Critical behavior at edge singularities in one-dimensional spin models

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cultivo de algas marinhas como desenvolvimento de comunidades costeiras

In northeastern Brazil, the extraction of agar has increased considerably in recent decades mainly using macroalgae of the genus Gracilaria. The pressure of the harvest of seaweed of this genus has compromised the sustainability of this natural resource. Given the current framework of decline in production of algae in the state of Rio Grande do Norte, it is necessary the deployment of crops that will assist in the development of coastal areas. This research aimed to develop studies on growth, productivity, efficiency and quality of agar of G. birdiae so as to provide subsidies for crops on commercial scale. The study was carried out in dry and rainy periods using rafts of cultivation. Algal biomass and the physical and chemical parameters of water were measured every fifteen days. In laboratory, the resistance and quality of agar were analyzed. The relative growth rate (TCR) was determined by the formula: RGR = ln (final weight / weight initial). 100 / interval time of sampling. During the study, environmental factors as salinity and temperature remained relatively constant (around 35 PSU and 28°C, respectively). The mean values of biomass ranged around 1952.67 ± 576g in the rainy period and 1925.67 ± 450g in the dry period, and they presented no significant variations. The maximum value of growth (TCR) was recorded in the dry season (7.45%.day-1), with an average over the study of 4.35%.day-1. The yield of agar ranged from 22% to 15%, and its resistance ranged from 850 to 650g. cm². The average obtained for the two periods was approximately 750 g cm². These results demonstrate the great potential of Gracilaria birdiae for mariculture can be used as an sustainable activity for coastal communities

Influência de diferentes níveis de cálcio em plantas de estilosantes (Stylosanthes guyanensis (Aubl.) Sw. cv. Cook), avaliados através de alguns parâmetros fisiológicos

O objetivo do presente trabalho foi estudar os efeitos de diferentes níveis de cálcio, no desenvolvimento de plantas de Stylosanthes guyanensis (Aubl.) Sw. cv. Cook, através de alguns parâmetros que compõem a análise fisiológica de crescimento. Para tal foram empregados 4 tratamentos a saber: T1 (200 mg de cálcio/litro); T2 (133,33 mg de cálcio/litro); T3 (66,66 mg de cálcio/litro) e T4 (omisso em cálcio). O trabalho foi montado em cultivo hidropônico, utilizando-se a solução nutritiva n° 1 de Hoagland & Arnon e conduzido em casa de vegetação. Foram realizadas observações em intervalos entre 5 coletas, distribuidas da seguinte maneira: intervalo I (entre 24° e 38° dia pós-germinação; intervalo II ( do 38° ao 52° dia); intervalo III (do 52° ao 66° dia) e intervalo IV (do 66° ao 80° dia). Os parâmetros estudados foram: a. taxa assimilatória líquida (TAL); b. taxa de crescimento relativo (TCR) e c. razão alfa. Dos resultados obtidos pode-se concluir que soluções com 200 e 133,33 mg de cálcio/litro, foram mais eficientes em promover o desenvolvimento de plantas de estilosantes.

Crescimento de plantas de Salvia officinalis sob ação de reguladores de crescimento vegetal

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Taxa de prenhez de vacas Nelore lactantes tratadas com progesterona associada à remoção temporária de bezerros ou aplicação de gonadotrofina coriônica eqüina

Avaliaram-se os efeitos da remoção temporária de bezerros (RTB) ou da aplicação de gonadotrofina coriônica eqüina (eCG) na taxa de prenhez (TP) de vacas Nelore lactantes tratadas com um dispositivo intravaginal liberador de progesterona (DILP). No experimento 1, 83 vacas Nelore e 102 mestiças (Nelore × Red Angus) foram distribuídas em três grupos. em dia aleatório do ciclo estral (D0), os animais do grupo 1 foram tratados com benzoato de estradiol (BE; 2,5 mg, IM, Estrogin®) e um DILP (1 g de progesterona, DIB®), removido no D9, quando também se administrou d-cloprostenol (150 µg, IM, Prolise®) e aproximadamente 12 horas após identificação do estro realizou-se a inseminação artificial. No grupo 2 (IATF), o tratamento foi semelhante ao aplicado no grupo 1, porém, administrou-se uma segunda dose de benzoato de estradiol (1 mg) no D10 e 30-36 horas mais tarde realizou-se a inseminação artificial em tempo fixo (IATF). No grupo 3 (IATF/RTB), os bezerros foram removidos a partir do D9 até a inseminação artificial com tempo fixo (IATF). As taxas de prenhez para as vacas Nelore e mestiças foram, respectivamente, de 7,69 e 41% (Controle); 23,52 e 59,57% (IATF); 69,44 e 55,81% (IATF/RTB). No experimento 2, 255 vacas Nelore lactantes foram distribuídas em três grupos. Os animais do grupo 4 (IATF) foram tratados com benzoato de estradiol (2 mg) e um DILP (1,9 g de progesterona, CIDR-B®) no D0 e no D8 sofreram remoção do DILP no D8 e administração de 25 mg de dinoprost (IM, Lutalyse®). No D9, foi aplicado benzoato de estradiol (1 mg) realizando-se a IATF 30-36 horas mais tarde. No grupo 5 (IATF/RTB), os bezerros foram removidos no D9 até a IATF. O grupo 6 (eCG) foi semelhante ao IATF, exceto pela aplicação de eCG no D9 (400 UI, IM, Novormon®). As taxas de prenhez foram de 50,57 (IATF), 53,57 (IATF/RTB) e 54,76% (eCG). A associação de RTB ao tratamento hormonal com DILP aumenta as taxas de prenhez, enquanto a adição de eCG ao tratamento não melhora as taxa de prenhez de vacas Nelore lactantes ciclando e em boa condição corporal.

B lineage acute lymphoblastic leukemia transformation in a child with juvenile myelomonocytic leukemia, type 1 neurofibromatosis and monosomy of chromosome 7 - Possible implications in the leukemogenesis

This report describes the case of an 8-month-old infant with a diagnosis of juvenile myelomonocytic leukemia (JMML) and type I neurofibromatosis that presented progression to B lineage acute lymphoid leukemia (ALL). The same rearrangement of gene T-cell receptor gamma (TCRgamma) was detected upon diagnosis of JMML and ALL, suggesting that both neoplasias may have evolved from the same clone. Our results support the theory that JMML may derive from pluripotential cells and that the occurrence of monosomy of chromosome 7 within a clone of cells having an aberrant neurofibromatosis type 1 (NFI) gene may be the cause of JMML and acute leukemia. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Distinct localization of T cell Agrin during antigen presentation - evidence for the expression of Agrin receptor(s) in antigen-presenting cells

Agrin is over-expressed by activated and autoimmune T cells, and synergizes with the T cell receptor (TCR) to augment cell activation. In the present study, we show that Agrin accumulates to distinct areas of the plasma membrane and that cell activation causes its redistribution. During antigen presentation, Agrin primarily accumulates to the periphery of the mature immunological synapse, mostly in lamellipodia-like protrusions that wrap around the antigen-presenting cell and, conversely, anti-Agrin sera induced a significant redistribution of TCR at the plasma membrane. We also provide evidence for the expression of Agrin receptors in peripheral blood monocytes, dendritic cells and a fraction of B cells. Interestingly, interferon-a treatment, which induces the expression of Agrin in T cells, also augmented Agrin binding to monocytes. Stimulation of monocytes with recombinant Agrin induced the clustering of surface receptors, including major histocompatibility complex class II, activation of intracellular signalling cascades, as well as enhanced dsRNA-induced expression of pro-inflammatory cytokines interleukin-6 and tumour necrosis factor-a. Collectively, these results confirm the location of Agrin at the immunological synapse between T cells and antigen-presenting cells and justify further characterization of its receptors in the immune system.

Efeitos de reguladores e estimulantes vegetais no desenvolvimento do milho (Zea mays L. cv. c-525)

Estudou-se, sob condições de casa de vegetação, o efeito da aplicação de reguladores e estimulantes vegetais no desenvolvimento do milho cultivar Cargill -525. Os reguladores e estimulantes utilizados foram: giberelina 100 ppm, ethephon 600 ppm, Agrostemin 0,8 g/l e Triacontanol 0,5 mg/l; aplicados por pulverização 34 dias após a semeadura, além do controle, foram determinados os parâmetros relativos a altura da planta, número de folhas, área foliar e peso da materia seca de raiz, caule e folhas. A partir dos dados de área foliar e peso da matéria seca total obtidos em 4coletas realizadas com intervalos de 14 dias, foram calculadas a taxa assimilatória líquida (TAL), taxa de crescimento relativo (TCR) e razão de área foliar (RAF). Giberelina 100 ppm aumentou inicialmente a altura das plantas de milho, sendo que ethephon 600 ppm reduziu a altura média do milho. 0 número de folhas foi diminuído nas plantas tratadas com giberelina, tendendo a aumentar no tratamento com ethephon. Giberelina reduziu o peso da matéria seca das plantas de milho, sendo que ethephon incrementou o peso de raízes, colmo e folhos. Triacontanol promoveu redução na TAL e na TCR do milho 'Cargill - 525' . Giberelina e ethephon tenderam a diminuir a RAF das plantas de Zea mays L.

Efeitos do agrostemin em plantas de soja (Glicine max (L.) Merrill cv. IAC-8), através dos parâmetros fisiológicos: razão de área foliar, taxa assimilatória líquida e taxa de crescimento relativo

O presente estudo teve por finalidade avaliar o efeito de um estimulante vegetal, Agrostemin, no desenvolvimento de plantas de soja (Glycine max (L.) Merrill cv. IAC-8), através de alguns parâmetros que compõem a análise de crescimento. O experimento foi conduzido em casa de vegetação. Foram estudados seis tratamentos, correspondentes às seguintes dosagens, épocas e formas de aplicação: testemunha (T1); 0,125g de Agrostemin/100g sementes (T2); 0,125g de Agrostemin/l00g sementes e pulverização foliar à 333 ppm (T3); 0,125g de Agrostemin/100g sementes e pulverização foliar à 500 ppm (T4); pulverização foliar à 333 ppm (T5) e pulverização foliar à 500 ppm (T6). Realizaram-se três épocas de coleta, à intervalos de 14 dias. O experimento foi em delineamento inteiramente casualizado. Os parâmetros estudados foram: razão de área foliar (RAF), taxa assimilatória líquida (TAL) e taxa de crescimento relativo (TCR). Dentre os resultados obtidos, concluiu-se que à medida que aumentou-se a concentração, diminuiram-se os parâmetros estudados, no intervalo 71-85.

Rapid degradation of propanil in rice crop fields

Propanil and its major degradation product, 3,4-dichloroaniline (DCA), were monitored in surface water and soil samples from two rice fields of the Ebre Delta area (Tarragona, Spain) following agricultural application. On-line solid-phase extraction (SPE) (water) and Soxhlet extraction (soil) followed by liquid chromatography/diode array detection (LC/DAD) were used for the trace determination of both compounds. Unequivocal confirmation/identification was conducted by using liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry, LC/APCI/MS (using negative and positive ionization modes). Concentrations of the herbicide propanil in water samples varied from 1.9 to 55.9 mu g/L. Propanil degraded very rapidly to DCA, and high concentrations of this product were found, varying from 16.5 to 470 mu g/L in water and 119 +/- 22 mu g/kg in soil samples. No detectable DCA (<0.001%) was found in the applied pesticide formulation, indicating that DCA formation took place after propanil application. These field results compared favorably with laboratory experiments showing that humic interactions had a strong influence on the pesticide degradation. The half-lifes under real conditions for propanil and DCA, calculated using a first-order decay, were 1.2 and 1.6 days, respectively.

Cellular immune responses in mice immunized with Anisakis simplex larval antigens

Cellular immune responses to Anisakis simplex L3 antigens were investigated in BALB/c mice injected subcutaneously with a homologous crude extract (CE). Popliteal lymph nodes (PLN) were found to be increased in size and weight after A. simplex CE footpad injection. The effects of A. simplex CE in vitro proliferation were assayed with non-fractionated PLN cells or nylon-wool purified T cells derived from pooled lymph node cells of mice subcutaneously injected with CE. Spleen cells from immunized animals (antigen alone, or larva alone, or antigen plus larva) were studied by flow cytometry. The immunization induced a high proportion of CD4 + and TCR alpha beta + T cells. The number of B cells (CD45 + and TCR alpha beta-) in pre-immunized and infected mice was lower than that observed in animals subjected to infection only. The number of CD4 + T cells increased in the infected and in the pre-immunized and infected mice. In the latter, a decrease of CD8a + T cells was noted. The greatest increase in CD8a+ and TCR alpha beta- T cells was found in mice that had been subjected to infection only. Histological analysis showed that the most prominent lesions were gastric and intestinal in animals infected orally with one larva.

Determination of rice herbicides, their transformation products and clofibric acid using on-line solid-phase extraction followed by liquid chromatography with diode array and atmospheric pressure chemical ionization mass spectrometric detection

A simultaneous method for the trace determination of acidic, neutral herbicides and their transformation products in estuarine waters has been developed through an on-line solid-phase extraction method followed by liquid chromatography with diode array and mass spectrometric detection. An atmospheric pressure chemical ionization (APCI) interface was used in the negative ionization mode after optimization of the main APCI parameters. Limits of detection ranged from 0.1 to 0.02 ng/ml for 50 mi of acidified estuarine waters preconcentrated into polymeric precolumns and using time-scheduled selected ion monitoring mode. Two degradation products of the acidic herbicides (4-chloro-2-methylphenol and 2,4-dichlorophenol) did not show good signal response using APCI-MS at the concentration studied due to the higher fragmentor voltage needed for their determination For molinate and the major degradation product of propanil, 3,4-dichloroaniline, positive ion mode was needed for APCI-MS detection. The proposed method was applied to the determination of herbicides in drainage waters from rice fields of the Delta del Ebro (Spain). During the S-month monitoring of the herbicides, 8-hydroxybentazone and 4-chloro-2-methylphenoxyacetic acid were successively found in those samples. (C) 2000 Elsevier B.V. B.V. All rights reserved.

Determination of 2,4-dichlorophenoxyacetic acid and its major transformation product in soil samples by liquid chromatographic analysis

The 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the most applied herbicides around the world to control broad leave herbs in many crops: In this study, a method was developed for simultaneous extraction and determination of 2,4D and its major transformation product, i.e., the 2,4-dichlorophenol (2,4-DCP), in soil samples. The herbicide and its degradation product were extracted twice from soil samples, after acidification, by dichloromethane on ultrasound system for 1 h. Both extracts were combined and filtrated in qualitative filter paper and Celitee. The total extract was concentrated in rotatory evaporator, dried under N-2 and finally dissolved in 1 ml of methanol. High Performance Liquid Chromatography with UV detection at 230 nm was used for analysis. Recoveries were obtained from soil samples fortified at 0.1, 1.0, 2.0, 3.0 and 4.0 mg kg(-1) levels and the results varied from 85 to 111% (for 2,4-D) and from 95 to 98% (for 2,4-DCP). For both compounds, the limits of quantification were 0.1 mg kg(-1), which were the loss level at which the accuracy and the precision were studied. Nevertheless, the limits of detection, calculated by considering the blank standard deviation and the minimum concentration level, were 0.03 and 0.02 mg kg for 2,4-D and 2,4-DCP, respectively. This proposed method was applied to soil samples of eucalyptus crops, which was previously treated with the herbicide. Despite that, neither 2,4-D nor its degradation product were detected 30 days after the herbicide application. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Multiresidue analysis of pesticides in water from rice cultures by on-line solid phase extraction followed by LC-DAD

An automated on-line solid phase extraction procedure followed by liquid chromatography with diode array detection was investigated for the determination of different classes of pesticides in water samples containing varied amount of humic substances. The different pesticides used were: carbendazin, carbofuran, atrazine, diuron, propanil, molinate, alachlor, parathion-ethyl, diazinon, trifluralin and the degradation products deisopropylatrazine and deethylatrazine. Humic substances extracted from a Brazilian sediment were used from 5 to 80 mg/l and their influence on recoveries was evaluated in neutral and acidic media. Recoveries higher than 70% were obtained for all the pesticides, from the preconcentration of 75 mi of aqueous sample fortified at 2 ng/ml using precolumns packed with PLRP-S. Good recoveries were obtained at neutral pH for most of the analytes up to 40 mg/l of humic acid. Only at 80 mg/l the recoveries were significantly affected, both at acidic and neutral pH. The method was applied to the determination of pesticides in river water spiked at 0.1 to 1 ng/ml. Detection limits obtained for water containing 10 mg/l of humic acid were between 0.05 and 0.3 ng/ml.