USE OF C. ELEGANS AS A BIOLOGICAL MODEL

Darlene Jones

Columbia High School, Columbia Brazoria ISD

Dr. John Ford, Associate Professor, Dept. of Nuclear Engineering, TAMU

Dr. Ford’s Research Group

Radiological Health EngineersRadiation Biologists

Health/Medical Physicists

Health physicists are involved in understanding, evaluating, and controlling the potential risks to the population from radiation relative to it’s benefits

RESEARCH QUESTIONDo the cells surrounding a cell exposed to ionizing radiation

exhibit cellular mutations because of the radiation

exposure?

Dr. Ford’s research used the organism C. elegans. C. elegans is a nematode that lives in the soil, eats bacteria, and is about 1 mm in length. It is an excellent “in vivo” (in living) model for biology studies.

Why is C. elegans used in research?

•Organism has simple growth conditions and reproduces rapidly with a life span of approximately 2-3 weeks.•The cell lineage of the organism is known and does not vary.•The organism can be easily genetically engineered for research purposes.•The genome for C. elegans has been completely sequenced.

RESEARCH EXPERIMENTWorms were selected that were in the L1 stage. They were placed in an anesthesia and a single cell in the intestinal tract of the worm was targeted and exposed to ionizing radiation using the accelerator beam line and stage shown below. The worms were then allowed to continue growing and when they reached L4 (adult) stage, they were fixed using a DNA stain and observed for any mutations.

Particle Source

Accelerator Beam line

Collimator and Irradiation Stage

RESEARCH RESULTS Examples of Anaphase Bridges in Non-targeted Cells

1 2 3 4 5 6 7 8 9

Worm 95

1 2 3 4 5 6 7 8 9

1 2 3 4 5 6 7 8 9

1 2 3 4 5 6 7 8 9

Worm 50

Worm 66

Worm 96

BYSTANDER EFFECT An effect/change in the cells surrounding the

irradiated cell. This slide illustrates the increase in p53 (transcriptase enzyme) levels and elevated SCE levels (Sister Chromatid Exchange) in the cells that

surround the irradiated cellThese observations then raise these questions:1)Is the bystander effect good or bad?2)How is this signal communicated between these cells?Future research will attempt to answer these questions.

HOW IS THIS RESEARCH RELEVANT?

Classroom ProjectProject Target: AP Biology – 12th Grade

Objectives:1)Exploration of Engineering Careers2)Overview of Radiation sources and the public’s exposure to radiation3)Exploration of the use of genetic engineering by integrating the biological model C. elegans mutants in a lab exercise4)Implementation of the engineering design process by students utilizing the worms5)Reinforcement: Presentation and Q & A from a radiation health engineer (health physicist) from STPNOC

TEKS CITED IN THE LESSONS1A demonstrate safe practices during laboratory investigations1B demonstrate an understanding of the use and conservation of resources and the proper disposal of materials2E plan and implement experimental investigations, selecting equipment and technology2F collect data and measurements using tools such as microscopes, computers, micropipettors, thermometers, petri dishes, biological specimens2G analyze, evaluate, make inferences, and predict trends from data2H communicate valid conclusions3A analyze, evaluate, and critique scientific explanations3B communicate scientific information gathered from journals, news reports3D evaluate the impact of scientific research on society and the environment3F research and describe the history of biology and contributions of scientists5A describe the stages of the cell cycle, including DNA replication, mitosis, and the importance of the cell cycle.5C describe the roles of DNA, RNA and environmental factors in cell differentiation

5D recognize that disruptions of the cell cycle lead to deseases such as cancer6A identify components of DNA and describe how information for traits of an organism is carried in DNA6B recognize that components that make up the genetic code are common to all organisms6C explain the purpose and process of transcription and tanslation using models of DNA and RNA6D recognize that gene expression is a regulated process6E identify and illustrate changes in DNA and evaluate the significance of these changes6H describe how techniques such as genetic modification is use to study the genomes of organisms

Some Possible PRE-TEST questions:

1. Radiation is:

A. Spokes on a wheel

B. Energy found only in space

C. Spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay

D. The visible part of the electromagnetic spectrum

2. Cancer is:

A. Always characterized by large deadly tumors.

B. A disease that only humans can get.

C. Any malignant growth or tumor caused by abnormal and uncontrolled cell division

D. Characterized by growths that are benign3. C. elegans is what type of organism?

A.Insect

B.Mammal

C.Reptile

D. Nematode

Exploration of Engineering Careers – First Six Weeks

Students prepare a 10 minute power point presentation on a STEM career.

Must explain required high school classes and university graduation requirements. Must include average compensation for graduates.

“A Day in the Life of ….”

Sample choices: Biomedical Engineering, Environmental Engineering, Genetic Engineering, Radiation Health Engineering, Chemical Engineering, Engineering Technology & Computer Engineering

Duration: 2 DaysTEKS: 3A,3B,3D

The class will explore the topic of radiation.

Engage - show the video “Debating the Facts on Radiation” highlighting our exposure to different forms of radiation.

Explain – Short teacher lecture and handouts on the topic of radiation (source- NRC website)

Explore- Students will work through the online calculator on the Nuclear Regulatory Commission website. Students will perform a lab, predicting which everyday objects are radioactive. Students will predict which materials will shield /block radiation. Students will measure the amount of radiation given off by the objects with a Geiger counter if available.

Exploration & Explanation of Radiation – Second Six Weeks

Duration: 2 DaysTEKS: 2C,2G,2H.3D

Radiation Dose Calculator Worksheet

A guest speaker from the Health Physics department at the South Texas Project Nuclear Power Plant will be invited to the classroom to discuss their responsibilities at the nuclear power facility. This will also include a Q & A session.

This will be the lead in activity for the discussion of Dr. Ford’s research.

This also provides students with the real world relevancy of STEM curriculum.

Duration: 1 DayTEKS: 1B,3D,3F

As the class progresses through our study of DNA and the cell cycle, I will introduce the power point highlighting the research project conducted in Dr. Ford’s lab using the C. elegans to study the effects of radiation on adjacent cells in tissue.Engage – teacher lecture with power point.Explore-Student web based research on C. elegansEvaluate – Quiz on C. elegans facts

Cell Cycle

Duration: 3 DaysTEKS: 3A,3B,3D,3E,3F5A,5C,5D,6E

The core element that I am adapting from Dr. Ford’s research is the use of C. elegans in my classroom.

The lab specimens will be ordered from Carolina Biological. Upon conclusion of our unit on protein synthesis and gene expression, the students will begin a lab using C. elegans.

The worms are fed lab strains of E. coli that express (dsRNA) corresponding to either of 2 target genes. The dsRNA initiates the destruction of mRNA expressed from the target genes. One will silence the bli-1 gene that will produce a worm with blisters on it’s cuticle. The other type will silence the dpy-11 gene (DMPY) and produce a short worm.

The lab will take 10 Days from start to completion. Timefor the lab will be available in AP Biology, as this activity covers numerous concepts. AP Biology is a Senior level course, notunder the TAKS time restraints, the AP Exam is given in May.

They will have to practice sterile technique and use a dissecting microscope, micropipettors, and petri dishes

Using C. elegans as a Biological Model – Third Six Weeks

Source: Carolina Biological Supply

Duration: 10 DaysTEKS: 1A,1B,2F,2H6A,6B,6C,6D,6E,6H

Lab Materials – AP Biology – C. elegans

dpy-11Shorter than wild type

Wild typeVery active; graceful serpentinemovement and tracks in agar

bli-1Adult worms develop blisters in their cuticle

Wild Type and Mutants used in Lab Experiment

•Students will be given a problem to solve using the worm cultures. They will be given the question: “Can we reverse the phenotypes expressed in the worms (dumpy and blisters)? •Students will define the goals and identify the constraints. •Students will research information on C. elegans. Students will need to use their knowledge of C. elegans life cycle in order to design an experiment to answer the question and solve the problem

Problem #1 – Lab Extension TEKS: 1A,2E,2F,2G,3A,3B,5C,

Students will be given this problem scenario: “ Two food sources are available for your consumption. One is contaminated with E. coli and the other is clean. The E. coli bacteria are too small to be seen, and the only tools available to the students is the stock of C. elegans worms and a dissecting microscope to observe them. They must design a “bacteria detector” using the worms in order to determine which food source is safe.

Engineering Design Process #2 – Lab Extension

Students will define the problem and identify the constraints. There are multiple constraints to consider: the distance between the worm & food source, effective transfer of the worms, whether or not they should be fluid or air, effect of temperature, etc

Students will research and gather information. The internet: Wormbook and Worm Atlas, and Journal articles provided by the teacher.

Students will create potential design solutions. Considerations: materials to build mazes on the agar plates could include straws, toothpicks, wooden block stamps, or placing the worms in the center of plate with samples surrounding them.

Students will analyze and choose the most appropriate solution. Students will brainstorm designs and construct top two designs to test with the worms.

Students will follow the steps of engineering design

TEKS: 1A,2E,2F,2G,3A3B,5C

Students will implement their design. Students will construct the mazes on the agar plates which allow them to track the worm’s movements.

Students will test and evaluate the design. Students will load the worms and test the effectiveness of their “Bio-Bacteria Detectors”Students will repeat as needed.

Students will be required to turn in a written summary of the design process. Scoring rubric will apply.

EXAMPLE OF A POSSIBLE DESIGN FOR THE BIO-BACTERIA

DETECTOR

Texas A & M University – E3 Program

Dr. John Ford – TAMU Nuclear Engineering

National Science Foundation

Nuclear Power Institute

Texas Workforce Commission

ACKNOWLEDGEMENTS

REFERENCES http://www.nrc.gov/reading-rm/basic-ref/teachers/

unit1.html http://www.youtube.com/watch?v=llgvpBPiCyI Get

the facts: Radiation Exposure in upstate North Carolina

http://avery.rutgers.edu/WSSP/StudentScholars/project/introduction/worms.html

http://ritter.tea.state.tx.us/rules/tac/chapter112/ch112c/html

www.rsc.org/loc, Maze exploration and learning in C. elegans

www.carolina.com

http://wiki.answers.com/Q/What_is_an_engineering_design_algorithm#ixzz1QWsrk7Uo

http://www.essap.tamu.edu