Distribution of the Bari-I transposable element in stable hybrid strains between Drosophila melanogaster and Drosophila simulans and in Brazilian populations of these species

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Production of bacteriocin-like inhibitory substances (BLIS) by Streptococcus salivarius strains isolated from the tongue and throat of children with and without sore throat

Cepas de Streptococcus salivarius, isoladas de crianças com e sem dor de garganta, foram testadas quanto à produção de bacteriocina contra Streptococcus pyogenes. Os resultados mostraram que as crianças que não tinham dor de garganta possuiam, na boca, cepas de bactérias produtoras de substâncias inibidoras semelhantes à bacteriocina contra S. pyogenes.

The distribution of the P-M hybrid dysgenesis system in Drosophila melanogaster strains from Brazil

Wild-caught flies of Drosophila melanogaster from seven natural populations of extreme regions of Brazil (Sao Luis, MA; Teresina, PI; Rio Cipo, MG; Maringa, PR; Sao Jose do Rio Preto, SP; Joinville, SC; and Porto Alegre, RS) were studied with the purpose of evaluating hybrid dysgenesis due to mobilization of P elements and the regulatory capacity of the strains' cytotypes. Diagnostic crosses were made and the strains classified according to their P-M phenotypes. Four strains were classified as moderate P (MA, MG, PI, and SP), two as Q (PR and RS) and one as M' (SC). Females of southern strains (PR, SC, and RS) presented in A crosses lower degrees of gonadal dysgenesis scores than those from northern strains (MA and PI).

Differentiation of Acidithiobacillus ferrooxidans and A-thiooxidans strains based on 16S-23S rDNA spacer polymorphism analysis

Restriction fragment length polymorphism (RFLP) and sequence analyses of the PCR-amplified 16S-23S rDNA intergenic spacer (ITS) were used for differentiating Acidithiobacillus thiooxidans strains from other related acidithiobacilli, including A. ferrooxidans and A. caldus. RFLP fingerprints obtained with AluI, DdeI, HaeIII, HinfI and MspI enabled the differentiation of all Acidithiobacillus reference strains into species groups. The A. thiooxidans strains investigated (metal mine isolates) yielded identical RFLP patterns to the A. thiooxidans type strain (ATCC 19377(T)), except for strain DAMS, which had a distinct pattern for all enzymes tested. Fourteen A. ferrooxidans mine strains were assigned to 3 RFLP groups, the majority of which were grouped with A. ferrooxidans ATCC 23270(T). The spacer region of one representative strain from each of the RFLP groups obtained was subjected to sequence analysis, in addition to eleven additional A. thiooxidans strains isolated from sediment and water samples, and A. caldus DSM 8584(T). The tRNA(IIe) and tRNA(Ala) genes, present in all strains analyzed, showed high sequence similarity. Phylogenetic analysis of the ITS sequences differentiated all three Acidithiobacillus species. Inter- and infraspecific genetic variations detected were mainly due to the size and sequence polymorphism of the ITS3 region. Mantel tests showed no significant correlation between ITS sequence similarity and the geographical origin of strains. The results showed that the 16S-23S rDNA spacer region is a useful target for the development of molecular-based methods aimed at the detection, rapid differentiation and identification of acidithiobacilli. (C) 2004 Elsevier SAS. All rights reserved.

Growth responses and photosynthetic characteristics of wild and phycoerythrin-deficient strains of Hypnea musciformis (Rhodophyta)

The phycoerythrin-deficient strain (green phenotype) of Hypnea musciformis (Rhodophyta) originated from a green branch, which had arisen as a spontaneous mutation in a wild plant (brown phenotype) collected from the Brazilian coast. The present study describes the growth responses to irradiance, photoperiod and temperature variations, pigment contents, and photosynthetic characteristics of the brown and green strains of H. musciformis. The results showed that growth rates increased as a function of irradiance (up to 40 mu mol photons m(-2) s(-1)) but, with further increase in irradiance (from 40 to 120 mu mol photons m(-2) s(-1)), became light-saturated and remained almost unchanged. The highest growth rates of the brown and green strains were observed in temperatures of 20-25 degrees C under long (14:10 h LD) and short (10:14 h LD) photoperiods. The brown strain had higher growth rates than the green strain in the short photoperiod, which could be related to the high concentrations of phycobiliproteins. Phycoerythrin was not detected in the green strain. The brown strain had higher concentrations of allophycocyanin and phycoerythrin in the short photoperiod while the green strain had higher concentrations of phycocyanin. The brown strain presented higher photosynthetic efficiency (alpha), and lower saturation parameter (I-k) and compensation irradiance (I-c) than the green strain. The brown strain exhibited the characteristics of shade-adapted plants, and its higher value of photosynthetic efficiency could be attributed to the higher phycoerythrin concentrations. Results of the present study indicate that both colour strains of H. musciformis could be selected for aquaculture, since growth rates were similar (although in different optimal light conditions), as the green strain seems to be adapted to higher light levels than the brown strain. Furthermore, these colour strains could be a useful experimental system to understand the regulation of biochemical processes of photosynthesis and metabolism of light-harvesting pigments in red algae.

Influence of strains and defects on ferroelectric and dielectric properties of thin-film barium-strontium titanates

Pristine, W and Mn 1% doped Ba(0.6)Sr(0.4)TiO(3) epitaxial thin films grown on the LaAlO(3) substrate were deposited by pulsed laser deposition (PLD). Dielectric and ferroelectric properties were determined by the capacitance measurements and X-ray diffraction was used to determine both residual elastic strains and defect-related inhomogeneous strains-by analyzing diffraction line shifts and line broadening, respectively. We found that both elastic and inhomogeneous strains are affected by doping. This strain correlates with the change in Curie-Weiss temperature and can qualitatively explain changes in dielectric loss. To explain the experimental findings, we model the dielectric and ferroelectric properties of interest in the framework of the Landau-Ginzburg-Devonshire thermodynamic theory. As expected, an, elastic-strain contribution due to the epilayer-substrate misfit has an important influence on the free-energy. However, additional terms that correspond to the defect-related inhomogeneous strain had to be introduced to fully explain the measurements.

Development of rapidly fermenting strains of saccharomyces-diastaticus for direct conversion of starch and dextrins to ethanol

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variable influence of ferric and cupric ions on Saccharomyces cerevisiae strains used in asymmetric organic synthesis.

Fe (III) and Cu (II) each at 50 mu M in four commercial strains of Saccharomyces cerevisiae induced an increase of NAD(P)(+) reduction in one strain (Turkish), but two others (Chilean and Brazilian), the presence of Fe(III) and/or Cu(II) diminished NAD(P)(+) reduction presumably due to free radicals formation inside these living cells. Suprisingly, in the American strain, Fe(III) induced a decrease and Cu (II) an increase of NAD(P)(+) reduction.

Comparison of the tensile bond strengths of cast metal crowns luted with resin cements

The limitation of photoactivation of dual-polymerized resin cements along the margins of metal restorations may adversely affect the mechanical properties of these cements, thus impairing the retention of restorations. The aim of this study was to assess the bond strength of cast metal crowns cemented with three dual-polymerized resin cements, using a chemically-activated resin cement and zinc phosphate as controls. Fifty nickel-chromium alloy crowns were cast and randomly assigned to five groups of equal size. Castings were cemented on their corresponding metal dies with one of the tested luting agents: Scotchbond Resin Cement, Enforce and Panavia F (dual-polymerized resin cements), Cement-It (chemically-activated resin cement) and Zinc Phosphate Cement (zinc phosphate cement). Specimens were stored in distilled water at 37 degreesC for 24 h and then loaded in tension until failure. Panavia F and Zinc Phosphate Cement provided the highest and lowest bond strength means, respectively. Scotchbond Resin Cement, Enforce and Cement-It cements exhibited similar intermediate values, but with statistically significant difference compared to the other materials (P < 0.05). Even with the restriction or absence of light activation, all tested dual-polymerized resin cements produced significantly higher bond strength than did the zinc phosphate cement and yielded similar or better results than the chemically activated cement. It should be pointed out that the findings of this study relate to a test scenario which does not mimic clinical circumstances and that further work is required to identify the clinical significance of the reported tensile bond strength differences between the different luting materials.

Protein profile of Acidithiobacillus ferrooxidans strains exhibiting different levels of tolerance to metal sulfates

Strains of Acidithiobacillus ferrooxidans exhibited differences in the inhibition of Fe(2+) oxidation in the presence of 250 mm of cadmium, zinc, and manganese sulfates in respirometric assays. Strains LR and I35 were practically not inhibited, whereas strains SSP and V3 showed significant inhibition (30-70%). Analysis by SDS-PAGE of total proteins from cells grown in the absence of metal sulfates showed different profiles between the more tolerant strains (LR and 135) and the more susceptible ones (SSP and V3). Total proteins of strains LR and V3 were also resolved by two-dimensional polyacrylamide gel electrophoresis (2-DE). A set of major proteins (40, 32, 22, and 20 kDa) could be identified only in the more tolerant strain LR. Our results show that protein profiles analysis could differentiate A. ferrooxidans strains that considerably differ in the tolerance to metal sulfates and present low genomic similarity as revealed by Random Amplified Polymorphic DNA (RAPD) data obtained previously in our laboratory.