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881.
Selection of mouse neuroblastoma cell-specific polyoma virus mutants with stage differentiative advantages of replication. 总被引:12,自引:1,他引:11 下载免费PDF全文
R Maione C Passananti V De Simone P Delli-Bovi G Augusti-Tocco P Amati 《The EMBO journal》1985,4(12):3215-3221
Two mouse neuroblastoma cell lines were analyzed for their permissivity for polyoma virus growth. One (N18) is fully permissive for polyoma replication, the other (41A3) shows limited permissivity and the viral genome persists, without noticeable cell death. Virus persistence does not seem to alter the cells' ability to differentiate in vitro and leads to selection of viral mutants altered in the untranscribed regulatory region of the genome. The mutant types obtained appear to be related to the degree of host cell differentiation. Nucleotide sequence analysis of the restriction fragment covering the regulatory region shows that duplications are present in all mutants, while deletions in the non-duplicated segment are only present in mutants selected from less differentiated cells. These alterations involve both domains of the regulatory region that are considered to be essential for DNA replication and for enhancer activity. Mixed infections with polyoma wild type show that the selected mutants have cis-advantage in replication in neuroblastoma cells and not in 3T6 cells. Mutants carrying the deletion in the non-duplicated segment of the enhancer show a selective advantage in replication over the undeleted one in mixed infection. This advantage is much stronger in neuroblastoma cells in suspension (less-differentiated stage) than in monolayer cells (more-differentiated stage). An interpretation of the overall structure of the regulatory enhancer region, based on the observed differences between the mutants selected at different stages of differentiation in neuroblastoma and previously described mutants selected in undifferentiated cells, is discussed. 相似文献
882.
883.
Jayneil R. Patel Yingqi Xu Claudia Capitini Fabrizio Chiti Alfonso De Simone 《Biomolecular NMR assignments》2018,12(2):273-277
The HypF protein is involved in the maturation and regulation of hydrogenases. The N-terminal domain of HypF (HypF-N) has served as a key model system to study the pathways of protein amyloid formation and the nature of the toxicity of pre-fibrilar protein oligomers. This domain can aggregate into two forms of oligomers having significantly different toxic effects when added to neuronal cultures. Here, NMR assignments of HypF-N backbone resonances are presented in its native state and under the conditions favouring the formation of toxic and non-toxic oligomers. The analyses of chemical shifts provide insights into the protein conformational state and the possible pathways leading to the formation of different types of oligomers. 相似文献
884.
885.
Simone Martinelli Oliver H.F. Krumbach Francesca Pantaleoni Simona Coppola Ehsan Amin Luca Pannone Kazem Nouri Luciapia Farina Radovan Dvorsky Francesca Lepri Marcel Buchholzer Raphael Konopatzki Laurence Walsh Katelyn Payne Mary Ella Pierpont Samantha Schrier Vergano Katherine G. Langley Douglas Larsen Ghayda M. Mirzaa 《American journal of human genetics》2018,102(2):309-320
886.
Seveso Davide Montano Simone Maggioni Davide Pedretti Francesca Orlandi Ivan Galli Paolo Vai Marina 《Coral reefs (Online)》2018,37(3):801-806
Coral Reefs - In corals, different biological processes are associated with the daily variation of temperature and light, which in shallow reefs can vary widely and regularly reach extreme levels.... 相似文献
887.
888.
Cytokine-Regulated Expression of Platelet-Derived Growth Factor Gene and Protein in Cultured Human Astrocytes 总被引:1,自引:0,他引:1
Francesca Ceccherini Silberstein Roberta De Simone Giulio Levi Francesca Aloisi 《Journal of neurochemistry》1996,66(4):1409-1417
Abstract: To elucidate mechanisms regulating the production of platelet-derived growth factor (PDGF) in the CNS, we analyzed the influence of a panel of cytokines on PDGF mRNA and protein levels in astrocyte-enriched cultures from the human embryonic brain and spinal cord. Using a specific ELISA, PDGF AB protein was detected in serum-free astrocyte supernatants and its levels were significantly increased after treatment of the cultures with transforming growth factor-β1 (TGF-β1 ) or tumor necrosis factor-α (TNF-α); the largest increase was detected after combined treatment with the two cytokines. Interleukin-1β (IL-1β) by itself had little or no effect but synergized with TGF-β1 in enhancing PDGF AB production. Supernatants from human astrocyte cultures stimulated the proliferation of rat oligodendrocyte progenitors, and most of the mitogenic activity could be accounted for by PDGF. By northern blot analysis, both PDGF A- and PDGF B-chain mRNAs were detected in untreated astrocytes. PDGF B-chain mRNA levels were increased by TGF-β1 , TNF-α, TNF-α/TGF-β1 , or IL-1β/TGF-β1 , whereas PDGF A-chain mRNA levels were not consistently affected by cytokine treatments. These in vitro data indicate that TGF-β1 , TNF-α, and IL-1β are able to stimulate astrocyte PDGF production. This cytokine network could play a role in CNS development and repair after injury or inflammation. 相似文献
889.
Serguei Zoubak Giuseppe D'Onofrio Simone Cacciò Giacomo Bernardi Giorgio Bernardi 《Journal of molecular evolution》1995,40(3):293-307
All 69 homologous coding sequences that are currently available in four mammalian orders were aligned and the synonymous (ie., third) positions of quartet (fourfold degenerate) codons were divided into three classes (that will be called conserved, intermediate, and variable), according to whether they show no change, one change, and more than one change, respectively. The three classes were analyzed in their compositional patterns. In the majority of GC-rich genes, the three classes of positions (but especially conserved positions) exhibited significantly different base compositions compared to expectations based on a random substitution process from the ancestral (consensus) sequence to the present-day (actual) sequences. Significant differences were rare in GC-poor genes.An analysis of the present results indicates that natural selection plays a role in the synonymous nucleotide substitution process, especially in GC-rich genes which represent the vast majority of mammalian genes.This paper is dedicated to the memory of Dr. Motoo Kimura (1924–1994)Correspondence to: Giorgio Bernardi 相似文献
890.
Simone A. French Cheryl L. Perry Gloria R. Leon Jayne A. Fulkerson 《Obesity (Silver Spring, Md.)》1996,4(1):27-33
Self-esteem has been hypothesized to be lower in obese adolescents relative to their normal weight peers and to be an important factor in preventing or reversing obesity. The present study examined the relationship between obesity and self-esteem cross-sectionally and prospectively over three years in a cohort of 1278 adolescents in grades 7 to 9 at baseline. Cross-sectional analyses revealed an inverse association between physical appearance self-esteem and body mass index in both males and females. In females, body mass index was inversely associated with global self-esteem, close friendship, and behavioral conduct self-esteem. In males, body mass index was inversely associated with athletic and romantic appeal self-esteem. Prospectively, in females, physical appearance and social acceptance self-esteem at baseline were inversely related to body mass index three years later. Baseline self-esteem was unrelated prospectively to change in body mass index in males. All associations were modest in magnitude. These results suggest that in a middle class white sample of adolescents, self-esteem specific to physical appearance is modestly associated with body mass index. Low self-esteem does not appear to predict the development of obesity over time. 相似文献