-induced, Ca2+-dependent damage to the fibre by the reduction of [Ca2+]cyto to help maintain fibre viability during the period associated with delayed onset muscle soreness

The concentration of free Ca 2+ in the sarcoplasmic reticulum of frog cut twitch skeletal muscle fibers estimated with tetramethylmurexide

The contractile response in skeletal muscle is controlled by the time course and magnitude of Ca2+ release from the sarcoplasmic reticulum (SR) into the myoplasm. In order to gain an understanding of how SR Ca2+ release is regulated, it is often useful to estimate the permeability of the SR to Ca2+ as this provides a measure of the extent of activation of SR Ca2+ release channels. The permeability of the SR is proportional to the rate of Ca2+ release normalized by the driving force for release which is primarily determined by the concentration of free calcium in the SR (denoted [Ca2+]SR). In past studies (e.g. [1–4]), the driving force for Ca2+ release was taken to be the concentration of total calcium in the SR (denoted [CaT]SR) rather than [Ca2+]SR owing to the lack of information about [Ca2+]SR. The primary aims of the experiments in this article were to establish the resting value of [Ca2+]SR (denoted [Ca2+]SR,R) with the absorbance indicator tetramethylmurexide (TMX) and, perhaps more importantly, the ratio of [Ca2+]SR,R and TMX’s apparent dissociation constant. This latter information is needed to establish the time course of [Ca2+]SR with TMX during SR Ca2+ release and, thereby, the time course of the true release permeability

Digestibilité et valeur énergétique de différentes luzernes déshydratées utilisées seules ou en mélange dans le régime du lapin en croissance

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