Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Catalysis. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Modulation of gill Na+,K+‐ATPase activity by ammonium ions: Putative coupling of nitrogen excretion and ion uptake in the freshwater shrimp Macrobrachium olfersii

Abstract: The effect of NH4+ ions on (Na+ ,K+)-ATPase hydrolytic activity was examined in a gill microsomal fraction from M. olfersii. In the absence of NH4+ ions, K+ ions stimulated ATP hydrolysis, exhibiting cooperative kinetics (nH=0.8), to a maximal specific activity of V=556.1±22.2 nmol.min−1.mg−1 with K0.5=2.4±0.1 mmol.L−1. No further stimulation by K+ ions was observed in the presence of 50 mmol.L−1 NH4+ ions. ATP hydrolysis was also stimulated by NH4+ ions obeying Michaelian kinetics to a maximal specific activity of V=744.8±22.3 nmol.min−1.mg−1 and KM=8.4±0.2 mmol.L−1. In the presence of 10 mmol.L−1 K+ ions, ATP hydrolysis was synergistically stimulated by NH4+ ions to V=689.8±13.8 nmol.min−1.mg−1 and K0.5=6.6±0.1 mmol.L−1, suggesting that NH4+ ions bind to different sites than K+ ions. PNPP hydrolysis was also stimulated cooperatively by K+ or NH4+ ions to maximal values of V= 235.5±11.8 nmol.min−1.mg−1 and V=234.8±7.0 nmol.min−1.mg−1, respectively. In contrast to ATP hydrolysis, K+ -phosphatase activity was not synergistically stimulated by NH4+ and K+ ions. These data suggest that at high NH4+ ion concentrations, the (Na+, K+)-ATPase exposes a new site; the subsequent binding of NH4+ ions stimulates ATP hydrolysis to rates higher than those for K+ ions alone. This is the first demonstration that (Na+, K+)-ATPase activity in a freshwater shrimp gill is modulated by ammonium ions, independently of K+ ions, an effect that may constitute a fine-tuning mechanism of physiological relevance to osmoregulatory and excretory processes in palaemonid shrimps. J. Exp. Zool. 301A: 63–74, 2004. © 2004 Wiley-Liss, Inc.

In Vitro Photodynamic Inactivation of Plant-Pathogenic Fungi Colletotrichum acutatum and Colletotrichum gloeosporioides with Novel Phenothiazinium Photosensitizers

Abstract: The increasing tolerance to currently used fungicides in both clinical and agricultural areas is of great concern. The nonconventional light-based approach of antimicrobial photodynamic treatment (APDT) is a promising alternative to conventional fungicides. We evaluated the effects of APDT with four phenothiazinium derivatives (methylene blue [MB], new methylene blue N [NMBN], toluidine blue O [TBO], and the novel pentacyclic phenothiazinium photosensitizer [PS] S137) on conidia of three fungal species (Colletotrichum acutatum, Colletotrichum gloeosporioides, and Aspergillus nidulans). The efficacy of APDT with each PS was determined, initially, based on photosensitizer MICs. Additionally, the effects of APDT with two selected PSs (NMBN and S137) on survival of conidia were evaluated. The subcellular localization of the PS in C. acutatum conidia was determined. The effects of photodynamic treatments on leaves of the plant host Citrus sinensis were also investigated. APDT with S137 showed the lowest MIC. MICs for S137 were 5 μM for the three fungal species when a fluence of 25 J cm(-2) was used. APDT with NMBN (50 μM) and S137 (10 μM) resulted in a reduction in the survival of the conidia of all species of approximately 5 logs with fluences of ≥15 J cm(-2). Washing of the conidia before light exposure did not prevent photodynamic inactivation. Both NMBN and S137 accumulated in cytoplasmic structures, such as lipid bodies, of C. acutatum conidia. No damage to orange tree leaves was observed after APDT.

Impact of photodynamic therapy on inflammatory cells during human chronic periodontitis

Abstract: The aim of this study was to evaluate the effects of the photodynamic therapy (PDT) on the inflammatory infiltrate and on the collagen network organization in human advanced chronic periodontitis. Two different drug delivery systems (DDS) were tested (liposomes and nanoemulsions) to determine if the effects of PDT could differ according to the DDS used. Sixteen patients presenting two teeth with chronic advanced periodontitis and important tooth mobility with clinical indication of extraction were included in the group liposomes (group L, n =8 ) or in the group nanoemulsions (group N, n = 8) in order to compare the effects of each DDS. Seven days before extractions one tooth of each patient was treated with PDT using phthalocyanine derivatives as photosensitizers and the contralateral tooth was taken as control. In group L the density of gingival collagen fibers (66 ± 19%) was significantly increased (p < 0.02) when compared to controls (35 ± 21%). Concerning the antigen-presenting cells, PDT had differential effects depending on the drug delivery system; the number of macrophages was significantly decreased (p < 0.05) in group L while the number of Langerhans cells was significantly decreased in group N (p < 0.02). These findings demonstrate that PDT presents an impact on gingival inflammatory phenomenon during chronic periodontitis and leads to a specific decrease of antigen-presenting cells populations according to the drug delivery system used.

The look of royalty: visual and odour signals of reproductive status in a paper wasp

Abstract: Reproductive conflicts within animal societies occur when all females can potentially reproduce. In social insects, these conflicts are regulated largely by behaviour and chemical signalling. There is evidence that presence of signals, which provide direct information about the quality of the reproductive females would increase the fitness of all parties. In this study, we present an association between visual and chemical signals in the paper wasp Polistes satan. Our results showed that in nest-founding phase colonies, variation of visual signals is linked to relative fertility, while chemical signals are related to dominance status. In addition, experiments revealed that higher hierarchical positions were occupied by subordinates with distinct proportions of cuticular hydrocarbons and distinct visual marks. Therefore, these wasps present cues that convey reliable information of their reproductive status.