Sun and Shade Acclimation of the Photosynthetic Apparatus in Gymnostomum aeruginosum
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Transcript of Sun and Shade Acclimation of the Photosynthetic Apparatus in Gymnostomum aeruginosum
Sun and Shade Acclimation of the Photosynthetic Apparatus in Gymnostomum aeruginosum
Adam Yock2003-04
http://www.scibridge.sdsu.edu/coursemats/introsci/diversity/chlorobionta/chlorobionta_cladogram.jpg
Chloroplast
ChloroplastGranum (stack of thylakoids)
Thylakoid
ChloroplastGranum (stack of thylakoids)
LHCRC
electron transport pathwaySun
Photons
Thylakoid
NADPHNADP+
ADP + P
ATP
PSIPSII
Light-Harvesting Complexes (LHC)• Photosystematic antennas• Contain chl a and b
Reaction Centers (RC)• Beginning of electron transport chain• Contain chl a
Introduction
Lower-order Plants(bryophytes)
Higher-order Plants
Sun-acclimated Specimen• More RC• Less LHC• Higher Chl a/b
Shade-acclimated Specimen
• Constant RC, LHC, and Chl a/b
• Less RC• More LHC• Lower Chl a/b
Reactions of Light-acclimated Specimens
LHCchl a/b
chl a/b
chl a/b
• Post and Vesk analyzed light adaptability in moss using chl a/b
Previous Studies
Analyze light adaptability in moss (Gymnostomum aeruginosum) using both a chlorophyll ratio (chl a/b) and a protein ratio (LHCp/RCp).
Purpose
Peas:• Both chl a/b and LHCp/RCp would significantly change
Moss: • Neither chl a/b nor LHCp/RCp would significantly change
Hypotheses
1:
p = 6. 2464 x 10-5p = 0.8868
Table 1: Average Chlorophyll/gram of Fresh Weight
Ave µg Chl a+Chl b/gFw SD t-testSun-acclimated Moss 559.6 105.8 p = 0.0050Shade-acclimated Moss 2259 776.6
Tris-Tricine 10-16% gradient Electrophoresis gel
2:
3:
Table 2: Thylakoid Protein Ratios (LHCp/RCp) in Peas
Table 3: Thylakoid Protein Ratios (LHCp/RCp) in Moss
•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
Further Study
• Dr. Verhoeven
• Ms. Fruen
• Breck Team Research 2003-04
Acknowledgements
Sun and Shade Acclimation of the Photosynthetic Apparatus in Gymnostomum aeruginosum
Adam Yock2003-04
• 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
Absorbance readings entered into the equations:
Analysis
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
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
Discussion
Methods: Collecting Moss/pea Samples
Peas:• Grown from seed
Moss:• Harvested from the banks of a small rivulet in St. Paul, MN
•Prepared-Moss ground in liquid nitrogen-Peas blended in a blended
•Vortexed and spun in centrifuge (moss twice, peas three times) •Aliquoted
Isolating Moss/pea Thylakoids
•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
Measuring Moss Chlorophyll Content
• Spun in centrifuge• Boiled
Moss/pea SampleElectrophoresis Preparation
Results