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Science:细菌其实是微小眼球

摘要 : “看”是一项复杂的任务。事实上,它是如此的复杂,以至于人眼要用约1亿个感光细胞完成这项任务。不过,一些单细胞细菌仅利用一个细胞,便能“看见”事物。

 

“看”是一项复杂的任务。事实上,它是如此的复杂,以至于人眼要用约1亿个感光细胞完成这项任务。不过,一些单细胞细菌仅利用一个细胞,便能“看见”事物。最新研究显示,集胞藻属中的蓝藻细菌利用像镜片一样的全身追踪光源的位置。

此前,研究人员认为,如果周围环境变得越来越暗,这些利用太阳作为能量的生物体会通过胡乱地四处移动和转换方向来朝着光线处迁移。不过,在日前出版的elife杂志上,研究人员报告称,这些细菌转而利用弯曲的细胞表面,将来自一个方向的光线聚焦到相反一侧的细胞膜上。这很像摄像机镜头把光线聚焦到胶卷的表面。

当透过显微镜镜头观察充满蓝藻细菌的载片时,这种方法变得显而易见。研究人员发现,每个细胞在相同位置都含有一个微小的光点。在那里,细菌会聚焦光源。他们甚至能通过朝细菌照射激光,模拟细菌自己创建的集中光点,从而诱骗其向相反方向移动。光点的大小表明,集胞藻属能在近20°的分辨率下——比人眼的精确度低约100倍——看见事物,但对于单细胞生物体来说,这仍然令人印象深刻。

科学家表示,这种聚焦光线的策略或许在细菌中普遍存在。考虑到蓝藻细菌是地球上最古老的一些生物体,它可能还是最早的视觉形式之一。

原文链接:

These bacteria are actually tiny eyeballs

原文摘要:

Seeing is a complex task—so complex, in fact, that the human eye uses about 100 million light-sensitive cells to do it. But some single-celled bacteria can “see” using only one cell. According to new research, cyanobacteria in the Synechocystis genus use their entire bodies like lenses to track the location of a light source. Previously, researchers thought that these organisms, which use the sun for energy, migrate toward light by moving around at random and switching directions if their surroundings get darker. But today in the journal eLife, researchers report that the bacteria instead use their curved cellular surfaces to focus light from one direction onto their cell membranes on the opposite side, much like a camera lens focuses light onto the surface of film. The method was obvious when—staring through the lens of a microscope at a slide full of cyanobacteria—the researchers saw that each cell contained a tiny point of light in the same location, wher the bacteria were focusing the source. The researchers were even able to trick the bacteria into moving in the opposite direction by shining a laser at them, mimicking the concentrated point of light that the bacteria create themselves. The size of the point suggests thatSynechocystis can see at a resolution of nearly 20°—about a hundred times less precise than a human eye, but still impressive for a single-celled organism. Scientists say this light-focusing strategy may be widespread among bacteria. And given that cyanobacteria are some of the oldest organisms on Earth, it may also be among the earliest forms of sight.

来源: Science 浏览次数:1

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