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71.
Leslie JR Imai F Fukuhara K Takegahara N Rizvi TA Friedel RH Wang F Kumanogoh A Yoshida Y 《Development (Cambridge, England)》2011,138(18):4085-4095
Different types of sensory neurons in the dorsal root ganglia project axons to the spinal cord to convey peripheral information to the central nervous system. Whereas most proprioceptive axons enter the spinal cord medially, cutaneous axons typically do so laterally. Because heavily myelinated proprioceptive axons project to the ventral spinal cord, proprioceptive axons and their associated oligodendrocytes avoid the superficial dorsal horn. However, it remains unclear whether their exclusion from the superficial dorsal horn is an important aspect of neural circuitry. Here we show that a mouse null mutation of Sema6d results in ectopic placement of the shafts of proprioceptive axons and their associated oligodendrocytes in the superficial dorsal horn, disrupting its synaptic organization. Anatomical and electrophysiological analyses show that proper axon positioning does not seem to be required for sensory afferent connectivity with motor neurons. Furthermore, ablation of oligodendrocytes from Sema6d mutants reveals that ectopic oligodendrocytes, but not proprioceptive axons, inhibit synapse formation in Sema6d mutants. Our findings provide new insights into the relationship between oligodendrocytes and synapse formation in vivo, which might be an important element in controlling the development of neural wiring in the central nervous system. 相似文献
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Kristopher T Kahle Nancy D Merner Perrine Friedel Liliya Silayeva Bo Liang Arjun Khanna Yuze Shang Pamela Lachance‐Touchette Cynthia Bourassa Annie Levert Patrick A Dion Brian Walcott Dan Spiegelman Alexandre Dionne‐Laporte Alan Hodgkinson Philip Awadalla Hamid Nikbakht Jacek Majewski Patrick Cossette Tarek Z Deeb Stephen J Moss Igor Medina Guy A Rouleau 《EMBO reports》2014,15(7):766-774
The KCC2 cotransporter establishes the low neuronal Cl− levels required for GABAA and glycine (Gly) receptor-mediated inhibition, and KCC2 deficiency in model organisms results in network hyperexcitability. However, no mutations in KCC2 have been documented in human disease. Here, we report two non-synonymous functional variants in human KCC2, R952H and R1049C, exhibiting clear statistical association with idiopathic generalized epilepsy (IGE). These variants reside in conserved residues in the KCC2 cytoplasmic C-terminus, exhibit significantly impaired Cl−-extrusion capacities resulting in less hyperpolarized Gly equilibrium potentials (EGly), and impair KCC2 stimulatory phosphorylation at serine 940, a key regulatory site. These data describe a novel KCC2 variant significantly associated with a human disease and suggest genetically encoded impairment of KCC2 functional regulation may be a risk factor for the development of human IGE. 相似文献
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Nikolajewa S Friedel M Beyer A Wilhelm T 《Journal of bioinformatics and computational biology》2006,4(2):609-620
We present a new classification scheme of the genetic code. In contrast to the standard form it clearly shows five codon symmetries: codon-anticodon, codon-reverse codon, and sense-antisense symmetry, as well as symmetries with respect to purine-pyrimidine (A versus G, U versus C) and keto-aminobase (G versus U, A versus C) exchanges. We study the number of tRNA genes of 16 archaea, 81 bacteria and 7 eucaryotes to analyze whether these symmetries are reflected in the corresponding tRNA usage patterns. Two features are especially striking: reverse stop codons do not have their own tRNAs (just one exception in human), and A** anticodons are significantly suppressed. Our classification scheme of the genetic code and the identified tRNA usage patterns support recent speculations about the early evolution of the genetic code. In particular, pre-tRNAs might have had the ability to bind their codons in two directions to the corresponding codons. 相似文献
76.
Phosphorylation of phenol by phenylphosphate synthase: role of histidine phosphate in catalysis 下载免费PDF全文
Narmandakh A Gad'on N Drepper F Knapp B Haehnel W Fuchs G 《Journal of bacteriology》2006,188(22):7815-7822
The anaerobic metabolism of phenol proceeds via carboxylation to 4-hydroxybenzoate by a two-step process involving seven proteins and two enzymes ("biological Kolbe-Schmitt carboxylation"). MgATP-dependent phosphorylation of phenol catalyzed by phenylphosphate synthase is followed by phenylphosphate carboxylation. Phenylphosphate synthase shows similarities to phosphoenolpyruvate (PEP) synthase and was studied for the bacterium Thauera aromatica. It consists of three proteins and transfers the beta-phosphoryl from ATP to phenol; the products are phenylphosphate, AMP, and phosphate. We showed that protein 1 becomes phosphorylated in the course of the reaction cycle by [beta-(32)P]ATP. This reaction requires protein 2 and is severalfold stimulated by protein 3. Stimulation of the reaction by 1 M sucrose is probably due to stabilization of the protein(s). Phosphorylated protein 1 transfers the phosphoryl group to phenolic substrates. The primary structure of protein 1 was analyzed by nanoelectrospray mass spectrometry after CNBr cleavage, trypsin digestion, and online high-pressure liquid chromatography at alkaline pH. His-569 was identified as the phosphorylated amino acid. We propose a catalytic ping-pong mechanism similar to that of PEP synthase. First, a diphosphoryl group is transferred to His-569 in protein 1, from which phosphate is cleaved to render the reaction unidirectional. Histidine phosphate subsequently serves as the actual phosphorylation agent. 相似文献
77.
Svetlana Friedel Andreas Börner Harald Todt Peter M. Jakob Ljudmilla Borisjuk 《Plant biotechnology journal》2015,13(2):188-199
The large numbers of samples processed in breeding and biodiversity programmes require the development of efficient methods for the nondestructive evaluation of basic seed properties. Near‐infrared spectroscopy is the state‐of‐the‐art solution for this analytical demand, but it also has some limitations. Here, we present a novel, rapid, accurate procedure based on time domain‐nuclear magnetic resonance (TD‐NMR), designed to simultaneously quantify a number of basic seed traits without any seed destruction. Using a low‐field, benchtop 1H‐NMR instrument, the procedure gives a high‐accuracy measurement of oil content (R2 = 0.98), carbohydrate content (R2 = 0.99), water content (R2 = 0.98) and both fresh and dry weight of seeds/grains (R2 = 0.99). The method requires a minimum of ~20 mg biomass per sample and thus enables to screen individual, intact seeds. When combined with an automated sample delivery system, a throughput of ~1400 samples per day is achievable. The procedure has been trialled as a proof of concept on cereal grains (collection of ~3000 accessions of Avena spp. curated at the IPK genebank). A mathematical multitrait selection approach has been designed to simplify the selection of outlying (most contrasting) accessions. To provide deeper insights into storage oil topology, some oat accessions were further analysed by three‐dimensional seed modelling and lipid imaging. We conclude that the novel TD‐NMR‐based screening tool opens perspectives for breeding and plant biology in general. 相似文献
78.
Caroline C. Friedel Adam W. Whisnant Lara Djakovic Andrzej J. Rutkowski Marie-Sophie Friedl Michael Kluge James C. Williamson Somesh Sai Ramon Oliveira Vidal Sascha Sauer Thomas Hennig Arnhild Grothey Andrea Mili Bhupesh K. Prusty Paul J. Lehner Nicholas J. Matheson Florian Erhard Lars Dlken 《Journal of virology》2021,95(3)
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Yogendra Patel Catherine A Heyward Michael RH White Douglas B Kell 《BMC systems biology》2011,5(1):32