Arabinogalactan-proteins (AGPs) are structurally complex hydroxyproline-rich cell wall glycoproteins ubiquitous in the plant kingdom. AGPs biosynthesis involves a series of post-translational ...modifications including the addition of type II arabinogalactans to non-contiguous Hyp residues. To date, eight Hyp-galactosyltransferases (Hyp-GALTs; GALT2-GALT9) belonging to CAZy GT31, are known to catalyze the addition of the first galactose residues to AGP protein backbones and enable subsequent AGP glycosylation. The extent of genetic redundancy, however, remains to be elucidated for the Hyp-GALT gene family.
To examine their gene redundancy and functions, we generated various multiple gene knock-outs, including a triple mutant (galt5 galt8 galt9), two quadruple mutants (galt2 galt5 galt7 galt8, galt2 galt5 galt7 galt9), and one quintuple mutant (galt2 galt5 galt7 galt8 galt9), and comprehensively examined their biochemical and physiological phenotypes. The key findings include: AGP precipitations with β-Yariv reagent showed that GALT2, GALT5, GALT7, GALT8 and GALT9 act redundantly with respect to AGP glycosylation in cauline and rosette leaves, while the activity of GALT7, GALT8 and GALT9 dominate in the stem, silique and flowers. Monosaccharide composition analysis showed that galactose was decreased in the silique and root AGPs of the Hyp-GALT mutants. TEM analysis of 25789 quintuple mutant stems indicated cell wall defects coincident with the observed developmental and growth impairment in these Hyp-GALT mutants. Correlated with expression patterns, galt2, galt5, galt7, galt8, and galt9 display equal additive effects on insensitivity to β-Yariv-induced growth inhibition, silique length, plant height, and pollen viability. Interestingly, galt7, galt8, and galt9 contributed more to primary root growth and root tip swelling under salt stress, whereas galt2 and galt5 played more important roles in seed morphology, germination defects and seed set. Pollen defects likely contributed to the reduced seed set in these mutants.
Additive and pleiotropic effects of GALT2, GALT5, GALT7, GALT8 and GALT9 on vegetative and reproductive growth phenotypes were teased apart via generation of different combinations of Hyp-GALT knock-out mutants. Taken together, the generation of higher order Hyp-GALT mutants demonstrate the functional importance of AG polysaccharides decorating the AGPs with respect to various aspects of plant growth and development.
The bonding in monomeric and dimeric molecular compounds of Cr, Mo, W and U is explored using the Quantum Theory of Atoms-in-Molecules (QTAIM). The metal-ligand and metal-metal bond critical point ...properties ρb, ∇(2)ρb and Hb, and also the bond delocalisation indices δ(A, B), are correlated with the data from previous Ziegler-Rauk energy decomposition studies of the same systems. For M2X6 (M = Mo, W, U; X = Cl, F, OH, NH2, CH3), ρb, Hb and δ(A, B) display anticorrelations with the total interaction energy of the two MX3 fragments, implying that the weaker metal-metal bonds (those between two uranium atoms) are the more covalent ones. By contrast, strongly positive correlations are observed between the QTAIM parameters and the energy decomposition orbital mixing energies. This is also the case for metal-carbon, metal-nitrogen and metal-oxygen bonds in (CO)5M-imidazole tautomers (M = Cr, Mo, W) and uranyl phosphinimine and phosphine oxide compounds. These targets were chosen specifically because their energy decompositions feature negligible net electrostatic + Pauli "pre-relaxation" effects, and the QTAIM parameters correlate strongly with the orbital mixing-dominated total interaction energies. The metal-metal bonds in M2X6 are found to have significantly positive ∇(2)ρb (in agreement with many previous QTAIM studies of metal-metal bonding), and an anticorrelation is found between the total X3M-MX3 interaction energies and ∇(2)ρb. The positive ∇(2)ρb are traced to the dominant λ3 principal curvature, which correlates well with the destabilising electronic kinetic energy density at the bond critical points, providing a rationalisation of the anticorrelation between the total X3M-MX3 interaction energies and ∇(2)ρb.
Plant fibres and the artefacts constructed from them often remain overlooked in the archaeological record because of their poor survival and the problems related to the precise identification of the ...species to which the fibres belong. The goal of this study was to design a simple and accurate method of identifying archaeological plant fibre sources. Twenty‐two fibre samples from two sets of ancient Egyptian botanical artefacts were examined under both a stereomicroscope and a compound microscope, and compared to a large reference collection and to previously published research. By examining longitudinal thin sections of the ancient plant specimens, we identified plant fibres from the following species: Hyphaene thebeica, Cyperus papyrus, Desmostachya bipinnata, Imperata cylindrica, Phragmites australis and Linum usitatissimum. Our identification of these plant fibres reveals essential information about the materials used for producing ropes, baskets, sandals, mats and fabric. The results of this study demonstrate the value of longitudinal thin sectioning and light microscopy as a major means of identifying the source material of botanical artefacts, and advance our knowledge of ancient Egyptian plant exploitation as well as the associated technologies involved in constructing these types of artefacts.
A large variety of techniques have been used for auricular haematoma management. The open surgical management of auricular haematoma involves incision, evacuation and the obliteration of dead space ...using biodegradable mattress sutures. Our goal was to describe open surgical management for primary, recurrent and spontaneous auricular haematoma.
Auricular haematoma patients who underwent open surgical management were prospectively audited (2010-2013). Information was collected on demographics, clinical presentation, aetiology, examination findings, previous interventions, details of open surgical management and post-operative follow up.
In all, 12 male and 3 female patients with a mean age of 33 years (range 16-86 years) were evaluated. Contact sport injury was the most common aetiology. Ten patients had undergone previous unsuccessful interventions to treat auricular haematoma before open surgical management was performed. All patients were managed successfully without significant recurrence. One patient had a minor local reaccumulation which required reinsertion of a mattress suture. One elderly patient developed localised cellulitis which responded well to antibiotics.
Open surgical management of auricular haematoma has been successful. The technique is simple and reliable, and can be accomplished in a clinical setting under local anaesthesia.
Following electricity sector reforms in the late 1990s, prices charged by government-owned distributors in the south and eastern states of Australia more than doubled and the productivity of these ...government distributors declined. Econometric analysis associates much higher regulated revenues and regulated asset values with government-owned than investor-owned distributors. This disparity is not observed in other countries. Various commonly repeated explanations for higher distributor spending (stricter network planning standards, flawed regulatory rules, flawed appeal mechanisms, catch-up for historic underspending) do not seem to explain the disparity. This analysis suggests that owning governments perceive their cost of capital to be lower than that of their regulated private peers. The perceived premium encouraged government distributors to expand their asset base, and hence their prices and profits. The private-interest theory of regulation provides a plausible explanation for this.
•Government distributors have much higher regulated asset values and revenues than investor-owned distributors.•The government distributors' perceived cost of capital is lower than regulators determined.•The gap encouraged government distributors to expand assets and hence prices and profits.•The private interest theory of regulation provides a plausible explanation for this.
The CLEO RICH detector Artuso, M.; Ayad, R.; Bukin, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2005, Letnik:
554, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We describe the design, construction and performance of a Ring Imaging Cherenkov Detector (RICH) constructed to identify charged particles in the CLEO experiment. Cherenkov radiation occurs in LiF ...crystals, both planar and ones with a novel “sawtooth”-shaped exit surface. Photons in the wavelength interval 135–165
nm are detected using multi-wire chambers filled with a mixture of methane gas and triethylamine vapor. Excellent
π
/
K
separation is demonstrated.
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