Fragaria vesca, the woodland strawberry, was grown under a series of controlled environments including variations in light intensity, average temperatures, and temperature amplitude around a constant mean. Observations on CO exchange capacities, leaf anatomy, and cell ultrastructure were made for each treatment to determine relationships between these variables. With increasing light intensity, leaf thickness, leaf density, and mesophyll cell surface area and volume per leaf surface area increased. Net photosynthesis (NPS) per leaf weight decreased with increasing light pretreatment while NPS per area increased from low to medium intensity, then decreased at the highest intensity. Depression of photosynthesis at the highest light pretreatment may have been due to massive starch accumulation in the chloroplasts associated with the sodium vapor lamps used. Correlation of all anatomical variables was highly significant with dark respiration and NPS per dry weight but insignificant for NPS per leaf area. In the variable temperature treatments, photosynthetic acclimation occurred with a shift in optimum temperature for NPS in the direction of prevailing growth temperature. Absolute rates were highest at moderate pretreatment temperatures and were reduced by extreme growth temperatures. Thick leaves with low density mesophyll became thinner and more dense with increasing growth temperature corresponding to an increase in maximum net photosynthetic rates. Leaves became thicker and more dense at the highest temperatures, but with an increase in cell damage and indications of changes in metabolic pathways. Highest correlations for gas exchange rates were with specific leaf weight (weight per area). Correlation with other anatomical variables were scattered or insignificant. It was concluded that adaptation to a range of environmental conditions cannot be consistently attributed to changes in mesophyll cell volume or surface area.

Experiments were conducted to examine whether leaf adaptation to light in Fragaria virginiana (Rosaceae) was determined by peak photon‐flux density or by total quanta received during the day. Leaf structure and apparent photosynthesis rates were similar under environments where total energy received was the same even though peak photon‐flux density was different. When peak photon‐flux density was held constant and total quanta varied, significant differences were noted in apparent photosynthesis, leaf thickness, specific leaf weight, mesophyll cell volume, and Ames/A ratio. High total quanta produced high‐light or sun‐type leaves even at relatively low peak intensities. Thus, total light energy received during the day has a greater influence on leaf adaptation to light than does peak photon‐flux density.

Apparent photosynthesis and dark respiration were followed during development in four light environments of leaves of Fragari igniaa Duchesne. Leaf expansion was completed more rapidly the higher the growth photon flux density and leaves senesced more quickly in high light. Maximum photosynthetic capacity coincided with the completion of blade expansion and declined quickly thereafter. Leaves were transferred from high to low and low to high photon flux densities at several stages during expansion. Leaf Experimental Treatments. Two sets of experiments were performed. In the first, the effects of irradiance and leaf age on photosynthetic performance were studied. Leaves were individually tagged as they appeared in each of the four light treatments. Length and width of leaflets were measured to the nearest 0.5 mm at 1-to 3-day intervals until expansion was essentially complete and at longer intervals thereafter. Longevity was estimated by allowing some leaves to die naturally. Apparent photosynthesis and dark respiration were measured on leaves of different ages.A second experiment examined adaptive capacity as a function of leaf age at the highest and lowest growth chamber light levels. Leaves which appeared after the plants had been in the high or low light levels for at least I week were individually tagged. A plant was transferred to the contrasting light level when its tagged leaf was at one of three stages of development (Fig.

Plants of a single geDotype of wild strawberry, Fragaria virgnuiana Duchesne, were grown with or without fertilizer in high (406 microeinsteins per square meter per second) and low (80 microeinsteins per square meter per second) light. High-light leaves were thicker than low-Ht leaves and had greater development of the mesophyll. Within a ight level, highnutrient leaves were thicker, but the proportions of leaf tissues did not change with nutrient level. Maximum net CO2 exchange rate and leaf size were greatest in high-light, high-nutrient leaves and lowest in high-Ught, low-nutrient leaves. Changes in mesophyli cell volume largely accounted for differences in CO2 exchange rate in low-Ught leaves, but not in highlight leaves.Leaf size in these experiments was apparently determined by nutrient and carbon supply. This may explain the observation that the largest leaves produced by wild strawberries in the field occur in high-light, mesic habitats, rather than in shady habitats.

Duramycin is a polypeptide antibiotic (molecular weight 2012) obtained from culture filtrates of Streptomyces cinnamomeus forma azacoluta. In this work, we show that low concentrations of duramycin induced aggregation of lipid vesicles containing unsaturated phosphatidylethanolamine and unsaturated monogalactosyl diglyceride, and of sarcoplasmic reticulum vesicles from rabbit skeletal muscle. Furthermore, duramycin inhibited the ATP-dependent Ca2+ uptake in sarcoplasmic reticulum vesicles without affecting the hydrolysis of ATP or the permeability of Ca2+. Also, duramycin only inhibited the bacteriorhodopsin proton pump reconstituted into phospholipid vesicles containing phosphatidylethanolamine. We have isolated a duramycin-resistant strain of Bacillus subtilis and have mapped the location of duramycin resistance. In this strain, the secretion of protons and influx of calcium were resistant to duramycin, and its lipid composition was profoundly different from that of the parent strain. No phosphatidylethanolamine was detected in the resistant strain. Our findings are consistent with the idea that duramycin recognizes a particular membrane conformation determined by the presence of phosphatidylethanolamine or monogalactosyl diglyceride.