ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb03136.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTLight‐limited rates of photosynthesis normalized for chlorophylla, (α), and actual photon absorption (quantum efficiency, Ф) were determined for six eponentially growing algal species grown under identical conditions. The same parameters, α and Ф, were also monitored for a single diatom species,Thalassiosira pseudonanaHasle&Heimdal, through its growth cycle in batch culture. Statistical differences in α could be demonstrated among the six different exponentially growing species while no differences could be shown forФ.Statistical differences among the six species were minimized when photosynthetic rates were normalized for in vivo fluorescence rather than extracted chlorophylla.Both α andФwere constant whileT. pseudonanawas in the exponential phase of growth, but both declined as the culture entered stationary phase. While cells were in exponential growth, differences in a were attributed to varying rates of in vivo light absorption per chlorophylla, thus providing experimental evidence that the in vivo chlorophyllaextinction coefficient, kc(m2· mg Chl a−1), cannot be assu

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00853.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe time in the cell cycle when CO2provision was required for cell development and division was determined in synchronous cultures ofChlamydomonas segnisEttl bubbled with air (0.03% CO2) or air enriched with 5% CO2under continuous light at 25°C and pH 7. Provision of CO2(% in air v/v) during the G1‐phase was found to be essential for the completion of the cell cycle. There was no demand for CO2supply throughout the S‐phase and mitosis. Using cultures adapted to CO2concentrations ranging from 0.03 to 5% in air, the apparent CO2concentration (Km) required for the cells to develop during the G‐1‐phase and to attain one half the maximal rates of photo‐synthetic O2evolution was calculated as 0.05%. This value increased to 0.1 and 0.5% during the S‐phase. For total protein and carbohydrate accumulation, which would reflect inorganic carbon (CO2+ HCO3−) assimilation, the Km(% CO2) were ca. 0.1 and 0.14 throughout the cell cycle, respectively. The CO2concentration at which the cells exhibited the shortest generation time (6.7 h) was 0.1%. These results showed that during development, cells photosynthesizing (evolving O2) at maximal rates but accumulating protein and carbohydrate at one half the maximal rates or less would complete their vegetative life cycle in the

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00854.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTA red alga with a cylindrical stipe bearing a single deciduous blade was collected in deep water off the east coast of Florida. It is described asMaripelta atlanticasp. nov., differing fromM. rotata(Dawson) Dawson (the type of the genus, from deep water off California and Baja California) chiefly by having an annular tetrasporangial nemathecium on the lower surface of the blade rather than scattered nemathecia on the upper surface. Both species are vegetatively and reproductively distinct fromM. thivyaeDawson, which is transferred toHalichrysis.New information is given regarding the reproduction and distribution ofM. rotata.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00855.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTA comparative study of nitrate‐limited growth and nitrate uptake was carried out in chemostat cultures ofAnkistrodesmus falcatus(Corda) Ralfs.,Asterionella formosaHass., andFragilaria crotonensisKit. In each species growth rate (μ) was related to total cell nitrogen or cell quota (q) by the empirical Droop growth function.Nitrate uptake was a function of both external N concentration and q. The apparent maximum uptake rate (Vm') at a given μ was inversely related to q – q0, where q0is the minimum quota. The apparent half‐saturation constant for uptake, (Km') appears to show a slight inverse trend with μ, although statistical analysis shows that this trend is inconclusive. When q approaches q0, Vm' is several orders of magnitude greater than μq, the calculated steady‐state uptake rate. As q increases, however, the difference between these two variables decreases sharply until q approaches qm, the cell quota for nitrogen‐rich cells. At this point the difference between μq and Vm' disappears. This behavior is explained by the feedback regulation of N uptake. The inverse relationship between Vm' and q – q0can be described by an empirical three‐

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00856.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTForty‐five species of dinoflagellates were surveyed for the presence of a pellicular layer in the amphiesma or cell covering. Such a layer was found in 15 of the 20 genera studied. Half the pellicles tested were resistant to acetolysis and may contain a sporopollenin‐like material similar to that of some dinoflagellate cyst walk. Most organisms which formed pellicles were capable of reinforcing this layer with cellulose. Pellicles ofHeterocapsa niei(Loeblich) Morrill&Loeblich andScrippsiella trochoidea(Stein) Loeblich were studied with the electron microscope. Evidence is presented indicating that dividing cells ofS. trochoideafrom new walls while still enclosed in the parental pellicular la

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00857.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe growth ofVolvox globatorL. andVolvox aureusEhr. was measured at five temperatures and nine phosphorus concentrations. Growth rates were hyperbolically related to phosphorus concentrations for all temperatures using a Monod growth model. Optimal growth rates of 1.17 and 1.00 doublings d−1were obtained at 20°C forV. globatorandV. aureus, respectively. Neither species grew at 5°C. The half‐saturation constants for growth, Ks, were lower forV. aureus.Phosphorus uptake by both species was also dependent upon external phosphorus concentrations and temperature. At all temperatures, maximum phosphorus uptake (μmol P colony−1min−1) was similar for both species; however, the half‐saturation constants for uptake showed significant differences between the species. Comparisons of the kinetic constants for growth and phosphorus uptake suggest thatV. aureuswill outcompeteV. globatorunder phosphorus limited

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00858.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe components of the flagellar apparatuses of the male and female gametes ofDerbesia tenuissima(De Not.) Crouan are compared with those in other swarmers of green algae. Both the male and female gametes were found to have a cruciate microtubular root system, a non‐striated capping plate which connects basal bodies, two electron dense terminal caps which partially cover the proximal end of the basal bodies, and two small system II fibrous roots. Similarities exist between these components and those suggested to be typical of ulvalean swarmers. Based upon these similarities, it is proposed that the Caulerpales be classified in the Ulvaphyceae rather than in the Charophyceae or Chlorophycea

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00859.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTJuvenile sporophytes of the giant kelp,Macrocystis pyrifera(L.) C. A. Agardh, were transplanted from local kelp beds to stations located various distances from the outfall from an electrical generating station that was known to cause an increase in the settlement of fouling organisms. Plants near the outfall became heavily fouled by the encrusting bryozoan,Membranipora membranacea(L.), and lost about one‐third of their blades during the course of the experiment. Blade loss was significantly correlated with amount of fouling. To test the hypothesis that fouling causes blade loss, we paired fouled and unfouled plants of about the same age, overall length, and number of fronds and placed them at stations in nearby kelp beds and near the outfall. At the stations in the kelp beds, the fouled plants lost blades more rapidly than the unfouled controls. However, at the station near the outfall the “control” plants quickly became fouled so there was little difference in treatments and there was no significant difference in blade loss. Plants fouled byMembraniporasuffered greater blade loss than clean plants probably because fouled blades are fragile and break off easily and because fish bite off chunks of blade while foraging on the attached bryo

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00860.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe adsorption of plutonium‐237, added from an acid solution, by two species of marine phytoplankton,Monochrysis lutheriDroop, a flagellated chrysomonad, andPhaeodactylum tricornutumBohlin, a diatom, is governed by a passive mechanism. This is clearly indicated by the observation that the rapid rates of sorption were not significantly different for live and heat‐killed cells incubated at 24°C and 0°C. The Q10values for the chrysomonad and the diatom of 0.95 and 1.18, respectively, are indicative of passive processes. The average ratio of (activity on algae/activity in filtrate) per unit volume at 24 h, the time when maximum levels of algal radioactivity were attained, of (32 ± 4)×103was not significantly different for the diatom or the chrysomonad. On a per cell basis, maximum levels of radioactivity were attained within 2 h. Less than 20% of the adsorbed237Pu desorbed aft

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1981.tb00861.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY