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891.
Elizabeth D. Hutchins Glenn J. Markov Walter L. Eckalbar Rajani M. George Jesse M. King Minami A. Tokuyama Lauren A. Geiger Nataliya Emmert Michael J. Ammar April N. Allen Ashley L. Siniard Jason J. Corneveaux Rebecca E. Fisher Juli Wade Dale F. DeNardo J. Alan Rawls Matthew J. Huentelman Jeanne Wilson-Rawls Kenro Kusumi 《PloS one》2014,9(8)
892.
Variability of human immunodeficiency virus type 1 group O strains isolated from Cameroonian patients living in France. 总被引:8,自引:3,他引:8 下载免费PDF全文
I Loussert-Ajaka M L Chaix B Korber F Letourneur E Gomas E Allen T D Ly F Brun-Vzinet F Simon S Saragosti 《Journal of virology》1995,69(9):5640-5649
Human immunodeficiency virus type 1 (HIV-1) nucleotide sequences encoding p24Gag and the Env C2V3 region were obtained from seven patients who were selected on the basis of having paradoxical seronegativity on a subset of HIV enzyme-linked immunosorbent assay detection kits and having atypical Western blot (immunoblot) reactivity. Sequence analyses showed that all of these strains were more closely related to the recently described Cameroonian HIV isolates of group O (HIV-1 outlier) than to group M (HIV-1 major). All seven patients had Cameroonian origins but were living in France at the time the blood samples were taken. Characterization of a large number of group M strains has to date revealed eight distinct genetic subtypes (A to H). Genetic distances between sequences from available group O isolates were generally comparable to those observed in M intersubtype sequence comparisons, showing that the group O viruses are genetically very diverse. Analysis of sequences from these seven new viral strains, combined with the three previously characterized group O strains, revealed few discernable phylogenetic clustering patterns among the 10 patients' viral sequences. The level of diversity among group O sequences suggests that they may have a comparable (or greater) age than the M group sequences, although for unknown reasons, the latter group dispersed first and is the dominant lineage in the pandemic. 相似文献
893.
Proviral tagging in E mu-myc transgenic mice lacking the Pim-1 proto-oncogene leads to compensatory activation of Pim-2. 总被引:4,自引:1,他引:4 下载免费PDF全文
N M van der Lugt J Domen E Verhoeven K Linders H van der Gulden J Allen A Berns 《The EMBO journal》1995,14(11):2536-2544
The Pim-1 proto-oncogene is one of the most potent collaborators of the myc proto-oncogenes in inducing lymphomagenesis in mice. Contrary to the profound effects when overexpressed in vivo, Pim-1-deficient mice showed only subtle phenotypic alterations, which could indicate the presence of redundantly acting genes. In line with this, a PCR-based screen has led to the identification of a closely homologous gene, Pim-2. The X-linked Pim-2 gene is 53% identical to Pim-1 at the amino acid level and shares substrate preference and the usage of non-AUG initiation codons with Pim-1. We have used these data to test whether the strong synergistic interaction between Pim-1 and c-myc can be utilized to gain access to Pim-1 compensatory pathways. We reasoned that, upon proviral tagging in compound mutant mice (E mu-myc/Pim-1-/- mice), the selective advantage of cells carrying provirally activated genes, that act downstream from or parallel to Pim-1, would increase. We show here that this is the case. A dramatic increase (from 15 to 80%) was found in the frequency of proviral activation of the Pim-2 gene. These data show that the described strategy of 'complementation tagging' represents a powerful new tool to identify components of pathways involved in processes as complex as multistep tumorigenesis. 相似文献
894.
Allen M. Schoffstall Robert J. Barto David L. Ramos 《Origins of life and evolution of the biosphere》1982,12(2):143-151
Nucleosides or deoxynucleosides were converted to a number of phosphorylated nucleotide and deoxynucleotide derivatives by ammonium or alkali dihydrogen phosphates in formamide. Conversions were smaller and slower at room temperature and greater and faster at elevated temperatures. Nucleotides afforded product mixtures similar to those obtained for nucleosides under the same conditions, indicating the occurrence of transphosphorylation processes. Products of reaction at elevated temperatures were cyclic nucleotides, nucleoside monophosphates, nucleoside diphosphates and cyclic nucleotide phosphates. The relative amounts of products formed were quite temperature dependent. Cyclic nucleotides were found to be in greatest abudance for reactions run at 125° or above. Relative yields of 2, 3 and 5 nucleotides and 3 and 5 deoxynucleotides from several experiments are reported. 5-Monophosphates were generally found to be present in larger quantities than 2 or 3 monophosphates. 2-Deoxyadenosine showed a preference for phosphorylation at the 3 position. Conclusions reached from mechanistic studies are that the phosphorylations are a series of equilibrium reactions, with cyclic nucleotides being formed irreversibly.Presented in part at the 3rd Northwest and 5th Rocky Mountain Joint Regional ACS Meeting of the American Chemical Society, Salt Lake City, Utah, June, 1980. 相似文献
895.
Paul B. Samollow Edwards S. Robinson Allen L. Ford John L. Vandeberg 《Genesis (New York, N.Y. : 2000)》1995,16(4):367-374
Metatherian (marsupial) mammals possess a non-random form of X-chromosome inactivation in which the paternally-derived X is always the one inactivated. To examine the progression of X-linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded Gpd gene products in heterozygous female Virginia opossums (Didelphis virginiana) across a moior portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post-partum development, expression of the paternal Gpd allele had not attained the adult, tissue-specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch-life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpdgene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) maior changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue-specific manner. © 1995 Wiley-Liss, Inc. 相似文献
896.
Allen M. Schoffstall 《Origins of life and evolution of the biosphere》1976,7(4):399-412
A possible prebiotic phosphorylation method has been investigated in which formamide served as the reaction medium. Nucleotides and nucleotide derivatives were formed when nucleosides were allowed to react with different orthophosphate, hydrogen phosphate or dihydrogen phosphate salts or with different condensed phosphate salts. The reaction products obtained from the phosphorylation of adenosine were 2, 3 and 5-AMPs, 2, 5 and 3, 5-ADPs, and 2, 3-cyclic AMP. The extent of phosphorylation in formamide exceeded 50% under favorable conditions after 15 days at 70°. The acidic dihydrogen phosphates and condensed hydrogen phosphates proved to be the best phosphorylating agents. The presence of water in the medium decreased the yield of nucleotide derivatives, but some phosphorylation of adenosine was detected using dihydrogen phosphate in formamide containing water. The phosphorylation reactions were also observed for deoxynucleosides. Little decomposition of the nucleosides was detected during the reaction time needed to form nucleotide derivatives. The facility with which phosphorylation takes place in formamide under very mild conditions may justify further studies both of prebiotic phosphorylation and synthetic phosphorylation using this solvent.This work was done while the author was on leave from the Department of Chemistry, University of Colorado, Colorado Springs, Colo, 80907, U.S.A. 相似文献
897.
Jakob G. Knudsen Maria Murholm Andrew L. Carey Rasmus S. Biens? Astrid L. Basse Tamara L. Allen Juan Hidalgo Bronwyn A. Kingwell Mark A. Febbraio Jacob B. Hansen Henriette Pilegaard 《PloS one》2014,9(1)
Expression of brown adipose tissue (BAT) associated proteins like uncoupling protein 1 (UCP1) in inguinal WAT (iWAT) has been suggested to alter iWAT metabolism. The aim of this study was to investigate the role of interleukin-6 (IL-6) in exercise training and cold exposure-induced iWAT UCP1 expression. The effect of daily intraperitoneal injections of IL-6 (3 ng/g) in C57BL/6 mice for 7 days on iWAT UCP1 expression was examined. In addition, the expression of UCP1 in iWAT was determined in response to 3 days of cold exposure (4°C) and 5 weeks of exercise training in wild type (WT) and whole body IL-6 knockout (KO) mice. Repeated injections of IL-6 in C57BL/6 mice increased UCP1 mRNA but not UCP1 protein content in iWAT. Cold exposure increased iWAT UCP1 mRNA content similarly in IL-6 KO and WT mice, while exercise training increased iWAT UCP1 mRNA in WT mice but not in IL-6 KO mice. Additionally, a cold exposure-induced increase in iWAT UCP1 protein content was blunted in IL-6 KO mice, while UCP1 protein content in iWAT was lower in both untrained and exercise trained IL-6 KO mice than in WT mice. In conclusion, repeated daily increases in plasma IL-6 can increase iWAT UCP1 mRNA content and IL-6 is required for an exercise training-induced increase in iWAT UCP1 mRNA content. In addition IL-6 is required for a full induction of UCP1 protein expression in response to cold exposure and influences the UCP1 protein content iWAT of both untrained and exercise trained animals. 相似文献
898.
S R Chan C G Rickert W Vermi K C F Sheehan C Arthur J A Allen J M White J Archambault S Lonardi T M McDevitt D Bhattacharya M V Lorenzi D C Allred R D Schreiber 《Cell death and differentiation》2014,21(2):234-246
We previously reported that STAT1 expression is frequently abrogated in human estrogen receptor-α-positive (ERα+) breast cancers and mice lacking STAT1 spontaneously develop ERα+ mammary tumors. However, the precise mechanism by which STAT1 suppresses mammary gland tumorigenesis has not been fully elucidated. Here we show that STAT1-deficient mammary epithelial cells (MECs) display persistent prolactin receptor (PrlR) signaling, resulting in activation of JAK2, STAT3 and STAT5A/5B, expansion of CD61+ luminal progenitor cells and development of ERα+ mammary tumors. A failure to upregulate SOCS1, a STAT1-induced inhibitor of JAK2, leads to unopposed oncogenic PrlR signaling in STAT1−/− MECs. Prophylactic use of a pharmacological JAK2 inhibitor restrains the proportion of luminal progenitors and prevents disease induction. Systemic inhibition of activated JAK2 induces tumor cell death and produces therapeutic regression of pre-existing endocrine-sensitive and refractory mammary tumors. Thus, STAT1 suppresses tumor formation in mammary glands by preventing the natural developmental function of a growth factor signaling pathway from becoming pro-oncogenic. In addition, targeted inhibition of JAK2 may have significant therapeutic potential in controlling ERα+ breast cancer in humans. 相似文献
899.
Distribution of the Products of Photosynthesis between Powdery Mildew and Barley 总被引:6,自引:3,他引:6 下载免费PDF全文
The photosynthetic assimilation of 14CO2 has been studied in healthy and mildew-infected barley. The parasite was separated from the host by removing the mycelium with a camel's hair brush. The ethanol soluble metabolites of the parasite, infected host and healthy host were extracted, separated by paper chromatography and individually identified. From this work it appears that there is a rapid movement of label from host to parasite mainly in the form of sucrose which is then quickly metabolized into many compounds. The majority is converted into mannitol, and lesser amounts are converted into trehalose, arabitol, aspartic acid, and glutamic acid. In conidia the major carbon reserve is arabitol instead of mannitol, with lesser amounts of trehalose and mannitol.
Photosynthetic uptake of 14CO2 by the complex decreases steadily after inoculation as compared with healthy leaves. However, the ethanol soluble metabolites of the infected host tissue differ only slightly from those of healthy host tissue. The major differences are a slight decrease in the amount of sucrose and increases in malic acid and serine.
相似文献900.
Serge Evrard Graeme Poston Peter Kissmeyer-Nielsen Abou Diallo Grégoire Desolneux Véronique Brouste Caroline Lalet Frank Mortensen Stefan St?ttner Stephen Fenwick Hassan Malik Ioannis Konstantinidis Ronald DeMatteo Michael D'Angelica Peter Allen William Jarnagin Simone Mathoulin-Pelissier Yuman Fong 《PloS one》2014,9(12)