Spatial portability of numerical models of leaf wetness duration based on empirical approaches

Leaf wetness duration (LWD) models based on empirical approaches offer practical advantages over physically based models in agricultural applications, but their spatial portability is questionable because they may be biased to the climatic conditions under which they were developed. In our study, spatial portability of three LWD models with empirical characteristics - a RH threshold model, a decision tree model with wind speed correction, and a fuzzy logic model - was evaluated using weather data collected in Brazil, Canada, Costa Rica, Italy and the USA. The fuzzy logic model was more accurate than the other models in estimating LWD measured by painted leaf wetness sensors. The fraction of correct estimates for the fuzzy logic model was greater (0.87) than for the other models (0.85-0.86) across 28 sites where painted sensors were installed, and the degree of agreement k statistic between the model and painted sensors was greater for the fuzzy logic model (0.71) than that for the other models (0.64-0.66). Values of the k statistic for the fuzzy logic model were also less variable across sites than those of the other models. When model estimates were compared with measurements from unpainted leaf wetness sensors, the fuzzy logic model had less mean absolute error (2.5 h day(-1)) than other models (2.6-2.7 h day(-1)) after the model was calibrated for the unpainted sensors. The results suggest that the fuzzy logic model has greater spatial portability than the other models evaluated and merits further validation in comparison with physical models under a wider range of climate conditions. (C) 2010 Elsevier B.V. All rights reserved.

Neoformation of micas in soils surrounding an alkaline-saline lake of Pantanal wetland, Brazil

The mineralogy and origin of micas were investigated in incipient soils surrounding a modem alkaline-saline lake of Nhecolandia, a sub-region of Pantanal wetland. Soils were sampled along a toposequence and analyzed by XRD, TEM-EDS, and ICP-MS. The studied micas, mainly concentrated in a green horizon, are dioctahedral, strongly associated with Fe(3+) and Al, and interstratified with smectite layers. Classification of individual crystals shows that glauconite and Fe-illite are the dominant micas, but one crystal of illite was recognized. Si-rich amorphous materials are associated with small crystallites in the mica-enriched horizon. A recent study shows that water samples from the studied lake and the surrounding water table have high pH, negative Eh, temperatures up to 40 C. high concentration of K. and low concentration of Si(OH)(4). Experimental studies of micas synthesis reported in the literature show that similar water conditions allow for dioctahedral mica crystallization from initial precipitation of amorphous hydroxides. Therefore, water characteristics combined with presence of Si-rich amorphous materials in the mica-enriched horizon suggest that the micas of the study area are neoformed. The alternated origin of illite, glauconite, and Fe-illite mixed-layer minerals probably occurs due to seasonal variations of pH. temperature, and chemical composition of waters in microenvironments, since the changes at this scale are possibly faster and more extreme. (C) 2010 Elsevier B.V. All rights reserved.

MINERALOGY AND GENESIS OF SMECTITES IN AN ALKALINE-SALINE ENVIRONMENT OF PANTANAL WETLAND, BRAZIL

Smectite formation in alkaline-saline environments has been attributed to direct precipitation from solution and/or transformation from precursor minerals, but these mechanisms are not universally agreed upon in the literature. The objective of this work was to investigate the mineralogy of smectites in the soils surrounding a representative alkaline-saline lake of Nhecolandia, a sub-region of the Pantanal wetland, Brazil, and then to identify the mechanisms of their formation. Soils were sampled along a toposequence and analyzed by X-ray diffraction, transmission electron microscopy-energy dispersive X-ray analysis, and inductively coupled plasma-mass spectrometry. Water was collected along a transect involving the studied toposequence and equilibrium diagrams were calculated using the databases PHREEQC and AQUA. The fine-clay fraction is dominated by smectite, mica, and kaolinite. Smectites are concentrated at two places in the toposequence: an upper zone, which includes the soil horizons rarely reached by the lake-level variation; and a lower zone, which includes the surface horizon within the area of seasonal lake-level variation. Within the upper zone, the smectite is dioctahedral, rich in Al and Fe, and is classified as ferribeidellite. This phase is interstratified with mica and vermiculite and has an Fe content similar to that of the mica identified. These characteristics suggest that the ferribeidellite originates from transformation of micas and that vermiculite is an intermediate phase in this transformation. Within the lower zone, smectites are dominantly trioctahedral, Mg-rich, and are saponitic and stevensitic minerals. In addition, samples enriched in these minerals have much smaller rare-earth element (REE) contents than other soil samples. The water chemistry shows a geochemical control of Mg and saturation with respect to Mg-smectites in the more saline waters. The REE contents, water chemistry, and the presence of Mg-smectite where maximum evaporation is expected, suggest that saponitic and stevensitic minerals originate by chemical precipitation from the water column of the alkaline-saline lake.

The Genome Sequence of Taurine Cattle: A Window to Ruminant Biology and Evolution

To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.

Molecular basis of infantile reversible cytochrome c oxidase deficiency myopathy

Childhood-onset mitochondrial encephalomyopathies are usually severe, relentlessly progressive conditions that have a fatal outcome. However, a puzzling infantile disorder, long known as `benign cytochrome c oxidase deficiency myopathy` is an exception because it shows spontaneous recovery if infants survive the first months of life. Current investigations cannot distinguish those with a good prognosis from those with terminal disease, making it very difficult to decide when to continue intensive supportive care. Here we define the principal molecular basis of the disorder by identifying a maternally inherited, homoplasmic m.14674T > C mt-tRNA(Glu) mutation in 17 patients from 12 families. Our results provide functional evidence for the pathogenicity of the mutation and show that tissue-specific mechanisms downstream of tRNA(Glu) may explain the spontaneous recovery. This study provides the rationale for a simple genetic test to identify infants with mitochondrial myopathy and good prognosis.

Effect of a thrombin receptor (protease-activated receptor 1, PAR-1) gene polymorphism in chronic hepatitis C liver fibrosis

Background and Aim: Tissue injury leads to activation of coagulation and generation of thrombin. Inhibition of thrombin receptor protease-activated receptor 1 (PAR-1) has been shown to reduce liver fibrosis in animals. This study aimed to evaluate the effect of PAR-1 gene polymorphism on rate of liver fibrosis (RF) in chronic hepatitis C. Methods: Polymorphisms studied: C > T transition 1426 bp upstream of translation start site (-1426C/T), 13 bp repeat of preceding -506 5`-CGGCCGCGGGAAG-3` sequence (-506I/D), and A > T transversion in intervening sequence (IVS) 14 bp upstream of exon-2 start site (IVS-14A/T). A total of 287 European and 90 Brazilian patients were studied. Results: 1426C/T polymorphism: There was a trend to higher RF in patients with the TT genotype (P = 0.06) and an association between genotype CC and slow fibrosis (P = 0.03) in Europeans. In males, RF was significantly higher in those with the TT genotype compared to CT (P = 0.003) and CC (P = 0.007). There was a significant association between TT and fast fibrosis (P = 0.04). This was confirmed in an independent cohort of Brazilians where RF was higher in TT than in CC (P = 0.03). Analysis of -506I/D showed no difference in RF and distribution of slow/fast fibrosis among different genotypes in both populations. Analysis of IVS-14A/T showed no difference between genotypes. Conclusion: In conclusion, these findings suggest that PAR-1 receptor polymorphisms influence the progression of liver fibrosis.

Estabilidade oxidativa e microbiológica em carne de galinha mecanicamente separada e adicionada de antioxidantes durante período de armazenamento a -18 °C

Com o objetivo de acompanhar a estabilidade físico-química e microbiológica da carne mecanicamente separada (CMS) de diferentes origens e estocada durante 99 dias a -18 °C, foi realizada prévia mistura de conservante (nitrito de sódio) e antioxidante (eritorbato de sódio) em CMS obtida de duas linhagens de aves: galinhas matrizes de corte e galinhas poedeiras comerciais brancas. Na CMS de cada linhagem foram realizados três diferentes tratamentos: 1) controle (sem aditivos); 2) adição de 150 ppm de nitrito; e 3) adição de 150 ppm de nitrito e 500 ppm de eritorbato. Os resultados encontrados demonstraram que a adição de nitrito isoladamente não impediu a oxidação lipídica, avaliada através do índice de TBARS, nem a alteração na cor, avaliada em colorímetro. Por outro lado, a adição de nitrito juntamente com eritorbato foi efetiva na redução dos problemas de oxidação lipídica na CMS de galinhas matrizes, e em menor grau, na CMS de poedeiras. A adição de nitrito e eritorbato na CMS também melhorou a preservação da cor vermelha desejável (a*) ao longo do tempo. A avaliação da estabilidade microbiológica da CMS, realizada no primeiro e último dia de estocagem congelada, para microrganismos mesófilos, Escherichia coli, Staphylococcus aureus, Clostridium perfringens e Pseudomonas spp., e quinzenalmente para microrganismos psicrotróficos, indicou que não houve uma variação significativa nas contagens em função do tratamento utilizado (diferentes aditivos adicionados). Não foi detectada Salmonella spp. em nenhuma das amostras analisadas. Em função da melhoria da estabilidade oxidativa, recomenda-se a adição de nitrito (150 ppm) e eritorbato (500 ppm) em CMS de galinhas matrizes a ser estocada congelada por um período prolongado.

Vitaminas D e C para poedeiras na fase inicial de produção de ovos

Um experimento foi conduzido com o objetivo de avaliar os efeitos de duas fontes de vitamina D e três níveis de vitamina C sobre as características de desempenho, a qualidade interna e externa dos ovos, os níveis de c��lcio total e iônico séricos e a resistência óssea de poedeiras. Foram utilizadas 288 galinhas da linhagem ISA Babcock B300® com 23 semanas de idade, durante um período experimental de 12 semanas. Utilizou-se o delineamento inteiramente ao acaso em arranjo fatorial 2 × 3, com os fatores: fontes de vitamina D (colecalciferol e 25-hidroxicolecalciferol - 25(OH)D3) e de vitamina C (0, 100 e 200 ppm), totalizando seis tratamentos com oito repetições de seis aves. O nível basal de colecalciferol foi de 2.756 UI/kg, correspondendo a 5,51 g do produto comercial Hy.D®/t de ração, como fonte de 25(OH)D3. Os fatores estudados não influenciaram o consumo de ração, a produção, o peso e a massa de ovos. Observou-se efeito da interação de fontes de vitamina sobre a conversão alimentar, que foi melhor quando utilizado metabólito 25(OH)D3 na ausência de vitamina C. Interações foram observadas para porcentagem de albúmen e porcentagem de gema, que aumentaram na presença de 200 ppm de vitamina C. O peso espec��fico dos ovos, as concentrações de c��lcio sérico, cinzas ósseas e a resistência à quebra não foram influenciadas pelas fontes de vitamina D e C. Houve interação para porcentagem e espessura de casca, cujos maiores valores foram obtidos com a suplementação de vitamina C na presença de 25(OH)D3. Em poedeiras na fase inicial de produção, a conversão alimentar é melhor com a utilização do 25(OH)D3 e a espessura e porcentagem de casca também melhoram com a utilização de 25(OH)D3 e a suplementação de vitamina C nas dietas (100 ou 200 ppm, respectivamente).

Efeito da lavagem e da adição de aditivos sobre a estabilidade de carne mecanicamente separada de tilápia do Nilo (Oreochromis niloticus) durante estocagem a -18 ºC

Este estudo teve como objetivo avaliar a influência da lavagem e da adição de eritorbato de sódio e tripolifosfato de sódio na estabilidade de Carne Mecanicamente Separada (CMS) de tilápia de Nilo (Oreochromis niloticus) durante 6 meses de armazenamento a -18 ºC. A CMS obtida por meio de máquina separadora de carne e ossos foi dividida em quatro tratamentos (CMS lavada com e sem aditivos, e CMS não lavada com e sem aditivos) e mantida sob congelamento a -18 ºC, por 180 dias. A estabilidade foi avaliada por meio de análises microbiológicas e determinações de nitrogênio não proteico (NNP), bases nitrogenadas voláteis (BNV), substâncias reativas ao ácido tiobarbitúrico (TBARS), pH e drip (perda de água no descongelamento). O processo de lavagem causou redução de aproximadamente 41, 44 e 66% nos teores de proteína bruta, lipídios e cinzas, respectivamente, reduzindo também os valores iniciais de NNP, BNV e TBARS. Durante o armazenamento, foram observados aumentos (p < 0,05) nos teores de NNP, BNV e pH em praticamente todos os tratamentos, exceto na CMS lavada com aditivos, que não apresentou aumentos significativos nos teores de NNP e pH. O uso de aditivos nas CMS diminuiu o drip ao longo do armazenamento, mas não alterou (p > 0,05) os teores de TBARS. Os parâmetros microbiológicos avaliados não ultrapassaram os limites permitidos pela legislação. As CMS permaneceram estáveis e em boas condições de utilização, independentemente da inclusão de aditivo, sendo viável sua estocagem a -18 ºC por 180 dias.

Phylogenetic analyses of Cladophora vagabunda (L.) C. Hoek (Cladophorales, Chlorophyta) from Brazil based on SSU rDNA sequences

The complete SSU rDNA was sequenced for 10 individuals of Cladophora vagabunda collected along the coast of Brazil. For C. rupestris (L.) Kütz. a partial SSU rDNA sequence (1634 bp) was obtained. Phylogenetic trees indicate that Cladophora is paraphyletic, but the section Glomeratae sensu lato including C. vagabunda from Brazil, Japan and France, C. albida (Nees) Kütz., C. sericea (Hudson) Kütz., and C. glomerata (L.) Kütz. is monophyletic. Within this group C. vagabunda is paraphyletic. The sequence identity for the SSU rDNA varied from 98.9% to 100% for the Brazilian C. vagabunda, and from 98.3% to 99.7% comparing the Brazilian individuals to the ones from France and Japan. Sequence identity of the Brazilian C. vagabunda to C. albida and C. sericea vary from 98.0% to 98.6%. The SSU rDNA phylogeny support partially the morphological characteristics presented by Brazilian populations of C. vagabunda. On the other hand, C. rupestris from Brazil does not group with C. rupestris from France, both sequences presenting only 96.9% of identity. The inclusion of sequences of individuals from Brazil reinforces the need of taxonomical revision for the genus Cladophora and for the complex C. vagabunda.

Deleterious effect of TRIS buffer on growth rates and pigment content of Gracilaria birdiae Plastino & E.C. Oliveira (Gracilariales, Rhodophyta)

This work evaluated the effects of Tris (hydroxymethyl)-aminomethane (TRIS) buffer and its interaction with nutrient concentration on the development of Gracilaria birdie, a common species on the Brazilian coast that has been exploited for agar production. Responses to different conditions were assessed through growth rates and pigment content (chlorophyll a, phycoerythrin, phycocyanin and allophycocyanin). Provasoli's nutrient solution with and without TRIS addition was tested at concentrations of 12.5, 25 and 50%. The pH was also monitored. G. birdiae grew better in the absence of TRIS and at low nutrient concentrations, 12.5 and 25% (growth rates of 10.8-11.3%.day-1). Higher contents of phycoerythrin and chlorophyll a were observed without TRIS at 12.5 and 25% (Phycoerythrin, 649.6-698.0 μg g-1 fresh biomass; Chlorophyll a, 156.0-168.6 μg g-1 fresh biomass). These findings highlight the deleterious effect of TRIS on growth and phycoerythrin and chlorophyll a content. They also demonstrate the importance of appropriate nutrient concentration for laboratory cultures, depending on the intrinsic characteristics of each species.

Phenology of an agarophyte Gracilaria birdiae Plastino and E.C. Oliveira (Gracilariales, Rhodophyta) in Northeastern Brazil

The reproductive phenology and thallus length of Gracilaria birdiae were studied over a period of 12 months in a natural bed in Northeastern Brazil. Fertile specimens of G. birdiae were observed during the entire study period. Tetrasporophytes were the most common with an annual mean of 80.1±5.6%, followed by cystocarpic plants (9.3±3.4%), male gametophytes (8.3±3.6%) and infertile plants (2.2±3.4%). Only male gametophytes and infertile plants showed a variation in occurrence frequency during the year (p<0.05). With respect to thallus length, a distinct seasonal variation was observed for all reproductive stages (p<0.05), with the highest values recorded during the rainy season (March to August) and the lowest in the dry season (September to February). The results demonstrate that the size of individuals in this population is significantly affected by the periodic changes in the environment caused by rainfall regimes and hydrodynamism.

COL18A1 is highly expressed during human adipocyte differentiation and the SNP c.1136C > T in its "frizzled" motif is associated with obesity in diabetes type 2 patients

Collagen XVIII can generate two fragments, NC11-728 containing a frizzled motif which possibly acts in Wnt signaling and Endostatin, which is cleaved from the NC1 and is a potent inhibitor of angiogenesis. Collagen XVIII and Wnt signaling have recently been associated with adipogenic differentiation and obesity in some animal models, but not in humans. In the present report, we have shown that COL18A1 expression increases during human adipogenic differentiation. We also tested if polymorphisms in the Frizzled (c.1136C>T; Thr379Met) and Endostatin (c.4349G>A; Asp1437Asn) regions contribute towards susceptibility to obesity in patients with type 2 diabetes (113 obese, BMI =30; 232 non-obese, BMI < 30) of European ancestry. No evidence of association was observed between the allele c.4349G>A and obesity, but we observed a significantly higher frequency of homozygotes c.1136TT in obese (19.5%) than in non-obese individuals (10.9%) [P = 0.02; OR = 2.0 (95%CI: 1.07-3.73)], suggesting that the allele c.1136T is associated to obesity in a recessive model. This genotype, after controlling for cholesterol, LDL cholesterol, and triglycerides, was independently associated with obesity (P = 0.048), and increases the chance of obesity in 2.8 times. Therefore, our data suggest the involvement of collagen XVIII in human adipogenesis and susceptibility to obesity.

Avaliação da cicatrização de feridas em dorso de ratos tratados com mitomicina C tópica e posterior reforço com injetável

Estudo experimental em animais. A mitomicina C vem sendo usada como inibidor de fibroblastos, acarretando, com isso, diminuição do processo cicatricial em feridas cirúrgicas. OBJETIVO: Este trabalho visa avaliar o uso de Mitomicina C para diminuir o processo cicatricial, através de seu uso tópico com reforços posteriores injetáveis. MATERIAL E MÉTODOS: Foi usado um modelo de feridas em dorso de ratos, com retirada circular da pele e cicatrização por segunda intenção. Foram usados 18 ratos, divididos em três grupos: controle; com uso tópico; e com reforço de mitomicina C injetável, mensalmente e por 2 meses. Após 3 meses os animais foram sacrificados e as cicatrizes retiradas cirurgicamente e submetidas a estudo histológico. RESULTADOS: Notou-se sob vários critérios que a cicatrização com o uso tópico é menos intensa, mas ao se usar o reforço injetável os parâmetros voltam a ser comparados ao do grupo controle. DISCUSSÃO: Acreditamos que a administração injetável de mitomicina C nas cicatrizes, pela sua elevada característica tóxica, acarreta destruição tecidual e neoformação cicatricial. CONCLUSÕES: A mitomicina C diminui o processo cicatricial quando usada topicamente, mas acarreta aumento da cicatrização quando nestas feridas são feitos reforços injetáveis.

Ácido clavulânico e cefamicina c: uma perspectiva da biossíntese, processos de isolamento e mecanismo de ação

The present article reviews different aspects of the chemistry of two widely used β-lactam antibiotics Clavulanic Acid and Cephamycin C. The article discusses important details of the biosynthesis of these compounds, their action mechanism and, principally, the methods employed in their isolation and purification, in accordance with the available literature. Despite the large quantity of available articles and patents concerning β-lactam antibiotics, those which describe the isolation and purification of Clavulanic Acid and Cephamycin C are rare. Overall, the intention of this article is to discuss the up-to-date scientific research related to the compounds under review.