摘要:

ABSTRACTTwo new propagule‐farming red algae from southern Australia,Deucalion levringii(Lindauer) gen. et comb. nov. andAnisoschizus propaguligen. et sp. nov., are described and defined largely on their development in laboratory culture.Deucalionis included in the tribe Compsothamnieae on the basis of its subapical procarp and alternate distichous branching. It differs from the other genera included in that tribe in that it produces 3‐celled propagules, polysporangia, a subapical cell of the fertile axis which bears 3 pericentral cells, and an apparently post‐fertilization involucre which develops from the hypogenous and sub‐hypogenous cells of the fertile axis. Its gametophyte morphology has been elucidated in culture, as only sporophytes are known from the field. Gametophytes do not appear to produce propagules.Anisoschizusis provisionally included in the tribe Spermothamnieae on the basis of its subdichotomous branching, possession of a prostrate system and the production of polysporangia. It differs from the other genera of the tribe in the production of 2‐celled propagules. Observations on the germination of the “monosporangia” ofMazoyerella arachnoideaandMonosporusspp. indicate that they are analagous to the propagules ofDeucalionandAnisoschizus.The nature of these propagules and their role in recycling the parent plant are discussed and contrasted with true monosporangia. It is recommended thatMonosporusbe maintained as a form genus containing representatives from more than one tribe, as exemplified by plants from Lord Howe I. provisionally identified asM. indicusBoergesen which have both prostrate and erect, as opposed to onl

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03171.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe timing of replication and division of theChlamydomonasEhrenberg nucleus in the vegetative cell cycle and at gametogenesis was examined, using fluorescence microspectrophotometry with two fluorochromes, mithramycin and 4′,6‐diamidino‐2‐phenylindole (DAPI). Under appropriate conditions, these bind specifically to DNA, and the fluorescence of the DNA fluorochrome complex is a quantitative measure of the DNA content. The alga is a haplont, which produces 2ndaughter cells at the time of vegetative reproduction; cytokinesis and daughter cell release lag behind karyokinesis. No nucleus was found to contain more than the 2c quantity of DNA. Hence daughter cell production proceeds by doubling of the nuclear DNA followed by karyokinesis, in a repetitive sequence. As reported previously forC. reinhardtiiDangeard, the gametes ofC. moewusiiGerloff contain the 1c amount of nuclear DNA. Several conflicting interpretations of the cell cycle sequence proposed in the literature were r

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03172.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTLynx Creek, a small intermittent creek in the Bradshaw Mountains of Arizona, is subjected to drainage from an abandoned copper mine. The mine‐drainage decreases the pH of the Creek about three units and greatly increases sulfate and heavy metal concentrations. Chemical recovery of the Creek occurs downstream through precipitation of metal hydroxides and dilution by tributaries. Changes in Creek chemistry are accompanied by changes in algal flora. Above the mine and downstream after substantial recovery, the flora is dominated byTribonema affine4, Achnanthesspp., andSynedra ulnaand several zygnematacean species. In the mine seep entering the Creek and in the Creek just below the seep the flora is reduced in species richness and dominated in abundance byMicrothamnion kuetzingianumandEunotia tenell

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03173.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe effect of temperature on the silicon limited growth and nutrient kinetics ofStephanodiscus minutusGrun. was examined using batch and semicontinuous culture methods. Short‐term batch culture methods gave maximum growth rates which were essentially constant over the temperature range of 10° to 20°C (μ3= 0.71–0.80 d−1). The half‐saturation constant for growth (Ks) was significantly lowest at 10°C (Ks= 0.31 μM Si; 0.22–0.41), and higher at both 15°C (Ks= 1.03 μM Si; 0.68–1.47) and 20°C (Ks= 0.88 μM Si; 0.60–1.22). Two methods were used to evaluate the semicontinuous experiments. The Droop relationship showed that the minimum cell quota was about 1.50 × 10−7nmol Si cell−1, but there was much overlap in the results at all three temperatures. The Monod growth relationship for the semicontinuous experiments gave estimates of Kswhich were lowest at 15°C (Ks= 0.12 μM Si), and higher at 10°C (Ks= 0.68 μM Si) and 20°C (Ks= 1.24 μM Si), although 95% confidence intervals overlapped. The maximum growth rate estimates for the semicontinuous experiments were similar at 10° and 15°, and higher at 20°C, but the number of points used in making the calculations makes the results less reliable than those from batch cultures. Generally, there were no consistent significant differences in the silicon limited growth of S. minutus over the temperature range studied. Our values of Ksfor S. minutus are the lowest recorded for a freshwater diatom, and are consistent with the distribution of this species in nature. Generally, this species becomes abundant in areas with high phosphorus loading and very low silicon levels (low Si:P loading rates). Stephanodiscus species are also fossil indicators of eut

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03174.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTLight intensity and temperature interactions have a complex effect on the physiological process rates of the filamentous bluegreen algaAnabaena variabilisKütz. The optimum temperature for photosynthesis increased with increasing light intensity from 10°C at 42 μE·m−2·s−1to 35°C at 562 μE·m−2·s−1. The light saturation parameter, IK, increased with increasing temperatures. The maximum photosynthetic rate (2.0 g C·g dry wt.−1·d−1) occurred at 35°C and 564 μE·m−2·s−1. At 15°C, the maximum rate was 1.25 g C·g dry wt.−1·d−1at 332 μE·m−2·s−1. The dark respiration rate increased exponentially with temperature. Under favorable conditions of light intensity and temperature the percent of extracellular release of dissolved organic carbon was less than 5% of the total C fixed. This release increased to nearly 40% under combinations of low light intensity and high temperature. A mathematical model was developed to simulate the interaction of light intensity and temperature on photosynthetic rate. The interactive effects were represented by making the light‐s

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03175.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTScanning electron microscopy of intergenicula in members of the subfamily Corallinoideae reveals two distinctive surface morphologies: a Corallina‐type (C‐type) with round to irregular cell outlines and round trichocyte bases, and aJania‐type (J‐type) with elongate, polygonal cell outlines and elongate trichocyte bases with excentric pores. The surface results from the calcified lateral walls of the epithallial cells projecting up from around collapsed protoplasts. Since J‐type surfaces and trichocytes only occur in unequivocal members of the tribe Janieae—especially the generaJaniaandHaliptilon, the presence of J‐type surfaces in questionable members ofCorallinareveals that they in fact belong toHaliptilon.Thus the two surface types clarify previously difficult taxonomic distinctions betweenHaliptilonandCorallinaand allow identification to genus from purely vegetative material. Seventeen new combinations inHaliptilonare proposed. These results have considerable biogeographic implications with tropical species found to belong toHaliptilon, andCorallinasensu stricto being recognized primarily as a temperate and col

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03176.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTShort‐term (within 5 min) and long‐term (≤2 h) rates of nitrate uptake were determined for the marine diatoms,Nitschiella longissima (Cleve), Skeletonema costatum(Greville) Cleve andAsterionella japonica(Cleve). Pigment levels, cell carbon, nitrogen and cell volume were also determined for cells in the logarithmic and stationary phases of growth. For each species, one clone isolated from oligotrophic coastal water and one clone isolated from eutrophic coastal water were compared. Long‐term NO3−uptake typically followed saturation kinetics describable by the Michaelis‐Menten expression. Under experimental conditions, half‐saturation constants ranged from 0.6 to 2.2 μM NO3−. Generally, the oligotrophic clones had lower Ks and Vmax(on a per cell basis) than their eutrophic counterparts, though this was only statistically significant in one pair of clones. Eutrophic and oligotrophic clones also differed in their short‐term response to nutrient addition; oligotrophic clones showed greatest rate of uptake at the lowest nitrate addition while uptake by eutrophic clones increased with increasing nitrate concentration. However, all clones had very similar Vmaxvalues expressed on a dry weight basis. Under N‐starvation, cellular C and pigment levels (and N to a lesser extent) generally declined more in eutrophic than in oligotrophic clones. While the differences between inshore and offshore clones were not great, the results are consistent with the hypothesis that eutrophic waters support algae which grow faster and are less conservative biochemically than cells in

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03177.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe ultraplanktonic green algaMonoraphidium contortumKorm. in Lake Tahoe (California‐Nevada) demonstrated several ecological and physiological attributes of a genetically adapted shade species.Monoraphidium contortumachieved maximum biomass during deep mixing in winter when light availability was at a minimum. During stratification it was found in maximum abundance in the deep euphotic region, 100–150 m. This species was also distributed through the deep aphotic zone where, despite prolonged darkness, it remained capable of immediate photosynthesis when re‐exposed to light levels in the euphotic zone. The spirally twisted cells were grazed by two calanoid copepods in Lake Tahoe as readily as much larger‐celled phytoplankton species of less complex morphology. Slow growth rates in combination with high susceptibility to copepod grazing may effectively excludeM. contortumfrom the upper 75 m, where it was rarely recorded. In culture it showed a marked incapacity to adjust to ‘sun’ conditions but was well adapted to low light regimes. Under a wide range of irradiances, photochemical capacity, photosynthetic capacity and growth rates were low, but cellular pigment content remained high. The ratio of Pmaxto respiration was at the lower end of the range for shade plants. Genetically distinct sun and shade populations of phytoplankton may play a determining role in major shifts of community structure over depth and time in

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03178.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTSporophytes ofMacrocystis pyrifera(L.) C. A. Agardh of various stages of growth were studied by light microscopy to determine the initiation and ontogeny of secretory cells and the accompanying duct system. Secretory cells are initiated by asymmetric, periclinal divisions of meristoderm cells; subsequent mitoses increase the number of secretory cells associated with each duct. Duct formation occurs by schizogeny of anticlinal cell walls adjacent to the site of secretory cell initiation. Differences in distribution and structure of the duct system occur in various parts of the sporophyte. The duct system does not have openings directly to the sporophyte surface. Histochemical techniques showed that the duct contents are mostly sulfated polysaccharides with perhaps some lipid.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03179.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTGrowth rates and cell volumes ofCeratium furcaEhrenberg andGonyaulax polyedraStein were determined during the log phase of growth in cultures which had been extensively adapted to one of three temperatures and five irradiances. At each temperature, curves for the growth rate vs. irradiance for both species had light‐limited and light‐saturated regions. Three properties of these curves characterized the response of each species to temperature: the light‐saturated growth rate, the irradiance at which growth became light‐saturated and the compensation irradiance for growth. For both species, the first two properties generally decreased with declining growth temperature, while the compensation irradiance declined forCeratiumbut had a V‐shaped response pattern forGonyaulax.The light‐saturated growth rates were generally higher forCeratiumthan forGonyaulax, while the irradiance at which growth became saturated and the compensation irradiance were lower forCeratium.The changes in cell volume associated with the irradiance and temperature of growth were very different forCeratiumandGonyaulax.The cell size ofGonyaulaxincreased as irradiance and temperature decreased, while cell volumes ofCeratiumdid not change with temperature but were smallest at the highest and lowest growth irradiances. In general, the growth rate patterns were similar forCeratiumandGonyaulax, while those for cell size were different. The maximum growth rate, the irradiance at which growth became saturated, the compensation irradiance, and the cell volume all showed thatCeratiumgrew at the same rate or faster thanGonyaulaxover the entire range of irradiances and temperatur

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1982.tb03180.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY