Cyanobacteria use micro-optics to sense light direction.
Cyanobacteria use micro-optics to sense light direction.
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DOI：
10.7554/elife.12620
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发表时间：
2016-02-09
期刊：
影响因子：
7.7
通讯作者：
Wilde A
中科院分区：
文献类型：
--
作者：
Schuergers N;Lenn T;Kampmann R;Meissner MV;Esteves T;Temerinac-Ott M;Korvink JG;Lowe AR;Mullineaux CW;Wilde A
细菌的趋光性早在世纪前就被发现了，但是这种小细胞能够感知光照方向的方法仍然令人困惑。单细胞蓝细菌集胞藻属PCC 6803与IV型皮利一起移动，并利用一系列光感受器测量光强度和颜色。在这里，我们表明，单个集胞藻细胞不响应光强度的时空梯度，而是他们直接和准确地感知光源的位置。我们表明，定向光传感是可能的，因为集胞藻细胞作为球形微透镜，使细胞看到光源，并向它移动。光源的高分辨率图像集中在细胞的边缘相对于源，触发移动远离聚焦点。球形蓝藻可能是世界上最小和最古老的相机眼睛的例子。http://dx.doi.org/10.7554/eLife.12620.001蓝细菌是一种蓝绿色的细菌，在环境中大量存在。海洋中的蓝细菌是世界上最重要的氧气生产者和二氧化碳消费者之一。集胞藻是一种球形单细胞蓝藻，直径约为千分之三毫米。因为集胞藻需要阳光来产生能量，所以寻找光线既不太弱也不太强的地方对它来说很重要。与某些细菌不同，集胞藻不能游泳，但它可以在表面爬行。它利用这种能力移动到光线条件更好的地方。人们已经知道，集胞藻细胞会朝着从一侧照射它们的光源移动，这意味着蓝细菌可以“看到”光在哪里。但是，如此微小的细胞如何准确地检测到光线来自哪里呢？Schuergers等人跟踪了集胞藻如何在不同的光照条件下移动，发现这些蓝藻的“视觉”秘密在于细胞充当微小的球形透镜。当光照射在细胞上时，光源的图像聚焦在细胞的相对边缘。被称为光感受器的光检测分子对光源的聚焦图像做出反应，这提供了引导细胞朝向光所需的信息。尽管细节不同，尽管集胞藻细胞的体积比人类眼球小5000亿倍，但集胞藻的视觉实际上与人类的视觉原理相似。Schuergers等人这一发现引发了更多的问题，因为其他类型的细菌也可能起到微小透镜的作用。关于蓝藻如何处理视觉信息，还有更多的东西有待了解。DOI：http://dx.doi.org/10.7554/eLife.12620.002网站
Bacterial phototaxis was first recognized over a century ago, but the method by which such small cells can sense the direction of illumination has remained puzzling. The unicellular cyanobacterium Synechocystis sp. PCC 6803 moves with Type IV pili and measures light intensity and color with a range of photoreceptors. Here, we show that individual Synechocystis cells do not respond to a spatiotemporal gradient in light intensity, but rather they directly and accurately sense the position of a light source. We show that directional light sensing is possible because Synechocystis cells act as spherical microlenses, allowing the cell to see a light source and move towards it. A high-resolution image of the light source is focused on the edge of the cell opposite to the source, triggering movement away from the focused spot. Spherical cyanobacteria are probably the world’s smallest and oldest example of a camera eye. DOI: http://dx.doi.org/10.7554/eLife.12620.001 Cyanobacteria are blue-green bacteria that are abundant in the environment. Cyanobacteria in the oceans are among the world’s most important oxygen producers and carbon dioxide consumers. Synechocystis is a spherical single-celled cyanobacterium that measures about three thousandths of a millimetre across. Because Synechocystis needs sunlight to produce energy, it is important for it to find places where the light is neither too weak nor too strong. Unlike some bacteria, Synechocystis can’t swim, but it can crawl across surfaces. It uses this ability to move to places where the light conditions are better. It was already known that Synechocystis cells move towards a light source that is shone at them from one side, which implies that the cyanobacteria can “see” where the light is. But how can such a tiny cell accurately detect where light is coming from? Schuergers et al. tracked how Synechocystis moved in response to different light conditions, and found that the secret of “vision” in these cyanobacteria is that the cells act as tiny spherical lenses. When a light is shone at the cell, an image of the light source is focused at the opposite edge of the cell. Light-detecting molecules called photoreceptors respond to the focused image of the light source, and this provides the information needed to steer the cell towards the light. Although the details are different, and although a Synechocystis cell is in terms of volume about 500 billion times smaller than a human eyeball, vision in Synechocystis actually works by principles similar to vision in humans. Schuergers et al.’s findings open plenty of further questions, as other types of bacteria may also act as tiny lenses. More also remains to be learnt about how the cyanobacteria process visual information. DOI: http://dx.doi.org/10.7554/eLife.12620.002