. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 86 D. W. PHIPPS AND R. L. PARDY 60r '£ c 'E J 20 PROJECTOR EMISSION SPECTRUM. 450 500 550 600 WAVEL: . 650 750 FIGURE 2. Emission spectrum of projector lamp as determined with a scanning spectroradiometer. Dotted lines define range of photosynthetically active radiation (). oxygen on O2 evolution were determined by varying O2 concentration at 1 mM KHCO3 and a fixed light intensity. Photosynthesis o/H. viridis symbionts in vitro Symbionts for in vitro studies were isolated from hosts by homogenizing ap- proximately 150
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 86 D. W. PHIPPS AND R. L. PARDY 60r '£ c 'E J 20 PROJECTOR EMISSION SPECTRUM. 450 500 550 600 WAVEL: . 650 750 FIGURE 2. Emission spectrum of projector lamp as determined with a scanning spectroradiometer. Dotted lines define range of photosynthetically active radiation (). oxygen on O2 evolution were determined by varying O2 concentration at 1 mM KHCO3 and a fixed light intensity. Photosynthesis o/H. viridis symbionts in vitro Symbionts for in vitro studies were isolated from hosts by homogenizing ap- proximately 150 hydra using a Potter Elvenjeim tissue homogenizer with a Teflon pestle in 100 mM potassium phosphate buffer (pH ) containing 1 mM MgSO4 and 1 mM CaCl2. Algae were pelleted from the homogenate using a tabletop centrifuge at 1700 X g for 1 min. The algal pellet was washed 6 times and finally resuspended in 5 ml of homogenization buffer. Buffer was added to yield a con- centration of approximately 2 X 107 algal symbionts in a 5 ml sample. This con- centration yielded maximum photosynthesis by the isolated symbionts as deter- mined in this laboratory (data not shown). A 5 ml aliquot was placed in the electrode chamber, and oxygen concentration was adjusted by bubbling with nitrogen. KHCO3 added to the chamber to a final concentration of 12 mM yielded sufficient CO2 to prevent CO2 limitation at higher light intensities. The electrode chamber was sealed with the Plexiglas light guide and measurements of oxygen evolved were made for 5-10 min in the light. Rates of oxygen evolution were determined from these data. Chlorophyll content Following O2 measurements on intact hydras, animals were homogenized as described previously. Total chlorophyll (Chi) content of symbionts both in situ and in vitro was assayed using a 10 n\ sample of suspension extracted in 3 ml of absolute methanol. Fluorescence of the methanolic extracts was measured in a Turner III Fluorimeter (Turner and Associate
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
