Jul/Aug ASPP Education Forum

wise at VAXA.CIS.UWOSH.EDU wise at VAXA.CIS.UWOSH.EDU
Wed Aug 9 09:02:36 EST 1995


Attached is the text of the Education Forum section of the American Society
of Plant Physiologists July/August Newsletter

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ASPP Education Forum
Edited by Robert R. Wise, Department of Biology, University of Wisconsin
Oshkosh, Oshkosh, WI 54901, e-mail wise at vaxa.cis.uwosh.edu

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Saw You in Charlotte

        This edition of the Education Forum should be awaiting our return
from the 1995 ASPP meetings in Charlotte, NC.  The Education Committee,
with help from many others, had a full dance card planned and, with luck,
everything was a smashing success.  A wrap up of the meetings and talk
about future projects will be in the Sept/Oct Education Forum.
        Hope everyone learned a lot, shared a lot, and had a great time.  

******** 

NATURE Launches Journal for Undergraduate Science Majors

        Nature, the prestigious science magazine from the UK, has announced
plans to publish a new journal designed for undergraduate science majors. 
Called "Nature Undergraduate" it will be published quarterly starting about
January of 1996.  The editors anticipate that the journal will be 80-90
pages in 4-color.  It will contain research articles by college and high
school research students, condensed summaries of student papers published
elsewhere, instructional articles, news and perspective sections, an
opportunities section (conferences, etc.) and a review section on current
interesting topics.  Nature Undergraduate is designed for undergraduates in
the natural sciences.  For more information contact Sharon Kedar (Rice
University and Nature), 11212 Korman Drive, Potomac, MD 20854,
301-399-3677, fax 301-299-9338.

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Plant Education Electronic Newsgroup Chartered

        According to BIOSCI/bionet Manager Dave Kristofferson, the
prototype Plant Education newsgroup was made official as of July 10, 1995. 
The voting was 186 for and 2 against.  The charter of the group reads, "The
purpose of the PLANT-EDUCATION newsgroup is to function as a means for
communication among all educators, including faculty, instructors, lab
preparators, and graduate assistants, involved in courses on any aspect of
plant biology".  Jon Monroe (James Madison University) and Susan Singer
(Carlton College) remain as the discussion leaders although the group
remains unmoderated.  Subscribers are invited (send message "subscribe
plant-ed" to <biosci-server at net.bio.net>) and contributions are encouraged.

******

Options Available for Plant Physiology Textbooks and Lab Manuals

        With the Fall semester fast approaching, the question of textbook
selection for plant physiology educators is once again at the forefront. 
Without claiming to be comprehensive, a compilation of current offerings is
given below.  Although most of the titles are recent (i.e. after 1990), it
is possible that some may be out of print or otherwise unavailable.
        Which book is the "best"?  That depends to a large degree on
students' background, the goals of the instructor, and whether the course
is introductory or advanced.  There has been considerable recent discussion
on the plant-ed newsgroup on the strengths and weaknesses of many of the
titles listed below.  For a look at that discussion, see the plant-ed
archives at <gopher/bio.net/PLANT-EDUCATION>.  [One contributor to
plant-ed, on the other hand, taught an introductory plant physiology class
using only the original literature and reviews].  

Anderson, J.W. and J. Beardall  (1991)  Molecular Activities of Plant
Cells:  An Introduction to Plant Biochemistry, Blackwell Scientific
Publications
Brett, C. and K. Waldron  (1990)  Topics in Plant Physiology, Vol. 2,
Physiology and Biochemistry of Plant Cell Walls, Unwin Hyman Ltd.
Chrispels, M. and D.E. Sadava  (1994)  Plant, Genes, and Agriculture, Jones
and Bartlett Publishers
Davies, P.J. (ed.)  (1987)  Plant Hormones and Their Role in Plant Growth &
Development, Martinus Nijhous Publishers
Dennis, D.T. and D.H. Turpin (eds.)  (1990)  Plant Physiology,
Biochemistry, and Molecular Biology.  John Wiley & Sons
Fosket, D.E.  (1994)  Plant Growth and Development:  A Molecular Approach,
Academic Press 
Galston, A.W.  (1994)  Life Processes of Plants.  Scientific American
Library  (dist. by W.H. Freeman)
Hart, J.W.  (1987)  Topics in Plant Physiology, Vol. 1, Light and Plant
Growth, Unwin Hyman Ltd.
Hershey, D.R.  (1995)  Plant Biology Science Projects, John Wiley & Sons
Hopkins, W.G.  (1995)  Introduction to Plant Physiology, John Wiley & Sons
Lyndon, R.F.  (1990)  Topics in Plant Physiology, Vol. 3, Plant
Development:  The Cellular Basis, Unwin Hyman Ltd.
Lea, P.J. and Leegood, R.C.  (1993)  Plant Biochemistry and Molecular
Biology, John Wiley & Sons
Meidner, H.  (1984)  Class Experiments in Plant Physiology, G. Allen & Unwin
Mohr, H. and P. Shopfer  (1995)  Plant Physiology, Springer-Verlag 
Moore, T.C.  (1981)  Research Experiences in Plant Physiology:  A
Laboratory Manual, Springer-Verlag
Murphy, T.M.  (1995)  Manual for Plant Physiology Laboratory, published by
author (contact at <tmmurphy at ucdavis.edu>)
Noggle, R. and G. Fritz  (1983)  Introductory Plant Physiology, Prentice Hall
Reiss, C.  (1994)  Experiments In Plant Physiology, Prentice Hall
Salisbury, F.B. and C.W. Ross  (1992)  Plant Physiology, 4th ed., Wadsworth
Publishing Company
Sebanek, J. (ed.)  (1992)  Plant Physiology, Elsevier 
Sinclair, T.  Hands-on, Low-cost Laboratory Exercises for Middle School and
High School Biology Classes,  expected publication in early 1996
Taiz, L. and E. Zeiger  (1991)  Plant Physiology,  Benjamin/Cummings Publishers
Ting, I.P.  (1982)  Plant Physiology, Addison-Wesley Publishing Company
Wilkins, M.B. (ed.)   (1987)  Advanced Plant Physiology, John Wiley & Sons

*******

Effect of Ultraviolet Light on Arabidopsis Plants:  A Laboratory Exercise
by Mark Shotwell (Slippery Rock University)

Introduction

        Plants growing in sunlight are constantly exposed to ultraviolet
radiation.  UV light induces the formation of cyclobutane pyrimidine dimers
(CPDs) and other photoproducts in DNA, which, if not removed, create
potentially lethal mutations.  These CPDs can be corrected by at least
three different mechanisms:  photoreactivation, excision repair, and
recombinational repair.  The first response is likely to be
photoreactivation, in which a photolyase uses radiant energy to break the
cyclobutane ring linking the pyrimidines.  Photolyases are energized by
light of wavelengths between 37-450 nm, in the near-UV range, which is
abundant in sunlight.  The CPDs not removed by the photolyase may be
corrected by excision repair, or another mechanism not yet identified.

        To better understand how plants respond to UV light, David Mount's
group in the Department of Molecular and Cellular Biology at the University
of Arizona isolated several mutants of Arabidopsis hypersensitive to UV
radiation.  Of these, the best characterized is the uvh1 mutant (Harlow et
al., 1994).  The experiment outlined below, developed in Mount's lab, uses
the uvh1 mutant to illustrate the effects of UV light on plants.  Its
purpose is twofold:  (1)  to determine the relative UV sensitivity of
wild-type Arabidopsis and the uvh1 mutant, and (2) to assess the role of
photoreactivation in the repair of UV damage in Arabidopsis.  The latter is
accomplished by incubating the plants after the UV exposures in either
white light (which contains the photoreactivating wavelengths) of gold
light (which lacks the photoreactivating wavelengths).  The exercise is
quite simple and can be completed in less than an hour.  The only piece of
equipment required is a UV crosslinker, which can be found in most
molecular biology labs.

Materials

Seeds of wild-type Arabidopsis thaliana Columbia ecotype (available form
the Arabidopsis Biological Resource Center) and the UV-hypersensitive
mutant uvh1 (soon to be available from ABRC;  until then from the author).
For each lab section of 24 students:  sixty-four 2.5 inch square pots, two
F1020 flats, two propagation domes. eighteen 4-inch white pot labels,
eighteen 4-inch yellow pot labels (available from Hummert International,
800-392-9113; cat nos. 12-1250, 11-3050, 11-2568, 49-1504, and 49-1596,
respectively).
Potting soil
UV crosslinker (e.g. Metro Mix 360)
Growing area with white fluorescence lights
Gold-light growth chamber (e.g. shop light with two gold fluorescent bulbs
(F40GO) mounted underneath a table wrapped in black plastic sheeting)
Lamp with yellow incandescent bulb (General Electric 60A/Y 60 watt Bug Lite)

PART ONE

1.      For each lab section, plant 32 pots of wild-type and 32 pots of
uvh-1, 12 to 20 seeds per pot.  Water thoroughly (with Miracle Gro if
desired).  Place pots in separate F1020 flats and cover each with a
propagation dome to maintain high humidity.  Place under fluorescent
lights.

2.      After 3 days remove the propagation domes.

3.      Grow seedlings for two weeks, watering when the soils dry out.

PART TWO

1.      Divide the class into 6 groups.

2.      Have each group get 6 pots of either wild-type or the uvh-1 mutant.

3.      Using white and yellow pot labels as appropriate, have the students
label their six pots with their initials, the lab section, either WT or
uvh-1, and:  1) 0-white, 2) 0-gold, 3) 100-white, 4) 100-gold, 5)
700-white, 6) 700-gold.

4.      Have the students place their 0-white pots in the white-light are
and their 0-gold pots in the gold-light chamber.

5.      Place three 100-white pots and three 100-gold pots in the UV
crosslinker.  Turn off the room lights and turn on the yellow light. 
Expose the plants to 100 J/m2 of ultraviolet light.  (Note:  J/m2 =
x100uJ/cm2, the units on the crosslinker).  Then place the pots under the
white lights or in the gold-light chamber as appropriate.

IMPORTANT:  Remember which pots have white labels and which have yellow
labels, since in the dim yellow light they will all look yellow.

VERY IMPORTANT:  Protect the 100-gold pots from white light as much as
possible so that photoreactivation cannot occur

6.      Repeat step 5 for the remaining three 100-white pots and three
100-gold pots.

7.      Repeat steps 5 and 6 for the 700 pots, but increase the UV dose to
700 J/m2.  As before, take care to shield the 7---gold pots from white
light.

8.      After three days, transfer all pots from the gold-light chamber to
the white-light area.  All the plants will receive white light for the next
four days.

PART THREE

1.      In the following week's lab, have the students retrieve their set
of 6 pots from the white -light area and arrange them according to UV dose.

2.      Ask the students to assess the damage to the plants caused by the
two doses of UV light and the whit-light and gold-light treatments.  Have
them grade the condition of the plants in each pot on the following scale: 
1)  not damaged, 2) slightly damaged, 3) moderately damaged, 4) severely
damaged, 5) dead.  
        The 0-white plants serve as the negative control;  thus, they
should be assigned a grade of 1.  The other plants should be compared to
the 0-white plants when assessing the damage.

3.      Make sure the students examine not just their own set of plants,
but one set of 6 of both the wild-type and the uvh-1.

4.      Have the students compile their data in one table (It will comprise
12 damage estimates, 6 each for wild-type and uvh-1).

5.      Interpreting the results will involve asking the following questions:
        a.      Is there a general effect on growth of Arabidopsis plants
caused by incubation in gold light?  (compare the 0-gold plants to the
0-white plants)

        b.      Is there an effect of increasing doses of UV light on
Arabidopsis plants?  (Compare the 100-white and 700-white plants to the
0-white plants).

        c.      Is the uvh-1 mutant more sensitive to UV light than the
wild-type?  (Compare the uvh-1 plants to the wild-type plants at each UV
dose.)  Is it possible to estimate the relative difference in sensitivity
between mutant and wild-type from these results.

        d.      Do the results support the involvement of photoreactivation
in the repair of UV damage to DNA in Arabidopsis plants?  (Compare the
100-gold plants to the 100-white plants, and the 700-gold plants to the
700-white plants).  Does photoreactivation occur in the wild-type plants" 
Does photoreactivation occur in the uvh-1 plants?  Based on these results,
which type of DNA repair appears to be defective in uvh-1 plants,
photoreactivation or another mechanism?

NOTES

1.      The key to the success of this experiment is selecting the right
doses of UV light.  Two or three preliminary experiments should thus be
done to determine the UV dose that results in significant damage to uvh-1
plants incubated in gold light but very little or no damage to plants
incubated in white light.  This should be between 50 and 150 J/m2.  This
will serve as the lower dose in the experiment.  Since uvh-1 plants are
about 7 times as sensitive as wild-type plants to UV, the higher dose
should be 7 times the lower dose (i.e. 350 to 1050 J/m2).  When the
experiment works just right, the uvh-1 plants that have received the lower
dose show the same damage as the wild-type plants that have received the
higher dose.  If the students pick up on this, they can arrive at the
relative difference in sensitivity between uvh-1 and wild-type.

2.      UV crosslinkers generate UV-C, not the less energetic but more
physiologically relevant UV-B.  (The Arabidopsis mutants are hypersensitive
to both).  The experiments may be done using UV-B after replacing the UV-C
bulbs in the cross-linker with UV-B bulbs and re-calibrating the machine
with a radiometer.  

REFERENCE

Harlow, G.R., Jenkins, M.E., Pittalwala, T.S. and Mount, D.W.  (1994) 
Isolation of uvh-1, an Arabidopsis mutant hypersensitive to ultraviolet
light and ionizing radiation.  The Plant Cell 6, 227-235

Robert R. Wise, PhD
Director, UWO Electron Microscope Facility
Department of Biology
University of Wisconsin Oshkosh
Oshkosh, WI  54901
(414) 424-3404
(414) 424-1101 fax
wise at vaxa.cis.uwosh.edu





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