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Glucagon Affinity Absorbents: Selective Binding of Receptors of Liver Cell Membranes 总被引:3,自引:0,他引:3
AFFINITY chromatography has been used in the rapid isolation of enzymes, antibodies, antigens and other ligand-binding proteins1–6. Selective adsorbents with biological specificity perhaps may best be used in the resolution and isolation of complex biological structures and important regulatory macromolecules present in cells in very low amounts. For example, polypeptide and steroid hormone receptors, drug receptors, transport proteins and repressor molecules may be well suited for study by this technique because they display specific binding functions with a high degree of affinity. 相似文献
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From compartmental analysis of 15N elution measurements, concentrationsand fluxes of NH+4 and NO3 were estimated for corticalcells in excised root segments, when bathed in a complete nutrientsolution, in which 20 mol m3 NH4+ or NO3 werethe single N sources. The results were compared with those fornutrient solution containing 20 mol m3 NH4NO3. No nitratereductase activity was detected in the roots but rapid assimilationof NH4+ occurred, due to glutamine synthetase activity. Theefflux curves for NH4+, on a 'µg 15N remaining againsttime' basis, deviated from the criteria determining conformityto first order kinetics, since the slowest rate constant wasan order of magnitude lower than that exhibited by the curvefor efflux versus time. The data were transformed to conformto the appropriate criteria, revealing a large slowly exchangingpool equated with assimilated NH4+. The presence of NO3had little effect on NH4+ uptake and exchange, but NH4+ suppressedNOj uptake and reduced exchange across plasmalemma and tonoplast.It was established that NH4+ absorption was an active process.However, NH4+ entering and leaving the vacuole was overestimated,since the flux equation used did not differentiate between total15NH4 influx at the plasmalemma and that at the tonoplast, afterassimilation. The only active NO3 transfer was influxat the plasmalemma. The results were compared with those ofothers using13N and 36C1O3 analogues to measure NH4+ and NO3fluxes in cereal roots. Key words: Ammonium, nitrate, compartmental analysis, 15N, active transport 相似文献
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Fernanda Hurbath BÁrbara SimÕes Santos Leal Otávio Luis Marques Da Silva Clarisse Palma-Silva INês Cordeiro 《分类学与生物多样性》2013,11(7):658-667
A new species of Euphorbia sect. Brasilienses V.W. Steinm. & Dorsey is described. Euphorbia tetrangularis Hurbath & Cordeiro is endemic to the Serra de Montevidéu, a part of the Espinhaço Range located in the state of Minas Gerais, Brazil. It differs from other species within the section based on the following characters: 4-ribbed branches, green cyathia, and green cyathial glands with erect appendages. This new species would qualify as critically endangered (CR) according to IUCN criteria. An inferred phylogeny based on a combined dataset of nuclear (ITS1) and plastid regions (psbA-trnH, trnC-ycf6, matK, atpI-atpH, psbJ-petA, trnQ-rps16?×?1) confirms the monophyly of Euphorbia sect. Brasilienses and supports the recognition of E. tetrangularis. The phylogeny also suggests that this group probably underwent a recent radiation. 相似文献
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A comparative perspective on longevity: the effect of body size dominates over ecology in moths 下载免费PDF全文
S. Holm R. B. Davis J. Javoiš E. Õunap A. Kaasik F. Molleman T. Tammaru 《Journal of evolutionary biology》2016,29(12):2422-2435
Both physiologically and ecologically based explanations have been proposed to account for among‐species differences in lifespan, but they remain poorly tested. Phylogenetically explicit comparative analyses are still scarce and those that exist are biased towards homoeothermic vertebrates. Insect studies can significantly contribute as lifespan can feasibly be measured in a high number of species, and the selective forces that have shaped it may differ largely between species and from those acting on larger animals. We recorded adult lifespan in 98 species of geometrid moths. Phylogenetic comparative analyses were applied to study variation in species‐specific values of lifespan and to reveal its ecological and life‐history correlates. Among‐species and between‐gender differences in lifespan were found to be notably limited; there was also no evidence of phylogenetic signal in this trait. Larger moth species were found to live longer, with this result supporting a physiological rather than ecological explanation of this relationship. Species‐specific lifespan values could not be explained by traits such as reproductive season and larval diet breadth, strengthening the evidence for the dominance of physiological determinants of longevity over ecological ones. 相似文献
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LOUWRANCE P. WRIGHT BRENDA D. WINGFIELD PEDRO W. CROUS MICHAEL J. WINGFIELD 《Molecular ecology resources》2007,7(2):343-345
Ten polymorphic microsatellite markers were developed for Cylindrocladium pauciramosum, a plant pathogen with a wide host range, which poses a serious problem in South African Eucalyptus nurseries. Polymorphism was evaluated on 43 isolates collected from Colombia and South Africa. Each locus had between three and six alleles. Testing for random mating showed multilocus equilibrium for a population of 40 isolates from a South African forestry nursery. Cross‐species transferability tested for 19 other Cylindrocladium species found amplification only in C. spathulatum, which is phylogenetically closely related to C. pauciramosum. 相似文献
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LAURA R. P. UTZ TAIZ L. L. SIMÃO LÚCIA S. L. SAFI EDUARDO EIZIRIK 《The Journal of eukaryotic microbiology》2010,57(5):415-420
ABSTRACT. We have generated 18S rRNA sequences for peritrichs collected in Brazil, including four Opercularia species, two different populations of Epistylis plicatilis (one epibiont and another free‐living), and one additional Epistylis species. Our Opercularia species clustered with the previously available Opercularia microdiscum, corroborating the monophyly of this genus. The Epistylis sampled here clustered with previously sequenced species of this genus. The two populations of E. plicatilis collected in Brazil clustered closely together despite their different ecological contexts, whereas both were very divergent from the sample assigned to the same species previously sampled in China. If affirmed by additional morphological corroboration of species assignment, this observation would indicate that samples from different continents morphologically allocated in the same species may in fact belong to distant evolutionary lineages. More broadly, our results support the recognition of two major clades within Peritrichia. Given the robustness of their support, we suggest that these two clades should be formally recognized as orders, and propose the names Vorticellida and Operculariida to designate them. Furthermore, Epistylis species occurred in both orders, tending to occupy basal positions. This suggests that characters used to define this genus may be plesiomorphic for Peritrichia, so that Epistylis may in fact represent an assemblage of basal species retaining ancestral features. 相似文献
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C. ALBUQUERQUE F. MORINHA J. MAGALHÃES J. REQUICHA I. DIAS H. GUEDES-PINTO E. BASTOS C. VIEGAS 《Journal of genetics》2015,94(4):651-659
Elevated levels of interleukin-1 (IL-1) have been shown to amplify the inflammatory response against periodontopathogenic bacteria. In humans, polymorphisms in the IL1A and IL1B genes are the most well-studied genetic polymorphisms associated with periodontal disease (PD). In contrast to human, there is a lack of knowledge on the genetic basis of canine PD. A case–control study was conducted in which a molecular analysis of dog IL1A and IL1B genes was performed. Of the eight genetic variants identified, seven in IL1A gene and one in IL1B gene, IL1A/1_g.388A >C and IL1A/1_g.521T >A showed statistically significant differences between groups (adjusted OR (95% CI): 0.15 (0.03–0.76), P= 0.022; 5.76 (1.03–32.1), P= 0.046, respectively). It suggests that in the studied population the IL1A/1_g.388C allele is associated with a decreased PD risk, whereas the IL1A/1_g.521A allele can confer an increased risk. Additionally, the IL1A/2_g.515G >T variation resulted in a change of amino acid, i.e. glycine to valine. In silico analysis suggests that this change can alter protein structure and function, predicting it to be deleterious or damaging. This work suggests that IL1 genetic variants may be important in PD susceptibility in canines. 相似文献