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1.
Sofia Duarte Isabel Fernandes Maria João Nogueira Fernanda Cássio Cláudia Pascoal 《Fungal Ecology》2013,6(3):187-191
Temperature is a key factor in determining the structure and performance of fungal assemblages on decomposing plant litter in streams. However, little is known of how temperature affects interspecific relationships among fungi. We compared the growth of four aquatic hyphomycetes co-occurring in temperate streams, in monocultures and all species combinations when exposed to five temperatures from 11 to 27 °C. In monocultures, maximum growth rates of Heliscus submersus, Lunulospora curvula and Varicosporium elodeae occurred at 27 °C whereas Articulospora tetracladia had the lowest growth rate. At 27 °C, the increase in species diversity had no effect on the growth of V. elodeae, increased the growth of H. submersus and L. curvula, and decreased the growth of A. tetracladia. Results suggest that within a species' optimal temperature range the growth of that species increases with higher fungal diversity, while outside this range growth decreases with diversity. 相似文献
2.
Time control is a crucial issue during embryonic development.Nevertheless, little is known about how embryonic cells measuretime. Until recently, the only molecular clock known to operateduring vertebrate embryonic development was the somitogenesisclock, exclusively functioning in coordinating the precise timingof each new pair of somites formed from the presomitic mesoderm.We have recently evidenced that a similar molecular clock alsounderlies the timing at which autopod chondrogenic precursorsare laid down to form a skeletal limb element. In addition,we herein suggest that the molecular clock is not the only parallelismthat can be established between somitogenesis and limb-bud development.In an evolutionary perspective, we support the previously proposedidea that the molecular mechanisms involved in the segmentationof the body axis may have been partially reused in the mesodermof the lateral plate, thereby allowing the emergence of pairedappendages. 相似文献
3.
Arias-Real Rebeca Gutirrez-Cnovas Cayetano Muoz Isabel Pascoal Cludia Menndez Margarita 《Ecosystems》2022,25(4):780-794
Ecosystems - Investigating the influence of biodiversity on ecosystem functioning over environmental gradients is needed to anticipate ecosystem responses to global change. However, our... 相似文献
4.
Trovatti E Silva NH Duarte IF Rosado CF Almeida IF Costa P Freire CS Silvestre AJ Neto CP 《Biomacromolecules》2011,12(11):4162-4168
Biocellulose (BC) is a highly pure form of cellulose, produced in the form of a swollen membrane, with several applications in the biomedical area. In this study, the behavior of BC membranes as systems for topical delivery of lidocaine was evaluated. The BC-lidocaine membranes were prepared and characterized in terms of structural and morphological properties. A uniform distribution of the drug inside the BC membranes was observed. In vitro diffusion studies with Franz cells were conducted using human epidermal membranes and showed that the permeation rate of the drug in BC membranes was slightly slower than that obtained with the conventional systems, which was attributed to the establishment of interactions between the lidocaine molecules and the BC membrane, as evidenced by FTIR and NMR analysis. These results indicate that this methodology can be successfully applied for the dermal administration of lidocaine regarding the release profile and ease of application. 相似文献
5.
Studies investigating the impacts of biodiversity loss on ecosystem processes have often reached different conclusions, probably
because insufficient attention has been paid to some aspects including (1) which biodiversity measure (e.g., species number,
species identity or trait) better explains ecosystem functioning, (2) the mechanisms underpinning biodiversity effects, and
(3) how can environmental context modulates biodiversity effects. Here, we investigated how species number (one to three species)
and traits of aquatic fungal decomposers (by replacement of a functional type from an unpolluted site by another from a metal-polluted
site) affect fungal production (biomass acumulation) and plant litter decomposition in the presence and absence of metal stress.
To examine the putative mechanisms that explain biodiversity effects, we determined the contribution of each fungal species
to the total biomass produced in multicultures by real-time PCR. In the absence of metal, positive diversity effects were
observed for fungal production and leaf decomposition as a result of species complementarity. Metal stress decreased diversity
effects on leaf decomposition in assemblages containing the functional type from the unpolluted site, probably due to competitive
interactions between fungi. However, dominance effect maintained positive diversity effects under metal stress in assemblages
containing the functional type from the metal-polluted site. These findings emphasize the importance of intraspecific diversity
in modulating diversity effects under metal stress, providing evidence that trait-based diversity measures should be incorporated
when examining biodiversity effects. 相似文献
6.
Adriana Medeiros Sofia Duarte Cludia Pascoal Fernanda Cssio Manuel Graa 《International Review of Hydrobiology》2010,95(1):12-26
We investigated the effects of heavy metals on leaf litter decomposition in streams. Leaves were immersed (10 days) at a reference (R) and a metal‐impacted (I) site and exposed in microcosms with increased Zn, Mn or Fe content, and to stream water from site R or I. Fungal biomass was higher in microcosms with leaves colonized at I and water from R. Fungal sporulation was higher in microcosms with leaves and water from R. Concentrations of 4.9, 9.6 and 5 ppm of Zn, Mn and Fe decrease fungal sporulation. The number of fungal species (spore counts and DGGE fingerprints) was lower in leaves colonized at site I. Cluster analyses of DGGE showed that Fe was the metal that most altered the structure of fungal community. Our results suggest that metal pollution affect leaf‐associated fungi depending on metal identity and concentration, and effects appear to be less pronounced in metal‐adapted communities. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
The contribution of fungi and bacteria to the decomposition of alder leaves was examined at two reference and two polluted sites in the Ave River (northwestern Portugal). Leaf mass loss, microbial production from incorporation rates of radiolabeled compounds into biomolecules, fungal biomass from ergosterol concentration, sporulation rates, and diversity of aquatic hyphomycetes associated with decomposing leaves were determined. The concentrations of organic nutrients and of inorganic nitrogen and phosphorus in the stream water was elevated and increased at downstream sites. Leaf decomposition rates were high (0.013 day(-1) < k < 0.042 day(-1)), and the highest value was estimated at the most downstream polluted site, where maximum values of microbial production and fungal biomass and sporulation were found. The slowest decomposition occurred at the other polluted site, where, along with the nutrient enrichment, the lowest current velocity and dissolved-oxygen concentration in water were observed. At this site, fungal production, biomass, and sporulation were depressed, suggesting that stimulation of fungal activity by increased nutrient concentrations might be offset by other factors. Although bacterial production was higher at polluted sites, fungi accounted for more than 94% of the total microbial net production. Fungal yield coefficients varied from 10.2 to 13.6%, while those of bacteria were less than 1%. The contribution of fungi to overall leaf carbon loss (29.0 to 38.8%) greatly exceeded that of bacteria (4.2 to 13.9%). 相似文献
8.
A heteroxylan was isolated from Eucalyptus globulus wood by extraction of peracetic acid delignified holocellulose with dimethyl sulfoxide. Besides (1-->4)-linked beta-D-xylopyranosyl units of the backbone and short side chains of terminal (1-->2)-linked 4-O-methyl-alpha-D-glucuronosyl residues (MeGlcA) in a 1:10 molar ratio, this hemicellulose contained galactosyl and glucosyl units attached at O-2 of MeGlcA originating from rhamnoarabinogalactan and glucan backbones, respectively. About 30% of MeGlcA units were branched at O-2. The O-acetyl-(4-O-methylglucurono)xylan showed an acetylation degree of 0.61, as determined by 1H NMR spectroscopy, and a weight-average molecular weight (M(w)) of about 36 kDa (P=1.05) as revealed from size-exclusion chromatography (SEC) analysis. About half of the beta-D-xylopyranosyl units of the backbone were found as acetylated moieties at O-3 (34 mol%), O-2 (15 mol%) or O-2,3 (6 mol%). Practically, all beta-D-xylopyranosyl units linked at O-2 with MeGlcA residues were 3-O-acetylated (10 mol%). 相似文献
9.
Evtiouguina M Barros-Timmons A Cruz-Pinto JJ Neto CP Belgacem MN Gandini A 《Biomacromolecules》2002,3(1):57-62
Cork particles, recovered as byproducts of the processing of this natural material, were oxypropylated under pressure and relatively high temperature in the presence of KOH as catalyst. Various parameters were explored in order to assess the most suitable conditions, which led to the almost complete conversion of the solid cork into a viscous polyol. This product was a mixture of oxypropylated cork macromolecules and propylene oxide oligomers, which were thoroughly characterized. The use of these polyols as macromonomers in the synthesis of polyurethane foams gave promising results, thus showing that it should be possible to exploit the residues of this important renewable resource to manufacture original materials. 相似文献
10.
Susana Pascoal Joana Esteves de Lima Jonathan D. Leslie Simon M. Hughes Leonor Saúde 《PloS one》2013,8(6)