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71.
72.
Carvalho OS Cardoso PC Lira PM Rumi A Roche A Berne E Müller G Caldeira RL 《Memórias do Instituto Oswaldo Cruz》2004,99(5):503-507
The specific identification of Lymnaeid snails is based on a comparison of morphological characters of the shell, radula, renal and reproductive organs. However, the identification is complicated by dissection process, intra and interspecific similarity and variability of morphological characters. In the present study, polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) techniques targeted to the first and second internal transcribed spacers (ITS1 and ITS2) rDNA and to the mitochondrial 16S ribosomal gene (16S rDNAmt) were used to differentiate the species Lymnaea columella, L. viatrix, and L. diaphana from some localities of Brazil, Argentina, and Uruguay as well as to verify whether the molecular results corroborates the classical morphological method.PCR-RFLP analysis of the ITS1, ITS2, and 16S using 12 restriction enzymes revealed characteristic patterns for L. columella and L. diaphana which were concordant with the classical morphology. On the other hand, for L. viatrix populations a number of 1 to 6 profiles were generated while morphology provided the species pattern results. 相似文献
73.
Ramalho PA Cardoso MH Cavaco-Paulo A Ramalho MT 《Applied and environmental microbiology》2004,70(4):2279-2288
Several model azo dyes are reductively cleaved by growing cultures of an ascomycete yeast species, Issatchenkia occidentalis. In liquid media containing 0.2 mM dye and 2% glucose in a mineral salts base, more than 80% of the dyes are removed in 15 h, essentially under microaerophilic conditions. Under anoxic conditions, decolorization does not occur, even in the presence of pregrown cells. Kinetic assays of azo reduction activities in quasi-resting cells demonstrated the following: (i) while the optimum pH depends on dye structure, the optimum pH range was observed in the acidic range; (ii) the maximum decolorizing activity occurs in the late exponential phase; and (iii) the temperature profile approaches the typical bell-shaped curve. These results indirectly suggest the involvement of an enzyme activity in azo dye reduction. The decolorizing activity of I. occidentalis is still observed, although at a lower level, when the cells switch to aerobic respiration at the expense of ethanol after glucose exhaustion in the culture medium. Decolorization ceased when all the ethanol was consumed; this observation, along with other lines of evidence, suggests that azo dye reduction depends on cell growth. Anthraquinone-2-sulfonate, a redox mediator, enhances the reduction rates of the N,N-dimethylaniline-based dyes and reduces those of the 2-naphthol-based dyes, an effect which seems to be compatible with a thermodynamic factor. The dye reduction products were tested as carbon and nitrogen sources. 1-Amino-2-naphthol was used as a carbon and nitrogen source, and N,N-dimethyl-p-phenylenediamine was used only as a nitrogen source. Sulfanilic and metanilic acids did not support growth either as a carbon or nitrogen source. 相似文献
74.
The cyanophycin synthetase gene cphA1 encoding the major cyanophycin synthetase (CphA) of Anabaena sp. strain PCC7120 was expressed in Escherichia coli conferring so far the highest specific CphA activity to E. coli (6.7 nmol arginine per min and mg protein). CphA1 and cphA genes of Synechocystis sp. strains PCC6803 and PCC6308 and Synechococcus strain MA19 were also expressed in wild types and polyhydroxyalkanoate-negative (PHA) mutants of Pseudomonas putida and Ralstonia eutropha. Recombinant strains of these bacteria expressing cphA1 accumulated generally more cyanophycin (23.0 and 20.0% of cellular dry matter, CDM, respectively) than recombinants expressing any other cphA (6.8, 9.0, or 15.8% of CDM for P. putida strains and 7.3, 12.6, or 14.1% of CDM for R. eutropha). Furthermore, PHA-negative mutants of P. putida (9.7, 10.0, 17.5, or 24.0% of CDM) and R. eutropha (8.9, 13.8, 16.0, or 22.0% of CDM) accumulated generally more cyanophycin than the corresponding PHA-positive parent strains (6.8, 9.0, 15.8, and 23.0% of CDM for P. putida strains and 7.3, 12.6, 14.1, or 20.0% of CDM for R. eutropha strains). Recombinant strains of Gram-positive bacteria (Bacillus megaterium, Corynebacterium glutamicum) were not suitable for cyanophycin production due to accumulation of less cyanophycin and retarded release of cyanophycin. PHA-negative mutants of P. putida and R. eutropha expressing cphA1 of Anabaena sp. strain PCC7120 are therefore preferred candidates for industrial production of cyanophycin. 相似文献
75.
Moreira R Pinho JR Fares J Oba IT Cardoso MR Saraceni CP Granato C 《Canadian journal of microbiology》2003,49(8):503-507
The aims of this study were to (i) evaluate the prevalence and the incidence of hepatitis C virus (HCV) infection in hemodialysis patients in two different centers in S?o Paulo (Brazil), (ii) determine the time required to detect HCV infection among these patients by serology or PCR, (iii) establish the importance of alanine aminotransferase determination as a marker of HCV infection, and (iv) identify the HCV genotypes in this population. Serum samples were collected monthly for 1 year from 281 patients admitted to hospital for hemodialysis. Out of 281 patients, 41 patients (14.6%) were HCV positive; six patients seroconverted during this study (incidence = 3.1/1000 person-month). In 1.8% (5/281) of cases, RNA was detected before the appearance of antibodies (up to 5 months), and in 1.1% (3/281) of cases, RNA was the unique marker of HCV infection. The genotypes found were 1a, 1b, 3a, and 4a. The presence of genotype 4a is noteworthy, since it is a rare genotype in Brazil. These data pointed out the high prevalence and incidence of HCV infection at hemodialysis centers in Brazil and showed that routine PCR is fundamental for improving the detection of HCV carriers among patients undergoing hemodialysis. 相似文献
76.
Barbosa AM Steluti RM Dekker RF Cardoso MS Corradi da Silva ML 《Carbohydrate research》2003,338(16):1691-1698
The exopolysaccharide, Botryosphaeran, produced by the ligninolytic, ascomyceteous fungus Botryosphaeria sp., was isolated from the extracellular fluid by precipitation with ethanol, and purified by gel permeation chromatography to yield a carbohydrate-rich fraction (96%) composed mainly of glucose (98%). Infra-red and 13C NMR spectroscopy showed that all the glucosidic linkages were in the beta-configuration. Data from methylation analysis and Smith degradation indicated that Botryosphaeran was a (1-->3)-beta-D-glucan with approx 22% side branching at C-6. The products obtained from partial acid hydrolysis demonstrated that the side branches consisted of single (1-->6)-beta-linked glucosyl, and (1-->6)-beta-linked gentiobiosyl residues. 相似文献
77.
Ribeiro-Dias F Shio MT Timenetsky J Oliane AP Metran CC Pessoa FB Jancar S 《Experimental cell research》2003,286(2):345-354
Mycoplasma arthritidis causes arthritis in rodents that resembles human rheumatoid arthritis. It produces a superantigen (MAM) that stimulates production of cytokines by making a bridge between lymphocyte T-cell receptor with the appropriate Vbeta chain, and H-2 1-Ealpha MHC class II molecules. Here we studied MAM-induced nitric oxide (NO) production in mouse peritoneal macrophages and found that it was: (1) time and concentration dependent, (2) possibly derived from inducible NOS synthase since it was reduced significantly by amino guanidine pretreatment, (3) restricted to H-2(K) (C3H/HePas and C3H/HeJ) and H-2(d) strains (BALB/c), (4) independent of TLR4 signaling since the coisogenic strains C3H/HePas and C3H/HeJ (TLR4 deficient) produced similar levels of NO following MAM stimulation, (5) potentiated by lipopolysaccharide, and (6) dependent on the presence of nonadherent peritoneal cells. Neutralization of interferon-gamma (IFNgamma in the peritoneal cell cultures with monoclonal antibodies abolished MAM-induced NO production. Addition of rIFNgamma to the adherent cells substituted the nonadherent cells for MAM-induced NO production. A macrophage cell line, J774A.1 (H-2(d)), also produced NO upon MAM stimulation but only when BALB/c spleen lymphocytes were added. Thus, in murine macrophages, MAM induces NO production that is dependent on signaling through MHC class II molecules and IFNgamma but independent of TLR4 expression. 相似文献
78.
The sulfated, methylated galactan isolated from the red seaweed Bostrychia montagnei, showed an unusually narrow structural dispersion. This agaran has the defining linear backbone of alternating 3-linked beta-D-galactopyranosyl units and 4-linked alpha-L-galactopyranosyl and 3,6-anhydrogalactopyranosyl residues. The D-units have C-6 methylation, C-6 single stubs of xylopyranosyl and minor to trace amounts of (possible) C-6 linked single stubs of galactopyranosyl. These units are mainly sulfated on C-4 with lesser sulfation at C-6 and minor at C-2. The L-residues are mainly methylated on C-2 of the 3,6-anhydrogalactopyranosyl and sulfated on C-3 of the L-galactopyranosyl; minor amounts of 2,3- and 3,6-disulfated and 2-O-methyl or 2-O-glycosyl 3-sulfated L-galactopyranosyl were also found. 相似文献
79.
Etoposide (VP-16) is known to promote cell apoptosis either in cancer or in normal cells as a side effect. This fact is preceded by the induction of several mitochondrial events, including increase in Bax/Bcl-2 ratio followed by cytochrome c release and consequent activation of caspase-9 and -3, reduction of ATP levels, depolarization of membrane potential (DeltaPsi) and rupture of the outer membrane. These events are apoptotic factors essentially associated with the induction of the mitochondrial permeability transition (MPT). VP-16 has been shown to stimulate the Ca2+-dependent MPT induction similarly to prooxidants and to promote apoptosis by oxidative stress mechanisms, which is prevented by glutathione (GSH) and N-acetylcysteine (NAC). Therefore, the aim of this work was to study the effects of antioxidants and thiol protecting agents on MPT promoted by VP-16, attempting to identify the underlying mechanisms on VP-16-induced apoptosis. The increased sensitivity of isolated mitochondria to Ca2+-induced swelling, Ca2+ release, depolarization of DeltaPsi and uncoupling of respiration promoted by VP-16, which are prevented by cyclosporine A proving that VP-16 induces the MPT, are also efficiently prevented by ascorbate, the primary reductant of the phenoxyl radicals produced by VP-16. The thiol reagents GSH, dithiothreitol and N-ethylmaleimide, which have been reported to prevent the MPT induction, also protect this event promoted by VP-16. The inhibition of the VP-16-induced MPT by antioxidants agrees with the prevention of etoposide-induced apoptosis by GSH and NAC and suggests the generation of oxidant species as a potential mechanism underlying the MPT that may trigger the release of mitochondrial apoptogenic factors responsible for apoptotic cascade activation. 相似文献
80.
Procópio DO Almeida IC Torrecilhas AC Cardoso JE Teyton L Travassos LR Bendelac A Gazzinelli RT 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(7):3926-3933
It has been proposed that self and protozoan-derived GPI anchors are natural ligands of CD1d. In this study, we investigated the ability of GPI anchors from Trypanosoma cruzi to bind to CD1d and mediate activation of NKT cells. We observed that GPI-anchored mucin-like glycoproteins (GPI mucins), glycoinositolphospholipids (GIPLs), and their phosphatidylinositol moieties bind to rCD1d and inhibit the stimulation of a NKT hybridoma by the alpha-galactosylceramide-CD1 complex. However, these GPI anchors and related structures were unable to activate NKT cells in vitro or in vivo. We found that high titers of Ab anti-GPI mucins, but not anti-GIPLs, were detected in sera from wild-type as well as in TAP1(-/-), CD1d(-/-), and MHC class II(-/-) mice after immunization. However, T-dependent anti-GPI mucin Ab isotypes, such as IgG1, IgG2a, IgG2b, and IgG3, were absent on MHC class II(-/-), but were conserved in CD1d(-/-) and TAP1(-/-) mice. Furthermore, we found that CD1d(-/-) mice presented a robust cytokine as well as anti-GPI mucins and anti-GIPL Ab responses, upon infection with T. cruzi parasites. These results indicate that, despite binding to CD1d, GPI mucins and related structures expressed by T. cruzi appear not to evoke dominant CD1d-restricted immune responses in vivo. In contrast, MHC class II is critical for the production of the major Ig G isotypes against GPI mucins from T. cruzi parasites. 相似文献