Neonatal Gonocyte Differentiation in Mongolian Gerbil Meriones unguiculatus Involves Asynchronous Maturation of Seminiferous Cords and Rapid Formation of Transitional Cell Stage

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Reproductive relationships and degree of synapsis in the polytene chromosomes of the Drosophila buzzatii species cluster

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

DNA Psi-condensation and reentrant decondensation: Effect of the PEG degree of polymerization

psi-Condensation of DNA fragments of about 4 kbp was induced by poly(ethylene glycol) (PEG), with degrees of polymerization ranging from 45 to 182, and univalent salt (NaCl). Using circular dichroism spectroscopy, we were able to accurately determine the critical amount of PEG needed to induce condensation, as a function of the NaCl concentration. A significant dependence on the PEG degree of polymerization was found. Phase boundaries determined for the multimolecular condensation were very similar to those observed previously for the monomolecular collapse, with two asymptotic regimes at low and high salt concentrations. We analyze our data using a theoretical model that properly takes into account both the polyelectrolyte nature of the DNA and the liquid crystallinity of the condensed phase. The model assumes that all PEG is excluded from the condensates and shows reentrant decondensation only at low salt. We also systematically study reentrant decondensation and find a very strong dependence on PEG molecular weight. At low PEG molecular weight, decondensation occurs at relatively low concentrations of PEG, and over a wide range of salt concentrations. This suggests that in the reentrant decondensation the flexible polymers used are not completely excluded from the condensed phase.

ON THE MINIMUM ABSOLUTE VALUE of THE DISCRIMINANT of ABELIAN FIELDS of DEGREE p(2)

Let p be a prime number. A formula for the minimum absolute value of the discriminant of all Abelian extensions of Q of degree p(2) is given in terms of p.

Effects of Chamomilla recutita (L.) on oral wound healing in rats

Objectives. The purpose of this study was to evaluate the effect of Chamomilla recutita on the healing of ulcers in rats.Study Design. A 5-mm wound was inflicted on the tongue of 36 rats. Treatment group animals were treated topically with 0.04 mL/day of chamomile ointment, whereas control group animals were not treated. Animals were sacrificed after 3, 7 or 10 days. Semi-quantitative analysis of the degree of inflammation, fibroblast count and wound size was performed, as well as histometric analysis of re-epithelialization and percentage of collagen fibers of the lesion.Results. Animals treated with chamomile showed the best results regarding epithelialization and percentage of collagen fibers after 10 days. As expected, time had a statistically significant effect (p<0.05) on fibroblast count, epithelialization, inflammation and wound size; animals sacrificed at 3 days showed the worst results.Conclusions. Chamomile stimulated re-epithelialization and the formation of collagen fibers after 10 days of treatment; it did not, however, influence inflammation or fibroblast count.

Effect of Low-Level Laser Therapy and Calcitonin on Bone Repair in Castrated Rats: A Densitometric Study

Objective: To investigate the healing of bone defects in male rats treated with salmon calcitonin, low-level laser therapy (LLLT), or both. Background: Healing of bone defects still represents a challenge to health professionals in several areas. In this article, the effect of calcitonin in combination with LLLT on bone repair was studied. Densitometry was used as a valuable tool for the measurement of bone regeneration. Methods: Sixty male Wistar rats underwent bilateral castration surgery before the creation of a surgical bone defect. The animals were randomly divided into four groups: control, treated with calcitonin (Ca), treated with LLLT (La), and treated with calcitonin and LLLT (CaLa). Groups Ca and CaLa received 2 IU/kg of synthetic salmon calcitonin intra-muscularly three times a week. Groups La and CaLa received laser therapy using a gallium-aluminum-arsenide laser (10mW, 20 J/cm(2), wavelength 830 nm). Control animals were submitted to sham irradiation. The animals were sacrificed 7, 14, and 21 days after surgery, and bone defects were analyzed using densitometry. Results: The CaLa group had a higher degree of bone regeneration 14 and 21 days after surgery. Conclusions: The La and CaLa had significantly higher bone mineral density than the control and Ca groups.

Conversion Degree of Indirect Resin Composites and Effect of Thermocycling on Their Physical Properties

Purpose: This study evaluated the degree of conversion (DC) of four indirect resin composites (IRCs) with various compositions processed in different polymerization units and investigated the effect of thermal aging on the flexural strength and Vicker's microhardness.Materials and Methods: Specimens were prepared from four IRC materials, namely Gr 1: Resilab (Wilcos); Gr2: Sinfony (3M ESPE); Gr3: VITA VMLC (VITA Zahnfabrik); Gr4: VITA Zeta (VITA Zahnfabrik) using special molds for flexural strength test (N = 80, n = 10 per group) (25 x 2 x 2 mm(3), ISO 4049), for Vicker's microhardness test (N = 80, n = 10 per group) (5 x 4 mm(2)) and for DC (N = 10) using FT-Raman Spectroscopy. For both flexural strength and microhardness tests, half of the specimens were randomly stored in distilled water at 37 degrees C for 24 hours (Groups 1 to 4), and the other half (Groups 5 to 8) were subjected to thermocycling (5000 cycles, 5 to 55 +/- 1 degrees C, dwell time: 30 seconds). Flexural strength was measured in a universal testing machine (crosshead speed: 0.8 mm/min). Microhardness test was performed at 50 g. The data were analyzed using one-way and two-way ANOVA and Tukey's test (alpha = 0.05). The correlation between flexural strength and microhardness was evaluated with Pearson's correlation test (alpha = 0.05).Results: A significant effect for the type of IRC and thermocycling was found (p = 0.001, p = 0.001) on the flexural strength results, but thermocycling did not significantly affect the microhardness results (p = 0.078). The interaction factors were significant for both flexural strength and microhardness parameters (p = 0.001 and 0.002, respectively). Thermocycling decreased the flexural strength of the three IRCs tested significantly (p < 0.05), except for VITA Zeta (106.3 +/- 9.1 to 97.2 +/- 14 MPa) (p > 0.05) when compared with nonthermocycled groups. Microhardness results of only Sinfony were significantly affected by thermocycling (25.1 +/- 2.1 to 31 +/- 3.3 Kg/mm(2)). DC values ranged between 63% and 81%, and were not significantly different between the IRCs (p > 0.05). While a positive correlation was found between flexural strength and microhardness without (r = 0.309) and with thermocycling (r = 0.100) for VITA VMLC, negative correlations were found for Resilab under the same conditions (r = -0.190 and -0.305, respectively) (Pearson's correlation coefficient).Conclusion: Although all four IRCs presented nonsignificant DC values, flexural strength and microhardness values varied between materials with and without thermocycling.

The adhesive system and root canal region do not influence the degree of conversion of dual resin cement

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

Bond strengths, degree of conversion of the cement and molecular structure of the adhesive-dentine joint in fibre post restorations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Influence of Chemical Activation on Tooth Bleaching Using 10% Carbamide Peroxide

The aim of this study was to assess the influence of manganese gluconate, a chemical activator of bleaching agents, at a concentration of 0.01% on the efficiency of a 10% carbamide peroxide-based bleaching agent. Forty bovine incisors were immersed in a 25% instant coffee solution for seven days and randomly divided into two groups. Group 1 was the control group and consisted of 10% carbamide peroxide-based bleaching gel only. Group 2 consisted of 10% carbamide peroxide-based bleaching gel and 0.01% manganese gluconate. Three readings of color were taken using the Vita Easy-shade spectrophotometer: the initial reading, a reading at seven days, and a reading at 14 days. Total color variation was calculated by Delta E*Lab. Data were submitted to the statistical t-test (5%), which showed that after seven days group 2 had a significant increase in the degree of tooth bleaching compared with group 1. The mean values (+/-SD) were 16.33 (+/-3.95) for group 1 and 19.29 (+/-4.97) for group 2. However, the results for group 1 and group 2 were similar after 14 days. Adding 0.01% manganese gluconate to 10% carbamide peroxide bleaching gel increased the degree of tooth bleaching after a seven-day treatment and did not influence the resulting shade after 14 days.

Highly corrosion resistant siloxane-polymethyl methacrylate hybrid coatings

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Itaipu reservoir limnology: eutrophication degree and the horizontal distribution of its limnological variables

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

Heterospecific sociality of birds on beaches from southeastern Brazil

Studies on the sociality of heterospecific assemblages of birds have promoted a greater understanding of the types of interactions and survivorship between coexisting species. This study verified the group compositions in bird assemblages and analyzed the sociality of migratory and resident species on sandy beaches of southeastern Brazil. A transect was established on the median portion of beaches and all the groups of bird species (monospecific, heterospecific) and solitary individuals were registered four days per month from November 2006 to April 2007. The sociality of each species was calculated by its frequency in heterospecific groups, its proportional number of contacts with other species in heterospecific groups, and the number of species that it associated with. Semipalmated Sandpiper Calidris pusilla (Linnaeus, 1766) and Semipalmated Plover Charadrius semipalmatus Bonaparte, 1825 (both migratory) had the highest degree of sociality and did not show a preference to associate with either residents or migratory species. Sanderling Calidris alba (Pallas, 1764) (migratory) occupied the third position in the sociality rank and associated with migratory species frequently. Southern Caracara Carara plancus (Miller, 1777) and Black Vulture Coragyps atratus (Beschstein, 1793) (both resident) were uniquely found among heterospecific groups with necrophagous and resident species. Kelp Gull Larus dominicanus Lichtenstein, 1823 (resident) associated more frequently with resident species. The sociality in assemblages of birds may promote advantages such as an increased collective awareness in dangerous situations and indication of sites with abundant food sources.

Predicting the occurrence of alate aphids in Brassicaceae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Salt stress change chlorophyll fluorescence in mango

Este trabalho teve como objetivo avaliar o efeito do estresse salino sobre a eficiência fotoquímica do fotossistema II (PSII) nas cultivares de manga 'Haden', 'Palmer', 'Tommy Atkins' e 'Ubá' enxertadas sobre o porta-enxerto 'Imbu'. Foi utilizada solução nutritiva de Hoagland modificada contendo 0; 15; 30e 45 mmol L-1 NaCl. Aos 97 dias após a exposição ao estresse salino, foram avaliados os parâmetros da fluorescência da clorofila (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs)/(Fm')], D = (1- Fv'/Fm') e ETR = (ΦPSII×PPF×0,84×0,5). Aos 100 dias, foram avaliados a emissão foliar, a área média de folhas (cm²), o índice de toxidez nas folhas e o índice de abscisão foliar. em todas as cultivares, em graus diferenciados, ocorreram decréscimo na eficiência fotoquímica do fotossistema II, na emissão de folhas, e aumento nos índices de toxidez e abscisão foliar, intensificados nas concentrações a partir de 15 mmol L-1 NaCl. As plantas cultivadas em 45 mmol L-1 NaCl apresentaram decréscimos na razão Fv/Fm de 27,9; 18,7; 20,5 e 27,4%, incremento no índice de toxidez foliar de 33,0; 67,5; 41,6 e 80,8% e no índice de abscisão foliar de 71,8; 29,2; 32,5 e 67,9% para as cultivares 'Haden', 'Palmer', 'Tommy Atkins' e 'Uba', respectivamente. Os decréscimos na razão Fv/Fm foram acompanhados de redução na emissão de folhas e aumento no índice de toxidez foliar, mostrando, portanto, o potencial da fluorescência da clorofila na detecção precoce de estresse salino em mangueira.