Effect of desert soil algae on the stabilization of fine sands

Four filamentous cyanobacteria, Microcoleus vaginatus, Phormidium tenue, Scytonema javanicum (Kutz.) and Nostoc sp., and a single-celled green alga, Desmococcus olivaceus, all isolated from Shapotou (Ningxia Hui Autonomous Region of China), were batch cultured and inoculated onto unconsolidated sand in greenhouse and field experiments. Their ability to reduce wind erosion in sands was quantified by using a wind tunnel laboratory. The major factors related to cohesion of algal crusts, such as biomass, species, species combinations, bioactivity, niche, growth phase of algae, moisture, thickness of the crusts, dust accretion (including dust content and manner of dust added) and other cryptogams (lichens, fungi and mosses) were studied. The best of the five species were M. vaginatus and P. tenue, while the best mix was a blend of 80% M. vaginatus and 5% each of P. tenue, S. javanicum, Nostoc sp. and D. olivaceus. The threshold friction velocity was significantly increased by the presence of all of the cyanobacterial species, while the threshold impact velocity was notably increased only by the filamentous species. Thick crusts were less easily eroded than thin crusts, while biomass was more effective than thickness. Dust was incorporated best into Microcoleus crust when added in small amounts over time, and appeared to increase growth of the cyanobacterium as well as strengthen the cohesion of the crust. Microbial crust cohesion was mainly attributed to algal aggregation, while lichens, fungi and mosses affected more the soil structure and physico-chemical properties.

Life history characteristics of three types of females in Brachionus calyciflorus Pallas (Rotifera) fed different algae

This study describes the life history characteristics of amictic, unfertilized mictic and fertilized mictic females of the rotifer Brachionus calyciflorus cultured individually on two different algae at 0.1 mg ml(-1) food concentration and 27 degreesC. The duration of the juvenile period of amictic females was significantly shorter on Chlorella pyrenoidosa Chick than on Scenedesmus obliquus Kutz or both algae together. The duration of the juvenile period of unfertilized mictic females was significantly longer, and the number of eggs produced by amictic females was significantly larger on Chlorella pyrenoidosa than on S. obliquus. When fed the same type of alga, the duration of the juvenile period of the fertilized mictic females was the longest among the three types of females, and the durations of the reproductive period of the amictic females and the post-reproductive period of the fertilized mictic females were longer than, or equal to those of the other two types of females, respectively. The number of eggs produced by an unfertilized mictic female was the largest among the three types of females, and that of amictic females was larger than or equal to that of fertilized mictic females, depending on the type of diet.

Two-stage photo-biological production of hydrogen by marine green alga Platymonas subcordiformis

A marine green alga, Platymonas subcordiformis, was demonstrated to photobiologically evolve hydrogen (H-2) after the first stage of photosynthesis, when subjected to a two-phase incubation protocol in a second stage of H2 production: anaerobic incubation in the dark followed by the exposure to light illumination. The anaerobic incubation induced hydrogenase activity to catalyse H? evolution in the following phase of light illumination. H,) evolution strongly depended upon the duration of anaerobic incubation, deprivation of sulphur (S) from the medium and the medium pH. An optimal anaerobic incubation period of 32 h gave the maximum H2 evolution in the second phase in the absence of sulphur. Evolution of H,) was greatly enhanced by 13 times when S was deprived from the medium. This result suggests that S plays a critical role in the mediation of H-2 evolution from R subcordiformis. A 14-fold increase in H-2 production was obtained when the medium pH increased from 5 to 8; with a sharp decline at pH above eight. H-2 evolution was enhanced by 30-50% when supplementing the optimal concentrations of 25 mM acetate and 37.5 mM glucose. (C) 2003 Elsevier B.V. All rights reserved.

Defensive and Sensory Chemical Ecology of Brown Algae

The ecological interaction of brown algae are important as these macroalgae are common and often keystone members in many benthic marine communities.This review highlights their chemical interactions,particularly with potential herbivores,but also with fouling oranganisms,with potential pathogens,with each other as gametes,and with their microenvironments when they are spores.Phlorotannins,which are phenolic compounds unique to brown algae,have been studied hesvily in many of these respects and sre highlightes here.This includes recent controversy about their roles as defences against herbivory,as well as new understanding of their roles in primary cellular functions that may,in many instances,be more important than ,and which at least have to be considered in convert with,any possible ecological functions.Brown algae have also been useful models for testing theoties about the evolution of and ecological constraints on chemical defence.Furthermore,their mocroscopic motile gametes and spores have the ability to react to their chemical environments behavirourally.

Evidence for positive selection in phycoerythrin genes of red algae and cyanobacteria Prochlorococcus and Synechococcus

Because of the shortage of phycoerythrin (PE) gene sequences from rhodophytes, peBA encoding beta- and alpha-subunits of PE from three species of red algae (Ceramium boydenn, Halymenia sinensis, and Plocamium telfariae) were cloned and sequenced. Different selection forces have affected the evolution of PE lineages. 8.9 % of the codons were subject to positive selection within the PE lineages (excluding high-irradiance adapted Prochlorococcus). More than 40 % of the sites may be under positive selection, and nearly 20 % sites are weakly constraint sites in high-irradiance adapted Prochlorococcus. Sites most likely undergoing positive selection were found in the chromophore binding domains, suggesting that these sites have played important roles in environmental adaptation during PE diversification. Moreover, the heterogeneous distribution of positively selected sites along the PE gene was revealed from the comparison of low-irradiance adapted Prochlorococcus and marine Synechococcus, which firmly suggests that evolutionary patterns of PEs in these two lineages are significantly different.

Transforming kelp into a marine bioreactor

The past decade has seen the genetic engineering of various types of seaweed. To date, genetic transformation studies have been carried out in several seaweeds, including the red seaweeds Porphyra, Gracilaria, Grateloupia, Kappaphyclus and Ceramium and the green seaweed Ulva. A genetic transformation model system has been established in the most commonly cultivated seaweed, the brown seaweed Laminaria japonica (kelp), based on the transfer of technology used in land plant transformation and also by modulating the seaweed life cycle. This model showed the potential for application of transgenic kelp to the production of valuable products and an indoor cultivation system for transgenic kelp was proposed, taking into account necessary factors for bio-safety. In this review, the establishment at use of the kelp transformation model is introduced, highlighting the potential for transforming kelp into a marine bioreactor.

An efficient method for DNA isolation from red algae

A simple, inexpensive and efficient method was developed for rapid isolation of total genomic DNA from 15 red algal species. It resulted in 0.1 mug high quality DNA from 1 mg fresh algal material, with an A(260)/A(280) ratio of 1.68 - 1.90. Using this rapidly isolated DNA, the 18S ribosomal RNA genes ( rDNA) and the nuclear ribosomal DNA of the internal transcribed spacer (ITS) regions were amplified. The tested DNA was suitable for restriction endonuclease digestion, genetic marker analysis and polymerase chain reaction (PCR) amplification, and may be valid for other genetic manipulation.

Phylogenetic studies on two strains of Antarctic ice algae based on morphological and molecular characteristics

The taxonomic characterization of two strains of Antarctic ice algae, Chlamydomonas sp. ICE-L and Chlamydomonas sp. ICE-W, were analyzed on the basis of morphological and molecular traits. The results indicate that they are the same species and belong to Chlamydomonas (Chlorophyta). According to I SS rDNA and ITS-I sequences they are very close relatives of Chlamydomonas sp. Antarctic 2E9, if not identified as such. They belong to the 'monadina clade', Cd. monadina and Cm. subdivisa as the sister group, on the basis of 18S rDNA sequence. They occur in 'Chlamydomonas clade' according to rbcL sequencing and are close relatives of Cd. kuwadae. The ITS sequences of ICE-L and ICE-W are 1302 base pairs and 1300 base pairs in length, the longest Volvocales ITS sequences ever reported.

Dominant chloramphenicol-resistant bacteria and resistance genes in coastal marine waters of Jiaozhou Bay, China

Studies of abundance, diversity and distribution of antibiotic-resistant bacteria and their resistance determinants are necessary for effective prevention and control of antibiotic resistance and its dissemination, critically important for public health and environment management. In order to gain an understanding of the persistence of resistance in the absence of a specific antibiotic selective pressure, microbiological surveys were carried out to investigate chloramphenicol-resistant bacteria and the chloramphenicol acetyltransferase resistance genes in Jiaozhou Bay after chloramphenicol was banned since 1999 in China. About 0.15-6.70% cultivable bacteria were chloramphenicol resistant, and the highest abundances occurred mainly in the areas near river mouths or sewage processing plants. For the dominant resistant isolates, 14 genera and 25 species were identified, mostly being indigenous estuarine or marine bacteria. Antibiotic-resistant potential human or marine animal pathogens, such as Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Shewanella algae, were also identified. For the molecular resistance determinants, the cat I and cat III genes could be detected in some of the resistant strains, and they might have the same origins as those from clinical strains as determined via gene sequence analysis. Further investigation about the biological, environmental and anthropogenic mechanisms and their interactions that may contribute to the persistence of antibiotic-resistance in coastal marine waters in the absence of specific antibiotic selective pressure is necessary for tackling this complicated environmental issue.

Application of Neomysis awatschensis as a standard marine toxicity test organism in China

The small mysid crustacean Neomysis awatschensis was collected in the west coast of Jiaozhou Bay, Qingdao, China in 1992 and acclimated and cultured in laboratory conditions since then. Standard acute toxicity tests using 4-6 d juvenile mysids of this species were conducted and the results were compared with Mysidopsis bahia, a standard toxicity test organism used in the US in terms of their sensitivities to reference toxins, as well as their taxonomy, morphology and geographic distributions. Because of its wide distribution along the Chinese coast, similar sensitivity to pollutants as M. bahia, short life history, small size and the case of handling, this study intended to use N. awatschensis as one of the standard marine organisms for toxicity testing in China. The species were applied to acute toxicity evaluations of drilling fluid and its additives I organotin TPT and toxic algae, and to chronic ( life cycle) toxicity assays of organotin TPT and a toxic dinofalgellate Alexandrium tamarense, respectively. Using N, awatschensis as a standard toxicity testing organism in marine pollution assessment in China is suggested.

The influence of diets containing dried bivalve feces and/or powdered algae on growth and energy distribution in sea cucumber Apostichopus japonicus (Selenka) (Echinodermata : Holothuroidea)

In recent years, bivalve feces and powdered algae have been used as the food sources of holothurians in China. In this study, growth and energy budget for sea cucumber Apostichopus japonicus (Selenka) with initial wet body,veights of 32.5 1.0 g (mean +/- SE, n=45) when fed with five different granule diets containing dried bivalve feces and/or powdered algae in water temperature 13.2-19.8 degrees C and salinity 30-32ppt were quantified in order to investigate how diets influence growth and energy distribution and to find out the proper diet for land-based intensive culture of this species. Results showed that diets affected the food ingestion, feces production, food conversion efficiency and apparent digestive ratios, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalve showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; this could be because feces-drying process removed much of the benefits. Dried bivalve feces alone, therefore, were not a suitable diet for sea cucumbers in intensive cultivation. The mixed diets of feces and powered algae showed promising results for cultivation of sub-adult Apostichopus japonicus, while animals fed with powdered algae alone, could not obtain the best growth. According to SGR of tested animals, a formula of 75% feces and 25% powdered algae is the best diet for culture of this species. Extruded diets were used in the present experiment to overcome shortcomings of the traditional powdered feeds, however, it seems a conflict exists between drying bivalve feces to form extruded diets and feeding sea cucumbers with fresh feces which contain beneficial bacteria. Compared with other echinoderms, in holothurians the energy deposited in growth is lower and the energy loss in feces accounts for the majority of the ingested energy. Such detailed information could be helpful in further development of more appropriate diets for culture of holothurians. (c) 2006 Elsevier B.V. All rights reserved.

The effect of the causative algae of large-scale HAB in the East China Sea on egg hatching of Argopecten irradians, and population growth of Brachionus plicatilis and Moina mongolica

The impacts of Prorocentrum donghaiense Lu and Alexandrium catenella Balech, causative species of the large-scale HAB in the East China Sea, were studied under laboratory conditions. According to bloom densities, the effects of monoculture and mixture of the two species were examined on the egg-hatching success of Argopecten irradians Lamarck, and the population growth of Brachionus plicatilis Muller and Moina mongolica Daday. The results showed that monoculture of A. catenella had a significant inhibition on the egg hatching success of A. irradians, and the population growth of B. plicatilis and M. mongolica. The median effective densities ( EDSo) inhibiting the egg hatching success of A. irradians for 24 h and the population growth of B. plicatilis and M. mongolica for 96 h were 800, 630, and 2 400 cells/cm(3), respectively. Monoculture of P. donghaiense has no such inhibitory effect on the egg hatching success of A. irradians; P. donghaiense at lower suitable densities could sustain the population growth of B. plicatilis (1 x 10(4) similar to 3 x 10(4)cells/cm(3)) and M. mongolica (2 x 10(4) similar to 5 x 10(4) cells/cm(3)); P. doaghaiense at higher densities had significantly adverse effect on the population growth of B. plicatilis (4 x 10(4) similar to 10 x 10(4) cells/cm(3)) and M. mongolica (10 x 10(4) cells/cm(3)). When the two algae were mixed according to bloom densities, P. donghaiense at suitable densities to some extent could decrease the toxicity of A. catenella to B. plicatilis and M. mongolica. The results indicated that the large-scale HAB in the East China Sea could have adverse effect on zooplankton, and might further influence the marine ecosystem, especially when there was also Alexandrium bloom.

Three dimensional fluorescence excitation-emission on matrix spectrum of dissolved organic substance in marine microalgaes growth process

The three-dimensional fluorescence spectrum was used to detect the changes in dissolved organic substances from the cultured Skeletonema costatum, Alexandrium tamarense, Alexandrium mimutum, Scrippsiella trochodea, Prorocentrum donghaiense and Prorocentrum micans. The result indicates that all of the microalgaes can produce FDOM in the growth courses. Diatom such as Skeletonema costatum can produce humic-like FDOM. However dinoflagellate can produce protein-like FDOM at exponential growth phase. When the algae grows into decadency phase, the intensity of humic-like and protein-like fluorescence augments rapidly, which may be due to a mass of FDOM realeased by the old or dead cell fragmentation and the degradation of bacteria by using non-FDOM. The fluorescent intensity of Alexandrium tamarense, Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans can reduce at anaphase of decadency phase because of the degradation of bacteria and light. The same genus of algae can produce similar FDOM, for example: Alexandrium tamarense, and Alexandrium mimutum, Prorocentrum donghaiense and Prorocentrum micans, but the positions of the fluorescence peaks are different.

Fatty acids of some algae from the Bohai Sea

The fatty acid compositions of 22 species of marine macrophytes, belonging to the Ceramiales, Cryptonemiales, Nemalionales, Laminariales, Chordariales, Scytosiphonales, Desmarestiales, Dictyosiphonales, Fucales, Dictyotales and Ulvales and collected from the Bohai Sea, were determined by capillary gas chromatography. The contents of polyunsaturated fatty acids (FAs) in the Bohai Sea algae, in comparison with the same species from the Yellow Sea were found to be lower. Red algae had relatively high levels of the acids 16:0, 18:1(n-7), 18:1(n-9), 20:5(n-3) and 20:4(n-6), and those examined were rich in C-20 PUFAs, these chiefly being arachidonic and eicosapentaenoic acids. The major FAs encountered in the Phaeophyta were 14:0, 16:0, 18:1(n-9), 18:2(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6) and 20:5(n-3). C18PUFAs are of greater abundance in the brown algae than in the red algae examined. All three green algae from the Ulvales had similar fatty acid patterns with major components, 16:0, 16:4(n-3), 18:1(n-7), 18:2(n-6), 18:3(n-3), and 18:4(n-3). They contained 16:3(n-3) and more 16:4(n-3), were rich in C18PUFAs, chiefly 18:3(n-3) and 18:4(n-3) and had 18:1(n-7)/18:1 (n-9) ratios higher than 1. (C) 2002 Elsevier Science Ltd. All rights reserved.

Ecotoxicology of marine biotoxins in bivalve shellfish

A small proportion of harmful algae produce toxins which are harmful to human health. Strict monitoring programmes are in place within Ireland and the EU to effectively manage risk to human consumers of shellfish species that have accumulated marine biotoxins in their tissues. However, little is known about the impacts of HABs on shellfish health. This study used Solid Phase Adsorption and Toxin Tracking (SPATT) for the passive sampling of algal biotoxins at Lough Hyne Marine Nature Reserve in West Cork, Ireland. Spatial and temporal monitoring of the incidence of a wide range of lipophilic toxins was assessed over a 4-month period. Active sampling accumulated sufficient quantities of toxin for use in subsequent experimentation. In addition to commonly occurring Diarrhetic Shellfish Poisoning (DSP) toxins, Dinophysis toxin-1 and Pinnatoxin-G were both detected in the samples. This is the first identification of these latter two toxins in Irish waters. The effects of the DSP toxin okadaic acid (OA) were investigated on three shellfish species: Mytilus edulis, Ruditapes philippinarum and Crassostrea gigas. Histological examination of the gill, mantle and hepatopancreas tissues revealed varying intensity of damage depending both on the tissue type and the species involved. At the cellular level, flow cytometric analysis of the differential cell population distribution was assessed. No change in cell population distribution was observed in Mytilus edulis or Ruditapes philippinarum, however significant changes were observed in Crassostrea gigas granulocytes at the lower levels of toxin exposure. This indicated a chemically-induced response to OA. DNA fragmentation was measured in the haemolymph and hepatopancreas cells post OA-exposure in Mytilus edulis and Crassostrea gigas. A significant increase in DNA fragmentation was observed in both species over time, even at the lowest OA concentrations. DNA fragmentation could be due to genotoxicity of OA and/or to the induction of cell apoptosis.