esr473/notes/photosynthesis-meas-norm.html
April 18, 2008
| Table 1: Measurement of photosynthesis in environmental algae samples | |||
| Measure | technique | scale | comments |
| CO2 decrease | IR in gas | I don't know how sensitive this is. | |
| C increase in cells | total C analyzer | hours | more appropriate for growth measurements |
| 14C | uptake from soluble, acid purgible, to solid non-purgable, detect with scintillation counting | 10 minutes to several hours | filter handling times radioisotope use |
| dissolved O2 | Clark electrode or chemiluminescent | minutes | sensitivity is lower measure photosynth and respiration |
| 18O/16O | need Mass Spec useful in studying Mehler rxn |
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| ETR | from variable fluorescence | seconds | two machines:
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| Table 2 parameters for normalizing | ||
| parameter | method | comments |
| Chla | extraction from cells in methanol or acetone read with spectorphotometer or fluorometer |
highly variable in cell due to acclimation to light environment Chla only found in algae (not in bacteria, organic detritus etc.)
|
| abs 680 or 750 | simple absorbance or light scatter | good as a quick check in a uni-algal, high density culture |
| Chl fluorescence | in vivo fluorescence | total Chla and fluorescence are both variable
|
| P700 | proxy for photosynthetic units | only possible on extremely dense cell preparations and using specs that can discriminate to .001 abs at 3 abs background
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| cell counts/cell volume | microscope/photomicroscope | time consuming analysis but provides a lot of other information
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| total carbon | CHN analyzer | includes non-algal buddies
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| total protein | grind, digest, BCA or other reagents | 50% of cell dry weight conservative in cell physiology
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| phycocyanin or other PBP | extract or fluorescence on broken cells | good proxy for cyanobacterial biomass
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