Sperm Motility of Mice under Simulated Microgravity and Hypergravity

For deep space exploration, reproductive health must be maintained to preserve the species. However, the mechanisms underlying the effect of changes in gravity on male germ cells remain poorly understood. The aim of this study was to determine the effect of simulated micro- and hypergravity on mouse sperm motility and the mechanisms of this change. For 1, 3 and 6 h, mouse sperm samples isolated from the caudal epididymis were subjected to simulated microgravity using a random position machine and 2g hypergravity using a centrifuge. The experimental samples were compared with static and dynamic controls. The sperm motility and the percentage of motile sperm were determined using microscopy and video analysis, cell respiration was determined by polarography, the protein content was assessed by Western blotting and the mRNA levels were determined using qRT-PCR. The results indicated that hypergravity conditions led to more significant changes than simulated microgravity conditions: after 1 h, the speed of sperm movement decreased, and after 3 h, the number of motile cells began to decrease. Under the microgravity model, the speed of movement did not change, but the motile spermatozoa decreased after 6 h of exposure. These changes are likely associated with a change in the structure of the microtubule cytoskeleton, and changes in the energy supply are an adaptive reaction to changes in sperm motility.

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Mouse and Fly Sperm Motility Changes Differently under Modelling Microgravity

Current Issues in Molecular Biology ◽

10.3390/cimb43020043 ◽

2021 ◽

Vol 43 (2) ◽

pp. 590-604

Author(s):

Irina V. Ogneva

Keyword(s):

Sperm Motility ◽

Sodium Fluoride ◽

Animal Species ◽

Simulated Microgravity ◽

Control Level ◽

Fruit Fly ◽

Actin Binding ◽

Random Positioning Machine ◽

Microgravity Conditions ◽

Mammalian Spermatozoa

Sperm motility is essential for the natural fertilization process in most animal species. Despite the fact that evolution took place under conditions of constant gravity, the motility of spermatozoa of insects and mammals under microgravity conditions changes in different ways. In this work, an attempt was made to explain this effect. The sperm motility of the fruit fly Drosophila melanogaster and the mouse was evaluated after exposure to a random positioning machine for 6 h. Sodium fluoride was used to inhibit serine/threonine phosphatases, sodium orthovanadate was used to inhibit tyrosine phosphatases, and 6-(dimethylamino)purine was used to inhibit protein kinases. The results obtained indicate that simulated microgravity leads to an increase in the speed of movement of fly spermatozoa by 30% (p < 0.05), and this effect is blocked by sodium fluoride. In contrast, a 29% (p < 0.05) decrease in the speed of movement of mouse spermatozoa under simulated microgravity is prevented by 6-(dimethylamino)purine. Moreover, after 6 h of exposure, the content of tubulin cytoskeleton and actin proteins remains at the control level in the spermatozoa of flies and mice. However, the content of the actin-binding protein alpha-actinin in fly sperm decreases by 29% (p < 0.05), while in mouse sperm, the relative content of alpha-actinin1 increases by 94% (p < 0.05) and alpha-actinin4 by 121% (p < 0.05) relative to the control, as determined by 6 simulated microgravity tests. It can be assumed that the effect of simulated microgravity on the motility of mammalian spermatozoa is mediated through the regulation of phosphorylation and that of insects through the regulation of dephosphorylation of motor proteins; moreover, the development of a response to changes in external mechanical conditions has a different time scale.

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Alterations in the Virulence Potential of Enteric Pathogens and Bacterial–Host Cell Interactions Under Simulated Microgravity Conditions

Journal of Toxicology and Environmental Health Part A ◽

10.1080/15287390500361792 ◽

2006 ◽

Vol 69 (14) ◽

pp. 1345-1370 ◽

Cited By ~ 53

Author(s):

V. Chopra ◽

A. A. Fadl ◽

J. Sha ◽

S. Chopra ◽

C. L. Galindo ◽

...

Keyword(s):

Host Cell ◽

Simulated Microgravity ◽

Cell Interactions ◽

Enteric Pathogens ◽

Bacterial Host ◽

Virulence Potential ◽

Host Cell Interactions ◽

Microgravity Conditions

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Effect of microgravity on the expression of mitochondrial enzymes in rat cardiac and skeletal muscles

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.2.593 ◽

1998 ◽

Vol 84 (2) ◽

pp. 593-598 ◽

Cited By ~ 14

Author(s):

Michael K. Connor ◽

David A. Hood

Keyword(s):

Skeletal Muscle ◽

Enzyme Activity ◽

Skeletal Muscles ◽

Male Rats ◽

Mitochondrial Enzymes ◽

Mrna Levels ◽

Triceps Brachii ◽

Protein Levels ◽

Functional Consequences ◽

Microgravity Conditions

Connor, Michael K., and David A. Hood. Effect of microgravity on the expression of mitochondrial enzymes in rat cardiac and skeletal muscles. J. Appl. Physiol. 84(2): 593–598, 1998.—The purpose of this study was to examine the expression of nuclear and mitochondrial genes in cardiac and skeletal muscle (triceps brachii) in response to short-duration microgravity exposure. Six adult male rats were exposed to microgravity for 6 days and were compared with six ground-based control animals. We observed a significant 32% increase in heart malate dehydrogenase (MDH) enzyme activity, which was accompanied by a 62% elevation in heart MDH mRNA levels after microgravity exposure. Despite modest elevations in the mRNAs encoding subunits III, IV, and VIc as well as a 2.2-fold higher subunit IV protein content after exposure to microgravity, heart cytochrome c oxidase (CytOx) enzyme activity remained unchanged. In skeletal muscle, MDH expression was unaffected by microgravity, but CytOx activity was significantly reduced 41% by microgravity, whereas subunit III, IV, and VIc mRNA levels and subunit IV protein levels were unaltered. Thus tissue-specific (i.e., heart vs. skeletal muscle) differences exist in the regulation of nuclear-encoded mitochondrial proteins in response to microgravity. In addition, the expression of nuclear-encoded proteins such as CytOx subunit IV and expression of MDH are differentially regulated within a tissue. Our data also illustrate that the heart undergoes previously unidentified mitochondrial adaptations in response to short-term microgravity conditions more dramatic than those evident in skeletal muscle. Further studies evaluating the functional consequences of these adaptations in the heart, as well as those designed to measure protein turnover, are warranted in response to microgravity.

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Scalable Microgravity Simulator Used for Long-Term Musculoskeletal Cells and Tissue Engineering

International Journal of Molecular Sciences ◽

10.3390/ijms21238908 ◽

2020 ◽

Vol 21 (23) ◽

pp. 8908

Author(s):

Alessandra Cazzaniga ◽

Fabian Ille ◽

Simon Wuest ◽

Carsten Haack ◽

Adrian Koller ◽

...

Keyword(s):

Tissue Engineering ◽

Simulated Microgravity ◽

Culture Media ◽

Three Dimensions ◽

C2c12 Cells ◽

Equal Treatment ◽

New Device ◽

Microgravity Conditions ◽

Validation Tests

We introduce a new benchtop microgravity simulator (MGS) that is scalable and easy to use. Its working principle is similar to that of random positioning machines (RPM), commonly used in research laboratories and regarded as one of the gold standards for simulating microgravity. The improvement of the MGS concerns mainly the algorithms controlling the movements of the samples and the design that, for the first time, guarantees equal treatment of all the culture flasks undergoing simulated microgravity. Qualification and validation tests of the new device were conducted with human bone marrow stem cells (bMSC) and mouse skeletal muscle myoblasts (C2C12). bMSC were cultured for 4 days on the MGS and the RPM in parallel. In the presence of osteogenic medium, an overexpression of osteogenic markers was detected in the samples from both devices. Similarly, C2C12 cells were maintained for 4 days on the MGS and the rotating wall vessel (RWV) device, another widely used microgravity simulator. Significant downregulation of myogenesis markers was observed in gravitationally unloaded cells. Therefore, similar results can be obtained regardless of the used simulated microgravity devices, namely MGS, RPM, or RWV. The newly developed MGS device thus offers easy and reliable long-term cell culture possibilities under simulated microgravity conditions. Currently, upgrades are in progress to allow real-time monitoring of the culture media and liquids exchange while running. This is of particular interest for long-term cultivation, needed for tissue engineering applications. Tissue grown under real or simulated microgravity has specific features, such as growth in three-dimensions (3D). Growth in weightlessness conditions fosters mechanical, structural, and chemical interactions between cells and the extracellular matrix in any direction.

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Physiological Responses of Jurkat Lymphocytes to Simulated Microgravity Conditions

International Journal of Molecular Sciences ◽

10.3390/ijms20081892 ◽

2019 ◽

Vol 20 (8) ◽

pp. 1892 ◽

Cited By ~ 3

Author(s):

Caterina Morabito ◽

Paola Lanuti ◽

Giusy A. Caprara ◽

Marco Marchisio ◽

Mariano Bizzarri ◽

...

Keyword(s):

Simulated Microgravity ◽

Immune Cell ◽

Cellular Level ◽

The Body ◽

Jurkat Cells ◽

Cell Phenotype ◽

Environmental Condition ◽

Mitochondria Membrane Potential ◽

Microgravity Conditions ◽

External Forces

The presence of microgravity conditions deeply affects the human body functions at the systemic, organ and cellular levels. This study aimed to investigate the effects induced by simulated-microgravity on non-stimulated Jurkat lymphocytes, an immune cell phenotype considered as a biosensor of the body responses, in order to depict at the cellular level the effects of such a peculiar condition. Jurkat cells were grown at 1 g or on random positioning machine simulating microgravity. On these cells we performed: morphological, cell cycle and proliferation analyses using cytofluorimetric and staining protocols—intracellular Ca2+, reactive oxygen species (ROS), mitochondria membrane potential and O2− measurements using fluorescent probes—aconitase and mitochondria activity, glucose and lactate content using colorimetric assays. After the first exposure days, the cells showed a more homogeneous roundish shape, an increased proliferation rate, metabolic and detoxifying activity resulted in decreased intracellular Ca2+ and ROS. In the late exposure time, the cells adapted to the new environmental condition. Our non-activated proliferating Jurkat cells, even if responsive to altered external forces, adapted to the new environmental condition showing a healthy status. In order to define the cellular mechanism(s) triggered by microgravity, developing standardized experimental approaches and controlled cell culture and simulator conditions is strongly recommended.

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Calpain activation mediates microgravity-induced myocardial abnormalities in mice via p38 and ERK1/2 MAPK pathways

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.011890 ◽

2020 ◽

Vol 295 (49) ◽

pp. 16840-16851

Author(s):

Liwen Liang ◽

Huili Li ◽

Ting Cao ◽

Lina Qu ◽

Lulu Zhang ◽

...

Keyword(s):

Nadph Oxidase ◽

Simulated Microgravity ◽

Heart Weight ◽

Calpain Inhibitor ◽

Protective Effects ◽

Tail Suspension ◽

Calpain Activation ◽

Microgravity Conditions ◽

Underlying Mechanisms ◽

Nadph Oxidase Activation

The human cardiovascular system has adapted to function optimally in Earth's 1G gravity, and microgravity conditions cause myocardial abnormalities, including atrophy and dysfunction. However, the underlying mechanisms linking microgravity and cardiac anomalies are incompletely understood. In this study, we investigated whether and how calpain activation promotes myocardial abnormalities under simulated microgravity conditions. Simulated microgravity was induced by tail suspension in mice with cardiomyocyte-specific deletion of Capns1, which disrupts activity and stability of calpain-1 and calpain-2, and their WT littermates. Tail suspension time-dependently reduced cardiomyocyte size, heart weight, and myocardial function in WT mice, and these changes were accompanied by calpain activation, NADPH oxidase activation, and oxidative stress in heart tissues. The effects of tail suspension were attenuated by deletion of Capns1. Notably, the protective effects of Capns1 deletion were associated with the prevention of phosphorylation of Ser-345 on p47phox and attenuation of ERK1/2 and p38 activation in hearts of tail-suspended mice. Using a rotary cell culture system, we simulated microgravity in cultured neonatal mouse cardiomyocytes and observed decreased total protein/DNA ratio and induced calpain activation, phosphorylation of Ser-345 on p47phox, and activation of ERK1/2 and p38, all of which were prevented by calpain inhibitor-III. Furthermore, inhibition of ERK1/2 or p38 attenuated phosphorylation of Ser-345 on p47phox in cardiomyocytes under simulated microgravity. This study demonstrates for the first time that calpain promotes NADPH oxidase activation and myocardial abnormalities under microgravity by facilitating p47phox phosphorylation via ERK1/2 and p38 pathways. Thus, calpain inhibition may be an effective therapeutic approach to reduce microgravity-induced myocardial abnormalities.

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