Antioxidant activity and mineral composition of three Mediterranean common seaweeds from Abu-Qir Bay,Egypt

Antioxidant activity and mineral composition were evaluated seasonally from spring to autumn 2010 in the three common seaweeds Ulva lactuca Linnaeus (Chlorophyta), Jania rubens (Linnaeus) J.V. Lamouroux and Pterocladia capillacea (S.G. Gmelin) Bornet (Rhodophyta). The antioxidant activity was measured with β-carotene, total phenol content and DPPH (2,2-diphenyl-1-picrylhydrazyl). Seaweeds were collected from the rocky site near Boughaz El-Maadya Abu-Qir Bay of Alexandria, Egypt. The results showed maximum increase of β-carotene in P. capillacea during summer. A significant increase in total phenolic content at P ⩽ 0.05 was found in the red alga (J. rubens) during summer. Also, U. lactuca showed the maximum antioxidant scavenging activity especially during summer. Minerals in all investigated samples were higher than those in conventional edible vegetables. Na/K ratio ranged between 0.78 and 2.4 mg/100 g, which is a favorable value. All trace metals exceeded the recommended doses by Reference Nutrient Intake (RNI). During summer season, it was found that Cu = 2.02 ± 0.13 and Cr = 0.46 ± 0.14 mg/100 g in U. lactuca and Fe had a suitable concentration (18.37 ± 0.5 mg/100 g) in P. capillacea. The studied species were rich in carotenoids, phenolic compounds, DPPH free radicals and minerals, therefore, they can be used as potential source of health food in human diets and may be of use to food industry.     

Ricerche Sull'Abscissione Nell'Olivo. I. Studio Morfogenetico Dell'Abscissione Fogliare

Abstract

Galls and regeneration in P. capillacea. – Galls arose from some cultured segments of Pterocladia capillacea in winter trough regeneration from cut-surfaces, especially at the proximal end. Bacteria were always present on the thallus and inside the old galls. They might be the agents of cecidogenesis, even though we never obtained galls in segments treated with these agents. We suggest that gall formation can be induced by bacteria only in winter, when the stimulus of natural differentiation appears to be very low.     

Bicarbonate Transport and Alkalization of the Medium by Four Species of Rhodophyta

Photosynthesis by four species of Rhodophyta: Ceramium rubrum,Ceramium tenuissimum, Gelidium crinale and Pterocladia capillaceawas optimal at 25 to 30?C and at pH 8.0 to 8.5. The measuredrates of photosynthesis exceeded the rate which could be supportedby the carbon dioxide arising from the dehydration of bicarbonatein the medium, from 2.7- to 10.9-fold at pH 8.0 and from 9-to 33.4-fold at pH 9.0, in the absence of measurable extracellularcarbonic anhydrase activity. Assays for malic enzyme and pyruvate,orthophosphate dikinase were negative, indicating that bicarbonateions are taken up by a transport system rather than by an accessorycarbon fixation pathway. When the algae were allowed to photosynthesizein an unbuffered system a DCMU (3-[3', 4'-dichlorophenyl]-1,1-dimethylurea)-sensitive alkalization of the medium was observed.This alkalization was shown to have a 1:1 stoichiometry withphotosynthetic carbon fixation. Alkalization of the medium occurredfrom 3.4 to 5.8 times the theoretical rate of supply of hydroxylions arising from the dehydration of bicarbonate. The data areconsistent with the operation of a bicarbonate transport systemin these macroalgae, in which electrical neutrality and pH balanceare maintained by hydroxyl ion efflux. A difference observedbetween the time-course of alkalization and oxygen evolutionsuggests that the transport of the two ions is not compulsorilycoupled. Key words: Bicarbonate transport, alkalization of the medium, Rhodophyta     

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.     

Local and temporal variations in essential elements and agar of the marine algaePterocladia capillacea

The concentrations of B, Ca, Co, Cu, Fe, K, Mg, Mn, Na, P, Zn and agar were determined in samples of the red alga,Pterocladia capillacea, collected during one year in three distinct locations having different hydrologic characteristics, close to the city of Arraial do Cabo, Rio de Janeiro, Brazil. Pattern recognition methods showed that, although these concentrations are subject to temporal variations, they are more dependent on the location from which the samples were collected. Algae from locations with high human activity were richer in P, B, Co, Zn and agar than those from other locations.     

Temperature responses of economically important red algae and their potential for mariculture in Brazilian waters

Data are presented on temperature responses, based onin vitro growth performance, of eight species of colloid-producing red algae; these include the five most important commercial species of agarophytes in South America. The temperature optima do not conform strictly to geographic distribution, and intolerance to high temperature is not the factor that controls the spreading of temperate species ofGracilaria to warmer areas. WithinPterocladia capillacea (Gmelin) Bornet et Thuret, populations from two distinct localities had different responses to temperature optima. Data suggest that the disjunct distribution of this species in the American Atlantic is due to its poor performance at temperatures above 26 °C. The fastest maximum growth rate was observed inHypnea cornuta (Lamouroux) J. Agardh (doubling time 2.8 d), and the slowest inP. capillacea from Cabo Frio (doubling time 50.0 d). All the species studied, including the valuable Chilean and Argentinean species ofGracilaria, could tolerate the temperature regimes of the Brazilian waters.     

Callus culture ofPterocladia capillacea (Rhodophyta) and analysis of cell wall polysaccharides

Calluses induced fromPterocladia capillacea have been kept in culture for more than three years. They exhibit a fast growth rate, owing to the release of single cells, which in turn develop into new callus. The effect of various media and culture conditions upon growth was investigated. In order to confirm the identity of the callus cells, a 0,45 mg incoculum was grown that yielded 15 g dried callus within six weeks. Polysaccharides from this material (5.5 g) were analysed by¹³C NMR spectroscopy. This produced a spectrum typical of agar and very similar to the one obtained for agar extracted fromP. capillacea plants. However, the callus agar displayed no gel-forming properties, even after alkali modification.author for correspondence     

Intrageneric differences in cystocarp structure in Gelidium and Pterocladia

Unilocular cystocarps, with ostioles opening to one frond surface, have traditionally distinguished Pterocladia from Gelidium, described as having bilocular cystocarps, with ostioles opening to both surfaces; however, unequally developed locules have been described in Pterocladia and differences in cystocarpic architecture between Pterocladia capillacea and the type species of the genus, P. lucida, have been recently found. As heterogeneity in cystocarp architecture raises questions of basic intergeneric distinction, a survey of reproductive morphology of species in both genera is presented in this study. Six morphologically-different types of cystocarps are distinguished among the five species of Pterocladia and the seven species of Gelidium examined.     

Pterocladia (Rhodophyta) and Ulva (Chlorophyta) as feed supplements for European seabass, Dicentrarchus labrax L., fry

The aim of this study was to evaluate the suitability of two marine macroalgae, Ulva lactuca (Chlorophyta) and Pterocladia capillacea (Rhodophyta), meals as a supplement to enhance the nutritional value of formulated feeds for European seabass Dicentrarchus labrax fry. Seven isoproteic (50 % crude protein), isocaloric (500 Kcal/100 g gross energy) diets containing four levels (0 or control, 5, 10, and 15 %) of either Ulva meal (UM) or Pterocladia meal (PM) were tested. Each diet was fed to triplicate groups of D. labrax fry (initial body weight, 0.23?±?0.02 g for Ulva- and 0.14?±?0.01 g for Pterocladia-fed fish), to apparent visual satiety for 8 weeks. The results indicated that feeding seabass at 5 % UM or PM level (U₅ and P₅ diets) produced the best growth, feed utilization, nutrient retention, and survival rates among all the dietary groups. Feeding fish with a 5 % PM-added diet has also improved stress response after a 5-min air exposure test, prior to the termination of the feeding trial. These findings suggest that both Pterocladia and Ulva meals could be potentially used as an additional feed component (at 5 %) for enhancement of seabass D. labrax fry performance, nutrients composition, and stress resistance especially when subjected to transportation from hatchery to weaning ponds/tanks.     

Caulerpa taxifolia in seagrass meadows: killer or opportunistic weed?

Seagrass habitats are being lost throughout the world and the invasive alga C. taxifolia has often been implicated in seagrass declines. Although C. taxifolia can impact a variety of species, evidence for its effects on seagrasses is largely correlative. This study combined observational studies and manipulative experiments done over many years to test hypotheses about effects of C. taxifolia on two Australian seagrasses, namely Posidonia australis and Zostera capricorni. Results indicated that C. taxifolia is not having adverse impacts on the coverage of these seagrasses in the sites studied. Rather, C. taxifolia appears to be an opportunist, persisting longer and its coverage being greater in previously non-vegetated sediments than amongst seagrasses. C. taxifolia co-existed with P. australis and did not cause reductions in the cover of the seagrass. Outcomes of experimental manipulations of C. taxifolia amongst Z. capriconi were less clear due to losses of Z. capriconi in all plots, regardless of the presence of C. taxifolia. It was possible that C. taxifolia may have enhanced the decline in canopy cover of Z. capricorni, but the presence of alga did not alter the final fate of Z. capricorni. There was also no evidence that long-term areal coverage of P. australis or Z. capriconi has been affected by the introduction of C. taxifolia in the embayments studied. A review of literature on effects of species of Caulerpa on seagrasses provided limited experimental evidence for negative impacts of this genus on seagrass abundance.     

Distribution and biomass assessment of macroalgae from Moroccan Strait of Gibraltar.

The taxonomic richness, population structure, biomass assessment, and geographic distribution of macroalgae were studied between May 2017 and July 2018 from the Moroccan strait of Gibraltar. The study was based on the economic, ecological and environmental interests of macroalgae on a national scale. Samples were harvested by Scuba diving. Sixty-seven species, including one recently introduced in the Strait, have been identified. They were distributed over four classes: Bangiophyceae (2 species), Florideophyceae (36 species), Phaeophyceae (17 species), and Ulvophyceae (12 species). The distribution map of the most abundant agarophytes, Gelidium attenuatum and Pterocladia capillacea, was constructed from GPS and field data using System Information Geographic software. G. attenuatum stands extended from 1 to 7 m depth, with maximum biomass at 1 m. The population analysis revealed thalli up to 15.8 cm long, with the length class 11–13 cm mostly represented. As for the population of P. capillacea, it was located from 0 to 1.50 m depth, with highest biomass at 0–0.50 m depth. Unlike Gelidium, P. capillacea stands were distributed from 5 to 12 cm, with 85% measuring between 7 and 11 cm long. The estimated total biomass of G. attenuatum and P. capillacea was 7.77 ± 3.57 t of fresh weight and distributed on two sectors: Mrisat (66.66%) and Oued-Alian (33.34%). This Finding indicates a relatively low biomass in the strait.     

Characterisation of the enigmatic,endemic red algaGelidium allanii (Gelidiales) from northern New Zealand — morphology,distribution, agar chemistry

Gelidium allanii Chapman is endemic to northern New Zealand with a highly localised distribution. This species has remained little known, having been collected from only one locality for more than 40 years. We compare this species with other New Zealand members of the Gelidiaceae, in particularGelidium caulacantheum andPterocladia capillacea, presenting new data on morphology, distribution and agar chemistry to more fully characteriseG. allanii.G. allanii possesses a very distinctive, highly pyruvated agar. New Zealand records of two Australian speciesG. australe andG. asperum are examined and it is concluded that there is no evidence for their occurrence in New Zealand.Author for correspondence     

Agar from some Hawaiian red algae

From describing the agars of Gelidiella acerosa Forssk., Gelidium pluma Loomis, G. pusillum (Stackh.) Lejolis, Gracilaria abbottiana Hoyle, G. bursapastoris (Gmelin) Silva, G. canaliculata (Kützing) Sonder, G. coronopifolia J.Ag., G. epihippisora Hoyle, Pterocladia caerulescens (Kützing) Santelices and P. capillacea (Gmelin) Born. & Thur. as found in Hawaiian samples of these species, it is concluded that the species of Gelidium and especially Pterocladia and Gelidiella may merit more consideration for usage due to their agar gel strengths.The nature of the gel from Gracilaria abbottiana suggests the generic status might well be reexamined. The agars from the Gelidiella and the other Gracilaria species should be studied further for their prospective values to the food industry other than gel strength. Mixtures of the agars from G. bursapastoris and G. coronopifolia would merit attention for the taste texture of their mixtures.     

The occurrence of Ezo epiyessoense Adey,Masaki & Akioka (Rhodophyta,Corallinaceae) in England with a summary of parasitism and endophytism in nongeniculate Corallinaceae

The parasitic, nongeniculate, coralline red alga Ezo epiyessoense (Rhodophyta, Corallinaceae) was described in 1974 by Adey, Masaki & Akioka on the basis of specimens growing on Lithophyllum yessoense in Japan. The authors considered Ezo to be an adelphoparasite because it resembled its host taxonomically in being a member of the coralline subfamily Lithophylloideae. The species had not been recorded outside Japan until the present observation in England where it was found growing on another lithophylloid species, Titanoderma pustulatum. The structure of the English material of E. epiyessoense is described and shown to closely resemble that of the type material despite its occurrence on a different host species. Tetrasporangia and trisporangia are recorded for the first time in Ezo. A summary is given of known nongeniculate coralline parasites, semi-endophytes and outgrowths.     

Resource biology of Pterocladia capillacea (Gelidiales,Rhodophyta) populations in Brazil

Pterocladia capillacea has been already exploited in Brazil and Uruguay, but exploitation was discontinued due to source depletion. Our attempts to cultivate this species in the sea, or in tanks, gave poor results. In this communication we present some ecological data as a contribution to evaluate the possibility of a production increase in natural beds on the southeast coast of Brazil.Our results show that: (i) the populations are perennial varying from 323 (i.c._0.05 = 51) to 600 (i.c._0.05 = 78) g dry weight throughout the year; (ii) horizontal distribution is affected by irradiance, with higher biomass in shaded areas and by water movement, with higher biomass in intermediate sites; (iii) vertical distribution is limited above by desiccation and below by herbivores — sea urchins removal increases cover by 20–50%; (iv) Sargassum vulgare is the main competitor for space, and its removal on areas of contact between both populations increases coverage of P. capillacea by ca 80%.     

Comparison of Ergot Alkaloid Biosynthesis Gene Clusters in Claviceps Species Indicates Loss of Late Pathway Steps in Evolution of C. fusiformis

The grass parasites Claviceps purpurea and Claviceps fusiformis produce ergot alkaloids (EA) in planta and in submerged culture. Whereas EA synthesis (EAS) in C. purpurea proceeds via clavine intermediates to lysergic acid and the complex ergopeptines, C. fusiformis produces only agroclavine and elymoclavine. In C. purpurea the EAS gene (EAS) cluster includes dmaW (encoding the first pathway step), cloA (elymoclavine oxidation to lysergic acid), and the lpsA/lpsB genes (ergopeptine formation). We analyzed the corresponding C. fusiformis EAS cluster to investigate the evolutionary basis for chemotypic differences between the Claviceps species. Other than three peptide synthetase genes (lpsC and the tandem paralogues lpsA1 and lpsA2), homologues of all C. purpurea EAS genes were identified in C. fusiformis, including homologues of lpsB and cloA, which in C. purpurea encode enzymes for steps after clavine synthesis. Rearrangement of the cluster was evident around lpsB, which is truncated in C. fusiformis. This and several frameshift mutations render CflpsB a pseudogene (CflpsB^Ψ). No obvious inactivating mutation was identified in CfcloA. All C. fusiformis EAS genes, including CflpsB^Ψ and CfcloA, were expressed in culture. Cross-complementation analyses demonstrated that CfcloA and CflpsB^Ψ were expressed in C. purpurea but did not encode functional enzymes. In contrast, CpcloA catalyzed lysergic acid biosynthesis in C. fusiformis, indicating that C. fusiformis terminates its EAS pathway at elymoclavine because the cloA gene product is inactive. We propose that the C. fusiformis EAS cluster evolved from a more complete cluster by loss of some lps genes and by rearrangements and mutations inactivating lpsB and cloA.     

First finding of the red epiphytic alga Pseudorhododiscus nipponicus Masuda, 1976 (Rhodophyta: Palmariales) in Avachinsky Gulf (Eastern Kamchatka)

The red epiphytic alga Pseudorhododiscus nipponicus Masuda (Palmariales: Rhodophysemataceae), which grows on Coccotylus truncatus (Pallas) M.J. Wynne et J.N. Heine (Rhodophyta: Phyllophoraceae), was found at Krasheninnikov Islet (Avachinsky Gulf, eastern Kamchatka) for the first time. Previously, this species was only known as endemic to Hokkaido Island (Japan). The finding of the monotypic genus Pseudorhododiscus at the coast of southeastern Kamchatka substantially extends its distribution area in the Pacific region.     

A brachylaimid trematode from marsupial mice with observations on its life cycle

A species of digenetic trematode, Brachylaime antechini (Family Brachylaimidae), is described from adult worms recovered from the intestine and rectum of two species of marsupial mice, Antechinus stuartii(10 of 56 infected) and Antechinus swainsonii (2 of 5 infected). On experimental evidence unencysted metacercariae from the kidney of a terrestrial gastropod, Strangesta capillacea, are considered to be larval stages of Brachylaime antechini. Miracidia, sporocysts and cercariae have not been recovered, but circumstantial evidence suggests that Strangesta capillacea fulfils the role of first intermediate host. Brachylaime antechini most closely resembles Brachylaime chiapensis, a parasite of deer mice in Mexico.     

Taxonomy of Ptychagnostus atavus: A key trilobite in defining a global Cambrian stage boundary

The taxonomy of Ptychagnostus atavus (Tullberg, 1880) and Ptychagnostus intermedius (Tullberg, 1880) has been confused, in part at least, because of inadequate or erroneous illustrations of specimens from syntype series. From further examination and new illustrations we conclude that those series are conspecific and that P. atavus is the senior synonym of P. intermedius. Laurentian agnostoids previously assigned to P. intermedius are reassigned to Ptychagnostus sinicus Lu, 1957. As revised, P. atavus is a common, globally distributed species in open-marine lithofacies. Clarification of its taxonomy is important because its first appearance datum (FAD) will likely define the base of a new global Cambrian stage.     

Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences for Persistence at the Edge of Their Geographic Range

Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae—shown to compete for space with corticated algae—suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.