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Tran Cong Tuoc Evangelos Pavlakis Marco Andreas Tylkowski Anastassia Stoykova 《Cellular and molecular life sciences : CMLS》2014,71(17):3199-3218
The mammalian neocortex is a sheet of cells covering the cerebrum that provides the structural basis for the perception of sensory inputs, motor output responses, cognitive function, and mental capacity of primates. Recent discoveries promote the concept that increased cortical surface size and thickness in phylogenetically advanced species is a result of an increased generation of neurons, a process that underlies higher cognitive and intellectual performance in higher primates and humans. Here, we review some of the advances in the field, focusing on the diversity of neocortical progenitors in different species and the cellular mechanisms of neurogenesis. We discuss recent views on intrinsic and extrinsic molecular determinants, including the role of epigenetic chromatin modifiers and microRNA, in the control of neuronal output in developing cortex and in the establishment of normal cortical architecture. 相似文献
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Somatic control over the germline stem cell lineage during Drosophila spermatogenesis 总被引:8,自引:0,他引:8
Stem cells divide both to produce new stem cells and to generate daughter cells that can differentiate. The underlying mechanisms are not well understood, but conceptually are of two kinds. Intrinsic mechanisms may control the unequal partitioning of determinants leading to asymmetric cell divisions that yield one stem cell and one differentiated daughter cell. Alternatively, extrinsic mechanisms, involving stromal cell signals, could cause daughter cells that remain in their proper niche to stay stem cells, whereas daughter cells that leave this niche differentiate. Here we use Drosophila spermatogenesis as a model stem cell system to show that there are excess stem cells and gonialblasts in testes that are deficient for Raf activity. In addition, the germline stem cell population remains active for a longer fraction of lifespan than in wild type. Finally, raf is required in somatic cells that surround germ cells. We conclude that a cell-extrinsic mechanism regulates germline stem cell behaviour. 相似文献
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Marine Jurassic strata in Vietnam have yielded characteristic ammonites and occur in: (1) west Quang Binh Province located in the eastern margin of the Nam Theun Basin (the main part of which is located in Middle Laos); (2) the Nong Son Basin situated in the north of the Kon Tum Geoblock; (3) the Da Lat Basin, the largest Jurassic basin in Vietnam, extending from the southern margin of the Kon Tum Geoblock to southeast of Ho Chi Minh City. In the first two, Lower Jurassic marine beds occupy the lower part of the section and grade up into Middle Jurassic red beds. In central Da Lat Basin the section consists completely of marine strata containing many ammonite levels dated from Early Sinemurian to Bajocian, whereas the marginal basin section is like the first two areas. Based particularly on biostratigraphical evidence, a marine transgression is considered to have entered the Indochina Block as early as the Late Hettangian. During the early transgression the fauna was distinctly endemic, showing the separate character of the basins, but since the Late Sinemurian, communication between the Da Lat and other basins was established; the marine regime in Da Lat Basin ended around the Late Bathonian. 相似文献
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N. Tran 《Cellular and molecular life sciences : CMLS》1972,28(9):1021-1022
Sommaire Les résultats obtenus démontrent une inhibition de l'activité de la DOPA decarboxylase par de haute concentration de PLP ou de faible concentration del-DOPA plus PLP. Ceci pourrait expliquer les observations cliniques et expérimentales précédentes démontrant que la pyridoxine antagonise l'effet del-DOPA utilisé dans le traitement de la maladie de Parkinson. 相似文献
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S. Padilla U. C. Tran M. Jiménez-Hidalgo J. M. López-Martín A. Martín-Montalvo C. F. Clarke P. Navas C. Santos-Ocaña 《Cellular and molecular life sciences : CMLS》2009,66(1):173-186
Coenzyme Q is a lipid molecule required for respiration and antioxidant protection. Q biosynthesis in Saccharomyces cerevisiae requires nine proteins (Coq1p–Coq9p). We demonstrate in this study that Q levels are modulated during growth by its conversion
from demethoxy-Q (DMQ), a late intermediate. Similar conversion was produced when cells were subjected to oxidative stress
conditions. Changes in Q6/DMQ6 ratio were accompanied by changes in COQ7 gene mRNA levels encoding the protein responsible for the DMQ hydroxylation, the penultimate step in Q biosynthesis pathway.
Yeast coq null mutant failed to accumulate any Q late biosynthetic intermediate. However, in coq7 mutants the addition of exogenous Q produces the DMQ synthesis. Similar effect was produced by over-expressing ABC1/COQ8. These results support the existence of a biosynthetic complex that allows the DMQ6 accumulation and suggest that Coq7p is a control point for the Q biosynthesis regulation in yeast.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Received 04 September 2008; received after revision 22 October 2008; accepted 23 October 2008 相似文献
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Thi Ngoc Tram Nguyen Diem-Huong Nguyen-Tran Long Giang Bach Tran Hoang Du Truong Ngoc Thuy Trang Le Dai Hai Nguyen 《自然科学进展(英文版)》2019,29(6):612-616
A hybrid of organic/inorganic system, hollow mesoporous silica nanoparticles functionalized with poly(ethylene glycol), was synthesized in the presence of coupling agent and aminated ends. Doxorubicin (DOX) was used as a model drug to evaluate the effect of PEGylation on the loading capacity and release pattern of the system. Characterization with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption, thermogravimetric analysis (TGA) and Fourier transformed infrared (FTIR) confirmed the PEG conjugation, as well as the amorphous mesoporous nature of the synthesized particles. Due to the capping effect of PEG molecules over the pores in the silica structure, the synthesized system was able to retain higher amount of cargo and establish a controlled manner when releasing. 相似文献
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General linear non-autonomous functional differential equations are considered. Explicit criteria for exponential stability are given. Furthermore, the authors present an explicit robust stability bound for systems subject to time-varying perturbations. Two examples are given to illustrate the obtained results. 相似文献
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Miley GK Overzier RA Tsvetanov ZI Bouwens RJ Benítez N Blakeslee JP Ford HC Illingworth GD Postman M Rosati P Clampin M Hartig GF Zirm AW Röttgering HJ Venemans BP Ardila DR Bartko F Broadhurst TJ Brown RA Burrows CJ Cheng ES Cross NJ De Breuck C Feldman PD Franx M Golimowski DA Gronwall C Infante L Martel AR Menanteau F Meurer GR Sirianni M Kimble RA Krist JE Sparks WB Tran HD White RL Zheng W 《Nature》2004,427(6969):47-50
The most massive galaxies and the richest clusters are believed to have emerged from regions with the largest enhancements of mass density relative to the surrounding space. Distant radio galaxies may pinpoint the locations of the ancestors of rich clusters, because they are massive systems associated with 'overdensities' of galaxies that are bright in the Lyman-alpha line of hydrogen. A powerful technique for detecting high-redshift galaxies is to search for the characteristic 'Lyman break' feature in the galaxy colour, at wavelengths just shortwards of Lyalpha, which is due to absorption of radiation from the galaxy by the intervening intergalactic medium. Here we report multicolour imaging of the most distant candidate protocluster, TN J1338-1942 at a redshift z approximately 4.1. We find a large number of objects with the characteristic colours of galaxies at that redshift, and we show that this excess is concentrated around the targeted dominant radio galaxy. Our data therefore indicate that TN J1338-1942 is indeed the most distant cluster progenitor of a rich local cluster, and that galaxy clusters began forming when the Universe was only ten per cent of its present age. 相似文献
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Thomas JW Touchman JW Blakesley RW Bouffard GG Beckstrom-Sternberg SM Margulies EH Blanchette M Siepel AC Thomas PJ McDowell JC Maskeri B Hansen NF Schwartz MS Weber RJ Kent WJ Karolchik D Bruen TC Bevan R Cutler DJ Schwartz S Elnitski L Idol JR Prasad AB Lee-Lin SQ Maduro VV Summers TJ Portnoy ME Dietrich NL Akhter N Ayele K Benjamin B Cariaga K Brinkley CP Brooks SY Granite S Guan X Gupta J Haghighi P Ho SL Huang MC Karlins E Laric PL Legaspi R Lim MJ Maduro QL Masiello CA Mastrian SD 《Nature》2003,424(6950):788-793
The systematic comparison of genomic sequences from different organisms represents a central focus of contemporary genome analysis. Comparative analyses of vertebrate sequences can identify coding and conserved non-coding regions, including regulatory elements, and provide insight into the forces that have rendered modern-day genomes. As a complement to whole-genome sequencing efforts, we are sequencing and comparing targeted genomic regions in multiple, evolutionarily diverse vertebrates. Here we report the generation and analysis of over 12 megabases (Mb) of sequence from 12 species, all derived from the genomic region orthologous to a segment of about 1.8 Mb on human chromosome 7 containing ten genes, including the gene mutated in cystic fibrosis. These sequences show conservation reflecting both functional constraints and the neutral mutational events that shaped this genomic region. In particular, we identify substantial numbers of conserved non-coding segments beyond those previously identified experimentally, most of which are not detectable by pair-wise sequence comparisons alone. Analysis of transposable element insertions highlights the variation in genome dynamics among these species and confirms the placement of rodents as a sister group to the primates. 相似文献