What Was Observed? (Introduction)

• Planaria, a type of flatworm, can regenerate body parts after injury, even including the brain and complex internal organs.
• The research focused on how bioelectric signals, which involve electrical charges across cells, influence the process of regeneration.
• When planaria are cut, their body parts must “figure out” where the head and tail should grow again, a process called establishing “anterior-posterior polarity.”
• The study found that early bioelectric signals, specifically the resting membrane potential (a type of electrical state in cells), are crucial for setting the correct head and tail pattern during regeneration.

What is Bioelectric Signaling?

• Bioelectric signaling refers to the electrical signals that flow through cells, controlling important processes like growth and regeneration.
• In this study, bioelectric signals were found to be crucial for establishing the body’s “front” (anterior) and “back” (posterior) during regeneration in planaria.
• Resting membrane potential (Vmem) is a type of bioelectric signal, and changes in this potential were observed within hours of the injury.

How Does Regeneration Work in Planaria?

• Planaria can regenerate lost body parts, including heads and tails, after being cut.
• The regeneration process begins when the animal is injured. Immediately after the injury, the cells at the cut edge start to divide and form a blastema (a mass of cells that will form new tissues).
• For proper regeneration, the blastema needs to understand which direction to grow: Should it form a head or a tail?
• Bioelectric signals in the first few hours after injury help the cells “decide” which way to go, ensuring the correct formation of body parts.

What is the Role of Resting Membrane Potential (Vmem)?

• Resting membrane potential (Vmem) refers to the electrical charge across the membrane of cells in the body.
• In planaria, the Vmem differs at the anterior (front) and posterior (back) sides of the body immediately after amputation.
• This difference in Vmem is important for helping the planaria “decide” where the head and tail should grow during regeneration.
• When Vmem is altered early in the regeneration process, it can result in abnormalities like double heads growing at both ends.

What Did the Researchers Do? (Methods)

• The researchers tested how changes to the Vmem, using chemicals called ionophores, could influence the regeneration process.
• Two ionophores were used to manipulate Vmem in regenerating planaria: nigericin and monensin.
• They exposed planaria fragments to these chemicals for the first 3 hours after amputation, then observed how the changes affected the animals’ regeneration over the next weeks.
• The researchers also used a special dye (DiBAC4(3)) to measure the Vmem in different parts of the animal.

How Did the Bioelectric Manipulations Affect Regeneration? (Results)

• When the Vmem was altered using ionophores (nigericin and monensin), the regeneration of planaria was dramatically changed.
• In some cases, planaria grew double heads (a head at both ends) instead of the usual head and tail.
• This result showed that changes to bioelectric signals early in the process affected the correct formation of anterior-posterior polarity during regeneration.
• Importantly, the double-headed phenotype persisted even after the chemicals were removed from the planaria, suggesting that bioelectric signals had a lasting effect on regeneration.

What is the Role of Notum in Regeneration? (Gene Expression)

• Notum is a gene that plays a key role in determining the front (head) and back (tail) of planaria during regeneration.
• Normally, notum is expressed at the anterior (head) side of the planaria, and this helps guide head formation.
• However, when bioelectric signals were altered early in regeneration, notum expression was disrupted, and abnormal double-headed planaria were observed.

Treatment with Ionophores: A Step-by-Step Method

• Planaria were amputated into fragments, and the fragments were treated with ionophores (nigericin or monensin) for 3 hours after the cut.
• After 3 hours, the chemicals were washed off, and the planaria were allowed to regenerate for two weeks.
• Results were observed at different time points, and the Vmem of the animals was measured using a dye.
• The treatment with ionophores caused some animals to grow two heads instead of one, demonstrating the importance of bioelectric signaling in regeneration.

Key Findings (Conclusion)

• Bioelectric signals play an important role in early regeneration events by influencing the polarity (head/tail orientation) of the regenerating planaria.
• Manipulating Vmem during the first few hours after injury can alter regeneration outcomes, leading to double-headed planaria.
• Notum gene expression, which normally helps define head formation, was disrupted when Vmem was altered, leading to abnormal regeneration patterns.
• These findings suggest that bioelectric signals are essential for controlling the patterning of body parts during regeneration.

观察到的结果 (引言)

• 涡虫是一种自由生活的扁形虫，具有惊人的再生能力，即使是复杂的内部器官和大脑也能再生。
• 这项研究关注的是生物电信号如何影响再生过程，尤其是在切割后如何影响身体的“头”和“尾”形成。
• 研究发现，在涡虫切割后的前几小时，生物电信号在形成正确的头尾极性中起着关键作用。

什么是生物电信号？

• 生物电信号指的是细胞中的电信号，它们控制生长和再生等重要过程。
• 在本研究中，生物电信号在涡虫的再生过程中起着至关重要的作用，特别是在再生过程中的“前”与“后”极性的确定。
• 休息膜电位（Vmem）是一种生物电信号，本研究发现，Vmem的变化在伤口后的几小时内就会影响极性建立。

涡虫如何再生？

• 涡虫可以再生丢失的身体部位，包括头部和尾部。
• 当涡虫受伤时，伤口边缘的细胞开始分裂并形成“伤口芽”（将形成新组织的细胞团）。
• 为了进行正确的再生，伤口芽需要知道从哪里开始生长：应该形成头部还是尾部？
• 在再生的前几小时，生物电信号帮助伤口芽的细胞“决定”该生长哪个部分，从而确保正确的身体部位形成。

休息膜电位（Vmem）的作用是什么？

• 休息膜电位（Vmem）是指细胞膜内外电荷的差异。
• 在涡虫中，伤口前后两侧的Vmem差异在切割后立即被观察到，这对于帮助涡虫决定哪里形成头部，哪里形成尾部至关重要。
• 当Vmem在再生的初期被改变时，可能会导致不正常的双头生长现象。

研究人员做了什么？ (方法)

• 研究人员测试了通过使用化学物质（离子载体）改变Vmem如何影响涡虫的再生过程。
• 研究使用了两种离子载体：尼吉瑞辛（nigericin）和莫奈辛（monensin）。
• 他们在切割后立即将涡虫的碎片暴露于这些化学物质中，观察在接下来的几周内这些变化如何影响动物的再生。
• 研究人员还使用了一种特殊的染料（DiBAC4(3)）来测量动物不同部位的Vmem。

生物电操控如何影响再生？ (结果)

• 当使用离子载体（尼吉瑞辛和莫奈辛）改变Vmem时，涡虫的再生过程发生了显著变化。
• 在一些情况下，涡虫的两个端部都生长出头部，形成双头涡虫。
• 这表明，在再生的早期改变生物电信号可以影响极性（头尾形成）以及再生的结果。
• 值得注意的是，双头的表型在去除化学物质后仍然保持不变，表明生物电信号对再生有持久的影响。

Notum基因在再生中的作用 (基因表达)

• Notum是一种在涡虫再生中起重要作用的基因，尤其在决定头尾形成时。
• 通常，Notum在涡虫的前端（头部）表达，并有助于头部的形成。
• 然而，当Vmem在再生初期被改变时，Notum的表达被打乱，观察到双头涡虫的异常再生。

使用离子载体的步骤：

• 涡虫被切割成碎片，并在切割后立即暴露于尼吉瑞辛或莫奈辛溶液中，持续3小时。
• 3小时后，化学物质被洗去，涡虫允许再生两周。
• 在不同时间点观察结果，并使用染料测量动物的Vmem。
• 使用离子载体处理的动物导致双头涡虫的形成，证明生物电信号在再生中的重要性。

关键发现 (结论)

• 生物电信号在再生的早期阶段通过影响Vmem来决定涡虫的极性。
• 在伤口后的前几小时改变Vmem可能导致双头涡虫的形成。
• Notum基因表达在Vmem改变时受到干扰，导致异常再生模式。
• 这些发现表明，生物电信号在再生过程中通过调节极性和身体部位的形成起着至关重要的作用。