摘要:

SUMMARYAlgae that impart a red color to snowfields are rather common in California. Red snow occurs mainly in the Sierra Nevada at altitudes of 10,000–12,000 ft (3050–3600 in) and can occur at high altitudes where snow persists in other parts of the state. The distribution in the Sierra was similar in 1969 and 1970, contrasting snowfall years. Colored snow was found from May to October in old, wet snow‐fields. The predominant color was red and occurred as surface patches in depressions in the snow. The color could extend as deep as 30 cm below the snow surface.Algae in the snowfields of the Tioga Pass area (Sierra Nevada) were large, red, spherical cells ofChlamydomonas nivalis.No other algae were seen. Their distribution, as measured by cell numbers and chlorophylla, was patchy. Algal cells and chlorophyllawere mainly distributed at or near the snow surface but extended down to a depth of 10 cm. Light intensity was greatly attenuated by snow, but enough light for photosynthesis was found at 50 cm below the surface. Nutrient content of one snow sample was very low. The populations were very actively photosynthetic and took up as much as 65% of added14CO2in only 3 hr. It was tentatively concluded that CO2limitsin situphotosynthesis. Photosynthesis was inhibited by melting snow samples. Rough calculations of the growth rate suggestedin situgeneration times of only a few days for these

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03994.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb02434.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYChlorophyllide c (chlorophyll c) wax found in axenic or unialgal cultures of 5 members of the class Xanthophyceae and in 2 members of the class Raphidophyceae (Chloromonadophyceae).Two other algae contained no chl c; neither had chlb.One of these plants,Pleurochloris magna, is presumably a member of the newly named class Eustigmatophyceae (Hibberd and Leedale). The other alga, clone GSB Sticho, is of uncertain, systematic position.Although, the xanthophyll pigments were not critically studied, there is enough evidence, to permit the conclusion that the xanthophyll suites of the chloromonads, the xanthophytes,P. magna, and clone GSB Sticho all differ in at least one respect.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03995.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe ontogeny ofP. lanosarhizoids was investigated by light and electron microscopy. A series of distinct, changes was recognized. Prior to penetration of the host,Ascophyllum nodosum, starch reserves were depleted and a large number of dictyosome vesicles accumulated in the cell. These appeared to have been discharged immediately prior to or during host, penetration with a concomitant increase in rhizoid wall thickness. Following initial penetration, the tip became highly convolute and dominated by ER, ribosomes, and mitochondria. Senescence was marked by almost complete, vacuolation of the cytoplasm, degeneration of most organelles, and the loss of color. These ultrastructural changes are correlated wth the habit ofP. lanosa.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03996.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYOnondaga Lake, possibly the most polluted lake in New York State, supports an algal flora characteristic of a eutrophic lake with an admixture of saline species. Floral diversity is noteworthy under the circumstances. Seasons in the lake may be identified by the succession of flora. High salinity of lake water results in layering at the outfall (as in an estuary, in reverse) such that river water may enter the lake at the outlet despite continuous net outflow. Certain species of algae appeared first at the outflow station and then spread through the lake. Phosphorus and nitrogen are never limiting, although seasonal diminution in the latter may influence the composition of the flora. Silica diminution was related to blooms of diatoms and may then be limiting for further growth of diatom populations. No obvious controlling relationship exists between herbivores and phytoplankton populations. The euphotic layer is typically much shallower than the thermocline. Therefore turbulence and mixing may play an important role in controlling certain populations. A brief midsummer clearing in 1969, characteristic for the lake, resulted in serious oxygen depletion and cannot be accounted for with the available data. Among metals, chromium and copper are high in the lake as the result of industrial discharges. The former may be inhibiting, the latter probably is inhibiting to algal growth. Consequently, measures underway to “clean up” the lake may result in increased blooms. Biomass calculations have been made for the major phytoplankters, and a list of 82 species is presen

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03997.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYMembrane filters retain14C bicarbonate,14C glycollate, and other14C labeled substances from filtrates of algal cultures and lake water. By refiltering different volumes of the filtrate from algal cultures and from lake water after incubation with14C bicarbonate, it was shown that the labeled material retained was not proportional to volume but showed a saturation effect with increasing volume filtered. When the radioactivity retained by a filter is divided by the volume filtered, decreasing values are obtained with increased volume filtered. This radioactivity may represent a significant addition to the radioactivity in particulate material on the filters, resulting in a similar type of curve when different volumes of lake water or cultures are filtered.Values of radioactivity per milliliter were constant usingChlorellain Chu 10 medium. However, the curve could, be obtained by increasing pH and bicarbonate concentrations in the medium and on resuspending the algae in Lake Ontario (winter) filtrate. The values of cpm/ml retained from filtrates were low inCryptomonascultures and the curve was not obtained unless population density was reduced, thus increasing the relative contribution to the radioactivity on the filters.The curve was not always obtained in lake water. It was significant in 10 out of 14 experiments in Lake Ontario and in 2 out of 5 experiments in Grenadier Pond. Changes in lake water rather than in experimental techniques were probably responsible. On 2 occasions when values of cpm/ml were constant in Lake Ontario, addition of sodium bicarbonate without a pH change resulted, in a significant curve.Our experiments do not disprove the possibility of cell damage during Millipore filtration, however, it has been shown that14C labeled substances retained from solutions can account for the entire range of decreasing values as a function of volume filtered.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03998.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYDeveloping germlings of the green algaOedogoniumhave been sectioned and some were found to contain particles presumed to be those of a virus. Fully formed particles were hexagonal in a 2‐dimensional section, about 240 nm in diameter with a densely stained surface layer and core; what appear to be different stages in their assembly were also seen. Many of the particles were clustered together in groups surrounded by aggregations of ribosomes. In cells containing many of the particles, the germlings' cytoplasm and organelles showed considerable evidence of disruption and breakdown. These particles have only been detected in germlings, so infection by this presumed virus was probably initiated in the naked, motile zoospor

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb03999.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe thermophilic blue‐green algaSynechococcus lividusstrain Y52 was shown to have plastoquinone (PQ) types A, B, and C. The values PQA per cell and chlorophyllaper cell are presented with the changes in the ratio of PQA to chlorophyllafor cells grown at different light intensitie

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04000.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe marine centric diatomBiddulphia levisproduced uniflagellate fusiform male gametes completely within the parent cell frustule. These gametes lacked both a central pair of microtubules in the flagellar axoneme and chloroplasts but did contain a cone of microtubules which passed posteriorly from the base of the kinetosome along the nuclear envelope. The gametes were released through a specialized pore in the girdle band leaving behind a cytoplasmic mass which contained chloroplasts and other cytoplasmic components. Tubules which resembled the flimmer hairs on the gamete flagellum occurred in cisternae of the cytoplasmic reticulum in the residual cytoplasm and in the nuclear envelope of the gametes. Gametogenesis inB. levisis compared with similar processes in other centric diatoms.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04001.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYExcretion of C14‐labeled organic material byDunaliella tertiolectawas observed under a variety of conditions. In healthy cultures, percent excretion tints related to cell density bill independent of light and preconditioning of the medium. Exaction was lower in nutrient‐limited culture than in an enriched medium, and in both cases was minimal during logarithmic growth. Increases in dissolved carbohydrate during stationary phase represented an accumulation of high molecular weight compounds.The general composition of labeled excretory products was similar in both actively growing and stationary cultures. The data suggest that excretion may involve different processes at high and low cell densit

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04002.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY