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121.
Phytic acid (PA) is the primary storage compound of phosphorus in seeds accounting for up to 80% of the total seed phosphorus and contributing as much as 1.5% to the seed dry weight. The negatively charged phosphate in PA strongly binds to metallic cations of Ca, Fe, K, Mg, Mn and Zn making them insoluble and thus unavailable as nutritional factors. Phytate mainly accumulates in protein storage vacuoles as globoids, predominantly located in the aleurone layer (wheat, barley and rice) or in the embryo (maize). During germination, phytate is hydrolysed by endogenous phytase(s) and other phosphatases to release phosphate, inositol and micronutrients to support the emerging seedling. PA and its derivatives are also implicated in RNA export, DNA repair, signalling, endocytosis and cell vesicular trafficking. Our recent studies on purification of phytate globoids, their mineral composition and dephytinization by wheat phytase will be discussed. Biochemical data for purified and characterized phytases isolated from more than 23 plant species are presented, the dephosphorylation pathways of phytic acid by different classes of phytases are compared, and the application of phytase in food and feed is discussed. 相似文献
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Didier Fraix-Burnet Philippe Choler Emmanuel J.P. Douzery Anne Verhamme 《Journal of Classification》2006,23(1):31-56
This series of papers is intended to present astrocladistics in some detail and evaluate this methodology in reconstructing
phylogenies of galaxies. Being based on the evolution of all the characters describing galaxies, it is an objective way of
understanding galaxy diversity through evolutionary relationships. In this first paper, we present the basic steps of a cladistic
analysis and show both theoretically and practically that it can be applied to galaxies. For illustration, we use a sample
of 50 simulated galaxies taken from the GALICS database, which are described by 91 observables (dynamics, masses and luminosities).
These 50 simulated galaxies are indeed 10 different galaxies taken at 5 cosmological epochs, and they are free of merger events.
The astrocladistic analysis easily reconstructs the true chronology of evolution relationships within this sample. It also
demonstrates that burst characters are not relevant for galaxy evolution as a whole. A companion paper is devoted to the formalization
of the concepts of formation and diversification in galaxy evolution. 相似文献
127.
The ELF4-ELF3-LUX complex links the circadian clock to diurnal control of hypocotyl growth 总被引:1,自引:0,他引:1
Nusinow DA Helfer A Hamilton EE King JJ Imaizumi T Schultz TF Farré EM Kay SA 《Nature》2011,475(7356):398-402
128.
Yokoyama S Woods SL Boyle GM Aoude LG MacGregor S Zismann V Gartside M Cust AE Haq R Harland M Taylor JC Duffy DL Holohan K Dutton-Regester K Palmer JM Bonazzi V Stark MS Symmons J Law MH Schmidt C Lanagan C O'Connor L Holland EA Schmid H Maskiell JA Jetann J Ferguson M Jenkins MA Kefford RF Giles GG Armstrong BK Aitken JF Hopper JL Whiteman DC Pharoah PD Easton DF Dunning AM Newton-Bishop JA Montgomery GW Martin NG Mann GJ Bishop DT Tsao H Trent JM Fisher DE Hayward NK Brown KM 《Nature》2011,480(7375):99-103
129.
Schreiber A Stengel F Zhang Z Enchev RI Kong EH Morris EP Robinson CV da Fonseca PC Barford D 《Nature》2011,470(7333):227-232
The anaphase-promoting complex or cyclosome (APC/C) is an unusually large E3 ubiquitin ligase responsible for regulating defined cell cycle transitions. Information on how its 13 constituent proteins are assembled, and how they interact with co-activators, substrates and regulatory proteins is limited. Here, we describe a recombinant expression system that allows the reconstitution of holo APC/C and its sub-complexes that, when combined with electron microscopy, mass spectrometry and docking of crystallographic and homology-derived coordinates, provides a precise definition of the organization and structure of all essential APC/C subunits, resulting in a pseudo-atomic model for 70% of the APC/C. A lattice-like appearance of the APC/C is generated by multiple repeat motifs of most APC/C subunits. Three conserved tetratricopeptide repeat (TPR) subunits (Cdc16, Cdc23 and Cdc27) share related superhelical homo-dimeric architectures that assemble to generate a quasi-symmetrical structure. Our structure explains how this TPR sub-complex, together with additional scaffolding subunits (Apc1, Apc4 and Apc5), coordinate the juxtaposition of the catalytic and substrate recognition module (Apc2, Apc11 and Apc10 (also known as Doc1)), and TPR-phosphorylation sites, relative to co-activator, regulatory proteins and substrates. 相似文献
130.
In Drosophila, four genes encode for laminin subunits and the formation of two laminin heterotrimers has been postulated. We report the
identification of mutations in the Drosophila LamininB2 (LanB2) gene that encodes for the only laminin γ subunit and is found in both heterotrimers. We describe their effects on embryogenesis,
in particular the differentiation of visceral tissues with respect to the ECM. Analysis of mesoderm endoderm interaction indicates
disrupted basement membranes and defective endoderm migration, which finally interferes with visceral myotube stretching.
Extracellular deposition of laminin is blocked due to the loss of the LanB2 subunit, resulting in an abnormal distribution
of ECM components. Our data, concerning the different function of both trimers during organogenesis, suggest that these trimers
might act in a cumulative way and probably at multiple steps during ECM assembly. We also observed genetic interactions with
kon-tiki and thrombospondin, indicating a role for laminin during muscle attachment. 相似文献