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Branch Points (branch + point)
Selected AbstractsSelf-Assembly of Functionalizable Two-Component 3D DNA Arrays through the Induced Formation of DNA Three-Way-Junction Branch Points by Supramolecular Cylinders,ANGEWANDTE CHEMIE, Issue 13 2010Roeland Boer Dr. Alles vereint: Indem sie DNA-Doppelstränge ,kontinuierlicher" Drei-Wege-Knoten mit stumpfen Enden durch nichtkovalente Wechselwirkungen um sich herum anordnen und die Bildung lokaler ,diskontinuierlicher" Drei-Wege-Knoten induzieren, fördern supramolekulare Zylinder die Bildung von 3D-DNA-Netzwerken mit einstellbaren physikalischen und chemischen Eigenschaften (siehe die Knotenanordnung im Ausschnitt der Gitterstruktur). [source] Branch point and donor splice-site COL7A1 mutations in mild recessive dystrophic epidermolysis bullosaBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2009B. Drera First page of article [source] Role of dopachrome conversion enzyme in the melanization of filarial worms in mosquitoesINSECT MOLECULAR BIOLOGY, Issue 6 2005C.-Y. Huang Abstract Melanization is an effective defence reaction of mosquito hosts against invading parasites. In mosquitoes, the biosynthesis of melanin is initiated by the hydroxylation of tyrosine to DOPA by phenoloxidase (PO). DOPA is a branch point of the melanization reaction; it may be oxidized to dopaquinone by PO or be decarboxylated to dopamine by dopa decarboxylase. Further oxidation of dopaquinone by PO produces dopachrome. Dopachrome is then converted to 5, 6-dihydroxyindole by dopachrome conversion enzyme (DCE) to produce melanin. The conversion of dopachrome is a rate-limiting step of the melanization reaction, and the presence of PO and DCE significantly accelerates melanization reactions. In this study, a cDNA encoding DCE was cloned from the mosquito Armigeres subalbatus. Real-time PCR analysis revealed increased transcripts from haemocytes in microfilariae (mf)-inoculated mosquitoes. Gene silencing using double-stranded RNA was used to elucidate the role of DCE in the melanization reaction of parasites in Ar. subalbatus. The levels of both DCE transcripts and protein in gene knockdown mosquitoes were dramatically reduced. Compared with controls, the degree of melanization of mf in DCE-knockdown mosquitoes was significantly decreased. These results suggest that DCE is a critical enzyme that is required for effective melanization immune responses. [source] Performance analysis and interoperability issue of consolidation algorithms in point-to-multipoint ABR servicesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2002Naris Rangsinoppamas Abstract In this paper we propose a performance analysis of the consolidation algorithms in point-to-multipoint ABR services in ATM network. We also present a new efficient consolidation algorithm, which overcomes some drawbacks of the previous works. The performance of the previous works and our proposed consolidation algorithms are analysed mathematically. General equations for calculating the response time and allowed cell rate of the source are derived. The derived equations show relatively good agreement with simulation results and can be applied for using in various network topologies. In addition, the interoperability issue in multicast available bit rate (ABR) is investigated. It is found that the branch points implemented with different consolidation algorithms can work interoperably. It is concluded from the simulation results that the performance of the point-to-multipoint ABR services is dominated by the most upper stream branch point (the nearest one to the source), therefore, in order to avoid the consolidation noise and get a faster response in the network, the most upper stream branch point has to be implemented with a high accuracy consolidation algorithm while the lower stream branch point(s) should be implemented with a fast response consolidation algorithm with a less degree of complexity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Molecular cloning, genomic organization and functional characterization of a new short-chain potassium channel toxin-like peptide BmTxKS4 from Buthus martensii Karsch(BmK)JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2004Sheng Jiqun Abstract Scorpion venom contains many small polypeptide toxins, which can modulate Na+, K+, Cl,, and Ca2+ ion,channel conductance in the cell membrane. A full-length cDNA sequence encoding a novel type of K+ -channel toxin (named BmTxKS4) was first isolated and identified from a venom gland cDNA library of Buthus martensii Karsch (BmK). The encoded precursor contains 78 amino acid residues including a putative signal peptide of 21 residues, propeptide of 11 residues, and a mature peptide of 43 residues with three disulfide bridges. BmTxKS4 shares the identical organization of disulfide bridges with all the other short-chain K+ -channel scorpion toxins. By PCR amplification of the genomic region encoding BmTxKS4, it was shown that BmTxKS4 composed of two exons is disrupted by an intron of 87 bp inserted between the first and the second codes of Phe (F) in the encoding signal peptide region, which is completely identical with that of the characterized scorpion K+ -channel ligands in the size, position, consensus junctions, putative branch point, and A+T content. The GST-BmTxKS4 fusion protein was successfully expressed in BL21 (DE3) and purified with affinity chromatography. About 2.5 mg purified recombinant BmTxKS4 (rBmTxKS4) protein was obtained by treating GST-BmTxKS4 with enterokinase and sephadex chromatography from 1 L bacterial culture. The electrophysiological activity of 1.0,M rBmTxKS4 was measured and compared by whole cell patch-clamp technique. The results indicated that rBmTxKS4 reversibly inhibited the transient outward K+ current (Ito), delayed inward rectifier K+ current (Ik1), and prolonged the action potential duration of ventricular myocyte, but it has no effect on the action potential amplitude. Taken together, BmTxKS4 is a novel subfamily member of short-strain K+ -channel scorpion toxin. © 2004 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:187,195, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20026 [source] An Algorithm for Simulating Equilibrium Adsorption Characteristics of Branched Copolymer Chains at Solid-Liquid InterfaceMACROMOLECULAR THEORY AND SIMULATIONS, Issue 4 2007Juedu Austine Abstract An algorithm is developed for simulating adsorption of tree type block-branched copolymer chains, of arbitrary architecture, from dilute solutions to solid surfaces. A continuum form of the self-consistent field (SCF) theory is used. The chain architecture is first represented by a convergent tree-graph, which is then converted into a special type of the connectivity matrix. This matrix is used for computing the configurational statistics of the chains in the adsorbed layer. The crucial step in the algorithm is to compute the junction (branch point) probability weights. A stepwise procedure for computing these probability weights is described. The capability of the algorithm has been demonstrated using illustrative examples. [source] Mapping of IS6110 flanking regions in clinical isolates of Mycobacterium tuberculosis demonstrates genome plasticityMOLECULAR MICROBIOLOGY, Issue 6 2000R. M. Warren Southern hybridization was used in combination with IS6110 insertion-locus-specific probes in a comparative study to determine the structure of chromosomal domains flanking IS6110 elements in clinical isolates of Mycobacterium tuberculosis. The resulting restriction fragment length polymorphism (RFLP) data demonstrated three mutational mechanisms responsible for the polymorphisms observed: IS6110 insertion, chromosomal mutation and deletion. The frequency of IS6110 insertion within many of the chromosomal regions demonstrates that preferential integration regions are common in M. tuberculosis. Mapping the IS6110 insertion positions and chromosomal deletions in relation to the M. tuberculosis H37Rv and M. bovis BCG genome sequences reveals numerous disruptions of predicted open reading frames (ORFs). A phylogenetic tree, based on the mutational data, showed a number of independently evolving lineages of M. tuberculosis, while analysis of the mutational events occurring at each branch point suggests both divergent and convergent evolution. A significant positive correlation was demonstrated between the mutation rate and the frequency of occurrence of different isolates in families of strains, suggesting that evolution may impact on strain ,fitness' or that strain proliferation may increase the chance of mutation. We conclude that the genome of clinical isolates of M. tuberculosis continues to evolve. [source] Structure and hydration of the amylopectin trisaccharide building blocks,Synthesis, NMR, and molecular dynamicsBIOPOLYMERS, Issue 12 2008Peter I. Hansen Abstract To gain insight into the molecular details and hydration of amylopectin, the five constituting trisaccharides have been chemically synthesized as their methyl ,-glycosides. All five trisaccharides were subjected to 950 MHz NMR spectroscopy for complete assignment and nanosecond molecular dynamics trajectories were calculated to study the structure and dynamics of the trisaccharides in aqueous solution. Systematic analysis of the simulation data revealed several examples of bridging water molecules playing an important role in the stabilization of specific amylopectin conformations, which was also supported by the experimental NMR data such as interresidue NOE's and heteronuclear scalar couplings between nuclei from neighboring residues. Although ,-maltotriose, ,-iso-maltotriose, ,-panose and ,-isopanose are relatively well characterized structures, the study also includes one less characterized trisaccharide with the structure ,Glcp(1,4),Glcp(1,6),Glcp. This trisaccharide, tentatively labelled ,-forkose, is located at the branch point of amylopectin, forking the amylopectin into two strands that align into double-helical segments. The results show that the conformation of ,-forkose takes a natural bend form which fits well into the structure of the double-helical segment of amylopectin. As the only trisaccharide in this study the structure of ,-forkose is not significantly influenced by the hydration. In contrast, ,-isopanose takes a restricted, but rather extended form due to an exceptionally strong localized water density. The two homo-linkage oligomers, ,-maltotriose and ,-iso-maltotriose, showed to be the most extended and the most flexible trimers, respectively, providing regular structure for crystalline domains and maximum linker flexibility for amorphous domains. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1179,1193, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Restoration of motor function of the deep fibular (peroneal) nerve by direct nerve transfer of branches from the tibial nerve: An anatomical study,CLINICAL ANATOMY, Issue 3 2004Kale D. Bodily Abstract Traction injuries of the common fibular (peroneal) nerve frequently result in significant morbidity due to tibialis anterior muscle paralysis and the associated loss of ankle dorsiflexion. Because current treatment options are often unsuccessful or unsatisfactory, other treatment approaches need to be explored. In this investigation, the anatomical feasibility of an alternative option, consisting of nerve transfer of motor branches from the tibial nerve to the deep fibular nerve, was studied. In ten cadaveric limbs, the branching pattern, length, and diameter of motor branches of the tibial nerve in the proximal leg were characterized; nerve transfer of each of these motor branches was then simulated to the proximal deep fibular nerve. A consistent, reproducible pattern of tibial nerve innervation was seen with minor variability. Branches to the flexor hallucis longus and flexor digitorum longus muscles were determined to be adequate, based on their branch point, branch pattern, and length, for direct nerve transfer in all specimens. Other branches, including those to the tibialis posterior, popliteus, gastrocnemius, and soleus muscles were not consistently adequate for direct nerve transfer for injuries extending to the bifurcation of the common fibular nerve or distal to it. For neuromas of the common fibular nerve that do not extend as far distally, branches to the soleus and lateral head of the gastrocnemius may be adequate for direct transfer if the intramuscular portions of these nerves are dissected. This study confirms the anatomical feasibility of direct nerve transfer using nerves to toe-flexor muscles as a treatment option to restore ankle dorsiflexion in cases of common fibular nerve injury. Clin. Anat. 17:201,205, 2004. © 2004 Wiley-Liss, Inc. [source] AMP-activated protein kinase , a sensor of glycogen as well as AMP and ATP?ACTA PHYSIOLOGICA, Issue 1 2009A. McBride Abstract The classical role of the AMP-activated protein kinase (AMPK) is to act as a sensor of the immediate availability of cellular energy, by monitoring the concentrations of AMP and ATP. However, the , subunits of AMPK contain a glycogen-binding domain, and in this review we develop the hypothesis that this is a regulatory domain that allows AMPK to act as a sensor of the status of cellular reserves of energy in the form of glycogen. We argue that the pool of AMPK that is bound to the glycogen particle is in an active state when glycogen particles are fully synthesized, causing phosphorylation of glycogen synthase at site 2 and providing a feedback inhibition of further extension of the outer chains of glycogen. However, when glycogen becomes depleted, the glycogen-bound pool of AMPK becomes inhibited due to binding to ,1,6-linked branch points exposed by the action of phosphorylase and/or debranching enzyme. This allows dephosphorylation of site 2 on glycogen synthase by the glycogen-bound form of protein phosphatase-1, promoting rapid resynthesis of glycogen and replenishment of glycogen stores. This is an extension of the classical role of AMPK as a ,guardian of cellular energy', in which it ensures that cellular energy reserves are adequate for medium-term requirements. The literature concerning AMPK, glycogen structure and glycogen-binding proteins that led us to this concept is reviewed. [source] Differential expression and localization of neuronal intermediate filament proteins within newly developing neurites in dissociated cultures of Xenopus laevis embryonic spinal cordCYTOSKELETON, Issue 1 2001Jayanthi Undamatla Abstract The molecular subunit composition of neurofilaments (NFs) progressively changes during axon development. In developing Xenopus laevis spinal cord, peripherin emerges at the earliest stages of neurite outgrowth. NF-M and XNIF (an ,-internexin-like protein) appear later, as axons continue to elongate, and NF-L is expressed after axons contact muscle. Because NFs are the most abundant component of the vertebrate axonal cytoskeleton, we must understand why these changes occur before we can fully comprehend how the cytoskeleton regulates axon growth and morphology. Knowing where these proteins are localized within developing neurites and how their expression changes with cell contact is essential for this understanding. Thus, we examined by immunofluorescence the expression and localization of these NF subunits within dissociated cultures of newly differentiating spinal cord neurons. In young neurites, peripherin was most abundant in distal neuritic segments, especially near branch points and extending into the central domain of the growth cone. In contrast, XNIF and NF-M were usually either absent from very young neurites or exhibited a proximal to distal gradient of decreasing intensity. In older neurites, XNIF and NF-M expression increased, whereas that of peripherin declined. All three of these proteins became more evenly distributed along the neurites, with some branches staining more intensely than others. At 24 h, NF-L appeared, and in 48-h cultures, its expression, along with that of NF-M, was greater in neurites contacting muscle cells, arguing that the upregulation of these two subunits is dependent on contact with target cells. Moreover, this contact had no effect on XNIF or peripherin expression. Our findings are consistent with a model in which peripherin plays an important structural role in growth cones, XNIF and NF-M help consolidate the intermediate filament cytoskeleton beginning in the proximal neurite, and increased levels of NF-L and NF-M help further solidify the cytoskeleton of axons that successfully reach their targets. Cell Motil. Cytoskeleton 49:16,32, 2001. © 2001 Wiley-Liss, Inc. [source] Murray's law and the hydraulic vs mechanical functioning of woodFUNCTIONAL ECOLOGY, Issue 6 2004K. A. McCULLOH Summary 1Murray's law states that the hydraulic conductance per blood volume of the cardiovascular system is maximized when the sum of the vessel radii cubed (, r3) is conserved. 2We hypothesize that Murray's law will apply to xylem conduits as long as they only transport water and do not also help support the plant. Specifically, the less volume of wood occupied by conduits, the more the conduits should conform to Murray's law. 3We tested the applicability of Murray's law along a continuum of decreasing conduit fraction from coniferous (91% conduits) to diffuse-porous (24% conduits) to ring-porous wood (12% conduits), using anatomical and functional tests. The anatomical test compared the , r3 conservation across branch points by direct measurements of conduit radii. The functional test compared the hydraulic conductivity between branches of different ages. 4As predicted, Murray's law was rejected in conifer wood where hydraulic function is coupled to mechanical support. The angiosperm wood did not deviate as strongly from Murray's law, especially the ring-porous type. For comparison we report previously published results from compound leaves and vines which showed general agreement with Murray's law. 5Deviation from Murray's law was associated with fewer, narrower conduits distally causing a decrease in , r3 distally. Although less efficient hydraulically, this configuration is not top-heavy and is more mechanically stable. With the evolution of vessels and fibres, angiosperm wood can more closely approach Murray's law while still meeting mechanical requirements. [source] The phosphatidylinositol-3 kinase (PI3K)-Akt pathway suppresses neurite branch formation in NGF-treated PC12 cellsGENES TO CELLS, Issue 8 2003Maiko Higuchi Background:, Previous studies have shown that phosphatidylinositol-3 kinase (PI3K) plays an important role in NGF (nerve growth factor)-induced neurite elongation. However, the roles of the PI3K pathway in neurite branch formation were not fully understood. Also, it was not clear where the PI3K pathway is activated during branch formation. Results:, We found that the treatment of PC12 cells with the PI3K inhibitor LY294002 resulted in a marked increase in the number of neurite branch points, suggesting a suppressive role of PI3K in neurite branch formation. Expression of a constitutively active form of Akt, a downstream effector of PI3K, decreased the number of branch points, whereas that of a dominant-negative form of Akt increased it. In contrast, inhibition of neither Rac, mTOR nor GSK3, other effectors of PI3K, promoted branch formation. Importantly, the phosphorylated form of endogenous Akt was localized at the tips of growth cones, but devoid of small branches in NGF-treated PC12 cells. A GFP-fusion protein of the plekstrin-homology (PH) domain of Akt was also localized at the tips of growth cones. Conclusions:, The PI3K-Akt pathway thus plays a key role in suppression of neurite branch formation in NGF-treated PC12 cells. Summary figure, Figure Summary figure,. working model for the regulation of neuritogenesis in PC12 cells. PI3K may mediate NGF regulation of neuritogenesis via two pathways. Rac induces neurite elongation and branch formation. Akt induces neurite elongation, but prevents branch formation. [source] Transplanted glioma cells migrate and proliferate on host brain vasculature: A dynamic analysisGLIA, Issue 8 2006Azadeh Farin Abstract Glioma cells have a remarkable capacity to infiltrate the brain and migrate long distances from the tumor, making complete surgical resection impossible. Yet, little is known about how glioma cells interact with the complex microenvironment of the brain. To investigate the patterns and dynamics of glioma cell infiltration and migration, we stereotactically injected eGFP and DsRed-2 labeled rat C6 glioma cells into neonatal rat forebrains and used time-lapse microscopy to observe glioma cell migration and proliferation in slice cultures generated from these brains. In this model, glioma cells extensively infiltrated the brain by migrating along the abluminal surface of blood vessels. Glioma cells intercalated their processes between the endothelial cells and the perivascular astrocyte end feet, but did not invade into the blood vessel lumen. Dynamic analysis revealed notable similarities between the migratory behavior of glioma cells and that previously observed for glial progenitor cells. Glioma cells had a characteristic leading process and migrated in a saltatory fashion, with bursts of migration separated by periods of immobility, and maximum speeds of over 100 ,m/h. Migrating glioma cells proliferated en route, pausing for as short as an hour to divide before the daughter cells resumed migrating. Remarkably, the majority of glioma cell divisions took place at or near vascular branch points, suggesting that mitosis is triggered by local environmental cues. This study provides the first dynamic analysis of glioma cell infiltration in living brain tissue and reveals that the migration and proliferation of transplanted glioma cells is directed by interactions with host brain vasculature. © 2006 Wiley-Liss, Inc. [source] Performance analysis and interoperability issue of consolidation algorithms in point-to-multipoint ABR servicesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2002Naris Rangsinoppamas Abstract In this paper we propose a performance analysis of the consolidation algorithms in point-to-multipoint ABR services in ATM network. We also present a new efficient consolidation algorithm, which overcomes some drawbacks of the previous works. The performance of the previous works and our proposed consolidation algorithms are analysed mathematically. General equations for calculating the response time and allowed cell rate of the source are derived. The derived equations show relatively good agreement with simulation results and can be applied for using in various network topologies. In addition, the interoperability issue in multicast available bit rate (ABR) is investigated. It is found that the branch points implemented with different consolidation algorithms can work interoperably. It is concluded from the simulation results that the performance of the point-to-multipoint ABR services is dominated by the most upper stream branch point (the nearest one to the source), therefore, in order to avoid the consolidation noise and get a faster response in the network, the most upper stream branch point has to be implemented with a high accuracy consolidation algorithm while the lower stream branch point(s) should be implemented with a fast response consolidation algorithm with a less degree of complexity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fructose and glucose mediates enterotoxin production and anaerobic metabolism of Bacillus cereus ATCC14579TJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009O. Ouhib-Jacobs Abstract Aims:, To determine the effects of carbohydrates on Bacillus cereus ATCC14579T anaerobic metabolism and enterotoxin production in amino acids rich medium. Methods and Results:,Bacillus cereus anaerobic growth on different carbohydrates (glucose, fructose, sucrose or glucose,fructose mixture) was examined in synthetic mMOD medium under continuous cultures (, = 0·2 h,1). Fermentation end-products, flux partitioning at each key branch points of the mixed acid pathway and consumption or production of amino acids were determined. On both fructose and sucrose, ATP production was favoured via acetate production from acetyl-CoA. In addition, amino acids present in the growth medium showed significant variations with high consumption of serine and net production of glutamate and alanine on some or all sugars. Enterotoxins Hbl and Nhe production was high during growth on fructose (or mixtures involving a fructose moiety). Conclusions:, Fructose was identified as a key sugar influencing anaerobic metabolism and toxin production of B. cereus. Significance and Impact of the Study:, The physiological differences associated with the fermentation of the various carbohydrates clearly modify toxinogenesis indicating that the risk of foodborne pathogens is to some extent dependent upon the prevailing nutritional environment. [source] Character of long-chain branching in highly purified natural rubberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sureerut Amnuaypornsri Abstract The nature of long-chain branching in natural rubber (NR) from Hevea brasiliensis was analyzed for NR purified by enzymatic deproteinization in the latex state followed by acetone extraction in the solid state to remove the proteins and neutral lipids, respectively. The treatment of purified NR in a toluene solution with a polar solvent, such as methanol or acetic acid, resulted in a clear decrease in the molecular weight, gel content, and Huggins' constant; this was caused by the decomposition of branch points in the purified rubber. This finding clearly showed that long-chain branching in the purified NR was mainly derived from the association of phospholipids linked with both terminal groups in the rubber chain via hydrogen bonds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Mechanistic understanding of the fermentative L -glutamic acid overproduction by Corynebacterium glutamicum through combined metabolic flux profiling and transmembrane transport characteristicsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2004Theodora Tryfona Abstract Since the 1950s when Micrococcus glutamicus later renamed Corynebacterium glutamicum was discovered, the production of amino acids by fermentative methods has become an important aspect of industrial microbiology. Numerous studies to understand and improve the metabolic conditions leading to amino acid overproduction have been carried out. Most amino acids are currently produced by use of mutants that contain combinations of auxotrophic and regulatory mutations. L -Glutamic acid is the amino acid produced in the greatest quantities (106 tonnes per year) and Corynebacteria are central to its industrial production. However, further improvements to strain performance are difficult to obtain by empirical optimization and a more rational approach is required. The use of metabolic flux analysis provides valuable information regarding bottlenecks in the formation of desired metabolites. Such techniques have found application in elucidating flux control, provided insight into metabolic network function and developed methods to amplify or redirect fluxes in engineered bioprocesses. Hence, branch points in biosynthesis, precursor supply in fuelling reactions and export of metabolites can be manipulated, resulting in high glutamic acid overproduction by Corynebacterium glutamicum fermentations. In this review, in addition to reviewing the state of play in metabolic flux analysis for glutamate overproduction, the metabolic pathways involved in the production of L -glutamic acid, the mechanisms mediating its efflux and secretion as well as their manipulation to achieve higher glutamate production, are discussed. The link between metabolic flux and transmembrane transport of glutamic acid are also considered. Copyright © 2004 Society of Chemical Industry [source] Studies on the effects of gentamicin on rat metanephric development in vitroNEPHROLOGY, Issue 1-2 2000Luise A Cullen SUMMARY: Reduced nephron endowment has been associated with increased risk of developing essential hypertension and chronic renal failure. Both in vivo and in vitro exposure of developing rat metanephroi to gentamicin has been reported to inhibit metanephric development resulting in reduced nephron endowment. The aim of the present study was to confirm that gentamicin results in reduced nephron endowment in vitro, and to extend understanding of the mechanisms responsible for this reduced endowment. Embryonic day 14 (E14) rat metanephroi were cultured for up to 4 days in serum-free medium with or without 50 ,g/mL gentamicin. Metanephroi cultured in the presence of gentamicin were 25% smaller than control metanephroi after 2 days culture and 30% smaller after 4 days (P < 0.001). This decrease in total metanephric volume was reflected in reduced volumes of ureteric duct epithelium, mesenchyme/interstitium and nephron epithelia. The reduced volume of ureteric duct epithelium in gentamicin-treated metanephroi was associated with a 30% reduction in the number of ureteric duct branch points at 2 days. Metanephroi cultured with gentamicin contained 20% fewer glomeruli than control metanephroi (P < 0.005) at 4 days. These glomeruli were 30% smaller than control glomeruli (P < 0.05). Qualitative observations of Pax-2 immunostained mesenchymal condensates indicated no difference in condensate size, location or morphology. These results confirm that in vitro exposure of developing rat metanephroi to gentamicin results in reduced nephron endowment. The defect in nephrogenesis centres around the inhibition of ureteric duct branching. [source] A systems biology investigation of the MEP/terpenoid and shikimate/phenylpropanoid pathways points to multiple levels of metabolic control in sweet basil glandular trichomesTHE PLANT JOURNAL, Issue 3 2008Zhengzhi Xie Summary The glandular trichome is an excellent model system for investigating plant metabolic processes and their regulation within a single cell type. We utilized a proteomics-based approach with isolated trichomes of four different sweet basil (Ocimum basilicum L.) lines possessing very different metabolite profiles to clarify the regulation of metabolism in this single cell type. Significant differences in the distribution and accumulation of the 881 highly abundant and non-redundant protein entries demonstrated that although the proteomes of the glandular trichomes of the four basil lines shared many similarities they were also each quite distinct. Correspondence between proteomic, expressed sequence tag, and metabolic profiling data demonstrated that differential gene expression at major metabolic branch points appears to be responsible for controlling the overall production of phenylpropanoid versus terpenoid constituents in the glandular trichomes of the different basil lines. In contrast, post-transcriptional and post-translational regulation of some enzymes appears to contribute significantly to the chemical diversity observed within compound classes for the different basil lines. Differential phosphorylation of enzymes in the 2- C -methyl- d -erythritol 4-phosphate (MEP)/terpenoid and shikimate/phenylpropanoid pathways appears to play an important role in regulating metabolism in this single cell type. Additionally, precursors for different classes of terpenoids, including mono- and sesquiterpenoids, appear to be almost exclusively supplied by the MEP pathway, and not the mevalonate pathway, in basil glandular trichomes. [source] Long-time asymptotics of the nonlinear Schrödinger equation shock problemCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 9 2007Robert Buckingham The long-time asymptotics of two colliding plane waves governed by the focusing nonlinear Schrödinger equation are analyzed via the inverse scattering method. We find three asymptotic regions in space-time: a region with the original wave modified by a phase perturbation, a residual region with a one-phase wave, and an intermediate transition region with a modulated two-phase wave. The leading-order terms for the three regions are computed with error estimates using the steepest-descent method for Riemann-Hilbert problems. The nondecaying initial data requires a new adaptation of this method. A new breaking mechanism involving a complex conjugate pair of branch points emerging from the real axis is observed between the residual and transition regions. Also, the effect of the collision is felt in the plane-wave state well beyond the shock front at large times. © 2007 Wiley Periodicals, Inc. [source] | |||||||||||||||||||