Pyrocystis noctiluca represents an excellent bioassay for shear forces induced in ground-based microgravity simulators (clinostat and random positioning machine).
Pyrocystis noctiluca represents an excellent bioassay for shear forces induced in ground-based microgravity simulators (clinostat and random positioning machine).
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DOI：
10.1038/s41526-017-0016-x
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发表时间：
2017
期刊：
影响因子：
5.1
通讯作者：
Hemmersbach R
中科院分区：
文献类型：
--
作者：
Hauslage J;Cevik V;Hemmersbach R
地面设施，如旨在模拟微重力条件的恒温器和随机定位机，是准备空间实验和识别重力相关信号通路的工具。一个先决条件是设施以适当的方式运行，并且必须考虑到可能引起的非重力效应，例如剪切力。鞭毛藻，这里的P. noctiluca，作为剪切应力和流体动力梯度的快速敏感报告系统，暴露在一个旋转器（绕一个轴恒定旋转，60转/分）或随机定位机上，这意味着绕两个轴旋转，其速度和方向是随机选择的。在剪切应力作用下，夜光藻细胞膜发生变形，产生可检测的生物发光。我们的研究结果表明，在随机定位机上的机械应力量比在恒定旋转时要高，这是由光子计数的差异所揭示的。我们得出的结论是，与测试的随机操作模式相比，单轴旋转诱导的剪切力形式的非重力效应可以忽略不计。我们第一次通过生物测定清晰地可视化了剪切力的设备依赖性发生，在定义适当的模拟方法时必须考虑到这一点，并避免对结果的误解。地球上的实验室现在可以通过生物发光分析来评估用于模拟生物体在太空中的生长和行为的工具的准确性。在设计以植物、细胞和小动物为对象的地外实验时，研究人员经常使用旋转机器来最小化重力效应。德国DLR航空航天中心的Jens Hauslage及其同事报告说，机械运动过程中产生的设备特定剪切力可能会导致对初始测试数据的误解。他们开发了一种基于海洋浮游生物的生物传感器，这种浮游生物被称为鞭毛藻，当被捕食者接触时，它们的细胞膜会自然发光。根据机械应力校准这种生物发光有助于确定提供微重力条件的“回转器”设备的顶状二维旋转。然而，随机定位机的意外3D运动产生了足够的剪切力来影响细胞信号传导途径或代谢反应的研究。
Ground-based facilities, such as clinostats and random positioning machines aiming at simulating microgravity conditions, are tools to prepare space experiments and identify gravity-related signaling pathways. A prerequisite is that the facilities are operated in an appropriate manner and potentially induced non-gravitational effects, such as shearing forces, have to be taken into account. Dinoflagellates, here P. noctiluca, as fast and sensitive reporter system for shear stress and hydrodynamic gradients, were exposed on a clinostat (constant rotation around one axis, 60 rpm) or in a random positioning machine, that means rotating around two axes, whose velocity and direction were chosen at random. Deformation of the cell membrane of P. noctiluca due to shear stress results in a detectable bioluminescence emission. Our results show that the amount of mechanical stress is higher on an random positioning machine than during constant clinorotation, as revealed by the differences in photon counts. We conclude that one axis clinorotation induced negligible non-gravitational effects in the form of shear forces in contrast to random operation modes tested. For the first time, we clearly visualized the device-dependent occurrence of shear forces by means of a bioassay, which have to be considered during the definition of an appropriate simulation approach and to avoid misinterpretation of results. Earth-based laboratories can now assess the accuracy of tools used to simulate living organism growth and behaviour in space with bioluminescent assays. Researchers often use rotating machines to minimize gravity effects during the design of extra-terrestrial experiments with plants, cells, and small animals. Jens Hauslage from the DLR German Aerospace Center and colleagues report that device-specific shear forces produced during mechanical movements may cause misinterpretations of initial test data. They developed a biosensor based on marine plankton, known as dinoflagellates, which have cell membranes that naturally emit light when touched by predators. Calibrating this bioluminescence against mechanical stress helped determine the top-like, 2D rotations of ‘‘clinostat’’ devices provided microgravity-like conditions. However, the unexpected 3D movements of Random Positioning Machines generated enough shear force to impact studies of cell signaling pathways or metabolic reactions.