Use of C. Elegans as a biological model

advertisement
OF C. ELEGANS
AS A BIOLOGICAL
USE
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 Engineers
Radiation 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 QUESTION
Do 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 EXPERIMENT
Worms 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
Worm 66
1 2 3 4 5 6 7 8 9
Worm 96
1 2 3 4 5 6 7 8 9
Worm 50
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 cell
These 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 Project
Project Target: AP Biology – 12th Grade
Objectives:
1) Exploration of Engineering Careers
2) Overview of Radiation sources and the public’s
exposure to radiation
3) Exploration of the use of genetic engineering by
integrating the biological model C. elegans mutants in
a lab exercise
4) Implementation of the engineering design process by
students utilizing the worms
5) Reinforcement: Presentation and Q & A from a
radiation health engineer (health physicist) from
STPNOC
TEKS CITED IN THE LESSONS
1A demonstrate safe practices during laboratory investigations
1B demonstrate an understanding of the use and conservation of
resources and the proper disposal of materials
2E plan and implement experimental investigations, selecting
equipment and technology
2F collect data and measurements using tools such as microscopes,
computers, micropipettors, thermometers, petri dishes, biological
specimens
2G analyze, evaluate, make inferences, and predict trends from data
2H communicate valid conclusions
3A analyze, evaluate, and critique scientific explanations
3B communicate scientific information gathered from journals,
news reports
3D evaluate the impact of scientific research on society and the
environment
3F research and describe the history of biology and contributions of
scientists
5A 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 cancer
6A identify components of DNA and describe how
information for traits of an organism is carried in DNA
6B recognize that components that make up the genetic
code are common to all organisms
6C explain the purpose and process of transcription
and tanslation using models of DNA and RNA
6D recognize that gene expression is a regulated
process
6E identify and illustrate changes in DNA and evaluate
the significance of these changes
6H 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 benign
3. C. elegans is what type of organism?
A. Insect
B. Mammal
C. Reptile
D. Nematode
Exploration of Engineering Careers –
First Six Weeks
Duration: 2 Days
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
TEKS: 3A,3B,3D
Exploration & Explanation of Radiation –
Second Six Weeks
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 (sourceNRC 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.
Duration: 2 Days
TEKS: 2C,2G,2H.3D
Radiation Dose Calculator Worksheet
Duration: 1 Day
TEKS: 1B,3D,3F
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.
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. elegans
Evaluate – Quiz on C. elegans facts
Cell Cycle
Duration: 3 Days
TEKS: 3A,3B,3D,3E,3F
5A,5C,5D,6E
Using C. elegans as a Biological
Model – Third Six Weeks
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. Time
for the lab will be available in AP Biology, as this activity
covers numerous concepts. AP Biology is a Senior level course, not
under 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
Lab Materials – AP
Biology – C. elegans
Duration: 10 Days
TEKS:
1A,1B,2F,2H6A,6B,6C,6D,6E,
6H
Source: Carolina Biological
Supply
Wild Type and Mutants used in Lab
Experiment
Wild type
Very active; graceful serpentine
movement and tracks in agar
bli-1
Adult worms develop blisters
in their cuticle
dpy-11
Shorter than wild type
Problem #1 – Lab Extension
•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
TEKS:
1A,2E,2F,2G,3A,
3B,5C,
Engineering Design Process #2 – Lab
Extension
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.
Students will follow the steps of
engineering design
TEKS:
1A,2E,2F,2G,3A
3B,5C
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 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
ACKNOWLEDGEMENTS
Texas A & M University – E3 Program
Dr. John Ford – TAMU Nuclear
Engineering
National Science Foundation
Nuclear Power Institute
Texas Workforce Commission
REFERENCES








http://www.nrc.gov/reading-rm/basicref/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/int
roduction/worms.html
http://ritter.tea.state.tx.us/rules/tac/chapter112/ch112c/ht
ml
www.rsc.org/loc, Maze exploration and learning in C.
elegans
www.carolina.com
http://wiki.answers.com/Q/What_is_an_engineering_desig
n_algorithm#ixzz1QWsrk7Uo
http://www.essap.tamu.edu
Download
Related flashcards

Peptide hormones

65 cards

Rose cultivars

52 cards

Peptides

79 cards

Create Flashcards