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R A OLSON

Publications and source records attributed to R A OLSON.

11 recordsLinked to original sources
PubMed1960

Absorption microscopy of enzymatically treated cell-free chloroplasts.

Monochromatic light microscopy at 435 mmicro shows in Euglena gracilis, the distribution of chlorophyll and the general orientation and geometry of chloroplasts in vivo. In addition it discloses, in swelling chloroplasts, a lamellar pigmented structure. Changes in this structure are observed in extruded swollen chloroplasts treated with lipolytic or proteolytic enzymes. Lipolytic enzymes produce an increase in the number of visible lamellae while proteolytic enzymes disrupt the lamellar array. Correlation of chloroplast swelling behavior and the effects of enzymatic degradation with current electron microscope observations support the following: (1) the pigment lamellae observed in vivo consist of component laminae; (2) the lamellae are separated by sites of swelling; and (3) the integrity of the lamellar structure is primarily dependent upon the intact state of the protein.

Chlorophyll↗
PubMed1953

Respiration and intensity dependence of photosynthesis in Chlorella.

1. Respiration changes as a result of illumination. 2. In the absence of glucose or other supply of substrate, respiration decays in the dark showing at least two types-a fast decay in a few minutes and a slow decay lasting hours. 3. Respiratory response to illumination is delayed. 4. Intermittent illumination (in the absence of glucose, etc.) produces a periodic variation in respiration with a delay or phase lag. 5. Periodic variation of respiration may produce a higher average value in the dark than in the light due to the lag and depending upon the period of intermittent illumination. 6. Based upon average respiration values our data confirm the Kok effect. 7. Interpolated values of respiration, however, result in photosynthetic rates which are linearly dependent upon intensity of illumination. 8. Thus the quantum efficiency is found to be independent of intensity, over the wide range of intensities investigated.

Cell Respiration↗
PubMed1953

Time course and quantum efficiency of photosynthesis in Chlorella.

1. Though the quantum yield remains constant for different samples of the same culture despite great changes in respiration due to dark adaptation, the quantum requirement for different cultures varies from 6.1 to 13.5 quanta per molecule of oxygen evolved (q/m). 2. This variation from one culture to another appears to depend upon chlorophyll concentration, though other paralleling factors cannot be ruled out. 3. Both chlorophyll concentration and quantum requirement show a random distribution. A statistical median for 50 cultures and 99 determinations gives q/m = 8.5 with a systematic uncertainty of perhaps 10 per cent. Since the variations are real, the median is regarded as less important than the lower limit approached (about q/m = 6). 4. Dark adaptation under aerobic conditions produces an initial photosynthetic rate of nearly zero. The immediate rise to steady state is somewhat logarithmic in character and may require over 3 minutes. 5. In intermittent light (of periods from 1 to 6 minutes) the induction observed in subsequent light periods starts from a finite initial rate and occupies a shorter time, often as little as 30 seconds. 6. The theoretical importance of aerobic induction is discussed. A chlorophyll cycle of two photochemical steps is found to satisfy most of the observed characteristics and to be compatible with an efficiency independent of intensity.

Chlorella↗