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排序方式: 共有322条查询结果,搜索用时 31 毫秒
71.
Hiroshi Sato Toshio Nagai Dhandapani Kuppuswamy Takahiro Narishige Masaaki Koide Donald R. Menick George Cooper IV 《The Journal of cell biology》1997,139(4):963-973
Increased microtubule density, for which microtubule stabilization is one potential mechanism, causes contractile dysfunction in cardiac hypertrophy. After microtubule assembly, α-tubulin undergoes two, likely sequential, time-dependent posttranslational changes: reversible carboxy-terminal detyrosination (Tyr-tubulin ↔ Glu-tubulin) and then irreversible deglutamination (Glu-tubulin → Δ2-tubulin), such that Glu- and Δ2-tubulin are markers for long-lived, stable microtubules. Therefore, we generated antibodies for Tyr-, Glu-, and Δ2-tubulin and used them for staining of right and left ventricular cardiocytes from control cats and cats with right ventricular hypertrophy. Tyr- tubulin microtubule staining was equal in right and left ventricular cardiocytes of control cats, but Glu-tubulin and Δ2-tubulin staining were insignificant, i.e., the microtubules were labile. However, Glu- and Δ2-tubulin were conspicuous in microtubules of right ventricular cardiocytes from pressure overloaded cats, i.e., the microtubules were stable. This finding was confirmed in terms of increased microtubule drug and cold stability in the hypertrophied cells. In further studies, we found an increase in a microtubule binding protein, microtubule-associated protein 4, on both mRNA and protein levels in pressure-hypertrophied myocardium. Thus, microtubule stabilization, likely facilitated by binding of a microtubule-associated protein, may be a mechanism for the increased microtubule density characteristic of pressure overload cardiac hypertrophy. 相似文献
72.
Consumers want meat products that are healthful and affordable. However, consumers will repurchase a product only if it tastes good. Consumers identified reasons for purchasing frankfurters and evaluated overall acceptability of 10 commercially available frankfurters. Consumers listed “taste” as the most important factor when purchasing frankfurters; only 16% of the consumers indicated that nutrition/health was the most important criterion. Nineteen consumer-perceived sensory and liking attributes were measured for the frankfurters in this study. The intensities of the attributes ranged from low to moderately high. All the frankfurters scored in the low to moderate range for overall acceptability. Most of the scores for liking of individual attributes correlated highly with overall liking, indicating that many of the questions relating to attribute liking could be eliminated. 相似文献
73.
Spa47 is an oligomerization‐activated type three secretion system (T3SS) ATPase from Shigella flexneri 下载免费PDF全文
Jamie L. Burgess Heather B. Jones Prashant Kumar Ronald T. Toth IV C. Russell Middaugh Edwin Antony Nicholas E. Dickenson 《Protein science : a publication of the Protein Society》2016,25(5):1037-1048
Gram‐negative pathogens often use conserved type three secretion systems (T3SS) for virulence. The Shigella type three secretion apparatus (T3SA) penetrates the host cell membrane and provides a unidirectional conduit for injection of effectors into host cells. The protein Spa47 localizes to the base of the apparatus and is speculated to be an ATPase that provides the energy for T3SA formation and secretion. Here, we developed an expression and purification protocol, producing active Spa47 and providing the first direct evidence that Spa47 is a bona fide ATPase. Additionally, size exclusion chromatography and analytical ultracentrifugation identified multiple oligomeric species of Spa47 with the largest greater than 8 fold more active for ATP hydrolysis than the monomer. An ATPase inactive Spa47 point mutant was then engineered by targeting a conserved Lysine within the predicted Walker A motif of Spa47. Interestingly, the mutant maintained a similar oligomerization pattern as active Spa47, but was unable to restore invasion phenotype when used to complement a spa47 null S. flexneri strain. Together, these results identify Spa47 as a Shigella T3SS ATPase and suggest that its activity is linked to oligomerization, perhaps as a regulatory mechanism as seen in some related pathogens. Additionally, Spa47 catalyzed ATP hydrolysis appears to be essential for host cell invasion, providing a strong platform for additional studies dissecting its role in virulence and providing an attractive target for anti‐infective agents. 相似文献
74.
Vertical polyacrylamide gel electrophoresis was used to separate enzyme proteins at 73 putative loci in natural house fly
populations sampled in central Iowa. Thirty-nine of the loci were polymorphic (53%). The mean effective number of alleles
per polymorphic locus was 1.93 and 1.47 alleles among 68 scored loci. Observed and expected heterozygosities at 34 house fly
loci were 0.1628 and 0.1834, respectively. No statistically significant differentiation was detected among nine central Iowa
fly populations in 1989 or among nine Iowa and three Minnesota populations in 1990.
Journal Paper No. J-14125 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project No. 2949. 相似文献
75.
Henry Hoppe IV Katherine M. Call Phaik-Mooi Leong William G. Thilly 《Mutation research》1991,250(1-2):411-421
Cell of the human lymphoblast line WI-L2 and its derivative TK-6 were synchronized by centrifugal elutriation and cell-cycle dependent mutation to 6TGR (HPRT) and OUAR (Na+, K+ ATPase) measured. Bromodeoxyuridine induced 6TGR and OUAR mutations within S phase while butylmethylsulfonate induced mutation displayed no cell-cycle dependence. The data indicate that centrifugal elutriation is a facile means to obtain a useful degree of synchrony for these cell lines. 相似文献
76.
Richard W. Joy IV Edward C. Yeung Lisheng Kong Trevor A. Thorpe 《In vitro cellular & developmental biology. Plant》1991,27(1):32-41
Summary The growth and development of white spruce somatic embryos was followed from the filamentous immature to the mature cotyledonary
embryo stage. Histochemical examination of the various stages of embryo development showed that lipids, proteins, and polysaccharides
were produced to varying degrees during the process. During early stages (1 to 2 wk on ABA), mostly polysaccharide was produced,
whereas during later stages, polysaccharides, lipids, and protein accumulated. Electron microscopy indicated that lipid deposition
in somatic embryos started during the first week after transfer to ABA-containing medium. Deposition of the storage products
began at the basal end of the embryonal mass and within the proximal zone of the suspensors. Accumulation continued to the
peripheral regions and then inward toward the cortex of the developing embryo. In all cases, polysaccharide accumulated first,
followed by lipid and lastly, protein. Quantitatively, cotyledonary stage somatic embryos had less lipid and protein and more
starch when compared to zygotic embryos at the same developmental stage. Total protein profiles elucidated by sodium dodecyl
sulfate-polyacrylamide gel electrophoresis indicated that the majority of proteins were similar in zygotic and somatic embryos.
Prominent protein bands were found at 30, 20, 19.5, 15, 14.4, 12, and 10 Kd. However, protein bands at 40, 15, and 12 Kd in
total protein from somatic embryos were either absent or highly underexpressed. 相似文献
77.
78.
S R Sunyaev F Eisenhaber I V Rodchenkov B Eisenhaber V G Tumanyan E N Kuznetsov 《Protein engineering》1999,12(5):387-394
Sequence weighting techniques are aimed at balancing redundant observed information from subsets of similar sequences in multiple alignments. Traditional approaches apply the same weight to all positions of a given sequence, hence equal efficiency of phylogenetic changes is assumed along the whole sequence. This restrictive assumption is not required for the new method PSIC (position-specific independent counts) described in this paper. The number of independent observations (counts) of an amino acid type at a given alignment position is calculated from the overall similarity of the sequences that share the amino acid type at this position with the help of statistical concepts. This approach allows the fast computation of position-specific sequence weights even for alignments containing hundreds of sequences. The PSIC approach has been applied to profile extraction and to the fold family assignment of protein sequences with known structures. Our method was shown to be very productive in finding distantly related sequences and more powerful than Hidden Markov Models or the profile methods in WiseTools and PSI-BLAST in many cases. The profile extraction routine is available on the WWW (http://www.bork.embl-heidelberg. de/PSIC or http://www.imb.ac.ru/PSIC). 相似文献
79.
Erik A Karlsson Christopher T Small Pamela Freiden MM Feeroz Frederick A Matsen IV Sorn San M Kamrul Hasan David Wang Lisa Jones-Engel Stacey Schultz-Cherry 《PLoS pathogens》2015,11(11)
Astroviruses (AstVs) are positive sense, single-stranded RNA viruses transmitted to a wide range of hosts via the fecal-oral route. The number of AstV-infected animal hosts has rapidly expanded in recent years with many more likely to be discovered because of the advances in viral surveillance and next generation sequencing. Yet no study to date has identified human AstV genotypes in animals, although diverse AstV genotypes similar to animal-origin viruses have been found in children with diarrhea and in one instance of encephalitis. Here we provide important new evidence that non-human primates (NHP) can harbor a wide variety of mammalian and avian AstV genotypes, including those only associated with human infection. Serological analyses confirmed that >25% of the NHP tested had antibodies to human AstVs. Further, we identified a recombinant AstV with parental relationships to known human AstVs. Phylogenetic analysis suggests AstVs in NHP are on average evolutionarily much closer to AstVs from other animals than are AstVs from bats, a frequently proposed reservoir. Our studies not only demonstrate that human astroviruses can be detected in NHP but also suggest that NHP are unique in their ability to support diverse AstV genotypes, further challenging the paradigm that astrovirus infection is species-specific. 相似文献
80.
Karen E. Sears Jennifer A. Maier Marcelo Rivas-Astroza Rachel Poe Sheng Zhong Kari Kosog Jonathan D. Marcot Richard R. Behringer Chris J. Cretekos John J. Rasweiler IV Zoi Rapti 《PLoS genetics》2015,11(8)
Variation among individuals is a prerequisite of evolution by natural selection. As such, identifying the origins of variation is a fundamental goal of biology. We investigated the link between gene interactions and variation in gene expression among individuals and species using the mammalian limb as a model system. We first built interaction networks for key genes regulating early (outgrowth; E9.5–11) and late (expansion and elongation; E11-13) limb development in mouse. This resulted in an Early (ESN) and Late (LSN) Stage Network. Computational perturbations of these networks suggest that the ESN is more robust. We then quantified levels of the same key genes among mouse individuals and found that they vary less at earlier limb stages and that variation in gene expression is heritable. Finally, we quantified variation in gene expression levels among four mammals with divergent limbs (bat, opossum, mouse and pig) and found that levels vary less among species at earlier limb stages. We also found that variation in gene expression levels among individuals and species are correlated for earlier and later limb development. In conclusion, results are consistent with the robustness of the ESN buffering among-individual variation in gene expression levels early in mammalian limb development, and constraining the evolution of early limb development among mammalian species. 相似文献