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71.
Berenice Kussumoto Alcantara Katja Machemer-Noonan Francides Gomes Silva Júnior Ricardo Antunes Azevedo 《PloS one》2015,10(12)
Aluminum (Al) toxicity is directly related to acidic soils and substantially limits maize yield. Earlier studies using hormones and other substances to treat the seeds of various crops have been carried out with the aim of inducing tolerance to abiotic stress, especially chilling, drought and salinity. However, more studies regarding the effects of seed treatments on the induction of Al tolerance are necessary. In this study, two independent experiments were performed to determine the effect of ascorbic acid (AsA) seed treatment on the tolerance response of maize to acidic soil and Al stress. In the first experiment (greenhouse), the AsA seed treatment was tested in B73 (Al-sensitive genotype). This study demonstrates the potential of AsA for use as a pre-sowing seed treatment (seed priming) because this metabolite increased root and shoot growth under acidic and Al stress conditions. In the second test, the evidence from field experiments using an Al-sensitive genotype (Mo17) and an Al-tolerant genotype (DA) suggested that prior AsA seed treatment increased the growth of both genotypes. Enhanced productivity was observed for DA under Al stress after priming the seeds. Furthermore, the AsA treatment decreased the activity of oxidative stress-related enzymes in the DA genotype. In this study, remarkable effects using AsA seed treatment in maize were observed, demonstrating the potential future use of AsA in seed priming. 相似文献
72.
van Hamersveld EH van der Lans RG Caulet PJ Luyben KC 《Biotechnology and bioengineering》1998,57(3):330-341
Flocculation of yeast cells occurs during the fermentation of beer. Partway through the fermentation the cells become flocculent and start to form flocs. If the environmental conditions, such as medium composition and fluid velocities in the tank, are optimal, the flocs will grow in size large enough to settle. After settling of the main part of the yeast the green beer is left, containing only a small amount of yeast necessary for rest conversions during the next process step, the lagering. The physical process of flocculation is a dynamic equilibrium of floc formation and floc breakup resulting in a bimodal size distribution containing single cells and flocs. The floc size distribution and the single cell amount were measured under the different conditions that occur during full scale fermentation. Influences on flocculation such as floc strength, specific power input, and total number of yeast cells in suspension were studied. A flocculation model was developed, and the measured data used for validation. Yeast floc formation can be described with the collision theory assuming a constant collision efficiency. The breakup of flocs appears to occur mainly via two mechanisms, the splitting of flocs and the erosion of yeast cells from the floc surface. The splitting rate determines the average floc size and the erosion rate determines the number of single cells. Regarding the size of the flocs with respect to the scale of turbulence, only the viscous subrange needs to be considered. With the model, the floc size distribution and the number of single cells can be predicted at a certain point during the fermentation. For this, the bond strength between the cells, the fractal dimension of the yeast, the specific power input in the tank and the number of yeast cells that are in suspension in the tank have to be known. Copyright 1998 John Wiley & Sons, Inc. 相似文献
73.
Cleo Alcantara Costa Leite E. W. Taylor C. D. R. Guerra L. H. Florindo T. Belão F. T. Rantin 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(8):721-731
The role of the vagus nerve in determining heart rate (f
H) and cardiorespiratory interactions was investigated in a neotropical fish, Piaractus mesopotamicus. During progressive hypoxia f
H initially increased, establishing a 1:1 ratio with ventilation rate (f
R). Subsequently there was a hypoxic bradycardia. Injection of atropine abolished a normoxic inhibitory tonus on the heart
and the f
H adjustments during progressive hypoxia, confirming that they are imposed by efferent parasympathetic inputs via the vagus
nerve. Efferent activity recorded from the cardiac vagus in lightly anesthetized normoxic fish included occasional bursts
of activity related to spontaneous changes in ventilation amplitude, which increased the cardiac interval. Restricting the
flow of aerated water irrigating the gills resulted in increased respiratory effort and bursts of respiration-related activity
in the cardiac vagus that seemed to cause f
H to couple with f
R. Cell bodies of cardiac vagal pre-ganglionic neurons were located in two distinct groups within the dorsal vagal motor column
having an overlapping distribution with respiratory motor-neurons. A small proportion of cardiac vagal pre-ganglionic neurons
(2%) was in scattered positions in the ventrolateral medulla. This division of cardiac vagal pre-ganglionic neurons into distinct
motor groups may relate to their functional roles in determining cardiorespiratory interactions. 相似文献
74.
Jader Nones Ana Paula Costa Rodrigo Bainy Leal Flávia Carvalho Alcantara Gomes Andréa Gon?alves Trentin 《Cell and tissue research》2012,350(2):305-315
The neural crest (NC) corresponds to a collection of multipotent and oligopotent progenitors endowed with both neural and mesenchymal potentials. The derivatives of the NC at trunk level include neurons and glial cells of the peripheral nervous system in addition to melanocytes, smooth muscle cells and some endocrine cells. Environmental factors control the fate decisions of NC cells. Despite the well-known influence of flavonoids on the central nervous system, the issue of whether they also influence NC cells has not been yet addressed. Flavonoids are polyphenolic compounds that are integral components of the human diet. The biological activities of these compounds cover a very broad spectrum, from anticancer and antibacterial activities to inhibition of bone reabsorption and modulation of inflammatory response. In the present work, we have investigated the actions of the flavonoids hesperidin, rutin and quercetin on NC cells of quail, in vitro. We show for the first time, that hesperidin and rutin increase the viability of trunk NC cells in culture, without affecting cell differentiation and proliferation. The molecular mechanism of this action is dependent on ERK2 and PI3K pathways. Quercetin had no effect on NC progenitors. Taken together, these results suggest that flavonoids hesperidin and rutin increase NC cell survival, which may be useful against the toxicity of some chemicals during embryonic development. 相似文献
75.
Ana Paula Souza Bruno Bezerril Andrade Dorlene Aquino Petter Entringer José Carlos Miranda Ruan Alcantara Daniel Ruiz Manuel Soto Clarissa R. Teixeira Jesus G. Valenzuela Camila Indiani de Oliveira Cláudia Ida Brodskyn Manoel Barral-Netto Aldina Barral 《PLoS neglected tropical diseases》2010,4(3)
Background
Leishmania is transmitted by female sand flies and deposited together with saliva, which contains a vast repertoire of pharmacologically active molecules that contribute to the establishment of the infection. The exposure to vector saliva induces an immune response against its components that can be used as a marker of exposure to the vector. Performing large-scale serological studies to detect vector exposure has been limited by the difficulty in obtaining sand fly saliva. Here, we validate the use of two sand fly salivary recombinant proteins as markers for vector exposure.Methodology/principal findings
ELISA was used to screen human sera, collected in an area endemic for visceral leishmaniasis, against the salivary gland sonicate (SGS) or two recombinant proteins (rLJM11 and rLJM17) from Lutzomyia longipalpis saliva. Antibody levels before and after SGS seroconversion (n = 26) were compared using the Wilcoxon signed rank paired test. Human sera from an area endemic for VL which recognize Lu. longipalpis saliva in ELISA also recognize a combination of rLJM17 and rLJM11. We then extended the analysis to include 40 sera from individuals who were seropositive and 40 seronegative to Lu. longipalpis SGS. Each recombinant protein was able to detect anti-saliva seroconversion, whereas the two proteins combined increased the detection significantly. Additionally, we evaluated the specificity of the anti-Lu. longipalpis response by testing 40 sera positive to Lutzomyia intermedia SGS, and very limited (2/40) cross-reactivity was observed. Receiver-operator characteristics (ROC) curve analysis was used to identify the effectiveness of these proteins for the prediction of anti-SGS positivity. These ROC curves evidenced the superior performance of rLJM17+rLJM11. Predicted threshold levels were confirmed for rLJM17+rLJM11 using a large panel of 1,077 serum samples.Conclusion
Our results show the possibility of substituting Lu. longipalpis SGS for two recombinant proteins, LJM17 and LJM11, in order to probe for vector exposure in individuals residing in endemic areas. 相似文献76.
Extracellular cyclic AMP-phosphodiesterase accelerates the development of aggregation competence in Dictyostelium discoideum when present during the preaggregation stage. The effect on development appears to depend only on hydrolysis of extracellular cyclic AMP and not on other properties of the phosphodiesterase molecule. Extracellular cyclic AMP-phosphodiesterase, as a promoter of differentiation, acts mainly throughout the first half of interphase. Our evidence supports the proposal that cyclic AMP oscillations control the rate and possibly the initiation of development. Since extracellular cyclic AMP-phosphodiesterase acts from the beginning of interphase cyclic AMP oscillations may also occur from early interphase, at least in the presence of this enzyme. This would imply that the cyclic AMP oscillator is a determinant, but not a product, of the developmental programme. 相似文献
77.
78.
Cornacini Maiara R. Manoel Ricardo O. Alcantara Marcelo A. M. Moraes Mário L. T. Silva Edvaldo A. A. Pereira Neto Leonel G. Sebbenn Alexandre M. Rossini Bruno C. Marino Celso L. 《Molecular biology reports》2021,48(4):3165-3172
Molecular Biology Reports - Astronium fraxinifolium is an endangered tree species from Brazil. Due to its significance in environmental reforestation, as well as the continued exploitation of its... 相似文献
79.
Natália F. Haddad Anderson J. Teodoro Felipe Leite de Oliveira Nathália Soares R?mulo Medina de Mattos Fábio Hecht R?mulo Sperduto Dezonne Leandro Vairo Regina Coeli dos Santos Goldenberg Flávia Carvalho Alcantara Gomes Denise Pires de Carvalho M?nica R. Gadelha Luiz Eurico Nasciutti Leandro Miranda-Alves 《PloS one》2016,11(2)
80.