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51.
Influence of drought on algal biofilms and meiofaunal assemblages of temperate reservoirs and rivers
Maria-José Caramujo Carlos Rafael B. Mendes Paulo Cartaxana Vanda Brotas Maria-José Boavida 《Hydrobiologia》2008,598(1):77-94
The role of hydrological droughts in shaping meiofauna abundance through alterations in biofilm biomass and composition was
investigated. In January 2005, continental Portugal was under a moderate to severe drought resulting from a 40% to 60% decrease
in rainfall during the previous 12 months relative to the long-term average (1961–1990). Reservoir capacity was reduced by
30–50% relative to average values and the width of streams was reduced by 20–80% in the Zêzere River Basin (central Portugal).
Algal biomass and algal class composition of biofilms was assessed through quantification of algal pigments in three reservoir
and six river locations. During drought, habitat alterations are expected to be sharp in rivers while, in the absence of water
quality deterioration, the habitat characteristics of reservoirs are expected to remain fairly unaffected. Chlorophylls and
carotenoid pigments were extracted from biofilm samples and analysed using high performance liquid chromatography (HPLC).
In the winter of 2003, during the period of average rainfall, biofilm biomass did not exceed 5 μg chlorophyll a cm−2 at any location. River biofilm biomass was roughly half of that measured in the reservoirs. In the winter of 2005 (drought),
biofilm biomass increased by more than 5-fold in river locations and remained low or decreased in the reservoirs. Algal biofilms
were either dominated by Bacillariophyceae or by Chlorophyceae regardless of the existence of drought. The relative contribution
of Bacillariophyceae to total biofilm biomass was higher during the drought than under average hydrological conditions. The
abundance of harpacticoids, cladocerans and ostracods was favoured by the drought only in the reservoirs where an increase
in diatom proportion in biofilms was observed. The increase in the abundance of cyclopoid copepods, turbellarians, nematodes
and chironomids in rivers during the drought could be explained by algal class composition and biomass of biofilms and environmental
variables (organic matter sediment content, phosphorus availability content and sediment granulometry). The hydrological drought
appears to regulate meiofauna abundance only in river locations, possibly through the promotion of the growth of biofilms
and the availability of organic matter deposited in rivers during the drought.
Handling editor: D. Ryder 相似文献
52.
Calvi SA Peraçoli MT Mendes RP Marcondes-Machado J Fecchio D Marques SA Soares AM 《Microbes and infection / Institut Pasteur》2003,5(2):107-113
Peripheral blood monocytes obtained from paracoccidioidomycosis patients and healthy individuals were preactivated with recombinant gamma interferon (IFN-gamma) in different concentrations (250, 500 and 1000 U/ml) and evaluated for fungicidal activity against Paracoccidiodes brasiliensis strain 18 (Pb 18, high-virulence strain) and strain 265 (Pb 265, low-virulence strain) by plating of cocultures and counting of colony-forming units, after 10 d. Monocytes from healthy individuals failed to present fungicidal activity against P. brasiliensis even after IFN-gamma activation at the three concentrations. However, patient monocytes activated with IFN-gamma (1000 U/ml) showed a significant fungicidal activity when compared to that obtained with non-activated or activated cells with other IFN-gamma concentrations (250 and 500 U/ml). Moreover, patient monocytes presented higher fungicidal activity than the control, even before the activation process. These results may be explained by the activation state of patients' cells as a function of the in vivo contact with the fungus, which was confirmed by their higher capacity to release H(2)O(2) in vitro. Unlike the results obtained with Pb 18, patient and control cells presented a significant fungicidal activity against Pb 265, after priming with IFN- gamma. These results are explained by the higher levels of TNF-alpha in supernatants of cultures challenged with Pb 265. Moreover, higher levels of the cytokine were obtained in patient cell supernatants. Taken together, our results suggest that for effective killing of P. brasiliensis by monocytes, an initial activation signal induced by IFN-gamma is necessary to stimulate the cells to produce TNF-alpha. This cytokine may be involved, through an autocrine pathway, in the final phase activation process. The effectiveness of this process seems to depend on the virulence of the fungal strain and the activation state of the challenged cells. 相似文献
53.
Gabriel Capella Machado Daniela Vanessa Moris Thales Domingos Arantes Luciane Regina Franciscone Silva Raquel Cordeiro Theodoro Rinaldo P?ncio Mendes Adriana Pardini Vicentini Eduardo Bagagli 《Memórias do Instituto Oswaldo Cruz》2013,108(5):637-643
We aimed to evaluate whether the occurrence of cryptic species of
Paracoccidioides brasiliensis, S1, PS2, PS3 and
Paracoccidioides lutzii, has implications in the
immunodiagnosis of paracoccidioidomycosis (PCM). Small quantities of the antigen
gp43 were found in culture filtrates of P. lutzii strains and
this molecule appeared to be more variable within P. lutzii
because the synonymous-nonsynonymous mutation rate was lower, indicating an
evolutionary process different from that of the remaining genotypes. The
production of gp43 also varied between isolates belonging to the same species,
indicating that speciation events are important, but not sufficient to fully
explain the diversity in the production of this antigen. The culture filtrate
antigen AgEpm83, which was obtained from a PS3 isolate, showed large quantities
of gp43 and reactivity by immunodiffusion assays, similar to the standard
antigen (AgB-339) from an S1 isolate. Furthermore, AgEpm83 was capable of
serologically differentiating five serum samples from patients from the Botucatu
and Jundiaí regions. These patients had confirmed PCM but, were non-reactive to
the standard antigen, thus demonstrating an alternative for serological
diagnosis in regions in which S1 and PS2 occur. We also emphasise that it is not
advisable to use a single antigen preparation to diagnose PCM, a disease that is
caused by highly diverse pathogens. 相似文献
54.
55.
Climate and land use changes will degrade the configuration of the landscape for titi monkeys in eastern Brazil 下载免费PDF全文
Sidney F. Gouveia João Pedro Souza‐Alves Ludmila Rattis Ricardo Dobrovolski Leandro Jerusalinsky Raone Beltrão‐Mendes Stephen F. Ferrari 《Global Change Biology》2016,22(6):2003-2012
Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species. 相似文献
56.
Mendes de Freitas R Aguiar LM Vasconcelos SM Sousa FC Viana GS Fonteles MM 《Life sciences》2005,78(3):253-258
The present study was undertaken in order to investigate the muscarinic (M(1)), dopaminergic (D(1) and D(2)) and serotonergic (5-HT(2)) receptors densities in hippocampus and striatum of Wistar rats after status epilepticus (SE) induced by pilocarpine. The control group was treated with 0.9% saline. An other group of rats received pilocarpine (400 mg/kg, s.c.) and both groups were sacrificed 1 h after treatment. The results have shown that pilocarpine administration and resulting SE produced a downregulation of M(1) receptor in hippocampus (41%) and striatum (51%) and an increase in the dissociation constant (K(d)) values in striatum (42%) alone. In both areas the 5-HT(2) receptor density remained unaltered, but a reduction (50%) and an increase (15%) in the K(d) values were detected in striatum and hippocampus, respectively. D(1) and D(2) receptor densities in hippocampus and striatum remained unaltered meanwhile K(d) values for D(1) receptor declined significantly, 33% in hippocampus and 26% in striatum. Similarly, K(d) values for D(2) decreased 55% in hippocampus and 52% in striatum. From the preceding results, it is clear that there is a possible relation between alterations in muscarinic receptor density and others systems studied as well as they suggest that changes in dissociation constant can be responsible for the establishment of pilocarpine-induced SE by altering the affinity of neurotransmitters such as acetylcholine, dopamine and serotonine. 相似文献
57.
58.
Marco Aurélio Soares Roberta Amália de Carvalho Araújo Marjorie Mendes Marini Luciana Márcia de Oliveira Leonardo Gomes de Lima Viviane de Souza Alves Maria Sueli Soares Felipe Marcelo Macedo Brigido Celia Maria de Almeida Soares Jose Franco da Silveira Jeronimo Concei??o Ruiz Patrícia Silva Cisalpino 《BMC genomics》2015,16(1)
Background
Species from the Paracoccidioides complex are thermally dimorphic fungi and the causative agents of paracoccidioidomycosis, a deep fungal infection that is the most prevalent systemic mycosis in Latin America and represents the most important cause of death in immunocompetent individuals with systemic mycosis in Brazil. We previously described the identification of eight new families of DNA transposons in Paracoccidioides genomes. In this work, we aimed to identify potentially active retrotransposons in Paracoccidioides genomes.Results
We identified five different retrotransposon families (four LTR-like and one LINE-like element) in the genomes of three Paracoccidioides isolates. Retrotransposons were present in all of the genomes analyzed. P. brasiliensis and P. lutzii species harbored the same retrotransposon lineages but differed in their copy numbers. In the Pb01, Pb03 and Pb18 genomes, the number of LTR retrotransposons was higher than the number of LINE-like elements, and the LINE-like element RtPc5 was transcribed in Paracoccidioides lutzii (Pb01) but could not be detected in P. brasiliensis (Pb03 and Pb18) by semi-quantitative RT-PCR.Conclusion
Five new potentially active retrotransposons have been identified in the genomic assemblies of the Paracoccidioides species complex using a combined computational and experimental approach. The distribution across the two known species, P. brasiliensis and P. lutzii, and phylogenetics analysis indicate that these elements could have been acquired before speciation occurred. The presence of active retrotransposons in the genome may have implications regarding the evolution and genetic diversification of the Paracoccidioides genus.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1564-7) contains supplementary material, which is available to authorized users. 相似文献59.
Mendes FS González-Pajuelo M Cordier H François JM Vasconcelos I 《Applied microbiology and biotechnology》2011,92(3):519-527
In this work, the production of 1,3-propanediol from glucose and molasses was studied in a two-step process using two recombinant
microorganisms. The first step of the process is the conversion of glucose or other sugar into glycerol by the metabolic engineered
Saccharomyces cerevisiae strain HC42 adapted to high (>200 g l−1) glucose concentrations. The second step, carried out in the same bioreactor, was performed by the engineered strain Clostridium acetobutylicum DG1 (pSPD5) that converts glycerol to 1,3-propanediol. This two-step strategy led to a flexible process, resulting in a 1,3-propanediol
production and yield that depended on the initial sugar concentration. Below 56.2 g l−1 of sugar concentration, cultivation on molasses or glucose showed no significant differences. However, at higher molasses
concentrations, glycerol initially produced by yeast could not be totally converted into 1,3-propanediol by C. acetobutylicum and a lower 1,3-propanediol overall yield was observed. In our hand, the best results were obtained with an initial glucose
concentration of 103 g l−1, leading to a final 1,3-propanediol concentration of 25.5 g l−1, a productivity of 0.16 g l−1 h−1 and 1,3-propanediol yields of 0.56 g g−1 glycerol and 0.24 g g−1 sugar, which is the highest value reported for a two-step process. For an initial sugar concentration (from molasses) of
56.2 g l−1, 27.4 g l−1 of glycerol were produced, leading to 14.6 g l−1 of 1.3-propanediol and similar values of productivity, 0.15 g l−1 h−1, and overall yield, 0.26 g g−1 sugar. 相似文献
60.
Leonardo Soriano Francisco de Assis Alves Mour?o Filho Luis Eduardo Aranha Camargo Mariangela Cristofani-Yaly Rodrigo Rocha Latado Camila de Andrade Pacheco Fernando Alves de Azevedo Beatriz Madalena Januzzi Mendes 《Plant Cell, Tissue and Organ Culture》2012,111(3):385-392
Protoplast fusion between sweet orange and mandarin/mandarin hybrids scion cultivars was performed following the model ??diploid embryogenic callus protoplast?+?diploid mesophyll-derived protoplast??. Protoplasts were isolated from embryogenic calli of ??Pera?? and ??Westin?? sweet orange cultivars (Citrus sinensis) and from young leaves of ??Fremont??, Nules??, and ??Thomas?? mandarins (C. reticulata), and ??Nova?? tangelo [C. reticulata?×?(C. paradisi?×?C. reticulata)]. The regenerated plants were characterized based on their leaf morphology (thickness), ploidy level, and simple sequence repeat (SSR) molecular markers. Plants were successfully generated only when ??Pera?? sweet orange was used as the embryogenic parent. Fifteen plants were regenerated being 7 tetraploid and 8 diploid. Based on SSR molecular markers analyses all 7 tetraploid regenerated plants revealed to be allotetraploids (somatic hybrids), including 2 from the combination of ??Pera?? sweet orange?+???Fremont?? mandarin, 3 ??Pera?? sweet orange?+???Nules?? mandarin, and 2 ??Pera?? sweet orange?+???Nova?? tangelo, and all the diploid regenerated plants showed the ??Pera?? sweet orange marker profile. Somatic hybrids were inoculated with Alternaria alternata and no disease symptoms were detected 96?h post-inoculation. This hybrid material has the potential to be used as a tetraploid parent in interploid crosses for citrus scion breeding. 相似文献