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D.?C.?DrakeEmail author B.?Maritz S.?M.?Jacobs C.?J.?Crous A.?Engelbrecht A.?Etale M.?J.?Fourie D.?G.?Furniss S.?L.?Scott S.?Parusnath D.?R.?Tye 《Hydrobiologia》2013,712(1):1-4
The biological and physico-chemical structure of near bottom habitats located under densely growing submerged vegetation, and their significance in the functioning of whole aquatic ecosystems, are very little known due to difficulties in sampling. Corer-type samplers, believed to be the best in littoral studies, do not work properly in such places, because their tube opening is easily clogged by plant shoots, acting as a stopper. In order to overcome this problem, an alteration to the shape of the tube ending is proposed. This can be done by its trimming at an accurate angle, or by fitting (permanently or interchangeably) a metal collar made of stainless steel to its end, so that the ending would resemble the shape of a needle. The modification can be applied to virtually all corer samplers. It was found to be efficient while sampling sediment cores for the purposes of both hydrobiological and paleolimnological studies on heavily overgrown macrophyte-dominated water ecosystems. 相似文献
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Luciano?da Rocha?Corrêa Daniel?Cristiano?Paim Joséli?Schwambach Arthur?Germano?Fett-NetoEmail author 《Plant Growth Regulation》2005,45(1):63-73
Comparisons between related species with different rooting capacities can provide insights into the mechanisms controlling adventitious root development. The availability of carbohydrates is often considered exclusively as an energetic requirement to drive root development; the major regulatory role in the process is often attributed to phytohormones, particularly auxin. The roles of light quantity (irradiance) and carbohydrate supply available to young aseptic donor-plants on the adventitious rooting response of Eucalyptus globulus (rooting recalcitrant) and Eucalyptus saligna (easy-to-root) were examined. The effects of the type of carbohydrate supply (sucrose or glucose) on the rooting response of cuttings was also evaluated. Light intensity supplied to mother-plants (30 or 60 mol m–2 s–1) had limited influence on the rooting response of both species, whereas dark periods were detrimental, particularly for E. globulus. In E. globulus, rooting was promoted by the absence of sucrose in donor-plant media. Presence of sucrose in donor plant medium promoted root number but did not affect rooting percentage of E. saligna. A positive effect of glucose on cutting rhizogenesis was found if this hexose was supplied during the root induction phase, followed by sucrose in the root formation step, especially for E. globulus. The same effect was not seen with fructose. The beneficial effect of glucose in the induction phase on root number was also evident under suboptimal auxin concentrations. 相似文献
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Cutolo M Capellino S Montagna P Ghiorzo P Sulli A Villaggio B 《Arthritis research & therapy》2005,7(5):R1124-R1132
Sex hormones seem to modulate the immune/inflammatory responses by different mechanisms in female and male rheumatoid arthritis
patients. The effects of 17β-oestradiol and of testosterone were tested on the cultured human monocytic/macrophage cell line
(THP-1) activated with IFN-γ in order to investigate their role in cell proliferation and apoptosis. Activated human THP-1
cells were cultured in the presence of 17β-oestradiol and testosterone (final concentration, 10 nM). The evaluation of markers
of cell proliferation included the NF-κB DNA-binding assay, the NF-κB inhibition complex, the proliferating cell nuclear antigen
expression and the methyl-tetrazolium salt test. Apoptosis was detected by the annexin V-propidium assay and by the cleaved
poly-ADP ribose polymerase expression. Specific methods included flow analysis cytometry scatter analysis, immunocytochemistry
and western blot analysis. Cell growth inhibition and increased apoptosis were observed in testosterone-treated THP-1 cells.
Increased poly-ADP ribose polymerase-cleaved expression and decreased proliferating cell nuclear antigen expression, as well
as an increase of IκB-α and a decrease of the IκB-α phosphorylated form (ser 32), were found in testosterone-treated THP-1
cells. However, the NF-κB DNA binding was found increased in 17β-oestradiol-treated THP-1 cells. The treatment with staurosporine
(enhancer of apoptosis) induced decreased NF-κB DNA binding in all conditions, but particularly in testosterone-treated THP-1
cells. Treatment of THP-1 by sex hormones was found to influence cell proliferation and apoptosis. Androgens were found to
increase the apoptosis, and oestrogens showed a protective trend on cell death – both acting as modulators of the NF-κB complex. 相似文献
6.
Carlos?Talavera Fernando?Contreras Francisco?Espadas Gabriela?Fuentes J.?M.?SantamaríaEmail author 《Plant Cell, Tissue and Organ Culture》2005,83(3):287-292
Plantlets of coconut were cultured in vitro under three different ambient conditions including a standard culture room, a culture room inside a glasshouse with natural light but controlled temperature, and a standard glasshouse with natural light and natural fluctuations of temperature. Plantlets from the 3 treatments were compared in terms of growth, plant survival as well as net photosynthesis and efficiency of PSII (Fv/Fm ratio) both at the end of the in vitro stage and at 3 stages of ex vitro acclimatization. At the end of the in vitro stage, plantlets cultured in vitro under glasshouse conditions showed the best performance showing the highest photosynthesis rate, dry weight and number of leaves. Plantlets from the standard culture room showed the lowest photosynthesis and growth rate. After 6 months of ex vitro acclimatization, plantlets originally grown in vitro under glasshouse conditions maintained better field survival and growth rates in terms of fresh weight, dry weight and leaf number than plantlets originally grown in vitro in the standard culture room. Although more studies are required to define the reason for this effect, it is clear that the conditions of standard culture rooms are not the best for in vitro cultivation of coconut and perhaps other tropical species. 相似文献
7.
Yan?Pu Trevor?Treasure Ronalds?Gonzalez Richard?A.?VendittiEmail author Hasan?Jameel 《Bioenergy Research》2013,6(3):1094-1103
Autohydrolysis is a hot water pretreatment to extract soluble components from wood that can be used prior to converting the woody residuals into paper, wood products, fuel, or other goods. In this study, mixed softwood chips were autohydrolyzed in hot water at 150, 160, 170, and 180 °C for 1 and 2 h residence times. The objective was to understand the tradeoff between the extraction of fermentable sugar and the residual solid total energy of combustion quantitatively. This process strategy will be referred to as “value prior to combustion”. High-performance liquid chromatography was used to determine chemical compositions (sugars and byproducts such as acetic acid, furfural, and hydroxymethylfurfural) of the extracted liquid and residuals; a bomb calorimeter was used to measure the heating value of original wood and solid residue. As the autohydrolysis temperature increased, material balances of the system indicated higher volatile byproducts loss. More hemicelluloses were solubilized by the hot water extraction process at higher temperatures and longer residence times, and a greater degree of sugar degradation was also observed. The maximum sugar yield was determined to occur at conditions of 170 °C for 2 h, during which 13 g of sugar was recovered from the extract out of 100 g of oven-dried wood. The heating value of the solid residues after extraction was greater than the original wood. The total energy content of the solid residual after extraction ranged from 85 to 98 % of the original energy content of the feed with higher temperatures reducing the total energy content. 相似文献
8.
AnxB1,a novel annexin previously isolated from Cysticercus cellulose,shows high thrombi affinity and anticoagulant activity in vivo.In order to investigate the relationship between structure and biological function,a predicted three-dimensional(3D)model of AnxB1 was generated by homology modeling.This model contains four homologous internal-domains and the Cα trace of domain Ⅰ,Ⅱ and IV shows high similarity.Based on the structure characterization,four sequence-deleted mutants were constructed and expressed as GST fusion proteins in E.coli.Two of the mutants,GST-M3 and GST-M4 reserved high anticoagulant activity(p<0.01 vs.GST).Furthermore,compared with the wild type GST-AnxB1,the immunogenicity of GST-M3 and GST-M4 was reduced significantly(p<0.01)and the molecular weight was lowered to 27 kD and 34 kD,respectively.These observations laid a solid foundation for further study on developing new thrombolytic agents with higher efficiency and lower side effect. 相似文献
9.
Insect cell culture for industrial production of recombinant proteins 总被引:18,自引:0,他引:18
Insect cells used in conjunction with the baculovirus expression vector system (BEVS) are gaining ground rapidly as a platform for recombinant protein production. Insect cells present several comparative advantages to mammalian cells, such as ease of culture, higher tolerance to osmolality and by-product concentration and higher expression levels when infected with a recombinant baculovirus. Here we review some of the recent developments in protein expression by insect cells and their potential application in large-scale culture. Our current knowledge of insect cell metabolism is summarised and emphasis is placed on elements useful in the rational design of serum-free media. The culture of insect cells in the absence of serum is reaching maturity, and promising serum substitutes (hydrolysates, new growth and production-enhancing factors) are being evaluated. Proteolysis is a problem of the BEVS system due to its lytic nature, and can, therefore, be a critical issue in insect cell bioprocessing. Several cell- or baculovirus proteases are involved in degradation events during protein production by insect cells. Methods for proteolysis control, the optimal inhibitors and culture and storage conditions which affect proteolysis are discussed. Finally, engineering issues related to high-density culture (new bioreactor types, gas exchange, feeding strategies) are addressed in view of their relevance to large-scale culture. 相似文献
10.
Predator-induced phenotypic plasticity is widespread among aquatic animals, however the relative contributions of behavioral and morphological shifts to reducing risk of predation remain uncertain. We tested the phenotypic plasticity of a Neotropical tadpole (Rana palmipes) in response to chemical cues from predatory Belostoma water bugs, and how phenotype affects risk of predation. Behavior, morphology, and pigmentation all were plastic, resulting in a predator-induced phenotype with lower activity, deeper tail fin and muscle, and darker pigmentation. Tadpoles in the predator cue treatment also grew more rapidly, possibly as a result of the nutrient subsidy from feeding the caged predator. For comparison to phenotypes induced in the experiment, we quantified the phenotype of tadpoles from a natural pool. Wild-caught tadpoles did not match either experimentally induced phenotype; their morphology was more similar to that produced in the control treatment, but their low swimming activity was similar to that induced by predator cues. Exposure of tadpoles from both experimental treatments and the natural pool to a free-ranging predator confirmed that predator-induced phenotypic plasticity reduces risk of predation. Risk of predation was comparable among wild-caught and predator-induced tadpoles, indicating that behavioral shifts can substantially alleviate risk in tadpoles that lack the typical suite of predator-induced morphological traits. The morphology observed in wild-caught tadpoles is associated with rapid growth and high competition in other tadpole species, suggesting that tadpoles may profitably combine a morphology suited to competition for food with behaviors that minimize risk of predation. 相似文献