摘要:

SUMMARYThe decline of growth rate with increasing species size of unicellular algae grown under uniform conditions is quantified by applying to published data the equation, growth, (cell · time)−1= a (cell carbon)bwhereaandbare coefficients. The degree of size‐dependence might be highest under optimal conditions of growth wherebis 0.75. Respiration rate is shown to decline with size in the same manner. It is postulated that gross photosynthesis and processes underlying growth are similarly size‐dependent. Growth, efficiency (net over gross photosynthesis) cannot be shown to be size‐dependent. Cell size, expressed as carbon, is proposed as a scaling factor in comparative algal ph

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00490.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYTwo clones ofPinnularia brebissonii(Kütz.) Rabh. var.brebissoniiwere established and maintained in logarithmic phase of growth. Initial length of the cells was 37 μm. As cell division occurred, the mean length of cells in each population decreased as predicted by the MacDonald‐Pfitzer hypothesis; however, the decrease in mean length was not uniform throughout the growth period. This nonuniformity is probably caused by nonrandom division of cells in the population or by a changing increment of size reduction due to division. The initial increment of size reduction was calculated as 0.7 μm/division. The smallest, cells observed were 8 μm long. As cells decrease in length, cell volume decreases and the proportion of cells with aberrant valve structure increases. More than 90% of the valves were abnormal in a population with mean length of 14 μm. The abnormalities of structure involved the raphe, the central area and the

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00491.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYGrowth ofScenedesmus quadricauda(Turp.) Bréb. was significantly increased when the cultures were grown in Ethephon 68–241 (2‐chloroethylphosphonic acid) at concentrations of 0.001–1.0 μg · ml−1. At 0.1 μg · ml−1, Ethephon caused a significant increase in RNA levels on a dry weight basis. Total protein and DNA levels increased but not significantly. These data indicate that ethylene, the decomposition product of Ethephon at physiological pH, has some effect on the metab

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00492.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe ultrastructure of chloroplasts from 28 of the 73 species ofCaulerpaLamouroux (Chlorophyta, Caulerpales) has been studied to aid in interpreting phylogenetic relationships among the 12 recognized sections. Variations of systematic value include pyrenoid occurrence and fine structure, thylakoid architecture and amount of photosynthate storage. Comparisons of field and culture specimens indicate these characters are consistent. Chloroplast thylakoids are grouped into bands, with the distribution of bands differing among species. In the most common arrangement, bands are evenly distributed throughout the chloroplast. A few species show lateral displacement of bands whereas others have a majority of bands arranged at one end of the chloroplast. Starch is stored cither as one or two large grains (>1 μm diam.) or numerous small grains (<0.5 μm diam.). Electron‐transparent regions are common in other species in which chloroplasts rarely store starch. Simple, embedded pyrenoids are present in several species of section Sedoideae. An opaque region occurs in chloroplasts ofC. elongatawhich may represent an intermediate stage in the evolutionary loss of the pyrenoid. It is suggested that the chloroplast ofCaulerpaevolved, from a large, complex, pyrenoid‐containing organelle housing both photosynthetic and amylogenic functions, to a small, structurally simpler one, specialized for photosynthesis alone. A phylogeny of the 12 sections ofCaulerpais constructed, based on chloroplast evolution which agrees with an earlier morphology‐based hypothesis on the origin and evolution ofC

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00493.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe yearly bloom ofPeridinium cinctumf.westii(Lemm.) Lef. in Lake Kinneret is described and compared with the distribution of dinoflagellates in other freshwater bodies. The physical conditions required by the Wyatt and Horwood model do not fit the actual physical events accompanying the onset of the bloom.In situmeasurements of the percentage of cells in division were undertaken to clarify various points about the internal dynamics of the population. The exponential increase of the population occurs when the diurnal percentage of cells in division is not higher than 10–15%. This percentage increases up to 45% in late February–March, but does not cause any increase of population. At this period, the loss rate is nearly equal to the rate of cell increase and is interpreted as massive mortal

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00494.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYMale and female strains ofEudorina elegansEhrenberg were examined by serological methods for flagellar and cellular antigenic differences. No significant differences could be detected between the strains by using agglutination, immobilization and diffusion tests. However, differentiated sperm were neither agglutinated nor immobilized by anti‐vegetative cell ser

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00495.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYStimulatory affects of humic acids of molecular weight 30,000 or greater on iron‐starvedScenedesmus obliquus(Turp.) Kütz. in association with bacteria were studied by growth and Fe uptake experiments. Humic acids stimulated growth of Fe‐starved cells by decreasing the lag phase and extending the growth phase. Humic acids stimulated increased algal growth in medium containing EDTA as well as in medium containing no EDTA, indicating humic acids are not stimulating algal growth under Fe limiting conditions by creating a soluble Fe pool. Humic acids decreased Fe availability to Fe‐starvedS. obliquus.Iron bound to humic acids is unavailable for uptake by Fe‐starved cells indicating growth stimulation is not due to chelation effects alone. Stimulation of growth is not a membrane phenomenon as humic acids show the same stimulatory effect when in contact with cells or separated by dialysis membrane. Humic acids also stimulate growth in the dark, with and without aeration, indicating use as a heterotrophic substrate. A photoheterotrophic mechanism is indicated by increased algal growth caused by illuminating cultures, containing humic acids but exclu

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00496.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00497.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYDuring spring, extensive blooms of microalgae grow on the underside of arctic sea ice. The brownish, algal layer penetratesca.2 cm into the bottom surface of the ice and the algae are potentially exposed to very high salinities. Four diatom species,Melosira juergensiiAg.,Porosira glacialis(Grun.) Jørg.,Navicula transitansvar.derasa(Grun.) Cleve, andCoscinodiscus lacustrisGrun., isolated from, sea ice samples taken from the Beaufort and Chukchi seas near Barrow, Alaska, were grown at 11 salinities ranging from 5 to 70‰ at 5 C under constant illumination. All of the species grew at 5‰ exceptN. transitanswhose lower growth limit was 15‰. Growth was high over a broad range of salinities, but none of the species grew at salinities above 60‰. These diatom species appear to be well suited to tolerate the salinities in the brine pockets near the bottom of annual arctic sea ice where they are found. High brine‐cell salinity, however, may limit the upward, penetration of ice algae into the bottom

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00498.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThree photosynthetic parameters of 7 species of marine diatoms were studied usingNa214CO3at 5–8 C using log phase axenic cultures. The cell volumes of the different species varied from 70 μm3to 40 × 105μm3. The present experiment is consistent with the interpretation that the initial slope α (mg C · [mg chl a]−1·h−1· w−1· m2) of photosynthesis vs. light curves is controlled by self‐shading of chlorophyllain the cell.Pm,the rate of photosynthesis at light saturation (mg C · [mg cell, C]−1· h−1) andR,the intercept at zero light intensity (mg C · [mg cell C]−1· H−1) are both dependent on the ratio of s

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb00499.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY