Comparison of the impact of CART19 Therapy and Stem Cell Transplantation on Acute Lymphoblastic Leukemia

Comparison of the impact of CART19 Therapy  and

Stem Cell Transplantation on Acute Lymphoblastic Leukemia  

Abstract

Two major ways to treat acute lymphoblastic leukemia are CART19 Therapy and Stem Cell Transplantation. In CART19, the patient’s T cells are reengineered to recognize the MHC Molecules on the surface of cancerous B cells and attack them. The basic Stem Cell Transplantation method is to use chemo or radiation therapy to stop the patient’s cancer cell mitosis and then give the patient the donor’s stem cells, which will produce blood cells that kill cancer cell. However, in the process of Stem Cell Transplantation, the patient might receive new cancer cells from the stem cells, get infection, have graft-versus-host disease, or the stem cells will not work at all. As a result, compared to Stem Cell Transplantation, CART19 Therapy is a better choice in treating acute lymphoblastic leukemia although studies on this treatment is still in progress.    

Introduction

About 80 percent of all childhood leukemia is acute lymphoblastic leukemia (ALL), also called acute lymphocyte or lymphoid leukemia. There are two basic types of lymphocytes, B-lymphocytes and T-lymphocytes. Their job is to identify and combat foreign substances, bacteria and viruses in the body. However, in ALL, the bone marrow makes immature lymphocytes (called lymphoblasts) that do not have the ability to fight infection and overproduce and crowd out normal blood-forming cells.The immature forms of B-lymphocytes and T-lymphocytes are the sources of the two corresponding subsets of ALL, T-ALL and B- ALL or pre-B ALL (The Children’s Hospital of Philadelphia, 1996). Most signs and symptoms of ALL result from shortages of normal blood cells, which happen when the leukemia cells crowd out the normal blood-making cells in the bone marrow. These shortages show up on blood tests, but they can also cause symptoms, including: Feeling tired, Feeling dizzy or lightheaded, Shortness of breath, Fever, Recurring infections, Bruising easily and Bleeding (American Cancer Society, 2014).

To cure ALL, there are all kinds of treatments. In this paper, I will be comparing the advantages and disadvantages of  CART19 Therapy and the stem cell transplantation treatment.

Body

Before comparing the two types of treatments, here are some informations on how the two treatments work.

1. CART19

In the CART19 treatment, T cells are reengineered to kill cancerous B cells. B cells and T cells are the main types of lymphocytes. B cells work chiefly by secreting substances called antibodies, which ambush foreign antigens circulating in the bloodstream, into the body’s fluids. They are powerless, however, to penetrate cells. The job of attacking target cells—either cells that have been infected by viruses or cells that have been distorted by cancer—is left to T cells or other immune cells (National Institute of Allergy and Infectious Disease, 2012).

Each B cell is programmed to make one specific antibody. For example, one B cell will make an antibody that blocks a virus that causes the common cold, while another produces an antibody that attacks a bacterium that causes pneumonia. When a B cell encounters the kind of antigen that triggers it to become active, it gives rise to many large cells known as plasma cells, which produce antibodies (National Institute of Allergy and Infectious Disease, 2012).

Unlike B cells, T cells do not recognize free-floating antigens. Rather, their surfaces contain specialized antibody-like receptors that see fragments of antigens on the surfaces of infected or cancerous cells. T cells contribute to immune defenses in two major ways: Some direct and regulate immune responses, whereas others directly attack infected or cancerous cells (National Institute of Allergy and Infectious Disease, 2012).

Another type of T cell, Helper T cells, or Th cells, coordinate immune responses by communicating with other cells. Some stimulate nearby B cells to produce antibodies, others call in microbe-gobbling cells called phagocytes, and still others activate other T cells. Cytotoxic T lymphocytes (CTLs)—also called killer T cells—perform a different function. These cells directly attack other cells carrying certain foreign or abnormal molecules on their surfaces. CTLs are especially useful for attacking viruses because viruses often hide from other parts of the immune system while they grow inside infected cells. CTLs recognize small fragments of these viruses peeking out from the cell membrane and launch an attack to kill the infected cell (National Institute of Allergy and Infectious Disease, 2012).

Natural killer (NK) cells are another kind of lethal white cell, or lymphocyte. Like CTLs, NK cells are armed with granules filled with potent chemicals . But CTLs look for antigen fragments bound to self-MHC molecules, whereas NK cells recognize cells lacking self-MHC molecules. Thus, NK cells have the potential to attack many types of foreign cells (National Institute of Allergy and Infectious Disease, 2012).

T cells aid the normal processes of the immune system. If NK T cells fail to function properly, asthma, certain autoimmune diseases—including Type 1 diabetes—or the growth of cancers may result (National Institute of Allergy and Infectious Disease, 2012).

In most cases, T cells only recognize an antigen if it is carried on the surface of a cell by one of the body’s own major histocompatibility complex, or MHC, molecules. MHC molecules are proteins recognized by T cells when they distinguish between self and nonself. A self-MHC molecule provides a recognizable scaffolding to present a foreign antigen to the T cell (National Institute of Allergy and Infectious Disease, 2012).

In CART19 Therapy, T cells are taken from a patient's own blood and genetically modified to express a protein which will recognize and bind to a MHC molecule target called CD19, which is found on cancerous B cells (The Children’s Hospital of Philadelphia, 1996).

This is how T cell therapy works:

1. B cells, which are found in the immune system, become cancerous in certain leukemias and lymphomas.
2. Cancerous B cells fly under the radar of immune surveillance, evading detection by T cells.
3. T cells are collected from a patient, then reengineered in a lab to recognize and attached to a protein that is found only on the surface of B cells. After this reengineering, T cells are called chimeric antigen receptor T cells. The cells are put back into the patient where they disperse to find cancerous B cells.
4. As the reengineered cells multiply in the body, they attach to and kill the rapidly dividing, cancerous B cells. They remain in the body long after to continue fighting any new cancerous B cells. (The Children’s Hospital of Philadelphia, 1996).

2. Cell Transplantation

In a typical stem cell transplant for cancer, very high doses of chemo are used, often along with radiation therapy, to try to destroy all the cancer cells. This treatment also kills the stem cells in the bone marrow. Soon after treatment, stem cells are given to replace those that were destroyed. These stem cells are given into a vein, much like a blood transfusion. Over time they settle in the bone marrow and begin to grow and make healthy blood cells

There are 3 basic types of transplants: Autologous, Allogeneic and Syngeneic. They are named based on who gives the stem cells (American Cancer Society, 2014).

I. Autologous stem cell transplants

These stem cells come from the patient. In this type of transplant, the patient’s stem cells are taken before he gets cancer treatment that destroys them. His stem cells are removed, or harvested, from either his bone marrow or his blood and then frozen. After the patient gets high doses of chemo and/or radiation the stem cells are thawed and given back to him (American Cancer Society, 2014).

II. Tandem transplants

Doing 2 autologous transplants in a row is known as a tandem transplant or a double autologous transplant. In this type of transplant, the patient gets 2 courses of high-dose chemo, each followed by a transplant of his own stem cells. All of the stem cells needed are collected before the first high-dose chemo treatment, and half of them are used for each transplant. Most often both courses of chemo are given within 6 months, with the second one given after the patient recovers from the first one (American Cancer Society, 2014).

III. Allogeneic stem cell transplants

In the most common type of allogeneic transplant, the stem cells come from a donor whose tissue type closely matches the patient’s. The best donor is a close family member, usually a brother or sister. If the patient does not have a good match in his family, a donor might be found in the general public through a national registry. This is sometimes called a MUD (matched unrelated donor) transplant (American Cancer Society, 2014).

Blood taken from the placenta and umbilical cord of newborns is a newer source of stem cells for allogeneic transplant. Called cord blood, this small volume of blood has a high number of stem cells that tend to multiply quickly. But the number of stem cells in a unit of cord blood is often too low for large adults, so this source of stem cells is limited to small adults and children. Doctors are now looking at different ways to use cord blood for transplant in larger adults, such as using cord blood from 2 donors (American Cancer Society, 2014).

For some people, age or certain health conditions make it more risky to wipe out all of their bone marrow before a transplant. For those people, doctors can use a type of allogeneic transplant that’s sometimes called a mini-transplant. Compared with a standard allogeneic transplant, this one uses less chemo and/or radiation to get the patient ready for the transplant. The idea is to kill some of the cancer cells along with some of the bone marrow, and suppress the immune system just enough to allow donor stem cells to settle in the bone marrow (American Cancer Society, 2014).

Unlike the standard allogeneic transplant, in mini-transplant, cells from both the donor and the patient exist together in the patient’s body for some time. But slowly, over the course of months, the donor cells take over the bone marrow and replace the patient’s own bone marrow cells. These new cells can then develop an immune response to the cancer and help kill off the patient’s cancer cells — the graft-versus-cancer effect (American Cancer Society, 2014).

One advantage of a mini-transplant is the lower doses of chemotherapy and/or radiation, and because the stem cells aren’t all killed, blood cell counts don’t drop as low while waiting for the new stem cells to start making normal blood cells. This makes it especially useful in older patients and those with other health problems who aren’t strong enough for a standard allogeneic stem cell transplant (American Cancer Society, 2014).

Mini-transplants treat some cancers better than others. They may not work well for patients with a lot of cancer in their body or those with fast-growing cancers. Also, although side effects from chemo and radiation may be less than those from a standard allogeneic transplant, the risk of graft-versus-host disease is not (American Cancer Society, 2014).

This procedure has only been used since the late 1990s and long-term patient outcomes are not yet clear. There are lower risks of some complications, but the cancer may be more likely to relapse. Ways to improve outcomes are still being studied (American Cancer Society, 2014).

IV. Syngeneic stem cell transplants – for those with an identical sibling

This is a special kind of allogeneic transplant that can only be used when the recipient has an identical sibling (twin or triplet) who will have the same tissue type.

V. Half-matched transplants

Some centers are doing half-match (haploidentical) transplants for people who don’t have closely matching family members. This technique is most often used in children, usually with a parent as the donor, though a child can also donate to a parent. Half of the HLA factors will match perfectly, and the other half typically don’t match at all, so the procedure requires a special way to get rid of a certain white blood cells that can cause graft-versus-host disease. It’s still rarely done, but it’s being studied in a few centers in the United States. Researchers are continuing to learn new ways to make haploidentical transplants more successful (American Cancer Society, 2014).

Advantages and disadvantages of CART19 Therapy and Stem Cell Transplantation:

CART19 Therapy

A lot of problems in cancer treatments are caused by MHC Molecules. Although MHC molecules are required for T cell responses against foreign invaders, they also create problems during organ transplantations. Virtually every cell in the body is covered with MHC proteins, but each person has a different set of these proteins on his or her cells. If a T cell recognizes a nonself-MHC molecule on another cell, it will destroy the cell. Therefore, doctors must match organ recipients with donors who have the closest MHC makeup. Otherwise the recipient’s T cells will likely attack the transplanted organ, leading to graft rejection.The biggest advantage of CART19 Therapy in the treatment of Acute Lymphoblastic Leukemia is that it reengineered the patient’s own T cell to recognize the MHC Molecules on cancerous blood cells and attack them. Therefore, CART19 Therapy will not cause graft rejection. However, according to Dr. Michel Sadelain who studies CART19 Therapy at Memorial Sloan-Kettering Cancer Center, the technology now only allow the reengineered T cells to recognize the outer structure of cancerous cells, while cancerous cells oftentimes share similar exterior structure with many other non-cancerous cells. As a result, reengineered T cells will attack those benevolent cells as well.

Stem Cell Transplantation

I. Autologous stem cell transplants

One advantage of autologous stem cell transplant is that the patient is getting his own cells back. When the patient donates his own stem cells, he does not have to worry about the graft attacking his body or about getting a new infection from another person. But there can still be graft failure and autologous transplants can’t produce the “graft-versus-cancer" effect, in which the donor stem cells make their own immune cells, which could help destroy any cancer cells that remain after high-dose treatment (American Cancer Society, 2014).

A possible disadvantage of an autologous transplant is that cancer cells may be picked up along with the stem cells and then put back into the patient’s body later. Another disadvantage is that the patient’s immune system is still the same as before when his stem cells engraft. The cancer cells were able to grow despite his immune cells before, and may be able to do so again (American Cancer Society, 2014).

To prevent this, doctors may give the patient anti-cancer drugs or treat his stem cells in other ways to reduce the number of cancer cells that may be present. Some centers treat the stem cells to try to remove any cancer cells before they are given back to the patient. This is sometimes called “purging.” It isn’t clear that this really helps, as it has not yet been proven to reduce the risk of cancer recurrence (American Cancer Society, 2014).

A possible downside of purging is that some normal stem cells can be lost during this process, causing the patient to take longer to begin making normal blood cells and have unsafe levels of white blood cells or platelets for a longer time. This could increase the risk of infections or bleeding problems (American Cancer Society, 2014).

One popular method now is to give the stem cells without treating them. Then, after transplant, the patient gets a medicine to get rid of cancer cells that may be in the body. This is called in vivo purging. Rituximab, a monoclonal antibody drug, may be used for this in certain lymphomas and leukemias, and other drugs are being tested. The need to remove cancer cells from transplants or transplant patients and the best way to do it is being researched (American Cancer Society, 2014).

II. Tandem transplants

Doctors do not always agree that Tandem transplant is really better than a single transplant for certain cancers. Because this involves 2 transplants, the risk of serious outcomes is higher than for a single transplant. Tandem transplants are still being studied to find out when they might be best used (American Cancer Society, 2014).

III. Allogeneic stem cell transplants

Transplants with a MUD are usually riskier than those with a relative who is a good match. The advantage of allogeneic stem cell transplant is that the donor stem cells make their own immune cells, which could help destroy any cancer cells that remain after high-dose treatment. This is called the graft-versus-cancer effect. Other advantages are that the donor can often be asked to donate more stem cells or even white blood cells if needed, and stem cells from healthy donors are free of cancer cells (American Cancer Society, 2014).

The disadvantage is that the donor cells could die or be destroyed by the patient’s body before settling in the bone marrow. Another risk is that the immune cells from the donor may not just attack the cancer cells -- they could attack healthy cells in the patient’s body. This is called graft-versus-host disease. There is also a very small risk of certain infections from the donor cells, even though donors are tested before they donate. A higher risk comes from infections the patient has had, and which his immune system has under control. These infections often surface after allogeneic transplant because his immune system is held in check by medicines called immunosuppressive drugs. These infections can cause serious problems and even death (American Cancer Society, 2014).

One advantage of a mini-transplant is the lower doses of chemotherapy and/or radiation, and because the stem cells aren’t all killed, blood cell counts don’t drop as low while waiting for the new stem cells to start making normal blood cells. This makes it especially useful in older patients and those with other health problems who aren’t strong enough for a standard allogeneic stem cell transplant (American Cancer Society, 2014).

Mini-transplants treat some cancers better than others. They may not work well for patients with a lot of cancer in their body or those with fast-growing cancers. Also, although side effects from chemo and radiation may be less than those from a standard allogeneic transplant, the risk of graft-versus-host disease is not.

This procedure has only been used since the late 1990s and long-term patient outcomes are not yet clear. There are lower risks of some complications, but the cancer may be more likely to relapse. Ways to improve outcomes are still being studied (American Cancer Society, 2014).

An advantage of syngeneic stem cell transplant is that graft-versus-host disease will not be a problem. There are no cancer cells in the transplant, either, as there would be in an autologous transplant (American Cancer Society, 2014).

A disadvantage is that because the new immune system is so much like the recipient’s immune system, there is no graft-versus-cancer effect, either. Every effort must be made to destroy all the cancer cells before the transplant is done to help keep the cancer from relapsing (American Cancer Society, 2014).

Conclusion

In all, it seems that CART19 Therapy has a higher chance of healing cancer because the patient’s own T cell will not cause graft-versus-host disease, and there is no chance for the patient to get his own cancer for using his own T cell since the cancerous cells in ALL are B cells. Furthermore, the reengineered T cells can attack cancer cells while the patient’s immune system does not react to them. Additionally, patients will not need to undergo the painful chemotherapy in CART19 treatment. It is true that reengineered T cells attack healthy cells as well, but further study should be able to fix that problem.

Work Cited List

American Cancer Society. 2014. web.

http://www.cancer.org/cancer/leukemia-acutelymphocyticallinadults/detailedguide/leukemia-acute-lymphocytic-signs-symptoms

National Institute of Allergy and Infectious Disease. 2012. web. http://www.niaid.nih.gov/topics/immuneSystem/immuneCells/Pages/bcells.aspx

Sadelain, Michel. Interview by Cynthia Fox. “Training T Cells to Fight Their Own Cancers” Jan. 15, 2014. web.

The Children’s Hospital of Philadelphia. 1996. web.

http://www.chop.edu/service/oncology/cancers-explained/acute-lymphoblastic-leukemia-in-children.html

Plant Transpiration Lab

1.     Water evaporates through stomata that are on the underside of the leaves and creates a transpiration force, which draws water up from the roots of plants and help plants absorb water and nutrients from the soil.

2.     The controls include the same amount of time, same temperature when heater’s not involved, same amount of air circulation when fan’s not involved and same amount of light when lamp’s not involved.

3.     The amount of light, temperature and the speed of air circulation can in crease the rate of transpiration, but not all transpiration rates increase. When more light is provided, Rubber plant, Dieffenbachia, Weeping fig and Zebra plant’s transpiration rate decreased.

4.     The transpiration rate increases more when the temperature is higher. It increases even more when there is wind. It’s because when temperature is higher, the water molecules are more active and easier to evaporate. When there’s wind, the water in the air is blown away, so the humidity is lower. The water molecules in the plant are more likely to evaporate.

5.     Rubber plant has the highest transpiration rate. Different plants have different transpiration rates because they live in different environments. Plants live in humid environments have higher transpiration rate. Plants that live in windy, hot or dry environments have lower transpiration rate.

6.     The plant would not be able to transpire because the stomata will be covered.

7.     The loss of water molecules draws new water molecules up the stem and allows the plant to absorb water and nutrients from the soil.

Plant Hormones

Auxin is a plant hormone produced in the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to grow larger than corresponding cells on the lighter side of the plant. This produces a curving of the plant stem tip toward the light, a plant movement known as phototropism.
Auxin also plays a role in maintaining apical dominance. Most plants have lateral (sometimes called axillary) buds located at nodes (where leaves attach to the stem). Buds are embryonic meristems maintained in a dormant state. Auxin maintains this dormancy. As long as sufficient auxin is produced by the apical meristem, the lateral buds remain dormant. If the apex of the shoot is removed (by a browsing animal or a scientist), the auxin is no longer produced. This will cause the lateral buds to break their dormancy and begin to grow. In effect, the plant becomes bushier. When a gardener trims a hedge, they are applying apical dominance.

Abscisic acid owes its names to its role in the abscission of plant leaves. In preparation for winter, ABA is produced in terminal buds. This slows plant growth and directs leaf primordia to develop scales to protect the dormant buds during the cold season, adjusting to cold conditions in the winter by suspending primary and secondary growth.

Abscisic acid is also produced in the roots in response to decreased soil water potential and other situations in which the plant may be under stress. ABA then translocates to the leaves, where it rapidly alters the osmotic potential of stomatal guard cells, causing them to shrink and stomata to close. The ABA-induced stomatal closure reduces transpiration, thus preventing further water loss from the leaves in times of low water availability. A close linear correlation was found between the ABA content of the leaves and their conductance (stomatal resistance) on a leaf area basis.

Ethylene is a small hydrocarbon gas. It is naturally occurring, but it can also occur as a result of combustion and other processes. You can't see or smell it. Some fruit will produce ethylene as ripening begins. Ethylene is responsible for the changes in texture, softening, color, and other processes involved in ripening.

Flowers

The pistil of this kind of flower are the yellowish and greenish little balls in the middle. They are shiny, so there is probably sticky liquid on it to stick on to pollen. The stamen is yellow, powdery and longer than the pistil. There are little bugs crawling under the stamen, so they are probably the one that pollenate this type of flower. These bugs may be attracted to the flower by fructose at the bottom of the stamen.

This type of flower has its pistil in the middle. It has sticky liquid on it and already has yellow pollen stuck on it. Its stamens are placed around the pistil.They are whiteish, yellowish and powdery. The same small bugs crawls inside the flower, so they are probably attracted to the flower by fructose at the bottom of the stamens and pistil, and they pollenate the flower.

This type of flower has a sticky pistil in the middle. Its stamens are red and are placed around the pistil. It has shiny, sticky and sweet liquid stuck to the wall of the pedal, which are probably fructose. The fact that it has fructose shows that it probably needs to attract insects to pollenate.

This type of flower has a pistil with a sticky and white head in the middle and yellow powdery stamens around the pistil. Judging from the layer of shiny yellow pollen stuck to the petals, this type of flower probably has the wind as the pollinator. 

Coevolution Pinterest

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Some Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar (see image at right). These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores.  the plants would not have evolved hollow thorns or nectar pores unless their evolution had been affected by the ants, and the ants would not have evolved herbivore defense behaviors unless their evolution had been affected by the plants.

Nature

The evolution of long bills and sickle-shaped bills in some Latin American hummingbirds matches the long or sharply curved flowers so that they can sip nectar (and pollinate).

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Birds have deeper, less curved bills in places where the pinecones have thick scales,than where the pinecones have thin scales. 

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In most of the Rocky Mountains, red squirrels are an important predator of lodgepole pine seeds. They harvest pinecones from the trees and store them through the winter. However, the pine trees are not defenseless: squirrels have a difficult time with wide pinecones that weigh a lot but have fewer seeds.

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Where squirrels are the main seed predator, trees should have stronger defenses against squirrel predation, and where birds are the main seed predator, trees should have stronger defenses against bird predation. This turns out to be true. Where there are squirrels, the pinecones are heavier with fewer seeds, but have thinner scales, like the pinecone on the left. Where there are only crossbills, pinecones are lighter with more seeds, but have thick scales, like the one on the right.

Predator-Prey Simulation: Population Growth

Graph:

Analysis:

   The relationship between predators and preys in a biome serves as natural selection and help to maintain a balanced ecosystem. In this stimulation, the number of paper pieces represents the population of the specie, and the paper with different colors and different sizes represent variation in organism. The organism developed different phenotypes as its adaptation to the environment. When natural selection happens, the best adaptation will be able to remain alive and reproduce.

   According to my data, within the first five generations, large populations of white, dark green and light green rabbits survived and were able to reproduce. Since the number of preys drastically increased, the population of wolf increased rapidly too because all wolves were able to get enough food and reproduce. However, the sudden growth in wolf population caused sharp decrease and even extinction in rabbit population. As a result, extinction occured to wolves too. 

   In the following generations, natural selections are obvious. I used white paper as the environment, which represent an environment with snow. The dark green rabbits went into extinction because its color can't serve as a camouflage in a mainly white environment, and it's easier for them to be targeted by wolves. Also, bigger wolves were able to get more food, so when food is scarce and there is a starvation, wolves that survived were mainly big wolves. Therefore, big wolves and rabbits of lighter colors were able to survive because of their better adaptations and reproduce. 

BREAKING NEWS: Volcanic Eruption in Roxanian Temperate Grassland

    4:23 am April 21st, on the Roxanian Temperate Grassland, a volcanic eruption broke out. The lava produced by the eruption killed large amounts of plants and animals. Tephra spreads across the grassland, covering plants on the grassland, which prevented plants from doing photosythesis. The explosion during the eruption also caused wide-ranged fire on the Grassland. As a result, most of the plants on the Roxianian Grassland were killed. A lot of the animals that had not yet fled from the disaster breath in the tephra and volcanic gas such as sulfur dioxide released during the eruption and died from suffocating. Others died from the lack of food source since most keystone specie plants died.

    The volcanic eruption also caused the temperature on the Roxanian Temperate Grassland to increase drastically. Due to the volcanic dust blown into the atmosphere and covering the sun, it will look like night throughout the day, and temperature will eventually drop below the normal temperature. The change in the amount of sunlight and temperature will affect organisms' routine and make it even harder for the remaining organisms to survive.

     Although the biome is almost completely destroyed, it will be comparatively easier for some organisms to adapt to the new environment. For example, some plants on the temperate grassland are adapted to occasional wild fire. For some of the plants, even if the parts above ground is burnt, their roots can resprout after the fire. Some require fire to carry out their germination process. These plants were probably able to survive the fire caused by the volcanic eruption and resprout after a short time.

    Volcanoes have an effect on animals that are sometimes positive. They wipe the ecology slate clean and destroy invasive species. Lava and ash can actually improve the soil around volcanoes. These two outcomes lead to a vibrant return of native plant life after a couple of years, which eventually bring back animals as well. 

Photo Credit: Robert Tumas

Photo Credit: Jessica Ball

Work Cited List

Nelson, Ted. "How Volcanoes Effect Animals." eHow.com. Web.

Lauren, Daniella. "How Do Volcanoes Affect Pants & Animals." eHow.com. Web.