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Jodyann Munroe Lab Report 5 4/12/18 Bio 162

Planarian regeneration and development

Abstract Planarians are unique organism due to their ability to be able to regenerate, planarians reproduce using asexual reproduction so the animal as the ability to rip itself apart thus creating two individuals. Within this experiment over a 7 day period three groups of two groups of three planarians used to document regenerative process while another group of three were used as a control group. One group was cut from the middle to the head with the hypothesis of the planaria growing two heads, while the other group was cut from the middle to the tail with the hypothesis of growing two tails. Within the group for the regenerating of two heads, all planaria showed signs of blastema formation. With the group for tail formation one planarian showed signs of blastema formation, the second planaria showed no signs, and the last planaria showed deformation due to the healing process. The control group showed no signs of change. The hypothesis was overall proven to be correct showing that planarians are capable of regenerating two heads and two tails, only if the incision is done properly.

Introduction

Regeneration is defined as the process of regenerating or being regenerated, in particular, the formation of a new animal or plant tissue.(Merriam Webster). Planarians are flatworms that participate in this process. In order for a planarian to reproduce, it must ‘tear’ itself in two and regenerate the lost half creating two identical halves. Planarians are freshwater flatworms that usually thrives in shallow streams under leaves or rocks where the area is dark. The water is also usually clean and unpolluted. The planaria used in this experiment were maintained in spring water considering that tap water could not be used based on the water being treated with chlorine which is toxic to the animals.Unlike the organism's natural habitat, wherein streams the current usually act as a self-filtrate. The artificial habitat made in lab was with a clear dish that contained spring water that needed to be changed every 2-3 days removing the “scuzz” that builds up from the planaria secreting mucus. During this experiment, there were two regenerative group and one control group. The type of regenerative mechanism that was fabricated was one group cut from the middle to the tail, and the other group cut from the middle to the head. It was the hypothesis that both regenerative groups would show the process of regeneration by showing blastema formation, while the control group remained the same. Methods The first step of the experiment was to observe the organism under a dissecting microscope. A ring of petroleum jelly was placed on a slide with the planarian in the center with a drop of water. After placing a thin glass over the organism and squeezing it enough to make the animal flat both the animals dorsal and ventral features were observed. The organism then released to be recovered in water and different planarian was used to observe some of its basic behavior characteristics. For the regeneration part of the experimental design was made to display how the animal is going to be cut. It was important to keep in mind that the regeneration process was

the data that was going to be collected not the complete regeneration. A plastic chamber containing ice was set to place to transfer the planarian to the top of the chamber surface using a wide-bore pipet and a drop of spring/pond water. After the flatworm was relaxed a cut from the middle to the head was made using a razor blade, the separate pieces were then held apart to prevent the flatworm from healing together the process the same process was repeated with three other flatworms, the animals were then placed in a petri dish with spring water/ pond water labeled “middle to head”. For the second group, the same process happens except the animals was cut from the middle to the tail, and was placed in a petri dish ( with spring/ pond water) labeled “middle to tail”. For the third and final group the animals remained the same, nothing was done, it was also placed in a petri dish with spring water /pond water and was labeled control.all three dishes were then placed in a cool, dark place. After 2 days the planaria water was changed, using spring water, removing the “scuzz”.

Results Within the group of planaria labeled “ middle to head” all three of the planarians had blastema formation. The animals were still responding to touch and was behaving it's usually self as it did before it got cut. For the group of planaria that was cut from the middle to tail, only one showed blastema formation, the other showed a deformation of the tail due to improper cutting and the last planaria showed no signs of change. The only things these animals had in common was that they all had normal behavior in response to touch. Lastly, within the control group, there was no change, the animal's behavior and physical mechanisms were all the same as there were a week ago.

Figure 1 figure 2

Planaria cut from the middle

planaria cut from the middle to the head

To the tail

Discussion

It was hypothesized in the beginning that both regenerative groups would show signs of the process for regeneration. Within the group of planarians cut from the middle to tail, the reason as to why all did not result in the same blastema formation was likely due to the lack of separating the two halves long enough to prevent healing. The environmental conditions were not entirely in favor of the animals due to the lack of darkest. Instead, the animal seemed to be exposed to a fair amount of light due to the petri dish

staying in a biology classroom where the light is on most of the time. Although the petri dish remained in the last row of a cart, artificial light was still present a majority of the time. Unlike the animal’s natural habitat where it might leave under a rock, where it was harder for the light to penetrate. Regeneration is common in another organism besides planarians. Take starfish, for example, they have the ability to grow back lost body parts and in humans the liver as the ability to completely regenerate if a part is lost. Planarians are unique because they can recover and regenerate into a new individual after being cut up 279 pieces. ( Unravelling How Planaria Regenerate). The regeneration in planarians is possible due to stem cells called neoblasts. These cells are found throughout the body, and when part of the flatworms' body is removed, the neoblast is activated to reform the tissues that have been lost. (“Planaria: Genes for Regeneration).

Acknowledgements My fellow group partners Shalese and liny

References

“Regeneration.” Merriam-Webster, Merriam-Webster, Rink, Jochen C. “Stem Cell Systems and Regeneration in Planaria .” Development Genes and Evolution, Springer-Verlag, Mar. 2013,

“Unravelling How Planaria Regenerate.” Nature News, Nature Publishing Group,

Rossant, Janet. “Planaria: Genes for Regeneration.” ELife, ELife Sciences Publications Limited, 15 Apr. 2014,...