Michael Levin Bioelectricity 101 Crash Course Lesson 11: Bioelectric Memory: How Planaria “Remember” Their Body Plan Summary
- Planarian regeneration is not simply about regrowing lost tissue; it’s about rebuilding a specific, complex pattern – the planarian body plan.
- The “memory” of this body plan is not solely encoded in the DNA sequence. The DNA provides the “parts list,” but not the assembly instructions.
- Bioelectric signals, specifically the pattern of resting membrane potentials (Vmem) across tissues, act as a kind of “template” or “blueprint” for regeneration.
- This bioelectric template is dynamic and can be altered, as demonstrated by the two-headed planaria experiments.
- Importantly, the altered bioelectric pattern can be stable, meaning that it persists even after the initial manipulation is removed.
- This stability is not due to changes in DNA sequence; it’s a form of non-genetic or epigenetic memory.
- The stability is thought to emerge in altered states that tissues have, which changes consistently, rather than occuring at just a specific region.
- Gap junctions, which allow direct electrical communication between cells, play a crucial role in maintaining and propagating the bioelectric pattern.
- The bioelectric memory explains why two-headed planaria often regenerate as two-headed, even after being cut again. The altered “blueprint” persists.
- Understanding bioelectric memory has significant implications for regenerative medicine, potentially allowing us to control and guide tissue regeneration.
- The planaria exhibits multiple body templates stored simaltenously, which has implications of it possibly “remembering” even more data than previous considered.
Michael Levin Bioelectricity 101 Crash Course Lesson 11: Bioelectric Memory: How Planaria “Remember” Their Body Plan
In previous lessons, we’ve seen how bioelectricity plays a crucial role in guiding planarian regeneration. We learned that it’s not just about growing back lost tissue, it is also growing it in the right places. We explored how manipulating electrical signals can even lead to dramatic changes in body plan, like the creation of two-headed worms. Now, we’ll tackle a deeper, related question: How do planaria remember what they’re supposed to look like? How does a tiny fragment “know” how to rebuild a complete, correctly proportioned worm, and not just a random blob of cells?
The answer, it turns out, is not entirely in the DNA. Think of the DNA as a parts list for a complex machine. It tells you what components are needed (the different types of cells, the proteins they produce, etc.), but it doesn’t tell you how those components should be assembled. For that, you need a blueprint, an instruction manual, a template. In planarian regeneration, bioelectricity provides that template. It is crucial.
This is the concept of bioelectric memory. It’s the idea that the pattern of electrical activity in a tissue – specifically, the spatial distribution of resting membrane potentials (Vmem) – acts as a kind of “memory” of the correct body plan. This memory isn’t stored in the sequence of DNA bases; it’s stored in the pattern of electrical charges across cells. It’s a form of non-genetic or epigenetic memory.
Think of it like this: imagine a magnetic whiteboard with a bunch of magnets arranged in a specific pattern. The whiteboard itself (the DNA) doesn’t change, but the arrangement of the magnets (the bioelectric pattern) does store information. You could rearrange the magnets to create a completely different pattern, and that new pattern would persist, even if you erased and redrew on the whiteboard.
In planarian regeneration, the “magnets” are the ion channels and pumps in cell membranes, and the “arrangement” is the pattern of Vmem across the tissue. This pattern is not static; it’s dynamic. It changes during development and regeneration, guiding cells to proliferate, differentiate, and migrate to the correct locations.
The two-headed planaria experiments provide compelling evidence for bioelectric memory. Recall that these worms are created by briefly altering the bioelectric state of a regenerating fragment, either by using ionophores to depolarize the cells, or, disrupting gap junction. Once this occurs, a reliable change happens: the regeneration of two heads from one single tissue region. Importantly, the initial manipulation (the ionophore treatment or junction meddling) is temporary. It’s just a short “kickstart.” Yet, the altered body plan – the two-headed phenotype – can persist. This is the real core “takeaway” of this research: a stable bioelectric change.
What’s even more remarkable is what happens when you cut a two-headed planarian again. Often, it will regenerate as another two-headed worm! The altered bioelectric pattern, the “memory” of the two-headed body plan, has been maintained, even through multiple rounds of regeneration. This isn’t a one-off fluke; it’s a demonstration of a stable, heritable (but non-genetic) change in the organism’s “target morphology” – its desired anatomical structure.
How is this bioelectric memory maintained? One key player is gap junctions. These are direct channels between cells that allow ions (and therefore electrical signals) to flow from one cell to another. Gap junctions allow cells to “share” their membrane potential, creating a coordinated electrical network across the tissue. If you disrupt gap junction communication, you disrupt the bioelectric pattern and impair regeneration. You could say they are not transmitting properly.
Think of gap junctions like the wiring in an electrical circuit. If you cut some of the wires, or connect them differently, you change the flow of electricity and alter the behavior of the circuit. Similarly, altering gap junction connectivity can change the bioelectric pattern in a tissue and, consequently, the outcome of regeneration.
The current understanding is that the bioelectric “memory” is a property of the entire tissue, not just individual cells. It’s a collective phenomenon, arising from the interactions between cells via gap junctions and other forms of communication. This means that even if you remove some cells (like by cutting the worm), the remaining cells still “remember” the overall pattern. The change, the bioelectric memory that “this planaria will produce two-heads”, is in fact across the whole system.
Furthermore, the existence of “cryptic” planaria, as discussed before, is fascinating. Worms that look normal (one-headed), can give rise to offspring and regenreates that grow two-heads anyway! How does this happen, the hidden two-head re-occuring?! Scientists, including Michael Levin, hypothesize that there exists, then, multiple layers and representations of this bioelectric memory, holding at one instance even contradictory blueprints simultaneously.
The implications of bioelectric memory are profound. It suggests that we can potentially reprogram the regenerative process, not by altering genes, but by altering electrical signals. This opens up entirely new avenues for regenerative medicine, offering the possibility of:
- Correcting birth defects: If we can understand how bioelectric patterns go wrong during development, we might be able to correct them.
- Inducing regeneration in non-regenerative species: Humans, for example, have very limited regenerative capacity. But if we could “teach” our cells to “remember” the correct body plan using bioelectric signals, we might be able to stimulate the regrowth of lost limbs or organs.
- Controlling tumor growth: Cancer can be seen, in part, as a disruption of normal bioelectric communication. Perhaps by restoring the correct bioelectric pattern, we could normalize tumor cells and prevent them from spreading.
In short, bioelectric memory is a revolutionary concept that challenges our traditional understanding of how biological form is determined and maintained. It highlights the crucial role of non-genetic factors, specifically electrical signals, in shaping life. It’s a new frontier in biology, with the potential to transform medicine and our understanding of the fundamental processes that govern growth, regeneration, and health.
Michael Levin Bioelectricity 101 Crash Course Lesson 11: Bioelectric Memory: How Planaria “Remember” Their Body Plan Quiz
1. Planarian regeneration is primarily about:
A) Regrowing lost tissue randomly.
B) Rebuilding a specific, complex pattern – the planarian body plan.
C) Increasing the planarian’s size.
D) Changing the planarian’s DNA.
2. The “memory” of the planarian body plan is solely encoded in:
A) The DNA sequence.
B) The pattern of bioelectric signals.
C) Chemical signals like hormones.
D) A and B
3. What acts as a “template” or “blueprint” for regeneration in planaria?
A) The DNA sequence.
B) The pattern of resting membrane potentials (Vmem) across tissues.
C) The physical structure of the planarian’s cells.
D) The planarian’s diet.
4. True or False: The bioelectric template is fixed and cannot be altered.
A) True
B) False
5. The stability of the altered bioelectric pattern in two-headed planaria is due to:
A) Changes in DNA sequence.
B) A form of non-genetic or epigenetic memory.
C) The continued presence of ionophores.
D) The planarian’s diet.
6. Which of the following best describes how “bioelectric memory” is stored:
A) It’s etched into the planarian’s DNA, like a computer file.
B) It’s distributed across connected tissues through consistent voltage gradients, and altered patterns, between the cells.
C) It is passed down by genetic processes.
D) All of the Above
7. What structures play a crucial role in maintaining and propagating the bioelectric pattern?
A) Mitochondria
B) Ribosomes
C) Gap junctions
D) The nucleus
8. What happens when a two-headed planarian (created through bioelectric manipulation) is cut again?
A) It always regenerates into a normal one-headed planarian.
B) It often regenerates into another two-headed planarian.
C) It fails to regenerate.
D) It regenerates into a random shape.
9. What can “Cryptic Planaria” do? A) Regenerate normally and reliably. B) Appear one-headed, but regrow to show a consistent two-headed form. C) They are very good at hiding. D) None of the above
10. The concept of bioelectric memory has significant implications for:
A) Understanding how computers work.
B) Regenerative medicine and potentially controlling tissue regeneration.
C) Developing new types of batteries.
D) Understanding the behavior of magnets.
11. The planarian “target morphology” can be best described as the:
A) Blueprint the body is aiming for, or to reachieve.
B) Number of heads, tails and pharynx it shows.
C) Specific electrical signals themselves.
D) A and B
12. What method would consistently help create, transmit and then change *bioelectric* “memory”, by definition?
A) Cutting
B) Changing cell junction and connection pathways
C) Using Ionophores like Nigericin and Monensin.
D) B and C
13. Is this “Memory” considered a gentic or epigentic change?
A) Genetic, in the genes.
B) Epigenetic
14. Why is this form of information considered a form of *memory*, anyway?
A) Like an action potential, it represents instant, one-shot, or quickly moving info, in a similar process of memory in neurons, and computer storage as well.
B) A consistent, held pattern or shape of electrical information guides what a tissue fragment forms
C) Chemicals in memory.
D) B and C
15. True or False: planaria exhibits a capacity to remember or be altered, so they “know” a single target form.
A) True
B) False
16. True or False: gap junction and bioelectric connections represent and have been shown to *change* fundamental planarian processes?
A) True.
B) False
17. Gap junctions allow cells to…
A) Communicate with the nucleus only
B) Share electrical signals by exchanging ions with another cell.
C) Grow hair
D) Be stable and change.
18. What occurs at the level of the entire tissue?
A) Bioelectric changes
B) Gene Editing and alterations
C) “Remembering” a target form
D) A and C.
19. Which better defines the term “non-genetic”?
A) Information in the form of voltage across cells, or the spatial positioning or junctions
B) Something encoded inside of genes and genetic instructions in DNA.
C) Bioelectric in this case.
D) A and C.
20. Which of the following is *not* listed as a implication from understanding this topic more:
A) Controlling the behavior of cancer and potentially harmful tumor spread.
B) Better ability to repair physical defects, including loss of body parts or damage, at birth.
C) Gaining fundamental insight and better treatment, medicine and approaches to influencing and understanding biological system
D) Ability to control the thoughts and mental activities inside of people
Michael Levin Bioelectricity 101 Crash Course Lesson 11: Bioelectric Memory: How Planaria “Remember” Their Body Plan Answer Sheet
1. B
2. B
3. B
4. B
5. B
6. B
7. C
8. B
9. B
10. B
11. D
12. D
13. B
14. B
15. B
16. A
17. B
18. D
19. D
20. D
迈克尔·莱文 生物电 101 速成课程 第十一课：生物电记忆：涡虫如何“记住”它们的身体蓝图 摘要
- 涡虫再生不仅仅是重新长出失去的组织；它是重建一个特定的、复杂的模式——涡虫的身体蓝图。
- 这种身体蓝图的“记忆”不仅仅编码在 DNA 序列中。DNA 提供了“零件清单”，但没有提供组装说明。
- 生物电信号，特别是组织间静息膜电位 (Vmem) 的模式，充当一种再生的“模板”或“蓝图”。
- 这种生物电模板是动态的，可以被改变，正如双头涡虫实验所证明的那样。
- 重要的是，改变后的生物电模式可以是稳定的，这意味着即使在最初的操纵被移除后，它仍然存在。
- 这种稳定性不是由于 DNA 序列的变化；它是一种非基因或表观遗传记忆的形式。
- 这种稳定性被认为出现在组织改变的状态中，这种状态会持续变化，而不是仅仅发生在特定区域。
- 间隙连接允许细胞之间进行直接的电通讯，在维持和传播生物电模式中起着至关重要的作用。
- 生物电记忆解释了为什么双头涡虫即使在再次被切割后也经常再生为双头。改变后的“蓝图”仍然存在。
- 了解生物电记忆对再生医学具有重要意义，有可能使我们能够控制和指导组织再生。
- 涡虫表现出多个同时存储的身体模板，这意味着它可能“记住”比以前认为的更多的数据。
迈克尔·莱文 生物电 101 速成课程 第十一课：生物电记忆：涡虫如何“记住”它们的身体蓝图
在前面的课程中，我们已经看到生物电在指导涡虫再生中起着至关重要的作用。 我们了解到这不仅仅是长回失去的组织，而且还包括在正确的位置生长它。 我们探讨了操纵电信号甚至如何导致身体结构的巨大变化，例如产生双头蠕虫。 现在，我们将解决一个更深层次的相关问题：涡虫如何记住它们应该是什么样子？ 一个小碎片如何“知道”如何重建一个完整的、比例正确的蠕虫，而不仅仅是一团随机的细胞？
事实证明，答案并不完全在于 DNA。 可以将 DNA 视为复杂机器的零件清单。 它告诉你需要什么组件（不同类型的细胞、它们产生的蛋白质等），但它并没有告诉你这些组件应该如何组装。 为此，你需要一张蓝图、一本说明书、一个模板。 在涡虫再生中，生物电提供了这个模板。这是至关重要的。
这就是生物电记忆的概念。 这是一种观点，即组织中电活动的模式——特别是静息膜电位 (Vmem) 的空间分布——充当正确身体结构的一种“记忆”。 这种记忆不是存储在 DNA 碱基序列中； 它存储在细胞间电荷的模式中。 这是一种非基因或表观遗传记忆的形式。
可以这样想：想象一个磁性白板，上面有一堆磁铁以特定的模式排列。 白板本身（DNA）不会改变，但磁铁的排列（生物电模式）确实存储了信息。 你可以重新排列磁铁以创建完全不同的模式，即使你擦除并在白板上重绘，该新模式也会持续存在。
在涡虫再生中，“磁铁”是细胞膜中的离子通道和泵，“排列”是组织中 Vmem 的模式。 这种模式不是静态的； 它是动态的。 它在发育和再生过程中发生变化，引导细胞增殖、分化和迁移到正确的位置。
双头涡虫实验为生物电记忆提供了令人信服的证据。 回想一下，这些蠕虫是通过短暂改变再生碎片的生物电状态来产生的，可以使用离子载体使细胞去极化，或者破坏间隙连接。 一旦发生这种情况，就会发生可靠的变化：从一个组织区域再生出两个头部。 重要的是，最初的操纵（离子载体处理或连接干扰）是暂时的。 这只是一个短暂的“启动”。 然而，改变后的身体结构——双头表型——可以持续存在。 这是这项研究真正的核心“要点”：稳定的生物电变化。
更值得注意的是，当你再次切割双头涡虫时会发生什么。 通常，它会再生为另一个双头蠕虫！ 改变后的生物电模式，即双头身体结构的“记忆”，即使经过多轮再生也一直保持着。 这不是一次性的偶然事件； 这是生物体“目标形态”（其所需的解剖结构）中稳定、可遗传（但非遗传）变化的证明。
这种生物电记忆是如何维持的？ 一个关键因素是间隙连接。 这些是细胞之间的直接通道，允许离子（以及电信号）从一个细胞流向另一个细胞。 间隙连接允许细胞“共享”它们的膜电位，从而在整个组织中创建一个协调的电网络。 如果你破坏了间隙连接通讯，你就会破坏生物电模式并损害再生。 你可以说它们没有正确传输。
可以把间隙连接想象成电路中的线路。 如果你切断一些电线，或者以不同的方式连接它们，你就会改变电流的流动并改变电路的行为。 类似地，改变间隙连接的连接性可以改变组织中的生物电模式，从而改变再生的结果。
目前的理解是，生物电“记忆”是整个组织的属性，而不仅仅是单个细胞的属性。 这是一种集体现象，由细胞之间通过间隙连接和其他形式的通讯产生的相互作用引起。 这意味着即使你移除一些细胞（比如通过切割蠕虫），剩余的细胞仍然“记住”整体模式。 变化，即“这条涡虫将产生两个头”的生物电记忆，实际上存在于整个系统中。
此外，正如之前所讨论的，“隐秘”涡虫的存在非常有趣。 看起来正常（单头）的蠕虫，无论如何都可以产生后代并再生出两个头！ 这是怎么发生的，隐藏的双头再次出现？！ 包括迈克尔·莱文在内的科学家假设，存在着这种生物电记忆的多层和表示，它们同时保存着甚至相互矛盾的蓝图。
生物电记忆的意义是深远的。 这表明我们有可能重新编程再生过程，不是通过改变基因，而是通过改变电信号。 这为再生医学开辟了全新的途径，提供了以下可能性：
- 纠正出生缺陷： 如果我们能够了解生物电模式在发育过程中是如何出错的，我们也许能够纠正它们。
- 在非再生物种中诱导再生： 例如，人类的再生能力非常有限。 但是，如果我们能“教会”我们的细胞使用生物电信号“记住”正确的身体结构，我们也许能够刺激失去的肢体或器官的再生。
- 控制肿瘤生长： 癌症在某种程度上可以被视为正常生物电通讯的破坏。 也许通过恢复正确的生物电模式，我们可以使肿瘤细胞正常化并阻止它们扩散。
简而言之，生物电记忆是一个革命性的概念，它挑战了我们对生物形态如何确定和维持的传统理解。 它强调了非遗传因素，特别是电信号，在塑造生命中的关键作用。 这是生物学的一个新领域，有可能改变医学和我们对控制生长、再生和健康的基本过程的理解。
迈克尔·莱文 生物电 101 速成课程 第十一课：生物电记忆：涡虫如何“记住”它们的身体蓝图 小测验
1. 涡虫再生主要是关于：
A) 随机重新长出失去的组织。
B) 重建一个特定的、复杂的模式——涡虫的身体蓝图。
C) 增加涡虫的大小。
D) 改变涡虫的 DNA。
2. 涡虫身体蓝图的“记忆”仅编码在：
A) DNA 序列。
B) 生物电信号的模式。
C) 激素等化学信号。
D) A 和 B
3. 什么充当涡虫再生的“模板”或“蓝图”？
A) DNA 序列。
B) 组织间静息膜电位 (Vmem) 的模式。
C) 涡虫细胞的物理结构。
D) 涡虫的饮食。
4. 对或错：生物电模板是固定的，不能被改变。
A) 对
B) 错
5. 双头涡虫中改变的生物电模式的稳定性是由于：
A) DNA 序列的变化。
B) 一种非基因或表观遗传记忆的形式。
C) 离子载体的持续存在。
D) 涡虫的饮食。
6. 以下哪项最好地描述了“生物电记忆”是如何存储的：
A) 它像计算机文件一样被蚀刻到涡虫的 DNA 中。
B) 它通过一致的电压梯度和细胞之间的改变模式分布在连接的组织中。
C) 它通过遗传过程传递。
D) 以上都是
7. 什么结构在维持和传播生物电模式中起着至关重要的作用？
A) 线粒体
B) 核糖体
C) 间隙连接
D) 细胞核
8. 当一个双头涡虫（通过生物电操纵产生）再次被切割时会发生什么？
A) 它总是再生为一个正常的单头涡虫。
B) 它通常会再生为另一个双头涡虫。
C) 它无法再生。
D) 它会再生为随机形状。
9. “隐秘涡虫”可以做什么？ A) 正常且可靠地再生。 B) 看起来是单头的，但重新生长以显示一致的双头形式。 C) 它们非常擅长隐藏。 D) 以上都不是
10. 生物电记忆的概念对以下方面具有重要意义：
A) 了解计算机的工作原理。
B) 再生医学和潜在地控制组织再生。
C) 开发新型电池。
D) 了解磁铁的行为。
11. 涡虫的“目标形态”可以最好地描述为：
A) 身体的目标或要实现的蓝图。
B) 它显示的头部、尾部和咽部的数量。
C) 特定的电信号本身。
D) A 和 B
12. 根据定义，哪种方法可以持续帮助创建、传输然后改变 *生物电* “记忆”？
A) 切割
B) 改变细胞连接和连接通路
C) 使用离子载体，如尼日利亚菌素和莫能菌素。
D) B 和 C
13. 这种“记忆”被认为是遗传的还是表观遗传的变化？
A) 遗传的，在基因中。
B) 表观遗传的
14. 为什么这种信息形式被认为是一种 *记忆* 形式？
A) 就像动作电位一样，它代表即时、一次性或快速移动的信息，在神经元和计算机存储的记忆过程中也是如此。
B) 一致的、保持的电信息模式或形状指导组织碎片形成
C) 记忆中的化学物质。
D) B 和 C
15. 对或错：涡虫表现出记忆或被改变的能力，所以它们“知道”一个单一的目标形式。
A) 对
B) 错
16. 对或错：间隙连接和生物电连接代表并已被证明可以 *改变* 基本的涡虫过程？
A) 对。
B) 错
17. 间隙连接允许细胞…
A) 仅与细胞核通讯
B) 通过与其他细胞交换离子来共享电信号。
C) 长出毛发
D) 保持稳定和变化。
18. 在整个组织层面发生了什么？
A) 生物电变化
B) 基因编辑和改变
C) “记住”一个目标形式
D) A 和 C。
19. 哪个选项更好地定义了“非基因”一词？
A) 以细胞间电压或空间定位或连接形式存在的信息
B) 编码在基因和 DNA 遗传指令中的东西。
C) 在这种情况下是生物电的。
D) A 和 C。
20. 以下哪一项 *没有* 被列为理解这个主题的意义：
A) 控制癌症和潜在有害肿瘤扩散的行为。
B) 更好地修复身体缺陷，包括出生时身体部位的缺失或损伤。
C) 获得基本见解和更好的治疗、医学和方法，以影响和理解生物系统
D) 控制人们思想和心理活动的能力
迈克尔·莱文 生物电 101 速成课程 第十一课：生物电记忆：涡虫如何“记住”它们的身体蓝图 答案表
1. B
2. B
3. B
4. B
5. B
6. B
7. C
8. B
9. B
10. B
11. D
12. D
13. B
14. B
15. B
16. A
17. B
18. D
19. D
20. D