Delayed light action spectra of several algae in visible and ultraviolet light

Action spectra for delayed light production by several algae were determined from 250 to 750 mµ incident light. In the visible portion of the spectrum the action spectra resemble those reported by previous workers for photosynthesis and light emission. Blue-green algae had a maximum at 620 mµ, red algae at 550 mµ, whereas green and brown algae have action spectra corresponding to chlorophyll and carotenoid absorption. In the ultraviolet portion of the spectrum delayed light is emitted by algae down to 250 mµ incident light. The action spectra of the different algae are not alike in the ultraviolet portion of the spectrum. This indicates that pigments other than chlorophyll must be sensitizing or shielding the algae in the ultraviolet region.     

Photosynthetic electron transport in thylakoid preparations from two marine red algae (Rhodophyta).

Thylakoid membrane preparations active in photosynthetic electron transport have been obtained from two marine red algae, Griffithsia monilis and Anotrichium tenue. High concentrations (0.5-1.0 M) of salts such as phosphate, citrate, succinate and tartrate stabilized functional binding of phycobilisomes to the membrane and also stabilized Photosystem II-catalysed electron-transport activity. High concentrations (1.0 M) of chloride and nitrate, or 30 mM-Tricine/NaOH buffer (pH 7.2) in the absence of salts, detached phycobilisomes and inhibited electron transport through Photosystem II. The O2-evolving system was identified as the electron-transport chain component that was inhibited under these conditions. Washing membranes with buffers containing 1.0-1.5 M-sorbitol and 5-50 mM concentrations of various salts removed the outer part of the phycobilisome but retained 30-70% of the allophycocyanin 'core' of the phycobilisome. These preparations were 30-70% active in O2 evolution compared with unwashed membranes. In the sensitivity of their O2-evolving apparatus to the composition of the medium in vitro, the red algae resembled blue-green algae and differed from other eukaryotic algae and higher plants. It is suggested that an environment of structured water may be essential for the functional integrity of Photosystem II in biliprotein-containing algae.     

Antitumor activity of marine algae

Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga Enteromorpha prolifera (51.7%). Five brown and four red algae showed appreciable antitumor activity against Meth-A fibrosarcoma. To identify specific molecules with antitumor activity, 15 kinds of polysaccharide preparations of seaweed origin and 24 kinds of lipid fractions extracted from various seaweeds were tested. Appreciable inhibition of Ehrlich carcinoma was found for fucoidan preparations from Undaria pinnatifida and Sargassum ringgoldianum, for carrageenans and for porphyran. Several glycolipid and phospholipid fractions from brown and red algae were effective against Meth-A fibrosarcoma.     

Biotic interactions of marine algae

Marine algae encompass lineages that diverged about one billion years ago. Recent results suggest that they feature natural immunity traits that are conserved, as well as others that appear to be phylum- or environment-specific. In particular, marine plants resemble terrestrial plants and animals in their basic mechanisms for pathogen recognition and signaling, suggesting that these essential cell functions arose in the sea. Specific traits are based on the synthesis of unique secondary defense metabolites, often making use of the variety of halides found in the sea.     

The marine algae of Orkney

Six species are described and compared with related algae. All were isolated in culture from terrestrial habitats on Signy Island, South Orkney Islands, Antarctica. They are: Botrydiopsis constricta sp. nov. (Mischococcales, Xanthophyceae), Heterothrix antarctica sp. nov. (Tribonematales, Xanthophyceae), Sphaerocystis oleifera sp. nov. (Chlorococcales, Chlorophyceae), Sphaerocystis signiensis sp. nov., Sphaerocystis bilobata sp. nov. and Fottea pyrenoidosa sp. nov. (Ulothricales, Chlorophyceae).     

The production of antimicrobial compounds by British marine algae I. Antibiotic-producing marine algae

Using five species of bacteria as the test organisms, 151 species of British marine algae have been screened for the production of antibiotics. Of these, Asparagopsis armata, Bonnemaisonia asparagoides, Bonnemaisonia hamifera, Chondrus crispus, Dilsea carnosa, Gloiosiphonia capillaris, Sphondylothamnion multifidum, Desmarestia aculeata, Desmarestia ligulata, Laminaria digitata, Dictyopteris membranacea, Dictyota dichotoma, Halidrys siliquosa and most members of the family Rhodomelaceae appear to possess outstanding antibacterial properties. Although the production of antibiotics would appear to be a characteristic of several families, it has not been possible to establish any major correlation between taxonomy and antibiotic production. In the case of two closely related and morphologically similar species, Chondrus crispus and Gigartina stellata, the former possesses considerable degrees of antimicrobial activity whilst the latter exhibits no such activity. The results also indicate that the production of antibiotics by the algae is affected by the season of the year.     

Photosynthetic action spectra of the energy storage in bundle sheath cells of Zea mays

Photosynthetic action spectra (Formula: see text), (Carpentier, R., Larue, B. and Leblanc, R. (1984) Arch. Biochem. Biophys. 228, 534-543.), from 400 to 750 nm were studied in bundle sheath cells of maize. Photosynthetic action spectra in the presence of 10 mM ascorbate or 4 mM ribose-5-phosphate were increased and shifted through all the spectra. After the addition of 10 microM DCMU photosynthetic action spectra were remarkably diminished. On the basis of these results we suggest that the role of PSII in BS chloroplasts will be to prevent the overoxidation of PSI. It appears that in addition to PSII some endogen electron donor may regulate the PSI activity in bundle sheath cells.     

Glutamate agonists from marine algae

The occurrence of three glutamate agonists — glutamic acid, D-homocysteic acid and kainic acid — in a spontaneous mutant of Palmaria palmata is reported. Glutamic acid and D-homocysteic acid, but not kainic acid, were found in the wild-type plant. The closely related glutamate agonist, domoic acid, was found in the red alga Chondria baileyana and in the diatom Nitzschia pungens forma multiseries. In the diatom, domoic acid can build up to high levels in excess of 3% (dry wt.), making N. pungens a potential commercial source of this neuroactive amino acid. Information is also presented on the distribution, chemistry and biological activity of neuroactive amino acids from algae, and a possible biogenic relationship among kainoid metabolites is discussed. author for correspondence     

Photosynthetic efficiency of marine plants

Multicellular marine plants were collected from their natural habitats and the quantum efficiency of their photosynthesis was determined in the laboratory in five narrow wave length bands in the visible spectrum. The results along with estimates of the relative absorption by the various plastid pigments show a fairly uniform efficiency of 0.08 molecules O₂ per absorbed quantum for (a) chlorophyll of one flowering plant, green algae, and brown algae, (b) fucoxanthol and other carotenoids of brown algae, and (c) the phycobilin pigments phycocyanin and phycoerythrin of red algae. The carotenoids of green algae are sometimes less efficient while those of red algae are largely or entirely inactive. Chlorophyll a of red algae is about one-half as efficient (_o2 = 0.04) as either the phycobilins, or the chlorophyll of most other plants. These results as well as those of high intensity and of fluorescence experiments are consistent with a mechanism in which about half the chlorophyll is inactive while the other half is fully active and is an intermediate in phycoerythrin- and phycocyanin-sensitized photosynthesis.     

Photosynthetic action spectra and adaptation to spectral light distribution in a benthic cyanobacterial mat

We studied adaptation to spectral light distribution in undisturbed benthic communities of cyanobacterial mats growing in hypersaline ponds at Guerrero Negro, Baja California, Mexico. Microscale measurements of oxygen photosynthesis and action spectra were performed with microelectrodes; spectral radiance was measured with fiber-optic microprobes. The spatial resolution of all measurements was 0.1 mm, and the spectral resolution was 10 to 15 nm. Light attenuation spectra showed absorption predominantly by chlorophyll a (Chl a) (430 and 670 nm), phycocyanin (620 nm), and carotenoids (440 to 500 nm). Blue light (450 nm) was attenuated 10-fold more strongly than red light (600 nm). The action spectra of the surface film of diatoms accordingly showed activity over the whole spectrum, with maxima for Chl a and carotenoids. The underlying dense Microcoleus population showed almost exclusively activity dependent upon light harvesting by phycobilins at 550 to 660 nm. Maximum activity was at 580 and 650 nm, indicating absorption by phycoerythrin and phycocyanin as well as by allophycocyanin. Very little Chl a-dependent activity could be detected in the cyanobacterial action spectrum, even with additional 600-nm light to excite photosystem II. The depth distribution of photosynthesis showed detectable activity down to a depth of 0.8 to 2.5 mm, where the downwelling radiant flux at 600 nm was reduced to 0.2 to 0.6% of the surface flux.     

New records of Malaysian marine algae

Checklists of the marine algae of Malaysia have been published. The last checklist included the marine algae of Singapore. The checklist recorded 212 taxa for the region. This paper lists an additional 7 taxa of Chlorophyta, 18 taxa of Rhodophyta and 5 taxa of Phaeophyta, which had been left out of the last checklist. These include marine algae from Pulau Pinang, Pulau Redang and Pulau Sibu. In addition, new records of Cyanophyta (2 species), Chlorophyta (4 species), Rhodophyta (10 species) and Phaeophyta (3 species) are reported.     

Relationship between action spectra for chlorophyll a fluorescence and photosynthetic O2 evolution in algae

Relative excitation spectra of chlorophyll a fluorescence areshown to be very close to relative action spectra of photosystemII O₂ evolution in seven micro- and macro-algae of five phyla.The conditions under which this correspondence should hold,based on theoretical considerations, and the applications ofthis correspondence to interpretation of fluorescence excitationspectra of chlorophyll a from natural populations are discussed.The spectra presented are interpreted in relation to the light-harvestingpigments and their association with the two photosystems.     

Ultrastructure and phototactic action spectra of two genera of cryptophyte flagellate algae,Cryptomonas and Chroomonas

Summary A comparative action spectroscopical study was made on phototaxis in two genera of cryptomonads (cryptophyte flagellate algae), namely,Cryptomonas (rostratiformis) andChroomonas (nordstedtii andcoeruled). The two genera differ in their characteristic phycobilin pigmentation and, among three species, onlyChroomonas coerulea possesses an eyespot. The two species with no eyespot,Cryptomonas rostratiformis andChroomonas nordstedtii, exhibited positive phototaxis, showing very similar action spectra characterized by a broad band in the region from 450 nm to 650 nm, with an action maximum at about 560 nm; these features are essentially the same as those observed previously forCryptomonas strain CR-1. InCryptomonas rostratiformis, a small peak was also found at 280 nm in the UV-B/C region.Chroomonas coerulea, with eyespot, did not exhibit distinct positive phototaxis in a wide spectral region at any given, even very low, light intensity, but exhibited negative phototaxis of spectral sensitivity maximal at 400–450 nm. These results indicate that the positive phototaxis ofCryptomonas (rostratiformis and CR-1) andChroomonas nordstedtii is mediated by the same, yet unidentified photoreceptor(s).Chroomonas nordstedtii, possessing no phycoerythrin absorbing at 545 nm, also exhibits positive phototaxis at ca. 560 nm, and this result disfavors the so far proposed possibility that the positive phototaxis of the cryptophytes may be mediated by phycobilin pigments. On the other hand, the spectral characteristics of negative phototaxis ofChroomonas coerulea can possibly be ascribed to the presence of an eyespot.     

The distribution of benthic marine algae

Hitherto only gametangial and carposporangial phases of Thuretellopsis peggiana Kylin have been reported. A study of this rare member of the Dumontiaceae (Cryptonemiales) in culture has disclosed the existence of an encrusting tetrasporangial phase, previously unknown, whilst the life history has been shown to be of the ‘Bonnemaisonia’ type.     

Antibiotic activity of lectins from marine algae against marine vibrios

Saline and aqueous ethanol extracts of marine algae and the lectins from two red algal species were assayed for their antibiotic activity against marine vibrios. Experimental studies were also carried out on the influence of environmental factors on such activity, using batch cultures. The results indicated that many of the saline extracts of the algal species were active and that the activity was selective against those vibrios assayed. The algal extracts were active against Vibrio pelagius and the fish pathogen V. vulnificus, but inactive against V. neresis. Algal lectins from Eucheuma serra (ESA) and Galaxaura marginata (GMA) strongly inhibited V. vulnificus but were inactive against the other two vibrios. The antibacterial activity of algal extracts was inhibited by pretreatment with various sugars and glycoprotein. Extracts of the two red algae, E. serra and Pterocladia capillacea, in saline and aqueous ethanol, inhibited markedly the growth rate of V. vulnificus at very low concentrations. Culture results indicated that metabolites active against V. vulnificus were invariably produced in P. capillacea over a wide range of temperature, light intensity, and nutritional conditions. Enhanced antibacterial activity occurred when P. capillacea was grown under higher irradiance, severe nutrient stress and moderate temperature (20 °C), reflecting the specific antibiotic characteristics of this alga. The strong antibiotic activity of lectins towards fish pathogenic bacteria reveals one of the important roles played by algal lectins, as well as the potential high economic value of those marine algae assayed for aquaculture and for biomedical purposes.     

Photosynthetic action spectra and adaptation to spectral light distribution in a benthic cyanobacterial mat.

We studied adaptation to spectral light distribution in undisturbed benthic communities of cyanobacterial mats growing in hypersaline ponds at Guerrero Negro, Baja California, Mexico. Microscale measurements of oxygen photosynthesis and action spectra were performed with microelectrodes; spectral radiance was measured with fiber-optic microprobes. The spatial resolution of all measurements was 0.1 mm, and the spectral resolution was 10 to 15 nm. Light attenuation spectra showed absorption predominantly by chlorophyll a (Chl a) (430 and 670 nm), phycocyanin (620 nm), and carotenoids (440 to 500 nm). Blue light (450 nm) was attenuated 10-fold more strongly than red light (600 nm). The action spectra of the surface film of diatoms accordingly showed activity over the whole spectrum, with maxima for Chl a and carotenoids. The underlying dense Microcoleus population showed almost exclusively activity dependent upon light harvesting by phycobilins at 550 to 660 nm. Maximum activity was at 580 and 650 nm, indicating absorption by phycoerythrin and phycocyanin as well as by allophycocyanin. Very little Chl a-dependent activity could be detected in the cyanobacterial action spectrum, even with additional 600-nm light to excite photosystem II. The depth distribution of photosynthesis showed detectable activity down to a depth of 0.8 to 2.5 mm, where the downwelling radiant flux at 600 nm was reduced to 0.2 to 0.6% of the surface flux.