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When sunlight shining on a leaf changes rapidly， plants must protect themselves from the ensuing sudden surges of solar energy. To cope with these changes， photosynthetic1 organisms—from plants to bacteria—have developed numerous tactics. Scientists have been unable， however， to identify the underlying design principle. 當照在叶片上的阳光急遽变化，植物就必须自我防护，以免受随之而来的太阳能骤增的伤害。为应对这些变化，能进行光合作用的有机体——从植物到细菌——已演化出众多策略。不过，科学家一直无法确定其背后的设计原则。
An international team of scientists， led by physicist Nathaniel M. Gabor at the University of California， Riverside， has now constructed a model that reproduces a general feature of photosynthetic light harvesting2， observed across many photosynthetic organisms.
Light harvesting is the collection of solar energy by protein-bound chlorophyll3 molecules. In photosynthesis4—the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water—light energy harvesting begins with sunlight absorption.
The researchers’ model borrows ideas from the science of complex networks， a field of study that explores efficient operation in cellphone networks， brains， and the power grid. The model describes a simple network that is able to input light of two different colors， yet output a steady rate of solar power. This unusual choice of only two inputs has remarkable consequences.
“Our model shows that by absorbing only very specific colors of light， photosynthetic organisms may automatic-ally protect themselves against sudden changes—or ‘noise’—in solar energy， resulting in remarkably efficient power conversion，” said Gabor， an associate professor of physics and astronomy， who led the study appearing in the journal Science. “Green plants appear green and purple bacteria appear purple because only specific regions of the spectrum from which they absorb are suited for protection against rapidly changing solar energy.”
Gabor first began thinking about photosynthesis research more than a decade ago， when he was a doctoral student at Cornell University. He wondered why plants rejected green light， the most intense solar light. Over the years， he worked with physicists and biologists worldwide to learn more about statistical methods and the quantum biology of photosynthesis.
Richard Cogdell， a botanist at the University of Glasgow in the United Kingdom and a coauthor on the research paper， encouraged Gabor to extend the model to include a wider range of photosynthetic organisms that grow in environments where the incident5 solar spectrum is very different. “Excitingly， we were then able to show that the model worked in other photosynthetic organisms besides green plants， and that the model identified a general and fundamental property of photosynthetic light harvesting，” he said. “Our study shows how， by choosing where you absorb solar energy in relation to the incident solar spectrum， you can minimize the noise on the output—information that can be used to enhance the performance of solar cells.”
Coauthor Rienk van Grondelle， an influential experimental physicist at Vrije Universiteit Amsterdam in the Netherlands who works on the primary physical processes of photosynthesis， said the team found the absorption spectra of certain photosynthetic systems select certain spectral excitation regions that cancel the noise and maximize the energy stored.
“This very simple design principle could also be applied in the design of human-made solar cells，” said van Grondelle， who has vast experience with photosynthetic light harvesting.
Gabor explained that plants and other photosynthetic organisms have a wide variety of tactics to prevent damage due to overexposure to the sun， ranging from molecular mechanisms of energy release to physical movement of the leaf to track the sun. Plants have even developed effective protection against UV light， just as in sunscreen.
“In the complex process of photosynthesis， it is clear that protecting the organism from overexposure is the driving factor in successful energy production， and this is the inspiration we used to develop our model，” he said. “Our model incorporates relatively simple physics， yet it is consistent with a vast set of observations in biology. This is remarkably rare. If our model holds up6 to continued experiments， we may find even more agreement between theory and observations， giving rich insight into the inner workings of nature.”
To construct the model， Gabor and his colleagues applied straightforward physics of networks to the complex details of biology， and were able to make clear， quantitative， and generic statements about highly diverse photosynthetic organisms.
“Our model is the first hypothesis-driven explanation for why plants are green， and we give a roadmap to test the model through more detailed experiments，” Gabor said.
Photosynthesis may be thought of as a kitchen sink， Gabor added， where a faucet flows water in and a drain allows the water to flow out. If the flow into the sink is much bigger than the outward flow， the sink overflows and the water spills all over the floor. “In photosynthesis， if the flow of solar power into the light harvesting network is significantly larger than the flow out， the photosynthetic network must adapt to reduce the sudden over-flow of energy，” he said. “When the network fails to manage these fluctuations， the organism attempts to expel the extra energy. In doing so， the organism undergoes oxidative7 stress， which damages cells.”
The researchers were surprised by how general and simple their model is.
“Nature will always surprise you，” Gabor said. “Something that seems so complicated and complex might operate based on a few basic rules. We applied the model to organisms in different photosynthetic niches8 and continue to reproduce accurate absorption spectra. In biology， there are exceptions to every rule， so much so that9 finding a rule is usually very difficult. Surprisingly， we seem to have found one of the rules of photosynthetic life.”
Gabor noted that over the last several decades， photosynthesis research has focused mainly on the structure and function of the microscopic components of the photosynthetic process.
“Biologists know well that biological systems are not generally finely tuned given the fact that organisms have little control over their external conditions，” he said. “This contradiction has so far been unaddressed because no model exists that connects microscopic processes with macroscopic properties. Our work represents the first quantitative physical model that tackles this contradiction.”
Next， supported by several recent grants， the researchers will design a novel microscopy technique to test their ideas and advance the technology of photo-biology10 experiments using quantum optics tools.
“There’s a lot out there to understand about nature， and it only looks more beautiful as we unravel its mysteries，” Gabor said.
如今，由加利福尼亞大学河滨分校物理学家纳撒尼尔·M.加博尔领导的国际科学家小组，已经构建出一个模型，可以重现光合作用光捕获的一般特性，这种特性广泛存在于众多能进行光合作用的有机体中。
光捕获是指与蛋白质结合的叶绿素分子吸收太阳能的过程。在光合作用（绿色植物及某些其他有机体利用太阳光把二氧化碳和水合成养料的过程）中，光能捕获始于吸收太阳光。
研究人员的这一模型借鉴了复杂网络学（一个探索手机网络、大脑和电网如何高效运行的研究领域）的理论。该模型描述的是一个简单网络，该网络能够输入两种不同颜色的光，却输出比率稳定的太阳能。这种只选择两个输入项的非常规方式带来了奇特的效果。
“我们的模型显示，通过只吸收极为特定颜色的光，能进行光合作用的有机体可以自动保护自己，免受太阳能突然变化——或是‘干扰’的伤害，从而产生超高效的能量转换。”该项研究（成果已发表在《科学》杂志上）的带头人、物理与天文学副教授加博尔说，“绿色植物呈现绿色，紫色细菌呈现紫色，是因为它们从中吸收光线的光谱只有特定区域适合防护太阳能的急遽变化。”
十多年前，当时还是康奈尔大学博士生的加博尔第一次有了研究光合作用的想法。他想弄清为什么植物排斥绿色光，这是最强的太阳光。这些年来，他与世界各地的物理学家和生物学家合作，深入了解光合作用的统计方法和量子生物学机制。
理查德·科格德尔是英国格拉斯哥大学的植物学家，也是该项研究论文的合著者，他鼓励加博尔扩大这一模型的适用范围，以涵盖更多能进行光合作用的有机体，它们生长在入射太阳光谱极为不同的环境中。 “令人振奋的是，接下来我们得以证明，这一模型对绿色植物之外的其他能进行光合作用的有机体也适用，并且该模型发现了光合作用光捕获的一个重要的普遍特性。”他说，“我们的研究表明，通过选择在入射太阳光谱的什么位置吸收太阳能，能最大程度减少对输出的干扰。此项信息可用于提高太阳能电池的性能。”
论文合著者里恩克·范格龙代勒是荷兰阿姆斯特丹自由大学一位有影响力的实验物理学家，从事光合作用基本物理过程的研究。他说，研究团队发现，某些光合系统的吸收光谱选择能消除干扰并尽可能多储存能量的光谱激发区。
“这个十分简单的设计原则也可以用在人造太阳能电池的设计上。”对光合作用光捕获甚为熟知的范格龙代勒说。
加博尔解释说，植物及其他能进行光合作用的有机体具备广泛多样的策略——从能量释放的分子机制到叶片追随太阳转动等——来防止太阳过度暴晒造成的损害。植物甚至演化出了对紫外线的有效防护，就像涂了防晒霜一样。
“显然，在光合作用的复杂过程中，保护有机体免于过度暴晒是成功产生能量的驱动因素，这是我们开发模型的灵感来源。”他说，“我们的模型包含的物理学知识较为简单，却与大量生物学的观察结果一致。这极为罕见。如果这一模型经得起后续实验的检验，我们有可能发现理论和观察结果间更多的一致性，从而让人们对大自然的奥秘有深刻的了解。”
为构建这一模型，加博尔及其同事把简明的网络物理学应用于生物学的复杂细节，得以就多种多样能进行光合作用的有机体得出清晰的一般定量表述。
加博尔说：“我们的模型首次用假设驱动来解释植物为何是绿色的，我们也提供了一个通过更详细的实验检验该模型的方案。”
加博尔补充说，可以把光合作用想象成一个厨房洗涤槽，水龙头往里注水，排水管向外排水。如果进水量远大于排水量，水槽就会满溢，水会流得满地都是。
“在光合作用中，如果进入光捕获网络的太阳能量明显大过排出量，光合作用网络就必须做调适以削减陡然满溢的能量。”他说，“如果该网络管理不好这种波动，有机体会设法排出多余的能量。这样做时，有机体经受氧化应激，会损害细胞。”
研究人员感到惊喜的是，他们的模型竟如此通用而又简单。
“大自然总会让你感到惊奇。”加博尔说，“看上去如此错综复杂的现象可能遵循几项基本规律。我们把这一模型应用到处于不同光合作用生态位的有机体身上，继续复现正确的吸收光谱。在生物学上，每一项规律都存在例外，以致发现一条规律通常是很难的。令人惊奇的是，我们似乎发现了能进行光合作用的生物的一条规律。”
加博爾指出，过去几十年来，光合作用研究主要聚焦于光合作用过程中微观成分的结构和功能。
“生物学家深知，鉴于有机体对其外部条件几无控制力，生物系统通常未经精微调节。”他说，“因为没有使微观过程和宏观特性相联系的模型，这一矛盾迄今没有得到处理。我们的成果是解决此项矛盾的第一个定量物理模型。”
接下来，在新近几项资金的支持下，研究人员将设计一项新的显微镜技术，以检验他们的设想，并运用量子光学工具提升光生物学实验技术。
加博尔说：“大自然有待人们弄清的东西很多，而随着我们揭开其神秘面纱，它只会看上去更加美丽。”
（译者为“《英语世界》杯”翻译大赛获奖者）
1 photosynthetic光合的。 2 light harvesting光捕获，指光合作用光反应过程中一系列光合色素分子吸收光能并传递到光合反应中心的过程。 3 chlorophyll叶绿素。 4 photo-synthesis光合作用。
5 incident（尤指光或其他辐射）入射的。
6 hold up（论点、理论等）经受得住检验。
7 oxidative氧化的。 8 niche生态位。 9 so much so （that） 以致。
10 photo-biology光生物学。
An international team of scientists， led by physicist Nathaniel M. Gabor at the University of California， Riverside， has now constructed a model that reproduces a general feature of photosynthetic light harvesting2， observed across many photosynthetic organisms.
Light harvesting is the collection of solar energy by protein-bound chlorophyll3 molecules. In photosynthesis4—the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water—light energy harvesting begins with sunlight absorption.
The researchers’ model borrows ideas from the science of complex networks， a field of study that explores efficient operation in cellphone networks， brains， and the power grid. The model describes a simple network that is able to input light of two different colors， yet output a steady rate of solar power. This unusual choice of only two inputs has remarkable consequences.
“Our model shows that by absorbing only very specific colors of light， photosynthetic organisms may automatic-ally protect themselves against sudden changes—or ‘noise’—in solar energy， resulting in remarkably efficient power conversion，” said Gabor， an associate professor of physics and astronomy， who led the study appearing in the journal Science. “Green plants appear green and purple bacteria appear purple because only specific regions of the spectrum from which they absorb are suited for protection against rapidly changing solar energy.”
Gabor first began thinking about photosynthesis research more than a decade ago， when he was a doctoral student at Cornell University. He wondered why plants rejected green light， the most intense solar light. Over the years， he worked with physicists and biologists worldwide to learn more about statistical methods and the quantum biology of photosynthesis.
Richard Cogdell， a botanist at the University of Glasgow in the United Kingdom and a coauthor on the research paper， encouraged Gabor to extend the model to include a wider range of photosynthetic organisms that grow in environments where the incident5 solar spectrum is very different. “Excitingly， we were then able to show that the model worked in other photosynthetic organisms besides green plants， and that the model identified a general and fundamental property of photosynthetic light harvesting，” he said. “Our study shows how， by choosing where you absorb solar energy in relation to the incident solar spectrum， you can minimize the noise on the output—information that can be used to enhance the performance of solar cells.”
Coauthor Rienk van Grondelle， an influential experimental physicist at Vrije Universiteit Amsterdam in the Netherlands who works on the primary physical processes of photosynthesis， said the team found the absorption spectra of certain photosynthetic systems select certain spectral excitation regions that cancel the noise and maximize the energy stored.
“This very simple design principle could also be applied in the design of human-made solar cells，” said van Grondelle， who has vast experience with photosynthetic light harvesting.
Gabor explained that plants and other photosynthetic organisms have a wide variety of tactics to prevent damage due to overexposure to the sun， ranging from molecular mechanisms of energy release to physical movement of the leaf to track the sun. Plants have even developed effective protection against UV light， just as in sunscreen.
“In the complex process of photosynthesis， it is clear that protecting the organism from overexposure is the driving factor in successful energy production， and this is the inspiration we used to develop our model，” he said. “Our model incorporates relatively simple physics， yet it is consistent with a vast set of observations in biology. This is remarkably rare. If our model holds up6 to continued experiments， we may find even more agreement between theory and observations， giving rich insight into the inner workings of nature.”
To construct the model， Gabor and his colleagues applied straightforward physics of networks to the complex details of biology， and were able to make clear， quantitative， and generic statements about highly diverse photosynthetic organisms.
“Our model is the first hypothesis-driven explanation for why plants are green， and we give a roadmap to test the model through more detailed experiments，” Gabor said.
Photosynthesis may be thought of as a kitchen sink， Gabor added， where a faucet flows water in and a drain allows the water to flow out. If the flow into the sink is much bigger than the outward flow， the sink overflows and the water spills all over the floor. “In photosynthesis， if the flow of solar power into the light harvesting network is significantly larger than the flow out， the photosynthetic network must adapt to reduce the sudden over-flow of energy，” he said. “When the network fails to manage these fluctuations， the organism attempts to expel the extra energy. In doing so， the organism undergoes oxidative7 stress， which damages cells.”
The researchers were surprised by how general and simple their model is.
“Nature will always surprise you，” Gabor said. “Something that seems so complicated and complex might operate based on a few basic rules. We applied the model to organisms in different photosynthetic niches8 and continue to reproduce accurate absorption spectra. In biology， there are exceptions to every rule， so much so that9 finding a rule is usually very difficult. Surprisingly， we seem to have found one of the rules of photosynthetic life.”
Gabor noted that over the last several decades， photosynthesis research has focused mainly on the structure and function of the microscopic components of the photosynthetic process.
“Biologists know well that biological systems are not generally finely tuned given the fact that organisms have little control over their external conditions，” he said. “This contradiction has so far been unaddressed because no model exists that connects microscopic processes with macroscopic properties. Our work represents the first quantitative physical model that tackles this contradiction.”
Next， supported by several recent grants， the researchers will design a novel microscopy technique to test their ideas and advance the technology of photo-biology10 experiments using quantum optics tools.
“There’s a lot out there to understand about nature， and it only looks more beautiful as we unravel its mysteries，” Gabor said.
如今，由加利福尼亞大学河滨分校物理学家纳撒尼尔·M.加博尔领导的国际科学家小组，已经构建出一个模型，可以重现光合作用光捕获的一般特性，这种特性广泛存在于众多能进行光合作用的有机体中。
光捕获是指与蛋白质结合的叶绿素分子吸收太阳能的过程。在光合作用（绿色植物及某些其他有机体利用太阳光把二氧化碳和水合成养料的过程）中，光能捕获始于吸收太阳光。
研究人员的这一模型借鉴了复杂网络学（一个探索手机网络、大脑和电网如何高效运行的研究领域）的理论。该模型描述的是一个简单网络，该网络能够输入两种不同颜色的光，却输出比率稳定的太阳能。这种只选择两个输入项的非常规方式带来了奇特的效果。
“我们的模型显示，通过只吸收极为特定颜色的光，能进行光合作用的有机体可以自动保护自己，免受太阳能突然变化——或是‘干扰’的伤害，从而产生超高效的能量转换。”该项研究（成果已发表在《科学》杂志上）的带头人、物理与天文学副教授加博尔说，“绿色植物呈现绿色，紫色细菌呈现紫色，是因为它们从中吸收光线的光谱只有特定区域适合防护太阳能的急遽变化。”
十多年前，当时还是康奈尔大学博士生的加博尔第一次有了研究光合作用的想法。他想弄清为什么植物排斥绿色光，这是最强的太阳光。这些年来，他与世界各地的物理学家和生物学家合作，深入了解光合作用的统计方法和量子生物学机制。
理查德·科格德尔是英国格拉斯哥大学的植物学家，也是该项研究论文的合著者，他鼓励加博尔扩大这一模型的适用范围，以涵盖更多能进行光合作用的有机体，它们生长在入射太阳光谱极为不同的环境中。 “令人振奋的是，接下来我们得以证明，这一模型对绿色植物之外的其他能进行光合作用的有机体也适用，并且该模型发现了光合作用光捕获的一个重要的普遍特性。”他说，“我们的研究表明，通过选择在入射太阳光谱的什么位置吸收太阳能，能最大程度减少对输出的干扰。此项信息可用于提高太阳能电池的性能。”
论文合著者里恩克·范格龙代勒是荷兰阿姆斯特丹自由大学一位有影响力的实验物理学家，从事光合作用基本物理过程的研究。他说，研究团队发现，某些光合系统的吸收光谱选择能消除干扰并尽可能多储存能量的光谱激发区。
“这个十分简单的设计原则也可以用在人造太阳能电池的设计上。”对光合作用光捕获甚为熟知的范格龙代勒说。
加博尔解释说，植物及其他能进行光合作用的有机体具备广泛多样的策略——从能量释放的分子机制到叶片追随太阳转动等——来防止太阳过度暴晒造成的损害。植物甚至演化出了对紫外线的有效防护，就像涂了防晒霜一样。
“显然，在光合作用的复杂过程中，保护有机体免于过度暴晒是成功产生能量的驱动因素，这是我们开发模型的灵感来源。”他说，“我们的模型包含的物理学知识较为简单，却与大量生物学的观察结果一致。这极为罕见。如果这一模型经得起后续实验的检验，我们有可能发现理论和观察结果间更多的一致性，从而让人们对大自然的奥秘有深刻的了解。”
为构建这一模型，加博尔及其同事把简明的网络物理学应用于生物学的复杂细节，得以就多种多样能进行光合作用的有机体得出清晰的一般定量表述。
加博尔说：“我们的模型首次用假设驱动来解释植物为何是绿色的，我们也提供了一个通过更详细的实验检验该模型的方案。”
加博尔补充说，可以把光合作用想象成一个厨房洗涤槽，水龙头往里注水，排水管向外排水。如果进水量远大于排水量，水槽就会满溢，水会流得满地都是。
“在光合作用中，如果进入光捕获网络的太阳能量明显大过排出量，光合作用网络就必须做调适以削减陡然满溢的能量。”他说，“如果该网络管理不好这种波动，有机体会设法排出多余的能量。这样做时，有机体经受氧化应激，会损害细胞。”
研究人员感到惊喜的是，他们的模型竟如此通用而又简单。
“大自然总会让你感到惊奇。”加博尔说，“看上去如此错综复杂的现象可能遵循几项基本规律。我们把这一模型应用到处于不同光合作用生态位的有机体身上，继续复现正确的吸收光谱。在生物学上，每一项规律都存在例外，以致发现一条规律通常是很难的。令人惊奇的是，我们似乎发现了能进行光合作用的生物的一条规律。”
加博爾指出，过去几十年来，光合作用研究主要聚焦于光合作用过程中微观成分的结构和功能。
“生物学家深知，鉴于有机体对其外部条件几无控制力，生物系统通常未经精微调节。”他说，“因为没有使微观过程和宏观特性相联系的模型，这一矛盾迄今没有得到处理。我们的成果是解决此项矛盾的第一个定量物理模型。”
接下来，在新近几项资金的支持下，研究人员将设计一项新的显微镜技术，以检验他们的设想，并运用量子光学工具提升光生物学实验技术。
加博尔说：“大自然有待人们弄清的东西很多，而随着我们揭开其神秘面纱，它只会看上去更加美丽。”
（译者为“《英语世界》杯”翻译大赛获奖者）
1 photosynthetic光合的。 2 light harvesting光捕获，指光合作用光反应过程中一系列光合色素分子吸收光能并传递到光合反应中心的过程。 3 chlorophyll叶绿素。 4 photo-synthesis光合作用。
5 incident（尤指光或其他辐射）入射的。
6 hold up（论点、理论等）经受得住检验。
7 oxidative氧化的。 8 niche生态位。 9 so much so （that） 以致。
10 photo-biology光生物学。