ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02542.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTTemperature tolerances were determined for Caribbean isolates (total 31) of seaureds belonging to three distributional groups: 1) species confined to the tropical western Atlantic (Botryocladia spinulifera, Chamaedoris peniculum, Cladophoropsis sundanensis, Dictyopteris justii, Dictyurus occidentalis, Haloplegma duperreyi, and Heterosiphonia gibbesii); 2) amphi‐Atlantic species with a (sub)tropical distribution that have their northern boundary in the eastern Atlantic at the tropical Cape Verde Islands (Bryothamnion triquetrum and Ceramium nitens) or the subtropical Canary Islands (Ceratodictyon intricatum, Coelothrix irregularis, Dictyopteris delicatula, Ernodesmis verticillata, and Lophocladia trichoclados; and 3) species with an am‐phi‐Atlantic tropical to warm‐temperate distribution also occurring in the Mediterranean (Cladophoropsis membranacea, Digenea simplex, Microdictyon boergesenii, and Wurdemannia miniata). For some isolates, growth response curves and temperature requirements for reproduction were also determined. Growth occurred in the range (18)20–30° C with optimum growth rates at 25°–30°C, irrespective of distribution group. Reproduction generally occurred at (20)25°–30° C although there were some exceptions. Species were extremely stenothermal, with those restricted to the western Atlantic surviving a total range of only 10/13° C (between 18/20° and 30/33° C). Tolerance to high temperatures was correlated with vertical position in the iniertidal/subtidal zone rather than biogeography grouping. Species restricted to the subtidal were the least tolerant, with permanent survival at 30° C but not at 33°C. Tolerance to low temperatures was not different in subtidal and intertidal species but was significantly better in am phi‐Atlantic than in western Atlantic species. In the former group, damage occurred at 15°–18° C but in the latter group at 18°‐20° C. We propose that these differences in low‐temperature tolerances in Caribbean populations of species from different distribution groups reflect adaptations to glacial cold‐stress in the tropical eastern Atlantic an

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02543.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTMicroalgal pigment composition, photosynthetic characteristics, single‐cell absorption efficiency (Qa(λ)) spectra, and fluorescence‐excitation (FE) spectra were determined for platelet ice and benthic communities underlying fast ice in McMurdo Sound, Antarctica, during austral spring 1988. Measurements of spectral irradiance (E(λ)) and photosynthetically active radiation (PAR) as well as samples for particulate absorption measurements were taken directly under the congelation ice, within the platelet layer, as profiles vertically through the water column, and at the benihic surface. Light attenuation by.sea ice, algal pigments, and particulates reduced PAR reaching the platelet ice layer to 3%(9–33 fimol photons m‐2‐−s‐1) of surface values and narrowed its spectral distribution to a band between 400 and 580 nm. Attenuation by the water column further reduced PAR reaching the sea floor (28–m depth) to 0.05% of surface levels (0.35 even at absorption minima. Strong spectral flattening, a characteristic of intense pigment packaging, was also apparent in the Qa(λ)spectra for benthic algae. FE and Qa(λ)spectra were similar in shape for platelet ice algae, indicating that the efficiency at which absorbed energy wastransferred to photosystem II (PSII) was independent of wavelength. Fluorescence emission by benthic algae was greatest for the 500–560–nm excitation wavelengths, suggesting that most energy absorbed by accessory pigments was transferred to PSII. These results suggest that under ice algae employ complementary pigmentation and maximize absorption efficiency as adaptive strategies to low‐light stress. Regulating the distribution of absorbed energy between PSI and PSII may be an adaptive respon

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02544.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTWe have prevously shown that a marine chlorophyte expressed flavodoxin under iron limitation but not under other nutrient stress conditions. Here we use polyclonal antiserum raised against the diatomPhaeodactylum tricornutumBohlin to show that a similar response is observed in this species. Using our antibody, western blotting techniques, and standard colorimetric detection (4‐chloro‐1‐naphthol), we can detect at least a 25–50‐fold increase in flavodoxin in iron‐depleted compared to iron‐replete cells. In iron‐limited batch cultures ofP. tricornulum,flavodoxin accumulation was inversely proportional to growth rate and was not detectable in cultures containing initially more than 750 nm of iron. We demonstrated that the accumulation of flavodoxin under iron stress is widespread among marine diatoms and that it may be possible to use the presence or absence of flavodoxin in natural marine diatom assemblages to detect iron limitation. However, our polyclonal antisera appears to be specific for diatoms and did not cross‐react withSynechococcussp., Micromonas pusilla (Butcher) Manton et Parke, Dunaliella tertiolectaButcher, Chlorellasp., Emiliania huxleii (Lohm.) Hay et Parke, orIsochrysis galbanaParke. A reverse bioassay experiment was conducted with natural phytoplankton assemblages containing mainly diatoms from Long Island Sound and in shelf waters near Cape Hatteras, two areas not suspected to be iron‐limited. Although flavodoxin was not detectedin situin these areas, natural populations of diatoms driven into iron limitation expres.sed flavodoxin. Flavodoxin was detected in mats of the diatomRhizosolenia castracaneiCleve collected from the Equatorial Pacific during a JGOFS cruise in 1992, consistent with the hypothesis that iron may be limiting in this high‐nutrient, l

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02545.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTSpirogyraLink (1820) is an anabranched filamentous green alga that forms free‐floating mats in shallow waters. It occurs widely in static waters such as ponds and ditches, sheltered littoral areas of lakes, and stow‐flowing streams. Field observations of its seasonal distribution suggest that the 70‐μm‐wide filament form ofSpirogyrashould have a cool temperature and high irradiance optimum for net photosynthesis. Measurements of net photosynthesis and respiration were marie at 58 combinations of tight and temperature in a controlled environment facility. Optimum conditions were 25°C and 1500 μmol photons m−2s−1, at which net photosynthesis averaged 75.7 mg O2gdm−1h−1. Net photosynthesis was positive at temperatures from 5° to 35°C at most irradiances except at combinations of extremely low irradiances and high temperatures (7 and 23 μmol photons m−2s−1at 30°C and 7, 23, and 35 μmol photons m−2s−1at 35°C). Respiration rates increased with both temperature and prior irradiance. Light‐enhanced respiration rates were significantly greater than dark respiration rates following irradiances of 750 μmol photons m−2s−1or greater. Polynomials were fitted to the data to generate response surfaces; such response surfaces can be used to represent net photosynthesis and respiration in ecological models. The data indicate that the alga can tolerate the cool water and high irradiances characteristic of early spring but cannot maintain positive net photosynthesis under conditions of high temperature and low li

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02546.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe diel pattern in algal habitat shift between sediment and water was recorded above (shallow site) and below (deep site) the thermocline in a stratified, unproductive forest lake. Migrating algae were caught in funnel traps, and the net transport was calculated. Diel recruitment patterns varied temporally within site and spatially between sites. For most species, recruitment and sinking was low at the deep site during stratification. When stratification began to break down in August, the migratory activity increased at the deep site, suggesting that the stratified conditions affected algal migratory behavior. Although light obviously affected algal migration, recruitment often deviated from consistent diel patterns, indicating that simple light‐dark cycles are not sufficient to explain algal migratory patterns. Instead, the study suggests that some algal species have receptors able to detect several environmental variables, including light and variables associated with stratified conditions. Hence, some algal species, but not others, may be able to optimize resource needs by properly adjusting the timing for recruitment from the sediment surface in relation to the risk of being trapped below the euphotic zone by a thermocline not possible to penetrat

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02547.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTAcclimation of the photosynthetic apparatus to light absorbed primarily by phycobilisomes (which transfer energy predominantly to photosystem II) or absorbed by chlorophyll a (mainly present in the antenna of photosystem I) was studied in the macroalga Palmaria palmata L. In addition, the influence of blue and yellow light, exciting chlorophyll a and phycobilisomes, respectively, ivas investigated. All results were compared to a white light control. Complementary chromatic adaptation in terms of an enhanced ratio of phycoerythrin to phycocyanin under green light conditions was observed. Red light (mainly absorbed by chlorophyll a) and green light (mainly absorbed by phycobilisomes) caused an increase of the antenna system, which was not preferentially excited. Yellow and blue light led to intermediate states comparable to each other and white light. Growth was reduced under all light qualities in comparison to white light, especially under conditions preferably exciting phycobilisomes (green light‐adapted algae had a 58% lower growth rate compared to white light‐adapted algae). Red and blue light‐adapted algae showed maximal photosynthetic capacity with white light excitation and significantly lower values with green light excitation. In contrast, green and yellow light‐adapted algae exhibited comparable photosynthetic capacities at all excitation wavelengths.Low‐temperature fluorescence emission analysis showed an increase of photosystem II emission in red light‐adapted algae and a decrease in green light‐adapted algae. A small increase of photosystem I emission teas also found in green light‐adapted algae, but this was much less than the photosystem II emission increase observed in red light‐adapted algae (both compared to phycobilisome emission). Efficiency of energy transfer from phycobilisomes to photosystem II was higher in red than in green light‐adapted algae. The opposite was found for the energy transfer efficiency from phycobilisomes to photosystem I.Zeaxanthin content increased in green and blue light‐adapted algae compared to red, white, and yellow light‐adapted algae.Results are discussed in comparison to published data on unicellular red

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02548.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTBathycoccus prasinosEikrem et Throndsen exhibited a complex carotenoid distribution pattern including the carotenes β,β‐carotene (0.8% of total carotenoids) and β, ° Carotene (0.4%) and several xanthophylls. These were prasinoxanthin (49% of total carotenoids), micromonal (16%), neoxanthin (14%), uriolide (7%), violaxanthin (0.8%), 31‐dehydrouriolide (0.8%), dihydrolutein (0.1%), two partly characterized esterified carotenols (together 10%), and five minor unidentified carotenols (together 2%). The identifications were based on high‐performance liquid chromatography (HPLC), thin‐layer chromatography (TLC), visible spectroscopy (VIS), and mass spectra (MS) and in part on1H nuclear magnetic resonance (NMR), circular dichroism (CD), and chemical derivatization. The carotenoid composition ofB. prasinoswas related to that of other prasinoxanthin / uriolide / micromonal‐producing prasinophytes(Mantoniella squamata, Micromonas pusilla,andPseudoscourfieldia marina).The relative distribution of chlorophylls (w/w) were chlorophylla (chla;63%), chlb (31%), and an unknown chl c‐like chlorophyll (7%) with spectral characteristics similar to magnesium 2,4‐divinylphaeoporphyrin a, monomethyl ester, compatible with other prasinophytes. The chemosystematic data and ultrastructural characteristics for the order Mamiellales are discussed. We conclude that HPLC studies alone are insufficient for the identification and characterization of the carotenoids, including the minor carotenoids essential for biosynthetic/chemosystemat

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02549.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe unicellular green algaChlamydomonas reinhardtiiDang. displays a high capacity for salicylhydroxamic acid (SHAM)—stimulated O2consumption, mediated by extracellular peroxidaie. Addition of exogenous NADH also resulted in stimulation of O2consumption. The SHAM‐and NADH‐stimulated peroxidase activity was partially sensitive to inhibition by exogenous superoxide dismutase, ascorbate, and gentisic acid. These compounds did not inhibit O2consumption in the absence of effectors. SHAM‐and NADH‐stimulated peroxidase activity also was sensitive to inhibition by cyanide, and cyanide titration curves indicated that O2consumption by peroxidase was more cyanide‐sensitive than O2consumption by cytochrome oxidase. The differential sensitivity to cyanide was used to estimate partitioning of O2consumption between mitochondrial respiration and extracellular peroxidase. We suggest that, despite a large capacity for peroxidase‐me‐diated O2consumption, peroxidase did not consume O2at detectable rates in the absence of effectors. Therefore, in the absence of effectors, measured rates of O2consumption represented the rate of mitochondr

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02550.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTPolysiphonia paniculataMontagne is an intertidal red alga known to produce large amounts of the compound dimethylsulfoniopropionate (DMSP). Conversion of this substrate into dimethylsulfide is accomplished inP, paniculataby an enzyme called DMSP lyase (dimethylpropiothetin dethiomethyla.se (4.4.1.3)). DMSP lyase has been purified and characterized fromP. paniculata.Enzymie activity is found in two different proteins: the larger with a molecular weight of 9.26 ± 104daltons and the smaller with a molecular weight of 3.65 ± 104daltons. Specific activity of the enzyme is 526 μmols min−1mg−1for the smaller protein a nd 263 μmols min−1mg−1for the la rger protein. The Michaelis‐Menten constant (Km) is 72.8 μM ± 17.15 and the vmaxis 1.62 μmols min−1± 0.928 for the 92.6‐kDa protein. The p1 of the larger protein is 5.8 and 5.9 for the smaller protein. Interaction with cysteine protease inhibitors L‐trans‐epoxysuccinyl‐leucylamido (4‐guanidino)‐butane, dithiobis‐(2‐nitrobenzoate), orN‐ethylmaleimide inactivated enzyme activity. The presence of either magnesium or calcium with DMSP lyase enhanced activity al concentrations between 20 and 40 μM but had little effect above these levels. Addition of the divalent chelators ethylenebis(oxyethylenenitrilo) tetraacetic acid and ethylenediaminetetraacetate decreased activity of the enzyme, but activity was restored when either chelator was removed and magnes

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1995.tb02551.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY