Polyhydroxyl fullerene can mitigate toxicity effects of cadmium on yeasts

With inception of nanotechnology, nanomaterials are currently in the prime-line of research. Polyhydroxyl fullerene is one of the widely commercialized nanomaterials and applied in electronics and biomedical fields. Unlike fullerene, polyhydroxyl fullerene is known to be biocompatible, and recent studies reported its antioxidant properties. On the other hand, cadmium toxicity has been often attributed to the ability of this metal to induce oxidative stress. To assess antioxidant properties of polyhydroxyl fullerene, the model yeast Saccharomyces cerevisiae was exposed to cadmium (≤ 5 ppm, 3 levels) in the presence or absence of polyhydroxyl fullerene (≤ 500 ppm, 3 levels) at different pH values (5.8, 6.3 and 6.8). The size distribution and dispersion of polyhydroxyl fullerene in the stock suspension were measured with DLS (z-average 143 nm, PdI 0.365). Yeast growth, plasma membrane integrity and accumulation of reactive oxygen species (ROS) were investigated in the presence or absence of Cd2+ and/or polyhydroxyl fullerene. Yeast growth was inhibited up to 34% by exposure to Cd2+, but was not affected by polyhydroxyl fullerene. At pH 5.8, the exposure to the highest concentration of Cd2+ (5 ppm) and polyhydroxyl fullerene (500 ppm) stimulated yeast growth by 59 and 61% at the exponential and late exponential growth phases, respectively. Growth increased even more when pH increased to 6.8. Severe plasma membrane disruption and ROS accumulation were observed after exposure to the highest concentration of Cd2+ in the absence of polyhydroxyl fullerene. Membrane disruption and ROS accumulation decreased with increasing concentration of polyhydroxyl fullerene and with the increase in pH to 6.8. Overall, results indicated that polyhydroxyl fullerene is not toxic to yeasts and may potentially trigger antioxidant defense mechanisms to mitigate metal-induced toxicity.Funding: FEDER-POFC-COMPETE and FCT supported this study (PEst-C/BIA/UI4050/2011, NANOECOTOX- PTDC/AAC-AMB/121650/2010) and A. Pradhan (SFRH/BD/45614/2008)

Nano copper oxide is a threat to an endemic shredder of the Iberian Peninsula

FEDER-POFC-COMPETE and the Portuguese Foundation for Science and Technology supported this study (PEst-C/BIA/UI4050/2011, NANOECOTOX-PTDC/AAC-AMB/121650/2010) and A. Pradhan was supported by the Portuguese Foundation for Science and Technology (SFRH/BD/45614/2008)

Impacts of CuO nanoparticles on aquatic detritus foodwebs

FEDER-POFC-COMPETE and the Portuguese Foundation for Science and Technology supported this study (PEst-C/BIA/UI4050/2011, NANOECOTOX-PTDC/AAC-AMB/121650/2010) and A. Pradhan was supported by FCT (SFRH/BD/45614/2008)

An ubiquitous perspective of the intraspecific diversity of the aquatic fungus articulospora tetracladia

The cosmopolitan Articulospora tetracladia is a dominant sporulating species on decomposing plant-litter in streams of Northwest Iberian Peninsula. In an attempt to elucidate the intraspecific genetic diversity of A. tetracladia of Iberian Peninsula, isolates were attained from various types of substrates from streams of North and Central Portugal and North Spain, between 2000 and 2010. Genetic diversity of these fungal populations was assessed by denaturing gradient gel electrophoresis (DGGE) fingerprints and by using ITS1-5.8S-ITS2 barcodes. The ITS1-5.8S-ITS2 barcodes published at the National Center for Biotechnology (NCBI) or National Institute of Technology and Evaluation Biological Resource Center (NBRC) were retrieved to probe into the genetic diversity of A. tetracladia isolated from Iberian Peninsula and other parts of the world (Central Europe, UK, Canada, Japan and Malaysia). The PCR-DGGE of ITS2 region of 50 Iberian fungal isolates distinguished 8 OTUs. The ITS sequences of 68 fungal isolates yielded nine OTUs, but 5 fungal isolates were not assigned to any of these OTUs. The A. tetracladia strains did not exhibit cohesiveness based on sampling date or substrate or geographic location. Overall results indicate that, apart Malaysian genotypes, A. tetracladia genotypes are geographically widespread irrespective of sampling time, sites or substrates. Moreover, PCR-DGGE appeared to be a rapid tool for assessing intraspecific diversity of aquatic hyphomycetes.FEDER-POFC-COMPETE and FCT supported this study (PEst-C/BIA/UI4050/2011 and PTDC/AAC-AMB/113746/2009) and SD (SFRH/BPD/47574/2008)

Does the riparian stand and age affect ecosystem functioning in streams?

In riparian restoration projects tree species are often planted in assemblages that diverge from patterns seen in natural communities. This restoration practice may have consequences on the aquatic ecosystem processes as streams obtain energy from leaf litter inputs in the riparian zones. Leaf litter decomposition in streams is a vital ecosystem-level process, which depends on the activity of microorganisms and invertebrates. In the current study we attempted to assess whether leaf age and type of different widespread tree species in the Northwest Portugal, namely oak (Quercus robur L.), alder (Alnus glutinosa (L.) Gaertn.) and eucalyptus (Eucalyptus globulus Labill.) affect ecosystem functioning in streams. Leaf mass loss and fungal biomass and invertebrate biomass and diversity were examined in five mixtures with varied percentage of juvenile and mature leaves of oak, alder and eucalyptus. Our results indicate that leaf age and type had a significant effect on leaf mass loss, fungal biomass, and invertebrate biomass, abundance and diversity. Age class showed a significant effect on the decomposition of alder leaves and the associated fungi and invertebrates, but effects were not evident for other leaf types. This study gives an insight into how changing the diversity and community of riparian forest stand through restoration practices influence the ecosystem process, and may have consequences for future management strategies.The European Regional Development Fund - Operational Competitiveness Program (FEDER-POFC-COMPETE

Plant-litter decomposition by microbes increases with temperature and nutrient load in streams

We examined the interactive effects of temperature and inorganic nutrients on leaf decomposition and activity of the associated microbes in streams. Leaves of alder and oak were immersed for 10 d in a stream (NW Portugal) to allow microbial colonization, and then were exposed in microcosms to N-NO3 (90-5000 μg/L; 6 levels) and P-PO4 (3-300 μg/L; 3 levels), alone or in all possible combinations. One set of microcosms was kept at 12ºC, a temperature typically found in autumn, and the other set at 18ºC to simulate a warming scenario. Leaf mass loss was higher for alder compared to oak, but fungal biomass was higher on oak leaves. This may be due to the transfer of fungal carbon from biomass into reproduction, because maximum fungal sporulation on alder leaves was one order of magnitude higher than on oak leaves. N immobilization in alder leaves was higher than in oak leaves and increased with N concentration and temperature in the stream water for both leaf types. Leaf mass loss and fungal biomass increased asymptotically with N concentration in the stream water (Michaelis-Menten kinetic), but P had no significant effect. For both leaf types, leaf decomposition and fungal biomass were higher at 18ºC. The increase in temperature led to a decrease of the N concentration needed to achieve half of maximum fungal biomass and sporulation (km) on both leaf types, and km values were higher for oak than for alder leaves. This suggests that, under the predicted warming scenario, maximum fungal biomass and reproduction may be attained at lower nutrient concentrations, which may result in faster leaf decomposition in streams with lower nutrient levels.FEDER-POFC-COMPETEFundação para a Ciência e a Tecnologia (FCT) - PEst-C/BIA/UI4050/2011, PTDC/CLI/67180/2006, SFRH/BD/42215/200

Humic acids and nanoparticle size change the toxicity of nano CuO to freshwater microbes and invertebrates

Increased commercial application of metal oxide nanoparticles increases the chance of their exposure to surface waters, generating a potential risk to biota and associated ecological processes. The probable threat however may depend on nanoparticle size and also the interactions with natural organic matter present in water, such as humic substances. In streams, microbes and invertebrate shredders are key players in detritus foodwebs to transfer energy from plant-litter to higher trophic levels. We investigated the impacts of nano CuO size (12, 50 and 80 nm powder) and concentration (up to 400 ppm; 5 levels) and the influence of humic acid (HA ≤100 ppm; 3 levels) on stream-dwelling microbial decomposers and the invertebrate shredder Allogamus ligonifer. In the absence of HA, the exposure of microbially-colonised leaves to different sizes of nano CuO reduced leaf decomposition. The effects became more severe as nano CuO concentration increased and nanoparticle size decreased. The exposure of shredders to sublethal concentrations of nano CuO decreased leaf consumption rate and the effects were stronger for nanoparticles with lower size. The exposure to higher concentrations of HA alone reduced leaf decomposition by microbes and leaf consumption by the invertebrate. Conversely, the exposure to HA led to a decrease in nano CuO toxicity, particularly at lower nanoparticle sizes.Acknowledgement: FEDER-POFC-COMPETE and FCT supported this study (PEst-C/BIA/UI4050/2011 and PTDC/AAC-AMB/121650/2010), AP (SFRH/BD/45614/2008) and PG (SFRH/BD/75516/2010)

Polyhydroxyfullerene binds cadmium ions and alleviates metal-induced oxidative stress in saccharomyces cerevisiae

The water-soluble polyhydroxyfullerene (PHF) is a functionalized carbon nanomaterial with several industrial and commercial applications. There have been controversial reports on the toxicity and/or antioxidant properties of fullerenes and their derivatives. Conversely, metals have been recognized as toxic mainly due to their ability to induce oxidative stress in living organisms. We investigated the interactive effects of PHF and cadmium ions (Cd) on the model yeast Saccharomyces cerevisiae by exposing cells to Cd (<= 5 mg liter(-1)) in the absence or presence of PHF (<= 500 mg liter(-1)) at different pHs (5.8 to 6.8). In the absence of Cd, PHF stimulated yeast growth up to 10.4%. Cd inhibited growth up to 79.7%, induced intracellular accumulation of reactive oxygen species (ROS), and promoted plasma membrane disruption in a dose- and pH-dependent manner. The negative effects of Cd on growth were attenuated by the presence of PHF, and maximum growth recovery (53.8%) was obtained at the highest PHF concentration and pH. The coexposure to Cd and PHF decreased ROS accumulation up to 36.7% and membrane disruption up to 30.7% in a dose- and pH-dependent manner. Two mechanisms helped to explain the role of PHF in alleviating Cd toxicity to yeasts: PHF decreased Cd-induced oxidative stress and bound significant amounts of Cd in the extracellular medium, reducing its bioavailability to the cells.FEDER-POFC-COMPETE; Portuguese Foundation for Science and Technology [PEst-OE/BIA/UI4050/2014, PTDC/AAC-AMB/121650/2010]; [SFRH/BD/45614/2008]; [Pest-OE/EQB/LA0023/2013

A decade's perspective on the impact of DNA sequencing on aquatic hyphomycete research

A decade has passed since the first DNA sequences of aquatic hyphomycete species have become available. They have illuminated aspects of their phylogeny and evolution that were inaccessible by conventional methods. Here we present examples of how the resulting information has modified our knowledge of aquatic hyphomycetes. Generating more and better DNA sequence data will continue to expand the range of questions we can investigate concerning the evolution and ecology of aquatic hyphomycetes. We highlight the importance of moving forward with next generation sequencing technologies to more accurately determine the true diversity and composition of fungal communities on environmental samples. In addition, sequences targeting functional genes will offer further insights into the roles of aquatic fungi in ecosystem processes.The European Regional Development Fund - Operational Competitiveness Programme (FEDER-POFC-COMPETE) and the Portuguese Foundation for Science and Technology supported this study (PEst-C/BIA/UI4050/2011 and PTDC/AACAMB/113746/2009) and S. Duarte (SFRH/BPD/47574/2008

Preliminary insights into the phylogeography of six aquatic Hyphomycete Species

Aquatic hyphomycetes occur worldwide on a wide range of plant substrates decomposing in freshwaters, and are known to play a key role in organic matter turnover. The presumed worldwide distribution of many aquatic hyphomycete species has been based on morphology-based taxonomy and identification, which may overlook cryptic species, and mask global-scale biogeographical patterns. This might be circumvented by using DNA sequence data. The internal transcribed spacer (ITS) region from rDNA was recently designated as the most suitable barcode for fungal identification. In this study, we generated ITS barcodes of 130 isolates belonging to 6 aquatic hyphomycete species (Anguillospora filiformis, Flagellospora penicillioides, Geniculospora grandis, Lunulospora curvula, Tetrachaetum elegans and Tricladium chaetocladium), and collected from streams of Southwest Europe (86 isolates) and East Australia (44 isolates). European and Australian populations of 4 species (A. filiformis, F. penicillioides, G. grandis and T. elegans) grouped into different clades, and molecular diversity indices supported significant differentiation. Continents did not share haplotypes, except for T. chaetocladium. Overall results show substantial population diversity for all tested species and suggests that the biogeography of aquatic hyphomycetes may be species-specific.The European Regional Development Fund - Operational Competitiveness Programme (FEDER-POFC-COMPETE) (PEst-C/BIA/UI4050/2011 and PTDC/AAC-AMB/113746/2009) and SD (SFRH/BPD/47574/2008). The Natural Sciences and Engineering Research Council of Canada (NSERC) also supported this study and FB.Fundação para a Ciência e a Tecnologia (FCT) - PEst-C/BIA/UI4050/2011, PTDC/AAC-AMB/113746/2009, SFRH/BPD/47574/200