Early γ oscillations synchronize developing thalamus and cortex     

Minlebaev M  Colonnese M  Tsintsadze T  Sirota A  Khazipov R 《Science (New York, N.Y.)》2011,334(6053):226-229

During development, formation of topographic maps in sensory cortex requires precise temporal binding in thalamocortical networks. However, the physiological substrate for such synchronization is unknown. We report that early gamma oscillations (EGOs) enable precise spatiotemporal thalamocortical synchronization in the neonatal rat whisker sensory system. Driven by a thalamic gamma oscillator and initially independent of cortical inhibition, EGOs synchronize neurons in a single thalamic barreloid and corresponding cortical barrel and support plasticity at developing thalamocortical synapses. We propose that the multiple replay of sensory input in thalamocortical circuits during EGOs allows thalamic and cortical neurons to be organized into vertical topographic functional units before the development of horizontal binding in adult brain.  相似文献   

The structure of the eukaryotic ribosome at 3.0 Å resolution     

Ben-Shem A  Garreau de Loubresse N  Melnikov S  Jenner L  Yusupova G  Yusupov M 《Science (New York, N.Y.)》2011,334(6062):1524-1529

Ribosomes translate genetic information encoded by messenger RNA into proteins. Many aspects of translation and its regulation are specific to eukaryotes, whose ribosomes are much larger and intricate than their bacterial counterparts. We report the crystal structure of the 80S ribosome from the yeast Saccharomyces cerevisiae--including nearly all ribosomal RNA bases and protein side chains as well as an additional protein, Stm1--at a resolution of 3.0 angstroms. This atomic model reveals the architecture of eukaryote-specific elements and their interaction with the universally conserved core, and describes all eukaryote-specific bridges between the two ribosomal subunits. It forms the structural framework for the design and analysis of experiments that explore the eukaryotic translation apparatus and the evolutionary forces that shaped it.  相似文献   

Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery     

Tyzio R  Cossart R  Khalilov I  Minlebaev M  Hübner CA  Represa A  Ben-Ari Y  Khazipov R 《Science (New York, N.Y.)》2006,314(5806):1788-1792

We report a signaling mechanism in rats between mother and fetus aimed at preparing fetal neurons for delivery. In immature neurons, gamma-aminobutyric acid (GABA) is the primary excitatory neurotransmitter. We found that, shortly before delivery, there is a transient reduction in the intracellular chloride concentration and an excitatory-to-inhibitory switch of GABA actions. These events were triggered by oxytocin, an essential maternal hormone for labor. In vivo administration of an oxytocin receptor antagonist before delivery prevented the switch of GABA actions in fetal neurons and aggravated the severity of anoxic episodes. Thus, maternal oxytocin inhibits fetal neurons and increases their resistance to insults during delivery.  相似文献   

Crystal structure of the eukaryotic ribosome   总被引：1，自引：0，他引：1  

Ben-Shem A  Jenner L  Yusupova G  Yusupov M 《Science (New York, N.Y.)》2010,330(6008):1203-1209

Crystal structures of prokaryotic ribosomes have described in detail the universally conserved core of the translation mechanism. However, many facets of the translation process in eukaryotes are not shared with prokaryotes. The crystal structure of the yeast 80S ribosome determined at 4.15 angstrom resolution reveals the higher complexity of eukaryotic ribosomes, which are 40% larger than their bacterial counterparts. Our model shows how eukaryote-specific elements considerably expand the network of interactions within the ribosome and provides insights into eukaryote-specific features of protein synthesis. Our crystals capture the ribosome in the ratcheted state, which is essential for translocation of mRNA and transfer RNA (tRNA), and in which the small ribosomal subunit has rotated with respect to the large subunit. We describe the conformational changes in both ribosomal subunits that are involved in ratcheting and their implications in coordination between the two associated subunits and in mRNA and tRNA translocation.  相似文献   

Synthesis, structure, and reactivity of an iron(V) nitride     

Scepaniak JJ  Vogel CS  Khusniyarov MM  Heinemann FW  Meyer K  Smith JM 《Science (New York, N.Y.)》2011,331(6020):1049-1052

Despite being implicated as important intermediates, iron(V) compounds have proven very challenging to isolate and characterize. Here, we report the preparation of the iron(V) nitrido complex, [PhB((t)BuIm)(3)Fe(V)≡N]BAr(F24) (PhB((t)BuIm)(3)(-) = phenyltris(3-tert-butylimidazol-2-ylidene)borato, BAr(F24) = B(3,5-(CF(3))(2)C(6)H(3))(4)(-)), by one electron oxidation of the iron(IV) nitrido precursor. Single-crystal x-ray diffraction of the iron(V) complex reveals a four-coordinate metal ion with a terminal nitrido ligand. M??bauer and electron paramagnetic resonance spectroscopic characterization, supported by electronic structure calculations, provide evidence for a d(3) iron(V) metal center in a low spin (S = 1/2) electron configuration. Low-temperature reaction of the iron(V) nitrido complex with water under reducing conditions leads to high yields of ammonia with concomitant formation of an iron(II) species.  相似文献   

Phenotypic and genotypic characteristics of Brucella isolates from the Republic of Kazakhstan     

Yespembetov  Bolat A.  Syrym  Nazym S.  Zinina  Nadezhda N.  Sarmykova  Makhpal K.  Konbayeva  Gulshat M.  Basybekov  Sovetzhan Z.  Mussayeva  Assiya K.  Kanatbayev  Serik G.  Bazarbayev  Marat  Siyabekov  Sarsenbek T. 《Tropical animal health and production》2019,51(8):2361-2370

Tropical Animal Health and Production - The purposes of this study were to determine phenotypic and genotypic characteristics of Brucella isolates from the Republic of Kazakhstan and to determine...  相似文献   

Translational operator of mRNA on the ribosome: how repressor proteins exclude ribosome binding     

Jenner L  Romby P  Rees B  Schulze-Briese C  Springer M  Ehresmann C  Ehresmann B  Moras D  Yusupova G  Yusupov M 《Science (New York, N.Y.)》2005,308(5718):120-123

The ribosome of Thermus thermophilus was cocrystallized with initiator transfer RNA (tRNA) and a structured messenger RNA (mRNA) carrying a translational operator. The path of the mRNA was defined at 5.5 angstroms resolution by comparing it with either the crystal structure of the same ribosomal complex lacking mRNA or with an unstructured mRNA. A precise ribosomal environment positions the operator stem-loop structure perpendicular to the surface of the ribosome on the platform of the 30S subunit. The binding of the operator and of the initiator tRNA occurs on the ribosome with an unoccupied tRNA exit site, which is expected for an initiation complex. The positioning of the regulatory domain of the operator relative to the ribosome elucidates the molecular mechanism by which the bound repressor switches off translation. Our data suggest a general way in which mRNA control elements must be placed on the ribosome to perform their regulatory task.  相似文献