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Ribosome profiling reveals dynamic translational landscape in maize seedlings under drought stress
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Lei Lei Junpeng Shi Jian Chen Mei Zhang Silong Sun Shaojun Xie Xiaojie Li Biao Zeng Lizeng Peng Andrew Hauck Haiming Zhao Weibin Song Zaifeng Fan Jinsheng Lai 《The Plant journal : for cell and molecular biology》2015,84(6):1206-1218
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W A Catterall 《Biochemical and biophysical research communications》1976,68(1):136-142
Both myoblasts and myotubes in cultures of clonal rat muscle cells have action potential Na+ ionophore activity. The ionophore is activated by batrachotoxin (K0.5 = 3 to 5 × 10?7 M) and veratridine (K0.5 = 4 to 6 × 10?5 M) which compete for the same activation site. As in denervated rat muscle, the ionophore of cultured muscle is 100 fold more resistant to inhibition by tetrodotoxin (K0.5 = 1.5 to 3 × 10?6 M) and 20 fold more resistant to inhibition by saxitoxin (K0.5 = 1.5 to 3 × 10?7 M) than in nerve, innervated muscle, or cultured neuroblastoma cells. 相似文献
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A. Nock 《Chromosoma》1981,83(2):209-220
Nuclear and cytoplasmic RNA of Stylonychia mytilus were analyzed on denaturing polyacrylamide gels. The molecular weight of rRNA precursor molecules is within a range of 2.1×106 daltons. A comparison between the electrophoretic pattern of nuclear non-ribosomal RNA and cytoplasmic mRNA indicates that a considerable amount of nuclear RNA sequences is of higher molecular weight than cytoplasmic RNA sequences. The molecular weight distribution of cytoplasmic RNA supports the assumption that also in Stylonychia an average sized mRNA molecule contains 1,200–1,500 nucleotides according to a molecular weight of 4×105 to 5×105 daltons. The size of the polyadenylic acid fragment of poly-A+ RNA molecules is about 120 nucleotides. The total mass of cytoplasmic RNA is around 7.5/1010 g/cell, corresponding to 1.2×107 average sized mRNA molecules per cell. RNA excess hybridization experiments show that 60% of the DNA sequences are transcribed into nuclear RNA and that the cytoplasmic mRNA sequences are homologous to about 40% of macronuclear DNA sequences. There is no indication of different frequency classes within the mRNA. The number of different mRNA species in a Stylonychia cell is 1.2–1.5×104. On the average each of them is present about 1,000 times in every cell. 相似文献
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Ovalbumin solution was illuminated with W-lamp in the presence of methylene blue as a sensitizer. The photosusceptibility of amino acid residues of ovalbumin was found to be in the following order, Try>His>Met>Ser. Sulfhydryl group, however, was scarcely decomposed until about eighty per cent of tryptophan residue was decomposed. Free tryptophan was much faster in photodecomposition than bound tryptophan in ovalbumin because of steric and protective effects.With the increase of methylene blue in the lower concentration than 1.0 × 10?5 m, the relative quantum yield for the decomposition of tryptophan residue increased. This was elucidated on the assumption that the adsorption of dye molecules on ovalbumin brought about the loss of photosensitizing ability. The pH dependence also was investigated and some other factors influencing photosensitized oxidation were examined. 相似文献
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Inhibition of photosynthesis after exposure to solar radiation was investigated in the marine green alga Dunaliella salina by monitoring photosynthetic optimal quantum yield Fv/Fm and efficiency of oxygen production. Samples were exposed to solar radiation in Ancient Korinth, Greece (37°58′ N, 23°0′ E) in August 1994. Within 30 min, Fv/Fm and efficiency of oxygen production decreased with similar kinetics with increasing exposure time. The inhibition, however, diminished when ultraviolet radiation was progressively excluded by means of colour filter glasses. Samples exposed for 3 h showed complete or partial recovery of photosynthesis, with almost the same rate under all irradition conditions. The fit of the experimental data with an analytical model describing inhibition of photosynthesis as a function of a linear combination of the photon fluence in the UV-B, UV-A and PAR allows one to estimate the relative mean effectiveness for inhibition by the three spectral ranges [about 2 × 10?4, 4 × 10?6 and 2 × 10?7 (μmol photons m?2)?1 for UV-B, UV-A and PAR, respectively]. 相似文献
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Differential rate of ribosomal protein synthesis in Escherichia coli B-r 总被引:18,自引:0,他引:18
The differential rate of ribosomal protein synthesis, αr (ribosomal protein synthesis rate/total protein synthesis rate), was measured for Escherichia coli strain B/r growing at different steady-state rates ranging from 0.67 to 2.3 doublings/hour. For growth rates above 1.2 doublings/hour, αr was found to be proportional to the growth rate μ (doublings/h), such that αr = 0.09 μ, and the ribosome efficiency (amino acids polymerized/second per ribosome), calculated from αr, was found to be 14 to 18 amino acids/second per ribosome. With decreasing growth rates below 1.2 doublings/hour, αr was found to be increasingly greater than 0.09 μ and the ribosome efficiency gradually decreased such that at μ = 0.67, αr = 0.085, and the ribosome efficiency was reduced by 30% and was equal to 10 to 13 ammo acids/second per ribosome. These results imply that the protein to DNA ratio is constant for μ > 1.2 and equal to 4 × 108 to 5 × 108 amino acids/genome. For μ < 1.2, this ratio gradually decreases such that at μ = 0.67, protein to DNA = 3 × 108 to 4 × 108 amino acids/genome. These relationships were verified by direct measurements of the amounts of DNA, RNA and protein at different steady-state growth rates. In addition, protein accumulation was measured following a nutritional shift-up from succinate to glucose minimal medium. The results indicate that the ribosome efficiency increases by approximately 40% within the first few minutes following the shift-up. 相似文献
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Single B-form DNA molecules undergo an overstretching transition at force Fov to a ~1.7-fold longer form when stretched. The nature of overstretched DNA has been debated for over 10?years. Either peeled (PL DNA), internally melted (M DNA), or unwound double-helical (S DNA) forms of overstretched DNA have been suggested. Here, we characterize the kinetics of the overstretching transition in polymeric torsionally unconstrained double-stranded (ds) DNA molecules. We pull ~50?Kbp λ–DNA molecules using optical tweezers with rates ν ~10?nm/s to 5?×?104?nm/s, (overstretching time between 0.2 and 103?s). The Fov(ν, [Na+]) dependence measured over a broad range of rates and solution ionic strength suggests the existence of all three forms of the overstretched DNA. Thus, at [Na+]?>?50?mM and the stretching time >>1?s, internal melting dominates overstretching. This B-to-M transition is highly cooperative (involves ~100?bp), and slow (on/off time ~1000?s). Faster overstretching during ?1?s leads to B-to-S DNA transition, which is less cooperative (involves ~10?bp) and faster (on/off time ~1?s). In contrast, in lower salt ([Na+]?<?50?mM), the overstretching during >1?s leads to DNA peeling. However, on the faster time scale of 0.2–1?s, even in low salt, the DNA overstretches into S DNA, as peeling becomes kinetically prohibited. Our conclusions are supported by several independent lines of evidence, including the salt and rate dependence of both the slope of the overstretched DNA force-extension curve and the value of the second transition force (from M or PL DNA into S DNA). 相似文献
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The translational and rotational dynamics of tobacco mosaic virus in sodium phosphate buffer (pH =7.5) solutions has been investigated by polarized and depolarized light scattering Rayleigh linewidth studies. For concentrations ranging from 1.75 × 10?4 g ml?1 to 0.25 × 10?4 g ml?1 the translational diffusion coefficient (DT) has been found to be slightly concentration dependent and extrapolation to zero concentration gives D020°C = 0.34 ± 0.01 × 10?7 cm2S?1. A full analysis of the polarized spectra obtained at high and low scattering angles and the depolarized spectra at near zero scattering angles has enabled these techniques to be compared and the rotational diffusion constant DR to be determined. At a solution concentration of 1.75 × 10?4 g ml?1 a mean value is found to be DR20°C = 350 ± 30s?1. These values of DT and DR are in approximate agreement with calculations based on models of the tobacco mosaic virus molecule as a cylindrical rod. 相似文献
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J Borejdo 《Biopolymers》1979,18(11):2807-2820
The rates of the translational motion of myosin fragments, heavy meromyosin (HMM), and heavy meromyosin subfragment-1 (HMM S-1) were measured during actin-activated ATPase reaction by the method of fluorescence correlation spectroscopy. This technique monitors the random fluctuations in the concentration of fluorescent molecules in an open volume which result from the translational diffusion of the molecular species under observation. The statistical behavior of the fluctuations is represented in the form of the autocorrelation function, which is related to the translational diffusion coefficient of the fluorescent molecules. The translational motion of fluorescently labeled myosin fragments was progressively slowed down after additions of increasing amounts of actin in the presence of excess MgATP. When these results are interpreted according to a simple binding scheme, the extent of the retardation can be used to obtain the apparent association constant for binding of S-1 and HMM to actin in the presence of MgATP. In 0.1M KCl and at 23°C, the apparent association constants were determined as KappHMM = 2.2 × 104M?1 and KappS-1 = 8.8 × 103 for HMM and S-1, respectively. 相似文献
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Hydrogen peroxide amplifies the chemiluminescence in the oxidation of luminol by sodium hypochlorite. A linear relationship between concentration of hydrogen peroxide and light intensity was found in the concentration range 5 × 10?8?7.5 × 10?6 mol/l. At 7.5 × 10?6 mol/l H2O2 the chemiluminescence is amplified 550—fold. The chemiluminescence spectra of these reactions have a wavelength maximum at 431 nm independent of the concentration of hydrogen peroxide. The results indicate that hydrogen peroxide is a necessary component in the chemiluminescent oxidation of the luminol by sodium hypochlorite. 相似文献
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Mouse kidney cytosol contains specific receptors that reversibly bind dihydrotestosterone at a concentration of 43 f moles/mg protein. [Nonstandard abbreviation: DHT, dihydrotestosterone, 17 β-hydroxy-5 α-androstan-3-one.] The equilibrium dissociation constant of the receptor-dihydrotestosterone complex is 1.3 × 10?9M for females and 1.7 × 10?9M for castrated males. The complex sediments at 8–9S in glycerol gradients. In males bearing the androgen-insensitivity mutation (analogous to human testicular feminization), the specific dihydrotestosterone receptor activity is decreased about 8 fold. The residual binding activity has wild type affinity (KD = 1.5 × 10?9M) for dihydrotestosterone and also sediments at 8–9S. Kidney cytosol from castrated mutant mice displays a new binding component with low affinity and high capacity for dihydrotestosterone. 相似文献
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Storch D Heilmayer O Hardewig I Pörtner HO 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2003,173(7):611-620
The translational system was isolated from the gills of the Antarctic scallop Adamussium colbecki (Smith) and the European scallop Aequipecten opercularis (Linnaeus) for in vitro protein synthesis capacities (g protein mg FW–1 day–1) and the translational capacities of RNA (kRNA in vitro mg protein mg RNA–1 day–1). In vitro protein synthesis capacity in the cold-adapted pectinid at 0 °C was similar to the one found in the temperate scallop at 25 °C. These findings might reflect cold compensated rates in Adamussium colbecki, partly explainable by high tissue levels of RNA. Cold-compensated in vitro protein synthesis capacities may further result from increments in the translational capacity of RNA. The thermal sensitivity of the translation machinery was slightly different in the two species, with significantly lower levels of Arrhenius activation energies Ea and Q10 in Adamussium colbecki in the temperature range 0–15 °C. Reduced protein synthesis and translational capacities were found in vitro in gills of long-term aquarium-maintained Adamussium colbecki and were accounted for by a loss of protein synthesis machinery, i.e. a reduction in RNA levels, as well as a decrease in the amount of protein synthesized per milligram of RNA (RNA translational capacity, kRNA in vitro). Such changes may involve food uptake or mirror metabolic depression strategies, like those occurring during winter. Consequences of high in vitro RNA translational capacities found in the permanently cold-adapted species are discussed in the context of seasonal food availability and growth rates at high latitudes.Abbreviations DPM disintegrations per minute - DTT dithiothreitol - Ea Arrhenius activation energy - ks fractional protein synthesis rate - kRNA in vivo translational efficiency - kRNA in vitro translational capacity - PCA perchloric acid - Phe phenylalanine - PLA phospho-L-arginine - PSU practical salinity units - RNAse ribonuclease - TCA trichloroacetic acidCommunicated by G. Heldmaier 相似文献
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Summary Two types of superactivity can be defined. One, is with respect to the activity for a fixed average substrate concentration in the water pool; the pushing of the charged substrate by the likewise charged micellar surface is responsible for the superactivity and its bell-shaped dependence on the hydration ratio. The other, is with respect to the activity in a bulk aqueous solution having a substrate concentration equal to a fixed overall concentration [S–]ov in the entire reverse micellar solution. In this case, the pushing effect, the constraint of a fixed [S–]ov and the partitioning of the substrate in the surfactant layer are responsible for the bell-shaped dependence. Superactivity exists for low substrate partitioning in the surfactant layer, subactivity for high partitioning. 相似文献
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In anoxic salt marsh sediments of Sapelo Island, GA, USA, the vertical distribution of CH4 production was measured in the upper 20 cm of surface sediments in ten locations. In one section of high marsh sediments,
the concentration and oxidation of acetate in sediment porewaters and the rate and amount of14C acetate and14CO2 incorporation into cellular lipids of the microbial population were investigated. CH4 production rates ranged from <1 to 493 nM CH4 gram sediment−1 day−1 from intact subcores incubated under nitrogen. Replacement with H2 stimulated the rate of methane release up to nine fold relative to N2 incubations. Rates of lipid synthesis from CO2 averaged 39.2 ×10−2nanomoles lipid carbon cm3 sediment−1 hr−1, suggesting that CO2 may be an important carbon precursor for microbial membrane synthesis in marsh sediments under anoxic conditions. Qualitative
measurements of lipid synthesis rates from acetate were found to average 8.7 × 10−2 nanomoles. Phospholipids were the dominant lipids synthesized by both substrates in sediment cores, accounting for an average
of 76.6% of all lipid radioactivity. Small amounts of ether lipids indicative of methanogenic bacteria were observed in cores
incubated for 7 days, with similar rates of synthesis for both CO2 and acetate. The low rate of ether lipid synthesis suggests that either methanogen lipid biosynthesis is very slow or that
methanogens represent a small component of total microbial lipid synthesis in anoxic sediments.
present address: The University of Maryland,, Chesapeake Biological Laboratory, Box 38, Solomons, MD 20688, USA 相似文献