Novel method for evaluating the health condition of mice in space through a video downlink

Clarification of the criteria for managing animal health is essential to increase the reliability of experiments and ensure transparency in animal welfare. For experiments performed in space, there is no consensus on how to care for animals owing to technical issues, launch mass limitation, and human resources. Some biological processes in mammals, such as musculoskeletal or immune processes, are altered in the space environment, and mice in space can be used to simulate morbid states, such as senescence acceleration. Thus, there is a need to establish a novel evaluation method and evaluation criteria to monitor animal health. Here, we report a novel method to evaluate the health of mice in space through a video downlink in a series of space experiments using the Multiple Artificial-gravity Research System (MARS). This method was found to be more useful in evaluating animal health in space than observations and body weight changes of the same live mice following their return to Earth. We also developed criteria to evaluate health status via a video downlink. These criteria, with “Fur condition” and “Respiratory” as key items, provided information on the daily changes in the health status of mice and helped to identify malfunctions at an early stage. Our method and criteria led to the success of our missions, and they will help establish appropriate rules for space experiments in the future.     

Distribution and characterization of the glutamate receptors in the CNS of ataxic mutant mouse

In a search for neurochemical involvement in cerebellar ataxia, Rolling Mouse Nagoya (C3Hf/Nem-rol), which shows only hypoplasia of the cerebellum but no pathological configuration of the cerebellar structure, was used to study glutamate receptors in the CNS. Kainic acid binding sites were significantly decreased in the thalamus, hypothalamus, pons, and cerebellum, and in the frontal cortex of both the ataxic mutant mouse and the non-ataxic heterozygote. Only spinal cord and midbrain of the ataxic mutant mouse showed decreased distribution of kainate binding sites in the membrane fraction.Among enzymes responsible for supplying glutamate to the receptor, GDH showed higher activity in the spinal cord of the ataxic mutanat mouse.     

Cell volume change of Escherichia coli under stringent control apparent increase of K in rel cells

With several pairs of rel⁺ and rel⁻ strains of Escherichia coli, the effects of amino acid starvation on the intracellular concentration of K⁺ and the rate of uptake of ⁴²K⁺ were investigated. In the early phase of the experiments, the intracellular concentration of K⁺ was estimated by the conventional method in which the cell volume per A₆₆₀ value of the culture was assumed to be constant, being not influenced by the variation of growth condition and strain. Apparently, the K⁺ concentration of rel⁺ cells was kept almost constant, while that of rel⁻ cells increased about 1.5-fold 2 h after the exposure to amino acid starvation. Unexpectedly, however, the above assumption was found not to be valid in the present study. The cell volume per A₆₆₀ changed only slightly in CP78 (rel⁺) cells, while it increased markedly in CP79 (rel⁻) cells after the exposure to amino acid starvation. Reestimation of the K⁺ concentrations based on the estimated respective values of cell volumes per A₆₆₀ revealed no significant difference between both strains. After all, the above apparent phenomenon was found to be due to the fact that the increase in cell volume of the rel⁺ cells was arrested upon amino acid starvation whereas that in the rel⁻ cells was not. The ⁴²K⁺ uptake by the rel⁺ cells was depressed upon amino acid starvation, whereas that by the rel⁻ cells increased. Some regulatory mechanism was suggested to operate in both strains to keep their K⁺ concentrations constant. When intracellular concentration of a metabolite is to be determined, importance of measurement of cell volume under the respective conditions, without assuming the constancy of the cell volume per A₆₆₀ of the culture, was pointed out.     

Delphinidin prevents disuse muscle atrophy and reduces stress-related gene expression

Delphinidin is a member of the anthocyanidin class of plant pigments. We examined the effects of delphinidin on muscle atrophy. Oral administration of delphinidin suppressed the muscle weight loss induced by mechanical unloading. Microarray analysis showed that delphinidin suppresses the upregulation of oxidative stress-related gene expression, including the expression of Cbl-b. Thus, delphinidin may prevent unloading-mediated muscle atrophy.     

Epigenetic landscape of interacting cells: A model simulation for developmental process

We propose a physical model for developmental process at cellular level to discuss the mechanism of epigenetic landscape. In our simplified model, a minimal model, the network of the interaction among cells generates the landscape epigenetically and the differentiation in developmental process is understood as a self-organization. The effect of the regulation by gene expression which is a key ingredient in development is renormalized into the interaction and the environment. At earlier stage of the development the energy landscape of the model is rugged with small amplitude. The state of cells in such a landscape is susceptible to fluctuations and not uniquely determined. These cells are regarded as stem cells. At later stage of the development the landscape has a funnel-like structure corresponding to the canalization in differentiation. The rewinding or stability of the differentiation is also demonstrated by substituting test cells into the time sequence of the model development.