Sun and Shade Acclimation of the Photosynthetic Apparatus in Gymnostomum aeruginosum

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Sun and Shade Acclimation of the Photosynthetic
Apparatus in Gymnostomum aeruginosum
Adam Yock 2003-04
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http//www.scibridge.sdsu.edu/coursemats/introsci/
diversity/chlorobionta/chlorobionta_cladogram.jpg
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Chloroplast
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Thylakoid
Chloroplast
Granum (stack of thylakoids)
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electron transport pathway
Sun
Photons
ADP P

NADPH
NADP
ATP
LHC
RC
PSI
PSII
Thylakoid
Chloroplast
Granum (stack of thylakoids)
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Introduction

• Reaction Centers (RC)
• Beginning of electron transport chain
• Contain chl a

• Light-Harvesting Complexes (LHC)
• Photosystematic antennas
• Contain chl a and b

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Reactions of Light-acclimated Specimens
chl a/b
LHC
chl a/b
chl a/b
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Previous Studies

• Post and Vesk analyzed light adaptability in
  moss using chl a/b

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Purpose
Analyze light adaptability in moss (Gymnostomum
aeruginosum) using both a chlorophyll ratio (chl
a/b) and a protein ratio (LHCp/RCp).
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Hypotheses

• Peas
• Both chl a/b and LHCp/RCp would significantly
  change
• Moss
• Neither chl a/b nor LHCp/RCp would
  significantly change

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p 6. 2464 x 10-5
p 0.8868
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Table 1 Average Chlorophyll/gram of Fresh Weight
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Tris-Tricine 10-16 gradient Electrophoresis gel
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3
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Table 2 Thylakoid Protein Ratios (LHCp/RCp) in
Peas
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Table 3 Thylakoid Protein Ratios (LHCp/RCp) in
Moss
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Further Study

• Explore the apparent discrepancy between the
  change in chlorophyll ratios and the change in
  the protein ratios
• Use at least three thylakoid isolations per
  specimen

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Acknowledgements

• Dr. Verhoeven
• Ms. Fruen
• Breck Team Research 2003-04

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Sun and Shade Acclimation of the Photosynthetic
Apparatus in Gymnostomum aeruginosum
Adam Yock 2003-04
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Analysis
Absorbance readings entered into the equations

• Chl a 12.25 x A663.6 2.55 x A646.6
• Chl b 20.31 x A646.6 4.91 x A663.6
• Chl a Chl b 17.76 x A646.6 7.34 x A663.6

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Discussion

• Chlorophyll Ratios
• Pea chl a/b changed significantly (p 6. 2464
  x 10-5)
• Agrees with hypothesis
• Moss chl a/b did not change significantly (p
  0.8868 )
• Agrees with hypothesis

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Discussion

• Protein Ratios
• Pea LHCp/RCp changed significantly (p 1.44 x
  10-5)
• Agrees with hypothesis
• Moss LHCp/RCp changed with marginal significance
  (p 7.00 x 10-2)
• Does not agree with hypothesis

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Methods Collecting Moss/pea Samples

• Peas
• Grown from seed
• Moss
• Harvested from the banks of a small rivulet in
  St. Paul, MN

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Isolating Moss/pea Thylakoids

• Prepared
• -Moss ground in liquid nitrogen
• -Peas blended in a blended
• Vortexed and spun in centrifuge (moss twice, peas
  three times)
• Aliquoted

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Measuring Moss Chlorophyll Content

• Mixed with acetone
• -Moss ground in acetone
• -Peas diluted with acetone and vortexed
• Spun in centrifuge (moss twice, peas once)
• Read supernatant in spectrophotometer at 663.6 nm
  and 646.6 nm

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Moss/pea Sample Electrophoresis Preparation

• Spun in centrifuge
• Boiled

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Results