Michael Levin Bioelectricity 101 Crash Course Lesson 12: Cryptic Planaria: Unveiling Hidden Bioelectric Potential Summary

• “Cryptic planaria” are planarians that appear completely normal (single-headed, with standard anatomy) after an initial treatment that disrupts their bioelectric network (like exposure to the gap junction blocker 8-OH).
• However, these seemingly normal planaria have a hidden alteration in their regenerative capacity.
• When cryptic planaria are cut again, even in plain water, a significant proportion of them regenerate as double-headed (DH) worms. This reveals their altered “target morphology.”
• The cryptic phenotype is not due to changes in neoblast distribution, expression of key anterior/posterior genes, or the presence of hidden anterior structures. It’s a genuine change in the regenerative program, not just incomplete penetrance of the initial treatment.
• The cryptic phenotype is associated with a distinct bioelectric signature: an abnormal region of depolarization (more positive membrane potential) at the posterior end, resembling the depolarization normally found in the head region.
• The existence of cryptic planaria demonstrates that an organism’s current morphology (what it looks like now) can be different from its target morphology (what it will regenerate into after injury).
• The altered regenerative pattern in cryptic planaria is stable over multiple rounds of cutting, but stochastic in its outcome (a consistent ratio of single-headed and double-headed regenerates).
• The discovery of cryptic planaria highlights the importance of bioelectricity as a form of “pattern memory” that can store information about body plan, independent of the current anatomical structure.
• Cryptic planaria underscores that some important physiological/bioelectric changes can be undetectable without specific and potentially invasive probing, and simple morphological outcome observations alone do not reliably tell if treatments/interventions work.

Michael Levin Bioelectricity 101 Crash Course Lesson 12: Cryptic Planaria: Unveiling Hidden Bioelectric Potential

Up to this point in our bioelectricity crash course, we’ve explored the basics of cellular electricity, the remarkable regenerative abilities of planarians, and how disrupting bioelectric communication (using tools like the gap junction blocker 8-OH) can lead to dramatic changes in body plan, like the creation of two-headed worms. We introduced the idea that bioelectricity acts as a kind of “software” that guides development and regeneration, complementing the “hardware” provided by the genes. Now, we’re going to encounter one of the most surprising and conceptually important discoveries in Michael Levin’s research: the cryptic planarian.

The story of the cryptic planarian begins with a seemingly simple observation. When planarian trunk fragments (pieces with the pharynx but no head or tail) are treated with 8-OH, they don’t all regenerate as two-headed worms. A significant portion, in fact the majority, appear to regenerate completely normally, forming a single head at the anterior end and a single tail at the posterior end. These look like perfectly ordinary, wild-type planarians.

For a long time, it was tempting to dismiss these seemingly normal planaria as “escapees” – individuals that, for whatever reason, were unaffected by the 8-OH treatment. This is a common assumption in biological experiments. If you apply a drug or make a genetic manipulation, and only some of the organisms show the expected effect, you usually assume that the treatment simply didn’t work on the others. Maybe the drug didn’t penetrate their tissues as effectively, or maybe they had some slight genetic variation that made them resistant. This is called “incomplete penetrance” – the treatment has an effect, but it doesn’t affect every individual in the same way.

But the researchers in Levin’s lab decided to test this assumption in a very direct way. They took these seemingly normal planarians – the ones that had regenerated a single head and tail after 8-OH treatment – and cut them again. This time, however, they didn’t use any 8-OH. They just cut them in plain spring water, the standard condition for planarian regeneration.

What they found was astonishing. A significant proportion of these seemingly normal planaria – around 25% in many experiments – regenerated as double-headed worms. This was completely unexpected. Wild-type planarians, cut in plain water, always regenerate with a single head and a single tail. Their regenerative pattern is incredibly robust. So, what was going on?

These seemingly normal planarians were not escapees. They had been affected by the initial 8-OH treatment, but the effect was hidden. It wasn’t visible in their current anatomy, but it was revealed when they were forced to regenerate again. This is why they were named “cryptic” planaria – their altered regenerative potential was concealed, cryptic.

Let’s break down the key implications of this discovery:

1. Current Morphology ≠ Target Morphology: This is perhaps the most fundamental point. What an organism looks like now (its current morphology) is not necessarily the same as what it will regenerate into after injury (its target morphology). The cryptic planarians are a perfect example. They look like normal, single-headed worms, but their internal program for regeneration has been altered. They are carrying a hidden blueprint for a two-headed body plan.
2. Stable, But Stochastic, Alteration: The change in the cryptic planarians is stable. If you keep cutting them, generation after generation, they will continue to produce a mixture of single-headed and double-headed regenerates, always in roughly the same proportion. It’s not a temporary effect. However, it’s also stochastic. This means it’s probabilistic, not deterministic. You can’t predict with certainty whether a particular cryptic planarian fragment will regenerate as single-headed or double-headed. But you can predict the overall ratio of the two outcomes within a population of cryptic planaria.
3. Bioelectricity as Pattern Memory: The existence of cryptic planaria provides powerful evidence for the idea that bioelectricity acts as a form of “pattern memory.” The initial 8-OH treatment disrupts the normal bioelectric network in the planarian fragment. This disruption doesn’t necessarily change the immediate outcome of regeneration (many fragments still form a single head and tail). But it does alter the long-term bioelectric pattern, and this altered pattern is what guides subsequent regeneration. It’s like the 8-OH has rewritten the planarian’s regenerative software.
4. Not Due to Obvious Anatomical or Molecular Changes: The researchers carefully examined the cryptic planaria to see if they could find any obvious anatomical or molecular differences that could explain their altered regenerative behavior. They looked at:
   • Hidden anterior structures: Did the cryptic planaria have some hidden extra head tissue in their posterior region that could trigger the formation of a second head? The answer was no.
   • Ectopic expression of anterior genes: Did the cryptic planaria have genes that are normally only expressed in the head region being expressed in their posterior region? Again, the answer was no. They checked key genes like ndk, which is crucial for head formation.
   • Altered neoblast distribution: Did the cryptic planaria have a different distribution of neoblasts (stem cells) that could explain their ability to form a second head? Once again, the answer was no.
   • Missing tail identity: Did the tail side have the markers expected of that tissue? They did.
   All of these tests came up negative. The cryptic planaria were, by all these standard measures, completely normal.
5. A Bioelectric Signature: If all these expected attributes of an altered morphology was not there, what did differ in them? Critically, while there seemed to be nothing anatomically or in major key gene-expressions wrong… what was profoundly different, the only thing in fact, was their bioelectric profile:
   • The critical difference was found using the voltage-sensitive dye DiBAC4(3). This dye allows researchers to visualize the distribution of membrane potential across the planarian’s body. What they found was that cryptic planaria had an abnormal region of depolarization (more positive membrane potential) at their posterior end. This depolarization resembled the pattern normally seen in the head region of wild-type planaria.

Think of it like this: the 8-OH treatment scrambled the planarian’s electrical map. In some cases, this scrambling resulted in the immediate formation of two heads. But in other cases, the scrambling was more subtle. It didn’t change the current map, but it changed the default settings for the map. When the planarian was cut again, the regeneration process defaulted to this altered bioelectric pattern, leading to the formation of a second head.

The discovery of cryptic planaria is a game-changer. It reveals a hidden layer of control in regeneration, a layer that’s not encoded in the genes or in the obvious anatomical structure, but in the dynamic pattern of electrical activity across the organism. It shows that bioelectricity is not just a byproduct of cellular processes, but an active player in shaping life, a kind of “electrical blueprint” that can be rewritten, with profound consequences for the organism’s future form. It is also an extremely stark lesson, that important biological/physiological processes can remain invisible to our present detection, only showing up much later and requiring very different thinking/hypothesis-testing.

Michael Levin Bioelectricity 101 Crash Course Lesson 12: Cryptic Planaria: Unveiling Hidden Bioelectric Potential Quiz

1. What is a “cryptic planarian”?

A) A planarian that has been genetically modified to have a hidden gene.
B) A planarian that appears normal but has a hidden alteration in its regenerative capacity.
C) A planarian that is resistant to the effects of 8-OH.
D) A planarian that has a cryptic coloration pattern.

2. What happens when a cryptic planarian is cut in plain water?

A) It always regenerates as a single-headed worm.
B) It always regenerates as a double-headed worm.
C) A proportion of them regenerate as double-headed worms.
D) It fails to regenerate.

3. The altered regenerative pattern in cryptic planaria is:

A) Temporary and easily reversed.
B) Stable over multiple rounds of cutting.
C) Due to changes in the expression of key developmental genes.
D) Caused by hidden anterior structures in the posterior region.

4. The “target morphology” of a cryptic planarian is:

A) The same as its current morphology (single-headed).
B) Different from its current morphology (potentially double-headed).
C) Always double-headed.
D) Undetermined until it is cut.

5. What technique was used to reveal the bioelectric difference between cryptic and wild-type planaria?

A) Gene sequencing
B) Microscopy of neoblast distribution
C) Voltage-sensitive dye imaging
D) In situ hybridization

6. What is the characteristic bioelectric signature of a cryptic planarian?

A) A region of hyperpolarization (more negative voltage) at the posterior end.
B) A region of depolarization (more positive voltage) at the posterior end.
C) No difference in membrane potential compared to wild-type.
D) Random fluctuations in membrane potential across the body.

7. The altered regenerative pattern in cryptic planaria is best described as:
A) Deterministic
B) Stochastic
C) Invariable
D) Fully penetrant

8. The initial 8-OH treatment in cryptic planarians…
A)…causes all of them to generate as double-headed worms.
B)… causes most to appear as normal-looking single-headed worms.
C) …changes nothing in terms of visible outcome or of regeneration capacity.
D)…kills them outright.

9. Which of the following was NOT found to be a cause of the cryptic phenotype?

A) Ectopic expression of anterior genes in the posterior
B) Altered neoblast distribution
C) Presence of hidden anterior structures
D) All of the Above

10. True or False: The existence of cryptic planaria suggests that an organism’s current morphology is always the same as its target morphology.

A) True
B) False

11. The term “incomplete penetrance” refers to:

A) A situation where a treatment only affects some individuals in a population.
B) A situation where a treatment has no effect at all.
C) A situation where a treatment always has the same effect on every individual.
D) A situation where a treatment causes a cryptic phenotype.

12. How did scientists test if initially-normal-looking worms after an 8-OH treatment are real “escapees” (unchanged in regenerative capacity), or if they do carry some “cryptic” (hidden) changes?

A) By measuring voltages at the ends using DiBAC4(3)
B) By simply looking at the outcomes, under the principle that if there is no change in outcome, the worm has not truly been affected.
C) By recutting them, including ones that showed completely normal one-head results, to check their “target” body plan.
D) Both A and C

13. What percentage of cryptic planaria, on average, regenerate as double-headed worms when cut again?

A) 100%
B) 0%
C) Around 25%
D) Around 75%

14. The stability of cryptic phenotype when cut across time proves:

A) That they are in fact not affected by the initial chemical perturbation
B) The probabilistic (non-deterministic, or random chance at individual levels) distribution between regenerating two heads or a tail, once affected
C)That chemical and electrical manipulation cannot permanently re-set or re-pattern it, to remove their chance of becoming a two-headed worm
D) Nothing much.

15. True or False: Cryptic planaria show a region of depolarization at the posterior end, and is the crucial factor distinguishing it from WT animals

A) True
B) False.

16. Bioelectricity, in the context of cryptic planaria, is best described as a form of:

A) Genetic mutation
B) Chemical signaling
C) Pattern memory
D) Cellular respiration

17. Why could have early scientists easily misinterpreted and dismissed that planarian are Cryptic?

A) Because there are no differences.
B) Because early technology could have likely failed to detect important clues, such as the membrane voltages at tail, causing a seemingly no-change outcome.
C)Because the technology is sensitive enough, that initial scientists simply were too poor to see/interpret them
D) Both B and C.

18. The term, Target Morphology best captures the:

A) …most accurate outcome.
B) …blueprint for building tissues.
C) …chance, distribution-based result when populations are taken into account.
D) All of the Above.

19. If Planaria can be stochastic when regenerating after gap-junction-blocking chemical exposure, what best describes their chance outcomes as “which end becomes a head vs tail”

A) It will become heads and tails always according to original body positions.
B) Head-tail fates of tissue will always vary and remain unknown, defying consistent trends.
C) While we do not fully know for a particular case which cut-wound will turn into which structure (tail or head), we can predict overall odds or probabilities.
D) None of The Above.

20. The study of cryptic planaria has significantly contributed on revealing a _____ of control, via bioelectricity.

A) Visible and Apparent Layer
B) Known layer.
C) Hidden and Encrypted Layer
D) Purely Gene/Chemical Expression Layer.

Michael Levin Bioelectricity 101 Crash Course Lesson 12: Cryptic Planaria: Unveiling Hidden Bioelectric Potential Answer Sheet

1. B

2. C

3. B

4. B

5. C

6. B

7. B

8. B

9. D

10. B

11. A

12. D

13. C

14. B

15. A

16. C

17. B

18. D

19. C

20. C

迈克尔·莱文 生物电 101 速成课程 第十二课：神秘涡虫：揭示隐藏的生物电潜力 摘要

• “神秘涡虫”是指在经过破坏其生物电网络的初始处理（如暴露于间隙连接阻断剂 8-OH）后，看起来完全正常（单头，具有标准解剖结构）的涡虫。
• 然而，这些看似正常的涡虫的再生能力发生了隐藏的变化。
• 当神秘涡虫再次被切割时，即使是在清水中，也有很大一部分会再生为双头 (DH) 涡虫。 这揭示了它们改变的“目标形态”。
• 神秘表型不是由于新生细胞分布的变化、关键前后基因的表达或隐藏的前部结构的存在造成的。 这是再生程序的真正变化，而不仅仅是初始处理的不完全外显。
• 神秘表型与独特的生物电特征相关：后部区域出现异常的去极化区域（更正的膜电位），类似于通常在头部区域发现的去极化。
• 神秘涡虫的存在表明，生物体的当前形态（现在的样子）可以与其目标形态（受伤后将再生成什么样子）不同。
• 神秘涡虫中改变的再生模式在多次切割中是稳定的，但在其结果中是随机的（单头和双头再生体的比例一致）。
• 神秘涡虫的发现强调了生物电作为一种“模式记忆”形式的重要性，它可以存储关于体型的信息，而与当前的解剖结构无关。
• 神秘涡虫强调，一些重要的生理/生物电变化在没有具体且可能具有侵入性的探测的情况下可能无法检测到，仅靠简单的形态学结果观察并不能可靠地说明治疗/干预措施是否有效。

迈克尔·莱文 生物电 101 速成课程 第十二课：神秘涡虫：揭示隐藏的生物电潜力

到目前为止，在我们的生物电速成课程中，我们已经探索了细胞电的基础知识、涡虫卓越的再生能力，以及破坏生物电通讯（使用间隙连接阻断剂 8-OH 等工具）如何导致体型的巨大变化，比如产生双头涡虫。我们引入了生物电作为一种“软件”来指导发育和再生的概念，补充了基因提供的“硬件”。现在，我们将接触迈克尔·莱文研究中最令人惊讶和概念上最重要的发现之一：神秘涡虫。

神秘涡虫的故事始于一个看似简单的观察。当涡虫躯干片段（带有咽部但没有头部或尾部的部分）用 8-OH 处理时，它们并不都再生为双头涡虫。事实上，很大一部分，实际上是大部分，看起来完全正常地再生，在前端形成一个头，在后端形成一个尾巴。这些看起来像完全普通的野生型涡虫。

长期以来，人们很容易将这些看似正常的涡虫视为“逃脱者”——即由于某种原因未受 8-OH 处理影响的个体。这是生物实验中的一个常见假设。如果你使用一种药物或进行基因操作，只有一些生物体表现出预期的效果，你通常会认为这种处理对其他生物体根本不起作用。也许药物没有像有效地穿透它们的组织，或者它们可能有一些轻微的基因变异使它们产生抗性。这被称为“不完全外显”——治疗有效果，但它不会以相同的方式影响每个个体。

但是莱文实验室的研究人员决定以一种非常直接的方式来检验这个假设。他们 എടു了这些看似正常的涡虫——那些在 8-OH 处理后再生出一个头和一个尾巴的涡虫——并再次切割它们。然而，这一次，他们没有使用任何 8-OH。他们只是把它们切在清水里，这是涡虫再生的标准条件。

他们的发现令人震惊。这些看似正常的涡虫中有很大一部分——在许多实验中约为 25%——再生为双头涡虫。这是完全出乎意料的。野生型涡虫，在清水中切割，总是再生出一个头和一个尾巴。它们的再生模式非常强大。那么，这是怎么回事呢？

这些看似正常的涡虫不是逃脱者。它们确实受到了最初 8-OH 处理的影响，但这种影响是隐藏的。在它们当前的解剖结构中看不到它，但当它们被迫再次再生时，它就被揭示出来了。这就是为什么它们被称为“神秘”涡虫——它们改变的再生潜力是隐藏的、神秘的。

让我们来分析一下这一发现的关键含义：

1. 当前形态 ≠ 目标形态：这可能是最根本的一点。生物体现在的样子（它的当前形态）不一定与它在受伤后再生成的样子（它的目标形态）相同。神秘涡虫就是一个很好的例子。它们看起来像正常的单头涡虫，但它们的内部再生程序已经改变。它们携带了双头体型的隐藏蓝图。
2. 稳定但随机的变化：神秘涡虫的变化是稳定的。如果你不断地切割它们，一代又一代，它们将继续产生单头和双头再生体的混合物，总是大致相同的比例。这不是一个暂时的效果。然而，它也是随机的。这意味着它是概率性的，而不是确定性的。你不能确定地预测特定的神秘涡虫片段会再生为单头还是双头。但是你可以预测神秘涡虫群体中两种结果的总体比例。
3. 生物电作为模式记忆：神秘涡虫的存在为生物电作为一种“模式记忆”形式的观点提供了强有力的证据。最初的 8-OH 处理会破坏涡虫片段中正常的生物电网络。这种破坏不一定会改变再生的直接结果（许多片段仍然形成一个头和一个尾巴）。但它确实改变了长期的生物电模式，而这种改变的模式是指导后续再生的。就像 8-OH 重写了涡虫的再生软件。
4. 并非由于明显的解剖或分子变化：研究人员仔细检查了神秘涡虫，看看他们是否能找到任何明显的解剖或分子差异来解释它们改变的再生行为。他们观察了：
   • 隐藏的前部结构：神秘涡虫的后部区域是否有一些隐藏的多余头部组织可以触发第二个头的形成？答案是否定的。
   • 前部基因的异位表达：神秘涡虫是否在它们的后部区域表达了通常只在头部区域表达的基因？同样，答案是否定的。他们检查了像 ndk 这样的关键基因，这对头部形成至关重要。
   • 改变的新生细胞分布：神秘涡虫是否具有不同的新生细胞（干细胞）分布，可以解释它们形成第二个头部的能力？答案是否定的。
   • 缺少尾部特征:尾部一侧有没有呈现该组织的标志？有.
   所有这些测试都呈阴性。按照所有这些标准衡量，神秘涡虫是完全正常的。
5. 生物电特征：如果所有这些预期的改变形态的属性都不存在，那么它们有什么不同呢？至关重要的是，虽然在解剖学上或主要的基因表达中似乎什么都没有错……但实际上非常不同，唯一不同的实际上是它们的生物电特征：
   • 使用对电压敏感的染料 DiBAC4(3) 发现了关键差异。这种染料使研究人员能够可视化涡虫身体的膜电位分布。他们发现的是，神秘涡虫的后部有一个异常的去极化区域（更正的膜电位）。这种去极化类似于通常在野生型涡虫的头部区域看到的模式。

可以这样想：8-OH 处理扰乱了涡虫的电图。在某些情况下，这种扰乱会导致立即形成两个头部。但在其他情况下，这种扰乱更为微妙。它没有改变当前的图，但它改变了图的默认设置。当涡虫再次被切割时，再生过程默认使用这种改变的生物电模式，导致形成第二个头部。

神秘涡虫的发现是一个游戏规则的改变者。它揭示了再生中隐藏的控制层，这一层不是在基因或明显的解剖结构中编码的，而是在整个生物体的电活动的动态模式中编码的。它表明，生物电不仅仅是细胞过程的副产品，而且是塑造生命的积极参与者，是一种可以重写的“电蓝图”，对生物体的未来形态产生深远的影响。同时，这是一个十分重要的经验, 一些重要的生理或者生物点过程可能会在现在的探测技术下隐藏起来， 直到很久以后才会显示出不一样。这需要十分不同的思考或者假设验证方法。.

迈克尔·莱文 生物电 101 速成课程 第十二课：神秘涡虫：揭示隐藏的生物电潜力 小测验

1. 什么是“神秘涡虫”？

A) 经过基因改造具有隐藏基因的涡虫。
B) 看起来正常但再生能力有隐藏变化的涡虫。
C) 对 8-OH 的影响有抵抗力的涡虫。
D) 具有神秘体色模式的涡虫。

2. 当神秘涡虫在清水中被切割时会发生什么？

A) 它总是再生为单头涡虫。
B) 它总是再生为双头涡虫。
C) 其中一部分再生为双头涡虫。
D) 它无法再生。

3. 神秘涡虫中改变的再生模式是：

A) 暂时的且容易逆转。
B) 在多次切割中保持稳定。
C) 由于关键发育基因表达的变化。
D) 由后部区域的隐藏前部结构引起。

4. 神秘涡虫的“目标形态”是：

A) 与其当前形态（单头）相同。
B) 与其当前形态不同（可能是双头）。
C) 总是双头。
D) 在被切割之前是不确定的。

5. 使用什么技术来揭示神秘涡虫和野生型涡虫之间的生物电差异？

A) 基因测序
B) 新生细胞分布显微镜检查
C) 电压敏感染料成像
D) 原位杂交

6. 神秘涡虫的特征性生物电特征是什么？

A) 后部区域出现超极化区域（更负的电压）。
B) 后部区域出现去极化区域（更正的电压）。
C) 与野生型相比，膜电位没有差异。
D) 整个身体的膜电位随机波动。

7. 神秘涡虫中改变的再生模式最好描述为：
A) 确定性的
B) 随机性的
C) 不变的
D) 完全外显的

8. 神秘涡虫中最初的 8-OH 处理…
A)…导致它们全部再生为双头涡虫。
B)…导致大多数看起来像是正常的单头涡虫。
C) …在可见结果或再生能力方面没有任何变化。
D)…直接杀死它们。

9. 以下哪一项不是神秘表型的原因？

A) 后部前部基因的异位表达
B) 新生细胞分布改变
C) 存在隐藏的前部结构
D) 以上都是

10. 对或错：神秘涡虫的存在表明生物体的当前形态始终与其目标形态相同。

A) 对
B) 错

11. 术语“不完全外显”是指：

A) 一种治疗仅影响群体中某些个体的情况。
B) 一种治疗根本没有效果的情况。
C) 一种治疗总是对每个个体产生相同效果的情况。
D) 一种治疗导致神秘表型的情况。

12. 科学家如何测试 8-OH 处理后最初看起来正常的蠕虫是真正的“逃脱者”（再生能力未改变），还是它们确实携带一些“神秘”（隐藏）的变化？

A) 使用 DiBAC4(3) 测量两端的电压
B) 仅仅通过观察结果，根据如果没有变化的结果，蠕虫并没有真正受到影响的原则。
C) 重新切割它们，包括那些显示出完全正常的单头结果的蠕虫，以检查它们的“目标”体型。
D) A 和 C

13. 平均而言，有多少百分比的神秘涡虫在再次切割时会再生为双头涡虫？

A) 100%
B) 0%
C) 25% 左右
D) 75% 左右

14. 神秘表型在切割时 across time 的稳定性证明：

A) 它们实际上并没有受到最初的化学扰动的影响
B) 一旦受到影响，在再生两个头部或一个尾巴之间的概率（非确定性或个体水平上的随机机会）分布
C) 化学和电操作无法永久地重置或重新模式化它，以消除它们变成双头蠕虫的机会
D) 没什么。

15. 对或错：神秘涡虫在后部显示出去极化区域，并且是将其与 WT 动物区分开来的关键因素

A) 对
B) 错。

16. 在神秘涡虫的背景下，生物电最好描述为一种：

A) 基因突变
B) 化学信号传导
C) 模式记忆
D) 细胞呼吸

17. 为什么早期的科学家很容易误解并忽略涡虫是神秘的？

A) 因为没有区别。
B) 因为早期的技术可能无法检测到重要的线索，例如尾部的膜电压，导致看似没有变化的结果。
C) 因为技术足够灵敏，最初的科学家只是太差劲了，无法看到/解释它们
D) B 和 C。

18. 术语“目标形态”最能捕捉到：

A) …最准确的结果。
B) …构建组织的蓝图。
C) …当考虑到群体时，基于机会的、分布的结果。
D) 以上都是。

19. 如果涡虫在暴露于阻断间隙连接的化学物质后可以随机再生，那么什么最能描述它们“哪一端变成头部与尾部”的机会结果？

A) 它将始终根据原始身体位置变成头部和尾部。
B) 组织头尾的命运将始终变化且未知，违背一致的趋势。
C) 虽然我们不完全知道特定情况下哪个切割伤口会变成哪个结构（尾巴或头部），但我们可以预测总体几率或概率。
D) 以上都不是。

20. 对神秘涡虫的研究极大地促进了揭示通过生物电进行控制的_____。

A) 可见且明显的层
B) 已知的层。
C) 隐藏和加密的层
D) 纯基因/化学表达层。

迈克尔·莱文 生物电 101 速成课程 第十二课：神秘涡虫：揭示隐藏的生物电潜力 答案表

1. B

2. C

3. B

4. B

5. C

6. B

7. B

8. B

9. D

10. B

11. A

12. D

13. C

14. B

15. A

16. C

17. B

18. D

19. C

20. C