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91.
Characterization of biofilm formation on a humic material 总被引:1,自引:0,他引:1
Rodrigues AL Brito AG Janknecht P Silva J Machado AV Nogueira R 《Journal of industrial microbiology & biotechnology》2008,35(11):1269-1276
Biofilms are major sites of carbon cycling in streams. Therefore, it is crucial to improve knowledge about biofilms’ structure
and microbial composition to understand their contribution in the self-purification of surface water. The present work intends
to study biofilm formation in the presence of humic substances (HSs) as a carbon source. Two biofilm flowcells were operated
in parallel; one with synthetic stream water, displaying a background carbon concentration of 1.26 ± 0.84 mg L−1, the other with added HSs and an overall carbon concentration of 9.68 ± 1.00 mg L−1. From the biofilms’ results of culturable and total countable cells, it can be concluded that the presence of HSs did not
significantly enhance the biofilm cell density. However, the biofilm formed in the presence of HSs presented slightly higher
values of volatile suspended solids (VSS) and protein. One possible explanation for this result is that HSs adsorbed to the
polymeric matrix of the biofilm and were included in the quantification of VSS and protein. The microbial composition of the
biofilm with addition of HSs was characterized by the presence of bacteria belonging to beta-Proteobacteria, Cupriavidus metallidurans and several species of the genus Ralstonia were identified, and gamma-Proteobacteria, represented by Escherichia coli. In the biofilm formed without HSs addition beta-Proteobacteria, represented by the species Variovorax paradoxus, and bacteria belonging to the group Bacteroidetes were detected. In conclusion, the presence of HSs did not significantly
enhance biofilm cell density but influenced the bacterial diversity in the biofilm. 相似文献
92.
The defensive secretion of the harvestman Camarana flavipalpi (Gonyleptidae) was chemically characterized, revealing the presence of a single, highly volatile component (2-methyl-5-ethyl-phenol). Individuals do not frequently use chemical defenses and rely mainly on thanatosis as defense. Two types of emission of secretions were recorded: a globule at the gland opening without liquid displacement and liquid displacement along the lateral margins of the dorsal scute with accumulation of fluid at the lateroposterior area of the body. The anterior opening of the ozopore is covered by an integumentary dome that faces the laterodorsal area of the scute. The lateral channel is well defined near the opening of the ozopore and along the lateral margin of the dorsal scute as rows of small granules. The ozopore morphology of C. flavipalpi is similar to closely related species and simplified when compared with other species that promptly release chemical secretions. 相似文献
93.
The effect of Quebrachitol (2-O-methyl-l-inositol), a bioactive component from Magonia glabrata fruit extract was investigated against gastric damage induced by absolute ethanol (96%, 0.2 ml/animal) and indomethacin (30 mg/kg, p.o.), in mice. Quebrachitol at oral doses of 12.5, 25, and 50 mg/kg markedly attenuated the gastric lesions induced by ethanol to the extent of 69%, 64%, and 53% and against indomethacin by 55%, 59%, and 26%, respectively. While pretreatment with TRPV1 antagonist capsazepine (5 mg/kg, i.p.) failed to block effectively the gastroprotective effect of quebrachitol (25 mg/kg) against ethanol damage, the non-selective cyclooxygenase inhibitor indomethacin (10 mg/kg, p.o.), almost abolished it. Furthermore, quebrachitol effect was significantly reduced in mice pretreated with l-NAME, or glibenclamide, the respective inhibitors of nitric oxide synthase and K+ATP channel activation. Thus we provide the first evidence that quebrachitol reduces the gastric damage induced by ethanol and indomethacin, at least in part, by mechanisms that involve endogenous prostaglandins, nitric oxide release, and or the activation of K+ATP channels. 相似文献
94.
Kadar E Checa AG Damasceno-Oliveira A Oliveira AN Machado JP 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2008,178(1):131-130
This study describes the micro-morphological features of the shell nacre in the vent mytilid Bathymodiolus azoricus collected along a bathymetric gradient of deep-sea hydrothermal vents of the mid-Atlantic ridge (MAR). Pressure-dependent
crystallisation patterns were detected in animals subjected to post-capture hydrostatic simulations. We provide evidence for
the following: (1) shell micro morphology in B. azoricus is similar to that of several vent and cold-seep species, but the prismatic shell layers may vary among bathymodiolids; (2)
nacre micro-morphology of mussels from three vent sites of the MAR did not differ significantly; minor differences do not
appear to be related to hydrostatic pressure, but rather to calcium ion availability; (3) decompression stress may cause drop
off in pH of the pallial fluid that damages nascent crystals, and in a more advanced phase, the aragonite tablets as well
as the continuous layer of mature nacre; and (4) adverse effects of decompression on calcium salt deposition in shells was
diminished by re-pressurisation of specimens. The implications of the putative influence of hydrostatic pressure on biomineralisation
processes in molluscs are discussed.
An erratum to this article can be found at 相似文献
95.
Machado MF Rioli V Dalio FM Castro LM Juliano MA Tersariol IL Ferro ES Juliano L Oliveira V 《The Biochemical journal》2007,404(2):279-288
The physicochemical properties of TOP (thimet oligopeptidase) and NEL (neurolysin) and their hydrolytic activities towards the FRET (fluorescence resonance energy transfer) peptide series Abz-GFSXFRQ-EDDnp [where Abz is o-aminobenzoyl; X=Ala, Ile, Leu, Phe, Tyr, Trp, Ser, Gln, Glu, His, Arg or Pro; and EDDnp is N-(2,4-dinitrophenyl)-ethylenediamine] were compared with those of site-mutated analogues. Mutations at Tyr605 and Ala607 in TOP and at Tyr606 and Gly608 in NEL did not affect the overall folding of the two peptidases, as indicated by their thermal stability, CD analysis and the pH-dependence of the intrinsic fluorescence of the protein. The kinetic parameters for the hydrolysis of substrates with systematic variations at position P1 showed that Tyr605 and Tyr606 of TOP and NEL respectively, played a role in subsite S1. Ala607 of TOP and Gly608 of NEL contributed to the flexibility of the loops formed by residues 600-612 (GHLAGGYDGQYYG; one-letter amino acid codes used) in NEL and 599-611 (GHLAGGYDAQYYG; one-letter amino acid codes used) in TOP contributing to the distinct substrate specificities, particularly with an isoleucine residue at P1. TOP Y605A was inhibited less efficiently by JA-2 {N-[1-(R,S)-carboxy-3-phenylpropyl]Ala-Aib-Tyr-p-aminobenzoate}, which suggested that the aromatic ring of Tyr605 was an important anchor for its interaction with wild-type TOP. The hydroxy groups of Tyr605 and Tyr606 did not contribute to the pH-activity profiles, since the pKs obtained in the assays of mutants TOP Y605F and NEL Y606F were similar to those of wild-type peptidases. However, the pH-kcat/Km dependence curve of TOP Y605A differed from that of wild-type TOP and from TOP Y606F. These results provide insights into the residues involved in the substrate specificities of TOP and NEL and how they select cytosolic peptides for hydrolysis. 相似文献
96.
Egle Machado de Almeida Siqueira Fernanda Ribeiro Rosa Adriana Medeiros Fustinoni Lívia Pimentel de Sant'Ana Sandra Fernandes Arruda 《PloS one》2013,8(8)
The bioactive compounds content and the antioxidant activity (AA) of twelve fruits native to the Cerrado were compared with the Red Delicious apple by means of the antiradical efficiency (using the 2,2-diphenyl-1-picrylhydrazil assay/DPPH), ferric reducing antioxidant power (FRAP) and the β-carotene/linoleic system. The antiradical efficiency (AE) and the kinetic parameters (Efficient concentration/EC50 and time needed to reach the steady state to EC50 concentration/TEC50) of the DPPH curve were also evaluated for comparison with the Trolox equivalent (TE) values. A strong, significant and positive correlation was observed between the TE and AE values, whereas a weak and negative correlation was observed between TE and EC50, suggesting that the values of AE and TE are more useful for the determination of antiradical activity in fruits than the widely used EC50. The total phenolic content found in the fruits corresponded positively to their antioxidant activity. The high content of bioactive compounds (flavanols, anthocyanins or vitamin C) relative to the apple values found in araticum, cagaita, cajuzinho, jurubeba, lobeira, magaba and tucum corresponded to the high antioxidant activity of these fruits. Flavanols and anthocyanins may be the main bioactive components in these Cerrado fruits. The daily consumption of at least seven of the twelve Cerrado fruits studied, particularly, araticum, cagaita, lobeira and tucum, may confer protection against oxidative stress, and thus, they may prevent chronic diseases and premature aging. The findings of this study should stimulate demand, consumption and cultivation of Cerrado fruits and result in sustainable development of the region where this biome dominates. 相似文献
97.
Jaqueline Raymondi Silva Larissa Campos de Medeiros Vinícius Pinho dos Reis Juliana Helena Chávez Thiago Demarchi Munhoz Gustavo Puia Borges Otavio Augusto Brioschi Soares Carlos Henrique Coelho de Campos Rosangela Zacarias Machado Cristiane Divan Baldani Maria Luana Cristiny Rodrigues Silva Joice Lara Maia Faria Edson Elias da Silva Luiz Tadeu Moraes Figueiredo 《Memórias do Instituto Oswaldo Cruz》2013,108(7):921-923
Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country. 相似文献
98.
The divergence of Drosophila pseudoobscura from its close relatives, D. persimilis and D. pseudoobscura bogotana, was examined using the pattern of DNA sequence variation in a common set of 50 inbred lines at 11 loci from diverse locations in the genome. Drosophila pseudoobscura and D. persimilis show a marked excess of low-frequency variation across loci, consistent with a model of recent population expansion in both species. The different loci vary considerably, both in polymorphism levels and in the levels of polymorphisms that are shared by different species pairs. A major question we address is whether these patterns of shared variation are best explained by gene flow or by persistence since common ancestry. A new test of gene flow, based on patterns of linkage disequilibrium, is developed. The results from these, and other tests, support a model in which D. pseudoobscura and D. persimilis have exchanged genes at some loci. However, the pattern of variation suggests that most gene flow, although occurring after speciation began, was not recent. There is less evidence of gene flow between D. pseudoobscura and D. p. bogotana. The results are compared with recent work on the genomic locations of genes that contribute to reproductive isolation between D. pseudoobscura and D. persimilis. We show that there is a good correspondence between the genomic regions associated with reproductive isolation and the regions that show little or no evidence of gene flow. 相似文献
99.
Environmental gradients in a southern Europe estuarine system: Ria de Aveiro,Portugal implications for soft bottom macrofauna colonization 总被引:4,自引:0,他引:4
Four seasonal sampling surveys were carried out between December 1985 and September 1986 in Canal de Mira (Ria de Aveiro,
Portugal). A total of 40 sampling stations, distributed over 13 transects, was used. Salinity, temperature, dissolved oxygen
and pH of the water mass were measured. Sediment temperature, and salinity and pH of interstitial water were determined. Sediment
variables also included granulometric composition and organic matter contents. Bottom macrofauna samples were collected at
each station.
Ordination (PCA and MDS) and classification of the sampling stations were performed, using the physicochemical and the biological
data sets separately. Average linkage cluster analysis using the unweighted paired-group method, arithmetic averages, was
used for both sets of data.
With a salinity range from 35.1‰ to 0.0‰, Canal de Mira behaves like a tidally and seasonally poikilohaline estuary. Water
temperature (8.5–24.7°C) decreased along the channel towards its inner part during the cold season; an inverse and more pronounced
trend was observed during the hot season. Dissolved oxygen contents was generally high during the day (50% to 240% saturation).
Oversaturation was observed throughout the growing season, with peaks in areas with large amounts of rooted vegetation. The
pH values, largely correlated with dissolved oxygen, ranged from 6.8 to 8.9. Four types of sediment were present in Canal
de Mira, medium and muddy sands being dominant.
Two major gradients were identified: (i) a typical longitudinal estuarine gradient, associated with distance from the mouth,
representing physicochemical variables such as tidal amplitude, salinity and temperature; this gradient was accompanied by
an upstream increase in dominance; the community composition changes were mainly related to salinity; (ii) a lateral gradient,
related to current velocity, depth and sediment composition; the subtidal community had a comparatively low species richness
and abundance. Groups of stations could be recognized along the environmental gradients. Benthic community changes, however,
appeared to be gradual rather than marked by abrupt transitions. 相似文献
100.
Ednildo A. Machado Pedro L. Oliveira Monica F. Moreira Wanderley de Souza Hatisaburo Masuda 《Archives of insect biochemistry and physiology》1998,39(4):133-143
The uptake of RHBP (Rhodnius heme-binding protein) by the ovaries of Rhodnius prolixus was characterized. RHBP purified from oocyte was labeled with 125I and used to study the process of uptake by the ovary in vivo and in vitro. After injection, the [125I]RHBP was readily removed from the hemolymph and accumulated especially in the ovary. The capacity of the ovary to take up [125I]RHBP from the hemolymph varied during the days following blood meal. It increased up to day 2, remained stable until day 5, and then decreased up to the end of oogenesis. In vitro, the uptake of [125I]RHBP was linear at least up to 60 min. The uptake was dependent on [125I]RHBP concentration and showed to be a saturable process. The addition of a molar excess of non-related proteins such as Vitellin (Vt), Lipophorin (Lp), and Bovine Serum Albumin (BSA) did not reduce [125I]RHBP uptake. Using immunogold technique the RHBP was localized at the microvilli, coated pits, and yolk granules. The main yolk protein, Vt, did not compete with RHBP for the uptake. Thus, it is discussed here that they bind to independent binding sites of the oocytes, and are directed later on to the same compartment. The need of both proteins for the completion of mature oocyte was verified in vivo. The reduction of heme-RHBP in the hemolymph, by changing the diet, decreased the number of eggs laid. Increasing the concentration of heme-RHBP in the hemolymph, the number of eggs produced increased in a dose dependent manner. In vitro, both apo-RHBP and heme-RHBP can be taken up by the oocyte. Since the mature oocyte contains only heme-saturated RHBP, the possible fate of apo-RHBP is also discussed. Arch. Insect Biochem. Physiol. 39:133–143, 1998. © 1998 Wiley-Liss, Inc. 相似文献