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31.
Greunke K Spillner E Braren I Seismann H Kainz S Hahn U Grunwald T Bredehorst R 《Journal of biotechnology》2006,124(2):446-456
Monoclonal IgY have the potential to become unique tools for diagnostic research and therapeutic purposes since avian antibodies provide several advantages due to their phylogenetic difference when compared to mammalian antibodies. The mechanism of avian immunoglobulin gene diversification renders chicken an excellent source for the generation of recombinant scFv as well as Fab antibody libraries of high diversity. One major limitation of these antibody fragments, however, is their monovalent format, impairing the functional affinity of the molecules and, thereby, their applicability in prevalent laboratory methods. In this study, we generated vectors for conversion of avian recombinant antibody fragments into different types of bivalent IgY antibody formats. To combine the properties of established mammalian monoclonal antibodies with those of IgY constant domains, we additionally generated bivalent murine/avian chimeric antibody constructs. When expressed in HEK-293 cells, all constructs yielded bivalent disulfide-linked antibodies, which exhibit a glycosylation pattern similar to that of native IgY as assessed by lectin blot analysis. After purification by one step procedures, the chimeric and the entire avian bivalent antibody formats were analyzed for antigen binding and interaction with secondary reagents. The data demonstrate that all antibody formats provide comparable antigen binding characteristics and the well established properties of avian constant domains. 相似文献
32.
Water channels in Chara corallina 总被引:4,自引:0,他引:4
Water relations parameters ofChara corallina inter-nodes weremeasured using the single cell pressure probe. The effect ofmercurials, which are recognized as non-specific water channelinhibitors, was examined. HgCl2 concentrations greater than5 mmol m3 were found to inhibit hydraulic conductivity{Lp) close to 90%, whereas pCMPS was found to have no effecton Lp. The activation energy of water flow was increased significantlyfrom 21.0 kJ mol1 to 45.6 kJ mol1, following theapplication of HgCl2. These results are in accordance with evidencefor Hg2+sensitive water channels in the plasma membrane of charophytes(Henzler and Steudle, 1995; Tazawa et al., 1996). The metaboliceffects must, however, be considered in view of the rapid inhibitionof respiration and the depolarization of the membrane potentialwith HgCl2 concentrations lower than those found to affect Lp.It was possible to measure simultaneously water relations andmembrane PD, in order to examine the contribution of potassiumchannels to Lp. Cells were induced into a K+ permeable state.The K+ channels, assumed to be open, were subsequently blockedby various blockers. No significant difference in Lp was foundfor any of these treatments. Finally, the permeability of C.corallina membranes to ethanol was examined. HgCl2 was foundto cause a decrease in reflection coefficient, coinciding witha decrease in Lp, but there was no change in the ethanol permeabilitycoefficient. This has been interpreted in terms of both thefrictional model and composite model of non-electrolyte membranetransport. Key words: Water channels, Chara, hydraulic, conductivity, membrane transport models, reflection coefficient 相似文献
33.
Superoxide dismutase, catalase and nitrogenase activities of symbiotic Frankia (Alnus incana) in response to different oxygen tensions 总被引:2,自引:0,他引:2
Presence and activity of the enzymes superoxide dismutase (SOD) and catalase were studied in Frankia in symbiosis with Alnus incana (L.) Moench. Analysis on native PAGE gels indicated that symbiotic Frankia contained an FeSOD and catalase. The activity of the enzymes was in the same range as reported for cultured Frankia . Attempts to characterize SOD by western blots with antisera from Escherichia coli and Azotobacter vinelandii did not give clear-cut results with the antibodies used. Alnus incana plants were grown with the root system in 5, 10, 21 or 40% O2 for up to 6 days. Nitrogenase activity, measured as ARA (acetylene reducing activity) dropped within 3 h when roots were exposed to low or high oxygen. At 40% O2 ARA was almost completely lost while at 5 and 10% O2 ARA decreased to 69 and 74% of the inital value, respectively, Nitrogenase activity recovered at ail oxygen tensions. Recovery rates resembled the continuous increase in ARA in plants continuosly kept at 21% O2 , and suggests that new vesicles with envelopes of appropriate thickness were formed. The ARA measurements confirm results from an earlier study where nitrogenase activity was measured as H2 evolution. There was a tendency for increased SOD and catalase activities in Frankia from root systems exposed to 40% O2 for 24 h but not earlier or later than this. When data from all experimental times were pooled. SOD activity increased significantly with increased oxygen tension whereas catalase activity decreased. Although ARA per plant varied with oxygen tension, there was no statistically significant correlation between ARA and SOD or between ARA and catalase. It seems that being linked to nitrogenase activity is only one role of SOD and catalase in this symbiotic Frankia . 相似文献
34.
Santiago Herrera-lvarez Elinor Karlsson Oliver A Ryder Kerstin Lindblad-Toh Andrew J Crawford 《Molecular biology and evolution》2021,38(5):1715
Gigantism results when one lineage within a clade evolves extremely large body size relative to its small-bodied ancestors, a common phenomenon in animals. Theory predicts that the evolution of giants should be constrained by two tradeoffs. First, because body size is negatively correlated with population size, purifying selection is expected to be less efficient in species of large body size, leading to increased mutational load. Second, gigantism is achieved through generating a higher number of cells along with higher rates of cell proliferation, thus increasing the likelihood of cancer. To explore the genetic basis of gigantism in rodents and uncover genomic signatures of gigantism-related tradeoffs, we assembled a draft genome of the capybara (Hydrochoerus hydrochaeris), the world’s largest living rodent. We found that the genome-wide ratio of nonsynonymous to synonymous mutations (ω) is elevated in the capybara relative to other rodents, likely caused by a generation-time effect and consistent with a nearly neutral model of molecular evolution. A genome-wide scan for adaptive protein evolution in the capybara highlighted several genes controlling postnatal bone growth regulation and musculoskeletal development, which are relevant to anatomical and developmental modifications for an increase in overall body size. Capybara-specific gene-family expansions included a putative novel anticancer adaptation that involves T-cell-mediated tumor suppression, offering a potential resolution to the increased cancer risk in this lineage. Our comparative genomic results uncovered the signature of an intragenomic conflict where the evolution of gigantism in the capybara involved selection on genes and pathways that are directly linked to cancer. 相似文献
35.
Wanlu Zhang Azqa Khan Jlenia Vitale Annett Neuner Kerstin Rink Christian Lüchtenborg Britta Brügger Thomas H. Sllner Elmar Schiebel 《Open biology》2021,11(11)
The integral membrane protein Apq12 is an important nuclear envelope (NE)/endoplasmic reticulum (ER) modulator that cooperates with the nuclear pore complex (NPC) biogenesis factors Brl1 and Brr6. How Apq12 executes these functions is unknown. Here, we identified a short amphipathic α-helix (AαH) in Apq12 that links the two transmembrane domains in the perinuclear space and has liposome-binding properties. Cells expressing an APQ12 (apq12-ah) version in which AαH is disrupted show NPC biogenesis and NE integrity defects, without impacting Apq12-ah topology or NE/ER localization. Overexpression of APQ12 but not apq12-ah triggers striking over-proliferation of the outer nuclear membrane (ONM)/ER and promotes accumulation of phosphatidic acid (PA) at the NE. Apq12 and Apq12-ah both associate with NPC biogenesis intermediates and removal of AαH increases both Brl1 levels and the interaction between Brl1 and Brr6. We conclude that the short amphipathic α-helix of Apq12 regulates the function of Brl1 and Brr6 and promotes PA accumulation at the NE possibly during NPC biogenesis. 相似文献
36.
Leys, used for grazing or production of forage to be conserved as silage or hay, are very important crops in northern areas.
In order to measure the N2 fixation in leys of varying ages and during different parts of the season, detailed measurements were taken of yield, N2 fixation and the amounts of N remaining in the field after harvesting red clover (Trifolium pratense L.)-grass leys at a site in northern Sweden, where they are generally harvested twice per growing season. Entire plants,
including stubble and roots, were sampled at the time of first and second harvest and, in addition, at the end of the growing
season in three neighbouring fields, carrying a first, a second and a third year ley, respectively. N2 fixation was measured by both 15N isotope dilution (ID) and 15N natural abundance (NA) methods. The proportion of clover dry matter (DM) in the stands increased from the first to the second
harvest, but the grasses dominated throughout the entire season, especially below ground. The N concentrations, in both herbage
and whole plants, were about twice as high in the clover as in the grasses. Seasonal variations in N concentrations were minor,
and total N contents followed the same trends as DM. The clover acquired nearly all of its N from N2 fixation: the proportion of N in clover herbage derived from N2 fixation was often >0.8 throughout the season. The variations in the amounts of N2 fixed during the course of the season corresponded well to the seasonal changes in clover biomass. Amounts of fixed N2 allocated to clover herbage during the whole season were in the range 4 to 6 g N m−2 in this unusually rainy year. Calculations of daily N allocation rates to herbage showed that N uptake rates were similar,
and high, in grasses during May–June and July–August, while N2 fixation rates in clover were about 10-fold as high in July–August as in May–June, reflecting the need for N in clover growth.
The proportion of N remaining in clover stubble and roots after the first and second harvests was about 60 and 25%, respectively,
while about 60% of the N in grasses remained in stubble and roots after both harvests. The considerable amounts of biomass
and N that were left in field after harvesting red clover-grass leys are important for re-growth of the plants and provide
substantial N fertilization for the next crop in the crop rotation. 相似文献
37.
38.
Ebersberger I de Matos Simoes R Kupczok A Gube M Kothe E Voigt K von Haeseler A 《Molecular biology and evolution》2012,29(5):1319-1334
The kingdom of fungi provides model organisms for biotechnology, cell biology, genetics, and life sciences in general. Only when their phylogenetic relationships are stably resolved, can individual results from fungal research be integrated into a holistic picture of biology. However, and despite recent progress, many deep relationships within the fungi remain unclear. Here, we present the first phylogenomic study of an entire eukaryotic kingdom that uses a consistency criterion to strengthen phylogenetic conclusions. We reason that branches (splits) recovered with independent data and different tree reconstruction methods are likely to reflect true evolutionary relationships. Two complementary phylogenomic data sets based on 99 fungal genomes and 109 fungal expressed sequence tag (EST) sets analyzed with four different tree reconstruction methods shed light from different angles on the fungal tree of life. Eleven additional data sets address specifically the phylogenetic position of Blastocladiomycota, Ustilaginomycotina, and Dothideomycetes, respectively. The combined evidence from the resulting trees supports the deep-level stability of the fungal groups toward a comprehensive natural system of the fungi. In addition, our analysis reveals methodologically interesting aspects. Enrichment for EST encoded data-a common practice in phylogenomic analyses-introduces a strong bias toward slowly evolving and functionally correlated genes. Consequently, the generalization of phylogenomic data sets as collections of randomly selected genes cannot be taken for granted. A thorough characterization of the data to assess possible influences on the tree reconstruction should therefore become a standard in phylogenomic analyses. 相似文献
39.
Per Putkonen Charlotta Nilsson Kerstin Hild Reinhold Benthin Martin Cranage Anne Marie Aubertin Gunnel Biberfeld 《Journal of medical primatology》1993,22(2-3):100-103
Several groups have reported protection against experimental SIV infection in macaques immunized with a whole inactivated virus vaccine. The aim of the current study was to investigate whether five macaques vaccinated with whole inactivated SIV and previously shown to be protected against challenge with two divergent strains of SIV grown on human cells could resist challenge with a subsequent homologous SIV grown on macaque cells. We show here that this same vaccine did not protect when the challenge virus was grown on primary cells of monkey origin. 相似文献
40.
The monolayer structure of pure dipalmitoylphosphatidylcholine (DPPC) and equimolar mixtures of DPPC/n-hexadecanol (C(16)OH) and DPPC/dipalmitoylglycerol (DPG) are studied by the film balance technique and grazing incidence X-ray diffraction measurements. At 20 degrees C, the binary systems exhibit complete miscibility. In contrast to pure DPPC monolayers, a condensing effect is observed in the presence of both non-phospholipid additives; but the phase transition behavior differs. The tilt angle of the hydrocarbon chains in the DPPC/C(16)OH mixture is significantly smaller than in pure DPPC monolayers. The tilt of the chains is even further reduced in the mixed monolayer of DPPC/DPG. A comparison of the three systems reveals distinct structural features such as phase state, chain tilt, and molecular area over a wide range of surface pressures. Therefore, these monolayers provide a highly suitable model to investigate the influence of structural parameters on biological processes occurring at the membrane surface, e.g. enzymatic reactions and adsorption events. 相似文献