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71.
Mohan Babu Roland Arnold Cedoljub Bundalovic-Torma Alla Gagarinova Keith S. Wong Ashwani Kumar Geordie Stewart Bahram Samanfar Hiroyuki Aoki Omar Wagih James Vlasblom Sadhna Phanse Krunal Lad Angela Yeou Hsiung Yu Christopher Graham Ke Jin Eric Brown Ashkan Golshani Philip Kim Gabriel Moreno-Hagelsieb Jack Greenblatt Walid A. Houry John Parkinson Andrew Emili 《PLoS genetics》2014,10(2)
Large-scale proteomic analyses in Escherichia coli have documented the composition and physical relationships of multiprotein complexes, but not their functional organization into biological pathways and processes. Conversely, genetic interaction (GI) screens can provide insights into the biological role(s) of individual gene and higher order associations. Combining the information from both approaches should elucidate how complexes and pathways intersect functionally at a systems level. However, such integrative analysis has been hindered due to the lack of relevant GI data. Here we present a systematic, unbiased, and quantitative synthetic genetic array screen in E. coli describing the genetic dependencies and functional cross-talk among over 600,000 digenic mutant combinations. Combining this epistasis information with putative functional modules derived from previous proteomic data and genomic context-based methods revealed unexpected associations, including new components required for the biogenesis of iron-sulphur and ribosome integrity, and the interplay between molecular chaperones and proteases. We find that functionally-linked genes co-conserved among γ-proteobacteria are far more likely to have correlated GI profiles than genes with divergent patterns of evolution. Overall, examining bacterial GIs in the context of protein complexes provides avenues for a deeper mechanistic understanding of core microbial systems. 相似文献
72.
Common antigens of mouse oval and biliary epithelial cells. Expression on newly formed hepatocytes 总被引:17,自引:0,他引:17
Natalya V. Engelhardt Valentina M. Factor Alla K. Yasova Valentina S. Poltoranina Vladimir N. Baranov Maria N. Lasareva 《Differentiation; research in biological diversity》1990,45(1):29-37
Two antigens - A6 and G7 - shared by mouse biliary epithelial and oval cells were revealed by monoclonal antibodies raised in rat immunized with oval-cell-enriched liver fraction. Oval cells were induced in CBA or F1 (CBA x C57BL6) mice by a combination of a single injection of the alkylating drug Dipin with partial hepatectomy. In normal liver A6 antigen was localized, using light and electron microscopy, in biliary epithelial cells of all ducts including Hering canals. Some bile ductal and Hering cells were A6-negative. Occasionally, A6 antigen was present in single hepatocytes forming the periportal ends of hepatic cords. In preneoplastic and tumorous liver A6 antigen was present in bile ductal and oval cells and in a fraction of newly formed hepatocytes and tumor cells. G7 antigen was revealed in normal, precancerous and tumorous liver in biliary epithelial and oval cells but not in hepatocytes. A6 and G7 antigens were not liver-specific: they were expressed in various normal organs and tissues, especially in epithelia. In studies of mouse liver lineages A6 antigen can be used as a common marker of biliary epithelial and oval cells and hepatocytes at certain stages of differentiation. G7 antigen is a marker of oval and biliary epithelial cells. There was a striking similarity in A6 antigen localization to that of human blood group antigens in normal liver and liver tumors. A6 antigen may thus provide a useful tool for the study of neoexpression of human blood group antigens in liver tumors. 相似文献
73.
Elena Gustchina Mi Li Rodolfo Ghirlando Peter Schuck John M. Louis Jason Pierson Prashant Rao Sriram Subramaniam Alla Gustchina G. Marius Clore Alexander Wlodawer 《PloS one》2013,8(11)
A series of mini-antibodies (monovalent and bivalent Fabs) targeting the conserved internal trimeric coiled-coil of the N-heptad repeat (N-HR) of HIV-1 gp41 has been previously constructed and reported. Crystal structures of two closely related monovalent Fabs, one (Fab 8066) broadly neutralizing across a wide panel of HIV-1 subtype B and C viruses, and the other (Fab 8062) non-neutralizing, representing the extremes of this series, were previously solved as complexes with 5-Helix, a gp41 pre-hairpin intermediate mimetic. Binding of these Fabs to covalently stabilized chimeric trimers of N-peptides of HIV-1 gp41 (named (CCIZN36)3 or 3-H) has now been investigated using X-ray crystallography, cryo-electron microscopy, and a variety of biophysical methods. Crystal structures of the complexes between 3-H and Fab 8066 and Fab 8062 were determined at 2.8 and 3.0 Å resolution, respectively. Although the structures of the complexes with the neutralizing Fab 8066 and its non-neutralizing counterpart Fab 8062 were generally similar, small differences between them could be correlated with the biological properties of these antibodies. The conformations of the corresponding CDRs of each antibody in the complexes with 3-H and 5-Helix are very similar. The adaptation to a different target upon complex formation is predominantly achieved by changes in the structure of the trimer of N-HR helices, as well as by adjustment of the orientation of the Fab molecule relative to the N-HR in the complex, via rigid-body movement. The structural data presented here indicate that binding of three Fabs 8062 with high affinity requires more significant changes in the structure of the N-HR trimer compared to binding of Fab 8066. A comparative analysis of the structures of Fabs complexed to different gp41 intermediate mimetics allows further evaluation of biological relevance for generation of neutralizing antibodies, as well as provides novel structural insights into immunogen design. 相似文献
74.
The origin of DNA replication in the human β-globin gene contains an initiation region (IR) and two flanking auxiliary elements. Two replicator modules are located within the upstream auxiliary sequence and the IR core, but the functional sequences in the downstream auxiliary element are unknown. Here, we use a combination of benzoylated-naphthoylated DEAE (BND) cellulose purification and nascent strand abundance assays to show that replication initiation occurs at the β-globin 3′ enhancer on human chromosome 11 in the Hu11 hybrid murine erythroleukemia (MEL) cell line. To examine replicator function, 3′ enhancer fragments were inserted into an ectopic site in MEL cells via an optimized FRT/EGFP-FLP integration system. These experiments demonstrate that the 1.6 kb downstream auxiliary element is a third replicator module called bGRep-E in erythroid cells. The minimal 260 bp 3′ enhancer is required but not sufficient to initiate efficient replication, suggesting cooperation with adjacent sequences. The minimal 3′ enhancer also cooperates with elements in an expressing HS3β/γ-globin construct to initiate replication. These data indicate that the β-globin replicator has multiple initiation sites in three closely spaced replicator modules. We conclude that a mammalian enhancer can cooperate with adjacent sequences to create an efficient replicator module. 相似文献
75.
76.
Rudaya AY Steiner AA Robbins JR Dragic AS Romanovsky AA 《American journal of physiology. Regulatory, integrative and comparative physiology》2005,289(5):R1244-R1252
Most published studies of thermoregulatory responses of mice to LPS involved a stressful injection of LPS, were run at a poorly controlled and often subneutral ambient temperature (T(a)), and paid little attention to the dependence of the response on the LPS dose. These pitfalls have been overcome in the present study. Male C57BL/6 mice implanted with jugular vein catheters were kept in an environmental chamber at a tightly controlled T(a). The relationship between the T(a)s used and the thermoneutral zone of the mice was verified by measuring tail skin temperature, either by infrared thermography or thermocouple thermometry. Escherichia coli LPS in a wide dose range (10(0)-10(4) microg/kg) was administered through an extension of the jugular catheter from outside the chamber. The responses observed were dose dependent. At a neutral T(a), low (just suprathreshold) doses of LPS (10(0)-10(1) microg/kg) caused a monophasic fever. To a slightly higher dose (10(1.5) microg/kg), the mice responded with a biphasic fever. To even higher doses (10(1.75)-10(4) microg/kg), they responded with a polyphasic fever, of which three distinct phases were identified. The dose dependence and dynamics of LPS fever in the mouse appeared to be remarkably similar to those seen in the rat. However, the thermoregulatory response of mice to LPS in a subthermoneutral environment is remarkably different from that of rats. Although very high doses of LPS (10(4) microg/kg) did cause a late (latency, approximately 3 h) hypothermic response in mice, the typical early (latency, 10-30 min) hypothermic response seen in rats did not occur. The present investigation identifies experimental conditions to study LPS-induced mono-, bi-, and polyphasic fevers and late hypothermia in mice and provides detailed characteristics of these responses. 相似文献
77.
Reslewic S Zhou S Place M Zhang Y Briska A Goldstein S Churas C Runnheim R Forrest D Lim A Lapidus A Han CS Roberts GP Schwartz DC 《Applied and environmental microbiology》2005,71(9):5511-5522
Rhodospirillum rubrum is a phototrophic purple nonsulfur bacterium known for its unique and well-studied nitrogen fixation and carbon monoxide oxidation systems and as a source of hydrogen and biodegradable plastic production. To better understand this organism and to facilitate assembly of its sequence, three whole-genome restriction endonuclease maps (XbaI, NheI, and HindIII) of R. rubrum strain ATCC 11170 were created by optical mapping. Optical mapping is a system for creating whole-genome ordered restriction endonuclease maps from randomly sheared genomic DNA molecules extracted from cells. During the sequence finishing process, all three optical maps confirmed a putative error in sequence assembly, while the HindIII map acted as a scaffold for high-resolution alignment with sequence contigs spanning the whole genome. In addition to highlighting optical mapping's role in the assembly and confirmation of genome sequence, this work underscores the unique niche in resolution occupied by the optical mapping system. With a resolution ranging from 6.5 kb (previously published) to 45 kb (reported here), optical mapping advances a "molecular cytogenetics" approach to solving problems in genomic analysis. 相似文献
78.
Geras'kin SA Kim JK Oudalova AA Vasiliyev DV Dikareva NS Zimin VL Dikarev VG 《Mutation research》2005,583(1):55-66
Results of a long-term (1997-2002) study of the Scots pine populations growing in the vicinity of the radioactive waste storage facility ('Radon' LWPE) are presented. Cytogenetic disturbances in reproductive (seeds) and vegetative (needles) tissues sampled from Scots pine populations were studied to examine whether Scots pine trees have experienced environmental stress in areas with relatively low levels of pollution. The data clearly indicate the presence of mutagenic contaminants in the environment of the pine trees. An increased number of mitotic abnormalities, especially multipolar mitoses was found in the pine tree populations submitted to man-made exposure, which suggests that the cytogenetic damage is mainly caused by chemical contamination. A higher radioresistance of the Scots pine seeds from the impacted populations was shown by use of acute gamma-irradiation. During the observation period 1997-2002, pine trees exposed to anthropogenic pollution showed a steady increase of cytogenetic alterations in the root meristem cells. 相似文献
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80.