Effects of temperature, irradiance and photoperiod on growth and pigment content in some freshwater red algae in culture

The responses of relative growth rate (% day-1) and pigment content (chlorophyll a, phycocyanin and phycoerythrin) to temperature, irradiance and photoperiod were analyzed in culture in seven freshwater red algae: Audouinella hermannii (Roth) Duby, Audouinella pygmaea (Kützing) Weber-van Bosse, Batrachospermum ambiguum Montagne, Batrachospermum delicatulum (Skuja) Necchi et Entwisle, 'Chantransia' stages of B. delicatulum and Batrachospermum macrosporum Montagne and Compsopogon coeruleus (C. Agardh) Montagne. Experimental conditions included temperatures of 10, 15, 20 and 25°C and low and high irradiances (65 and 300 μmol photons m-2 s-1, respectively). Long and short day lengths (16:8 and 8:16 LD cycles) were also applied at the two irradiances. Growth effects of temperature and irradiance were evident in most algae tested, and there were significant interactions among treatments. Most freshwater red algae had the best growth under low irradiance, confirming the preference of freshwater red algae for low light regimens. In general there was highest growth rate in long days and low irradiance. Growth optima in relation to temperature were species-specific and also varied between low and high irradiances for the same alga. The most significant differences in pigment content were related to temperature, whereas few significant differences could be attributed to variation in irradiance and photoperiod or interactions among the three parameters. The responses were species-specific and also differed for pigments in distinct temperatures, irradiances and photoperiods in the same alga. Phycocyanin was generally more concentrated than phycoerythrin and phycobiliproteins were more concentrated than chlorophyll a. The highest total pigment contents were found in two species typical of shaded habitats: A. hermannii and C. coeruleus. The expected inverse relationship of pigment with irradiance was observed only in C. coeruleus. In general, the most favorable conditions for growth were not coincident with those with highest pigment contents.

Photoacclimation in three species of freshwater red algae

Three freshwater Rhodophyta species (Audouinella eugenea, A. hermannii and Compsopogon coeruleus) were tested as to their responses (photosynthesis, growth and pigment concentration) to two irradiances (low light, LL, 65 μmol m -2 s-1 and high light, HL, 300 μmol m-2 s-1) and two periods (short time, ST, 4 d, and long time, LT, 28 d). Higher growth rates were consistently observed at LL but significant differences were observed only for A. hermannii. Higher values of photoinhibition at LL were found for the three species, which is consistent with the dynamic photoinhibition as a reversible photoprotective mechanism against high irradiance. Light-induced decreases of effective quantum yield (EQY) were observed in the three species consisting of pronounced decreases from LL to HL. Rapid increases of non-photochemical quenching (NPQ) were observed mainly at LL, indicating energy dissipation by reaction centers. Results revealed distinct photoacclimation strategies to deal with high irradiances: the two Audouinella species had only characteristics of shade-adapted algae: acclimation by changes of size of photosy stem units (PSU) under LT and by PSU number under ST; higher values of the photoinhibition parameter (β) and NPQ, and lower values of EQY at LL; higher recovery capacity of potential quantum yield (PQY) at LL and under ST; highly significant positive correlation of electron transport rate (ETR) with NPQ. In addition, C. coeruleus mixed some characteristics of sun-adapted algae: acclimation by changes of PSU number under LT and by PSU size under ST; higher recovery capacity of EQY than the other two species; weak or no correlation of ETR with NPQ. Thus, these characteristics indicate that C. coeruleus cope with high irradiances more efficiently than the Audouinella species.

Identification of quinolactin alkaloids from fungi associated to Brazilian red algae Dichotomaria marginata by LC-PDA-MS and LC-MSn

Fungi isolated from marine organisms have been shown to produce several interesting secondary metabolites with important biological activities. Such chemical diversity may be associated to environmental stress conditions and may represent an important source of NCE for bioprospection. Quinolactins belong to a rare fungi-alkaloid class with a unique N-methyl-quinolone moiety fused to a lactam ring and present several bioactivities1. Fungi strain Dm1 was isolated from red alga Dichotomaria marginata, collected from Brazil SE coast, and was grown in sterile rice solid media at 26oC 2, which was then extracted with MeOH. The MeCN fr. from the MeOH extract was chromatographed over Sephadex LH-20 and fr. 4 afforded quinolactin (QL) alkaloids B1, B2 and A, whereas fr. 5 afforded quinolactin D1 after purification by HPLC-DAD. Structural determination of pure compounds was based on HRMS, UV, and NMR spectral analyses, in addition to comparison with literature data and Antimarin® databank. UV data indicated the presence of similar chromophores with λmax at ca. 247 and 320nm. HRMS and tandem MS analyses using both negative and positive ion modes for the isolated compounds indicated their molecular formula and structural features, as for QL B1: C15H16O2N2 [M+H 257], which showed one fragment at m/z 214 [-CHNO]; QL B2: C15H16O3N2 [M+H 273], with product ions at m/z 230 [-CHNO.] and m/z 186 [-C4H9NO.]; for QL A: C16H18N2O2 [M+H 271], which presented one ion at m/z 214, due to loss of fragment (-C4H9) from the molecular ion; and for QL D1: C16H18N2O3 [M+H 287], with product ions at m/z 186 [-CHNO] and m/z 230 [-C4H9]. Such data suggested fragmentation proposals, e.g. for Quinolactin B1 (Fig. 1), which confirmed the structures of the isolated quinolactins, and may represent an important contribution for the sustainable exploration of marine biodiversity.

Photosynthetic characteristics of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Daily dynamics of photosynthesis of the freshwater red alga Sirodotia delicatula (Batrachospermales, Rhodophyta)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of a novel freshwater gigartinalean red alga from Belize, with a description of Sterrocladia belizeana sp nov (Rhodophyta)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Heydrichia (?) poignantii, sp nov (Sporolithaceae, Sporolithales, Rhodophyta), a 100 million year old fossil coralline red alga from north-eastern Brazil, and a new Hauterivian record of Sporolithon from Switzerland

Fossil specimens of Heydrichia (?) poignantii, sp. nov. (Sporolithaceae, Sporolithales, Rhodophyta), representing the first confirmation of the genus in the fossil record, were discovered in thin sections of Albian limestones from the Riachuelo Formation, Sergipe Basin, and in thin sections of Albian -Cenomanian limestones from the Ponta do Mel Formation, Potiguar Basin in north-eastern Brazil. A detailed morphological-anatomical account of the species is provided, and its placement in Heydrichia is discussed in relation to current classification proposals. Comparisons with the four other known species of the genus, all non-fossil, show that H. poignantii is the only known species of Heydrichia in which thalli are encrusting to sparsely warty to horizontally layered with overlapping lamellate branches that commonly appear variously curved or arched, and in which thalli have sporangial complexes that become buried in the thallus. The evolutionary history of Heydrichia remains uncertain, but available data suggest that the genus may have diverged from the sporolithacean genus Sporolithon, known as early as Hauterivian times (c. 129.4-132.9 +/- 1 Ma) from Spain (and newly reported here from Switzerland), or it may have arisen from a graticulacean alga such as Graticula, dating from mid-Silurian times (c. 427-435 Ma). Current data also suggest that Heydrichia is more likely to have arrived in Brazil from Central Atlantic waters than from higher latitude South Atlantic waters. This implies that currently living species in southern Africa probably arose later from ancestors further equatorward in the South Atlantic, although confirming studies are needed. All non-fossil species of Heydrichia are known only from the southern hemisphere.

Effects of Low Molecular Weight Sulfated Galactan Fragments From Botryocladia Occidentalis on the Pharmacological and Enzymatic Activity of Spla2 From Crotalus Durissus Cascavella

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Distribution of Rhodophyta in streams from São Paulo State, southeastern Brazil

Distribution of Rhodophyta was investigated in 172 stream segments, which were sampled from May to October in 1992-1993 and 1996-1997 in six natural regions (parts of biomes or geological areas) of São Paulo State, southeastern Brazil. Red algae occurred in 60.5 % of stream segments sampled, a high frequency in comparison with other major surveys in the world (18-65 %). 17 species of freshwater red algae were found, of which the most widespread was Batrachospermum delicatulum occurring in 17 sites of five regions. The proportion of morphological types was as follows: gelatinous filaments (62.5 %), free filaments (19 %), tufts (12.5 %) and crusts (6 %); all but free filaments can be considered as having mechanisms to tolerate stress provoked by current velocity. No significant difference was found between the frequency distributions of variables measured for all streams and for those with red algae. Rhodophyta occurred under the following conditions (means): temperature (19.0 degrees C), current velocity (48 cm s(-1)), specific conductance (74 mu S cm(-1)), turbidity (8 NTU), oxygen (67.3 %) and pH (6.9 +/- 0.7). on the basis of species composition among the regions, the following patterns were evident: 1) the number of red algal species per region ranged from 1 to 10; 2) the highest proportion of sites with red algae (65-73 %) was found in hard water regions and in Atlantic rainforest, whereas the lowest (50 %) was found in tropical rainforest; 3) more than half of the species were exclusive from a single region, whereas the higher proportion of exclusive species was in the subtropical rainforest (50 %). No combination of stream variables was clearly associated with the occurrence of red algae for the regions as a whole. Species composition for streams and rivers of São Paulo State revealed higher similarities with other tropical regions and had few species in common with freshwater red algal floras of other continents.

SYSTEMATICS of THE BATRACHOSPERMALES (RHODOPHYTA)-A SYNTHESIS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rhodophyta de ambientes lóticos de unidades de conservação da região sul do Brasil

Species of Rhodophyta from 10 Conservation Units from the south region of Brazil were surveyed. The samplings were carried out in 105 stream reaches, consisting of 10 m length transects. The floristic survey involved 80 populations, representing three genera, Batrachospermum, Kumanoa and Hildenbrandia plus the 'Chantransia' stages. Batrachospermum was represented by five species (B. arcuatum Kylin, B. atrum (Hudson) Harvey, B. helminthosum Bory, B. keratophytum Bory and B. puiggarianum Grunow in Wittrock & Nordstedt). The genus Kumanoa was represented by K. abilii (Reis) Necchi Junior & Vis and K. ambigua (Montagne) Entwisle et al., while Hildenbrandia only by H. angolensis W.West & G.S.West. Our results confirm Batachospermum as the best represented genus, in terms of species number, among freshwater Rhdophyta. B. arcuatum was a new record for the south region of Brazil, thus extending its austral distribution range.

Growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of Hypnea musciformis (Rhodophyta)

The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype) collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 mu mol photons m(-2) s(-1)) but, with further increase in irradiance (from 40 to 120 mu mol photons m(-2) s(-1)), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed in temperatures of 20-25 degrees C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins. Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher photosynthetic efficiency (alpha), and lower saturation parameter (I-k) and compensation irradiance (I-c) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting pigments in red algae.

Light-related photosynthetic characteristics of freshwater rhodophytes

Photosynthetic characteristics in response to irradiance were analysed in 21 field and culture populations of thirteen freshwater red algal species applying two distinct techniques (chlorophyll fluorescence and oxygen evolution). Photosynthesis-irradiance (PI) curves indicated adaptations to low irradiances in all species analysed, essentially characterized by occurrence of photoinhibition, low values of the saturation parameter (I-k < 225 mu mol m(-2) s(-1)) and compensation irradiance (I-c < 20 mu mol m(-2) s(-1)) and relatively high values of the effective quantum yield of photosystem II (Delta F/F'(m) >= 45). These characteristics have been reported in freshwater red algae and were confirmed from data based on the two techniques, indicating they are typically shade-adapted plants. on the other hand, some species (e.g. Batrachospermum delicatulum) can tolerate high irradiances (up to 2400 mu mol m(-2) s(-1)), suggesting they have mechanisms that enable them to avoid photodarnage of the photosynthetic apparatus. One of these mechanisms is the increase in dissipation of excessive energy captured by reaction centres after exposure to continuous irradiance, as reflected by the non-photochemical quenching fluorescence parameter in dark/light induction curves. Photo-inhibition occurred in all algae tested by both techniques. Light acclimation was evident particularly in field populations, as revealed by lower values of the saturation parameter (Ik) and the compensation irradiance (I-c) and higher values of Delta F/F'(m) in algae under low irradiances (shaded or heavily shaded stream segments), and vice-versa. Forms living within the boundary layer (e.g. crusts), in a region of reduced current velocity, tended to be more shade-adapted than semi-erect plants (e.g. non-mucilaginous or mucilaginous filaments), as indicated by highest values of photosynthetic efficiency (alpha = 0.31) and effective quantum yield (Delta F/F'(m) = 0.88) under natural conditions. Higher photo- synthetic rates (P-max) for the same species or population were observed under culture than field conditions when measured with the oxygen evolution technique, whereas the opposite trend was observed using chlorophyll fluorescence. (c) 2005 Elsevier B.V. All rights reserved.

Light-related photosynthetic characteristics of lotic macroalgae

Photosynthetic characteristics in response to irradiance were analysed in 42 populations of 33 macroalgal species by two distinct techniques (chlorophyll fluorescence and oxygen evolution). Photosynthesis-irradiance (PI) curves based on the two techniques indicated adaptations to low irradiance reflected by low saturation values, high to moderate values of photosynthetic efficiency (alpha) and photoinhibition (beta), for Bacillariophyta and Rhodophyta, which suggests they are typically shade-adapted algae. In contrast, most species of Chlorophyta were reported as sun adapted algae, characterized by high values of I-k and low of alpha, and lack of or low photoinhibition. Cyanophyta and Xanthophyta were intermediate groups in terms of light adaptations. Photoinhibition was observed in variable degrees in all algal groups, under field and laboratory conditions, which confirms that it is not artificially induced by experimental conditions, but is rather a common and natural phenomenon of the lotic macroalgae. Low values of compensation irradiance (I-c) were found, which indicate that these algae can keep an autotrophic metabolism even under very low irradiances. High ratios (>2) of photosynthesis/respiration were found in most algae, which indicates a considerable net gain. These two physiological characteristics suggest that macroalgae may be important primary producers in lotic ecosystems. Saturation parameters (I-k and I-s) occurred in a relatively narrow range of irradiances (100-400 mumol photons m(-2) s(-1)), with some exceptions (higher in some filamentous green algae or lower in red algae). These parameters were way below the irradiances measured at collecting sites for most algae, which means that most of the available light energy was not photochemically converted via photosynthesis. Acclimation to ambient PAR was observed, as revealed by lower values of I-k and I-c and higher values of alpha and quantum yield in algae from shaded streams, and vice versa. Forms living within the boundary layer (crusts) showed responses of shade-adapted species and had the highest values of P-max, alpha and quantum yield, whereas the opposite trend was observed in gelatinous forms (colonies and. laments). These results suggests adaptation to the light regime rather than functional attributes related to the growth form.

Microhabitat and plant structure of Compsopogon coeruleus (Compsopogonaceae, Rhodophyta) populations in streams from São Paulo State, southeastern Brazil

Microhabitat distribution was investigated in three populations of C. coeruleus to determine the distributional patterns and their controlling factors, as well as morphometric adaptations to varying conditions on a scale of a few centimetres. Morphometric variations and their relations with physical variables (current velocity, irradiance, depth and type of substratum) revealed some particular characteristics for each population and indicate particular adaptations. However, some trends were clear: 1) larger plants (length and/or diameter) produced a higher quantity of monosporangia in the three populations; 2) plant length and diameter were positively correlated in two populations; 3) plant diameter was positively correlated with current velocity in two populations; 4) higher percent cover was associated with substrata composed of macrophytes in two populations. C. coeruleus occurred under relatively wide microhabitat conditions and had high niche width values, suggesting a tolerance to considerable variation in physical variables. These characteristics contribute to the species' wide distribution in Brazilian streams, both spatial (at distinct scales) and seasonal. (C) ADAC / Elsevier, Paris.