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14 Δεκ 2012 (πριν από 4 χρόνια και 6 μήνες)

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U
SE

OF

C. E
LEGANS

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 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

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 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


12
th

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


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 Days

TEKS: 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 Days

TEKS: 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 Day

TEKS: 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. elegans

Evaluate



Quiz on
C. elegans
facts



Cell Cycle

Duration: 3 Days

TEKS: 3A,3B,3D,3E,3F

5A,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. 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

Using
C. elegans
as a Biological
Model


Third Six Weeks

Source: Carolina Biological
Supply

Duration: 10 Days

TEKS:
1A,1B,2F,2H6A,6B,6C,6D,6E,
6H

Lab Materials


AP
Biology


C. elegans

dpy
-
11

Shorter than wild type

Wild type

Very active; graceful serpentine

movement and tracks in agar

bli
-
1

Adult 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,3A
3B,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.

E
XAMPLE

OF

A

POSSIBLE

DESIGN

FOR

THE

B
IO
-
B
ACTERIA

D
ETECTOR

Texas A & M University


E3 Program


Dr. John Ford


TAMU Nuclear
Engineering


National Science Foundation


Nuclear Power Institute


Texas Workforce Commission

ACKNOWLEDGEMENTS

R
EFERENCES


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/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