STARSET_MirrorWhat octopus and human brains have in common
If we go far enough back in evolutionary history, we encounter the last known common ancestor of humans and cephalopods: a primitive wormlike animal with minimal intelligence and simple eyespots. Later, the animal kingdom can be divided into two groups of organisms—those with backbones and those without. While vertebrates, particularly primates and other mammals, went on to develop large and complex brains with diverse cognitive abilities, invertebrates did not. With one exception: the cephalopods.
如果我们回溯到进化史的足够远的地方，我们会遇到人类和头足类动物的最后一个已知的共同祖先:一种原始的蠕虫状动物，智商最低，眼睛上有简单的斑点。后来，动物王国可以分为两类生物——有脊骨的和没有脊骨的。脊椎动物，尤其是灵长类动物和其他哺乳动物，继续发展出具有不同认知能力的大而复杂的大脑，而无脊椎动物则没有。只有一个例外:头足类动物。
Scientists have long wondered why such a complex nervous system was only able to develop in these mollusks. Now, an international team led by researchers from the Max Delbrück Center and Dartmouth College in the United States has put forth a possible reason. In a paper published in Science Advances, they explain that octopuses possess a massively expanded repertoire of microRNAs (miRNAs) in their neural tissue—reflecting similar developments that occurred in vertebrates.
科学家们一直想知道为什么如此复杂的神经系统只能在这些软体动物身上发育。现在，由Max Delbrück中心和美国达特茅斯学院的研究人员领导的一个国际团队提出了一个可能的原因。在《科学进展》杂志上发表的一篇论文中，他们解释说，章鱼在神经组织中拥有大量扩展的microRNAs (miRNAs)，这反映了脊椎动物发生的类似发展。
“So this is what connects us to the octopus,” says Professor Nikolaus Rajewsky, scientific director of the Berlin Institute for Medical Systems Biology of the Max Delbrück Center (MDC-BIMSB), head of the Systems Biology of Gene Regulatory Elements Lab, and the paper’s last author. He explains that this finding probably means miRNAs play a fundamental role in the development of complex brains.
“所以这就是我们和章鱼之间的联系，”Nikolaus Rajewsky教授说，他是Max Delbrück中心(MDC-BIMSB)柏林医疗系统生物学研究所的科学主任，基因调控元件系统生物学实验室的负责人，也是这篇论文的最后一位作者。他解释说，这一发现可能意味着miRNA在复杂大脑的发育中起着重要作用。
In 2019, Rajewsky read a publication about genetic analyses conducted on octopuses. Scientists had discovered that a lot of RNA editing occurs in these cephalopods—meaning they make extensive use of certain enzymes that can recode their RNA.
2019年，拉杰夫斯基读到一篇关于对章鱼进行基因分析的出版物。科学家们发现，这些头足类动物体内发生了大量的RNA编辑，这意味着它们大量使用某些酶来重新编码它们的RNA。
“This got me thinking that octopuses may not only be good at editing, but could have other RNA tricks up their sleeve too,” says Rajewsky. And so he began a collaboration with the Stazione Zoologica Anton Dohrn marine research station in Naples, which sent him samples of 18 different tissue types from dead octopuses.
Rajewsky说:“这让我想到章鱼可能不仅擅长编辑，而且可能还有其他RNA的诀窍。”因此，他开始与那不勒斯的Stazione zoanton Dohrn海洋研究站合作，该研究站向他发送了18种不同类型的死亡章鱼组织样本。
The results of the analyses were surprising: “There was indeed a lot of RNA editing going on, but not in areas that we believe to be of interest,” says Rajewsky. The most interesting discovery was in fact the dramatic expansion of a well-known group of RNA genes, microRNAs.
分析结果令人惊讶:“确实有很多RNA编辑在进行，但不是在我们认为感兴趣的领域，”Rajewsky说。事实上，最有趣的发现是一组著名的RNA基因microRNAs的戏剧性扩张。
A total of 42 novel miRNA families were found—specifically in neural tissue and mostly in the brain. Given that these genes were conserved during cephalopod evolution, the team concludes they were clearly beneficial to the animals and are therefore functionally important.
总共发现了42个新的miRNA家族，特别是在神经组织中，大部分在大脑中。考虑到这些基因在头足类动物进化过程中是保守的，研究小组得出结论，它们显然对动物有益，因此在功能上很重要。
Rajewsky has been researching miRNAs for more than 20 years. Instead of being translated into messenger RNAs, which deliver the instructions for protein production in the cell, these genes encode small pieces of RNA that bind to messenger RNA and thus influence protein production. These binding sites were also conserved throughout cephalopod evolution—another indication that these novel miRNAs are of functional importance.
Rajewsky研究mirna已经超过20年了。这些基因不是被翻译成信使RNA，传递细胞中蛋白质生产的指令，而是编码与信使RNA结合的小片段RNA，从而影响蛋白质生产。这些结合位点在头足类动物的进化过程中也是保守的，这也表明这些新的mirna具有重要的功能。
New microRNA families
新的microRNA家族
“This is the third-largest expansion of microRNA families in the animal world, and the largest outside of vertebrates,” says lead author Grygoriy Zolotarov, MD, a Ukrainian scientist who interned in Rajewsky’s lab at MDC-BIMSB while finishing medical school in Prague, and later. “To give you an idea of the scale, oysters, which are also mollusks, have acquired just five new microRNA families since the last ancestors they shared with octopuses—while the octopuses have acquired 90.”
“这是动物世界中microRNA家族的第三大扩张，也是脊椎动物之外最大的扩张，”第一作者Grigoriy Zolotarov医学博士说，他是乌克兰科学家，在布拉格完成医学院学习期间曾在Rajewsky在MDC-BIMSB的实验室实习。“为了给你一个规模的概念，牡蛎，也是软体动物，自它们与章鱼共有的最后一个祖先以来，只获得了五个新的microRNA家族，而章鱼已经获得了90个。”
Oysters, adds Zolotarov, aren’t exactly known for their intelligence.
Zolotarov补充说，牡蛎并不是以它们的智力而闻名的。
Rajewsky’s fascination with octopuses began years ago, during an evening visit to the Monterey Bay Aquarium in California. “I saw this creature sitting on the bottom of the tank and we spent several minutes—so I thought—looking at each other.” He says that looking at an octopus is very different to looking at a fish: “It’s not very scientific, but their eyes do exude a sense of intelligence.” Octopuses have similarly complex “camera” eyes to humans.
Rajewsky对章鱼的迷恋始于几年前，在一次晚上参观加州蒙特利湾水族馆时。“我看到这个生物坐在水箱底部，我们花了几分钟——所以我想——看着对方。”他说，看章鱼和看鱼是非常不同的:“这不是很科学，但它们的眼睛确实散发出一种智慧。”章鱼有着和人类相似的复杂的“照相机”眼睛。
From an evolutionary perspective, octopuses are unique among invertebrates. They have both a central brain and a peripheral nervous system—one that is capable of acting independently. If an octopus loses a tentacle, the tentacle remains sensitive to touch and can still move. The reason why octopuses are alone in having developed such complex brain functions could lie in the fact that they use their arms very purposefully—as tools to open shells, for instance.
从进化的角度来看，章鱼在无脊椎动物中是独一无二的。它们有一个中央大脑和一个周围神经系统——一个能够独立行动的系统。如果章鱼失去了触须，它的触须仍然对触摸很敏感，并且仍然可以移动。章鱼之所以能发展出如此复杂的大脑功能，可能是因为它们有目的地使用它们的手臂——例如，作为打开外壳的工具。
Octopuses also show other signs of intelligence: They are very curious and can remember things. They can also recognize people and actually like some more than others. Researchers now believe that they even dream, since they change their color and skin structures while sleeping.
章鱼还显示出其他智慧的迹象:它们非常好奇，能记住事情。它们还能认出人，实际上更喜欢某些人。研究人员现在认为，它们甚至会做梦，因为它们在睡觉时改变颜色和皮肤结构。
Alien-like creatures
像外星人的生物
“They say if you want to meet an alien, go diving and make friends with an octopus,” says Rajewsky. He’s now planning to join forces with other octopus researchers to form a European network that will allow greater exchange between the scientists. Although the community is currently small, Rajewsky says that interest in octopuses is growing worldwide, including among behavioral researchers.
Rajewsky说:“他们说，如果你想认识外星人，就去潜水，和章鱼交朋友。”他现在正计划与其他章鱼研究人员联合起来，建立一个欧洲网络，让科学家之间有更多的交流。Rajewsky说，尽管目前这个群体很小，但全世界对章鱼的兴趣正在增长，包括行为研究人员。
Read more at Phys.org
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