摘要:

SUMMARYField and laboratory procedures demonstrate that the effluent from the Willimantic, Connecticut, sewage treatment plant changes the numerical composition of the dominant epilithic algae in the Shetucket River. This effect is due to the effluent altering the competitive balance betweenchlorellasp. andAchnanthes deflexaReim. Thechlorellacompletely dominates highly polluted stretches of the river, and shares dominance withA. deflexain other areas. The degree of river pollution can be estimated by enumerating the natural standing crops of these 2 algae. A 2‐membered assay utilizing these organisms is a sensitive laboratory pollution monitor and a useful predictive tool. Dominant stands of these epilithic species develop in polluted and unpolluted zones in this river due to competition for the limited area on the cobble

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02858.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe predominant sulfated polysaccharide, ˛‐carrageenan, was localized in the middle lamella of epidermal, cortical and medullary cells ofEucheumanudumJ. Agardh. Autoradiographic studies with35SO4= indicated that the label was first incorporated in the inner wall and ultimately deposited in the middle lamella of all cells, and in an outer wall layer of the epidermal cells. There was no evidence for cytoplasmic incorporation of the label. The middle lamella stained with alcian blue, was γ‐metachromatic with toluidina blue O and bound diaminobenzidine‐osmium tetroxide. This region was also positive with periodic acid‐Schiff's (PAS) ragent, possibly demonstrating cellulose and/or a nonsulfated precursor of ˛‐carrageenan.A proposed model for extracellular sulfation includes production and secretion of a nonsulfated polygalactan and sulfotransferase enzyme(s) by the golgi apparatus and endoplasmic reticulum, respectively. Free sulfate in the wall would be bound to the precursor polysaccharide, with much of the resulting carrageenan migrating to the middle lamella facilitating mutual

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02859.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYInformation on the nutrient kinetics ofAsterionella formosaHass. andCyclotella meneghinianaKutz. under either phosphate or silicate limitation was obtained for use in a Monod model and in a variable internal stores model of growth. Short‐term batch culture growth experiments were fit to the Monod model and long‐term semicontinuous culture experiments and short‐term uptake experiments were fit to the variable internal stores model. Mathematical analysis indicates that the parameters of the 2 models may be expressed in terms of each other at steady state.The qualitative results of both batch and steady state culture methods agree. For limiting phosphate experiments.A. formosais better able to grow at low PO4‐P concentrations thanC. meneghiniana, as shown by its lowerKfor PO4‐P limited growth. ThekQofA. formosacompared toC. meneghinianafound in long‐term semicontinuous culture indicates thatA. formosais almost an order of magnitude more efficient at using internal phosphate for growth. The qualitative results under silicate‐limited growth ofC. meneghinianais less than that ofA. formosa.The kQfrom semicontinuous culture experiments indicates thatC. meneghinianais the more efficient at using internal silicate for growth. Nutrient uptake experiments showed more variability from a Michaelis‐Menten relationship than short‐term growth experiments. There were no significant differences between the 2 species in half saturation constants for either phosphate or silicate uptake. We observed a marked dependence of the coefficient of luxury consumption (R)of phosphate on the steady state growth rate.A. formosahas a higherRth

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02860.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe effects of nutrients, temperature and light on gametogenesis inScenedesmus obliquus(Turp.) Kütz, were studied in culture. Concentrations of nitrogen in the medium employed showed a marked influence on gamete production. Gametogenesis is inhibited by N excess but is not a response to N starvation or depletion. A drop in N level from that of the growth medium is not required, nor does itper setrigger gametogenesis. The N concentration satisfying growth requirements insufficiently low to permit sexual differentiation. Nitrogen level in the growth medium has no effect on subsequent N to maintain a typical culture. Number of gametes present at maximum production time is inversely related to N concentration, but neither time of onset of gametogenesis, nor time of maximum gamete production is affected by N concentration. Cultures incubated at 15 C in medium lacking N take a minimum of 20—24 h to develop cells irreversibly committed to gamete formation. At the concentrations tested, no medium component other than the N‐containing salt affected gametogenesis. Temperature influences both time of maximum production and numbers present at maximum production time. Time of maximum production is inversely related to incubation temperature; a 15 C incubation temperature yielded highest gamete production. Light enhances gametogenesis but gamete formation can occur in absence of light. Achievement of a light‐saturated response is dependent upon illumination given at two critical periods: one occurs shortly after N withdrawal; the other occurs later, when cells are becoming irreversibly committed to gamete formation. Ability to produce gametes diminished with prolonged laboratory c

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02861.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYSilicic acid transport was studied in the photosynthetic diatomNavicula pelliculosa(Bréb.) Hilse using [68Ge] germanic acid (68Ge(OH)4) as a tracer of silicic acid (Si(OH)4). The initial uptake rate of Si(OH)4was dependent on cell number, pH, temperature, light and was promoted by certain monovalent cations in the medium. Na+was more effective than K+, whereas Li+and NH+4were ineffective at promoting uptake.Uncouplers and inhibitors of oxidative phosphorylation and of photophosphorylation reduced uptake by 40–99% of control values. Uptake was also especially sensitive to the sulfhydryl blocking agents at 10−5M and to the ionophorous compound valinomycin (10−7M) which inhibited uptake by 82%.The Si(OH)4transport system displayed Michaelis‐Menten‐type saturation kinetics with kinetic parameters ofKS=4.4 p. mol Si(OH)4· 1−1,Vmax=334 pmol Si(OH)4· 106cells−1· min−1. Calculations of the acid soluble silicic acid pool size based on 60 s uptake at 20 μM Si(OH)4suggested that intracellular levels of Si could reach 20 mM and as much as 5 mM could exist as free silicic acid, representing maintenance of a 250‐fold concentration gradient compared with the medium.Efflux from preloaded cells was dependent on temperature and the Si(OH)4concentration of the external medium. In the presence of 100 μMM “cold” Si(OH)4, approximately 30% of the Si(OH)4in preloaded cells was exchanged in 20 min.The initial uptake rate of Si(OH)4in logarithmic phase cells was constant, but the uptake rate increased in a linear fashion for 6 h in stationary phase cells.These results suggest that the first step in silica mineralization by diatoms is the active transmembrane transport of Si(OH)4by an energy dependent, saturable, membrane‐carrier mechanism which requires the monovalent cations Na+and K+and is sensitive to sulfhydryl blocking agents. Silicic acid transport activity also appears to be regulated during differen

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02862.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYFouling plates (Plexiglas squares and concrete blocks) were bolted in a horizontal position to racks on the ocean floor at a depth of 12 m. Some of these were periodically taken from the sea, subjected to nondestructive microscopic survey in the laboratory, and then replaced. Others were: a) left undisturbed as controls; b) variously caged to exclude larger predatory animals; or, c) had sediment removed from them at intervals. Populations developing on the periodically surveyed plates were similar to those on undisturbed plates. Populations on undisturbed plates were significantly different from those on partially caged plates. The exclusion of large predators by complete caging resulted in highly significantly different communities from those on partially caged plates. Completely caged Communities were composed mainly of worms, barnacles and bryozoans. Summer‐installed plates supported significantly different populations at the end of the experimental period (12 mo) from winter‐installed plates. Plant growth rates were slow, not exceeding 2 cm/mo, and the mortality rates were often high. A few species had high rates of recruitment and survival each month. Most had high recruitment only in the most favorable growth periods and high loss rates. Physical conditions on the sea floor were measured. The methods developed during this study make it possible to quantitatively describe the growth and reproduction of populations of benthic marine algae in the

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02863.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYUsing cultures of a number of different marine algae (diatomsSkeletonema costatum(Grev.) Cleve andPhaeodactylum tricornutumBohlin, chrysophyteIsochrysis galbanaParke, green flagellateDunaliella tertiolectaButcher, dinoflagellateGonyaulax tamarensisLebour) the short‐term, pattern of14CO2assimilation has been investigated. In all exceptD. tertiolectathe labelling of amino acids and intermediates of the tricarboxylic acid (Krebs) cycle was significantly heavier than that of sugar phosphates. Over periods of 30–120 s labelling in amino acids and Krebs cycle intermediates accounted for 41–95% of the14Cfixed (depending on the alga). Over shorter times (<10 s) the pattern in the 2 diatoms showed significant labelling of C4acids (and related com‐pounds) and little labelling of sugar phosphates. The reverse wits seen withD. tertiolecta.Also, in the 2 diatoms and inG. tamarensissignificant inhibition of photosynthesis by oxygen could only be achieved with 100% oxygen; atmospheric levels having little effect. Parallel measurements of 2 carboxylating enzymes showed that ribulose‐1,5‐diphosphate carboxylase (RuDPCase) was significantly greater than phospho (enol)pyruvate carboxylase (PEPCase) activity only in the green flagellate. It is suggested that photosynthesis in marine diatoms depends on an active PEPCase utilizing bicarbonate as a substrate and that a less active RuDPCase utilizes CO2. InD. tertiolectathe pattern more closely resembles that of a “Calvin (C3)” plant. The dinoflagellate and the chrysophyte appeared to show a mixed C3and C

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02864.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYContinuous culture techniques are used to study long‐term population interactions betweenPlectonema boryanumGomont, a filamentous bluegreen alga, and the LPP‐viruses which infect it. After LPP‐I (virulent cyanophage) infection of sensitive algae, 3 oscillations occur in cell density with concomitant oscillations in virus titer before final stabilization of both algal and viral concentrations. After LPP‐ID and LPP‐2 (temperate viruses) infection, oscillation in cell density occurred with burst of virus particles. Resistant algae always repopulated the chemostat; lysogeny was not established. The interaction between Plectonema that was resistant to virus infection and the 3 LPP‐cyanophages resulted in rapid elimination of the viruses from the chemostat in the effluent. When lysogenicP. boryanumwas tested, a law population of virus was present in the chemostat throughout the incubation period indicative of spontancous induction. Clones of lysogenic algae we

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02865.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYIn a series of 188 experiments on the, light‐saturation curve for natural assemblages of phytoplankton at 3 stations in Nova Scotia coastal waters, it was found that both the initial slope (α) of the curve and the assimilation number (PmB)varied about 5‐fold throughout the year. No differences could be detected between stations, but both α andPmBdecreased with depth. The mean value of α for all the experiments was 0.21 mg C[mg Chl a]−1· h−1· W−1· m2with a range from 0.03 to 0.63. An explanation is offered for the nonconstancy of a in terms of the effect of cell‐size and shape on self‐shading. An estimate is made from first principles of the physiological maximum‐attainable value of α. This estimate corresponds, within the limits of experimental error, to the highest values of α observed in the study. It is deduced that on the average the phytoplankton were photosynthesizing at only 44% maximum capacity. The mean value ofPmBfor all experiments was 4.9 mg C[mg Chl a]−1· h−1, with a range from 0.73 to 24.8. In the matrix of partial correlation coefficients, α andPmBwere positively correlated with each other; α was correlated with mean solar radiation averaged over the 3 days prior to the experiment, but uncorrelated with temperature;PmBwas correlated strongly with temperature but uncorrelated with recent solar radiation. The results show thatPmBcould be estimated from α and temperature using an empirical multiple regression equation, independent of depth. It is suggested that α andPmBare both correlated with some other factor not measured in the study, perhaps the mean cell‐size of the populations, or the nutrient status of the cells. The predictability of primary production is discu

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02866.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYScanning electron micrographs and autoradiographs ofAnabaena circinalisRabenh. andAphanizomenon flos‐aquae(L.) Ralfs in samples from fresh‐water communities show that bacteria are attached specifically at the polar region of heterocysts of these known N2fixers. This algal‐bacterial association occurs most frequently during bloom conditions. The possible roles of this association in maintaining nuisance bloom conditions are disc

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02867.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY