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1.
The structure of the viral RNA in alfalfa mosaic virus (AlMV) was investigated by means of 31P-nuclear magnetic resonance (NMR). It was found that the 31P-NMR line width of AlMV Top a particles is significantly smaller than that of the larger Bottom particles. At low temperatures, the totational correlation time of the 31P nuclei essentially equals the tumbling rate of the virus particle, indicating that the RNA is contained rigidly inside the virion. At more elevated temperatures, the NMR line width sharpens more than expected on the basis of viscosity changes and the RNA exhibits internal mobility. The occurrence of internal mobility is paralleled by an increased internal mobility of the N-terminal part of the coat protein, as could be observed by 1H-NMR spectroscopy. The influence of EDTA on the 31P-NMR line width appeared to be negligible, which is in agreement with the idea that AlMV does not 'swell' like several other RNA-containing plant viruses.  相似文献   
2.
The collective redox activities of transition‐metal (TM) cations and oxygen anions have been shown to increase charge storage capacity in both Li‐rich layered and cation‐disordered rock‐salt cathodes. Repeated cycling involving anionic redox is known to trigger TM migration and phase transformation in layered Li‐ and Mn‐rich (LMR) oxides, however, detailed mechanistic understanding on the recently discovered Li‐rich rock‐salt cathodes is largely missing. The present study systematically investigates the effect of oxygen redox on a Li1.3Nb0.3Mn0.4O2 cathode and demonstrates that performance deterioration is directly correlated to the extent of oxygen redox. It is shown that voltage fade and hysteresis begin only after initiating anionic redox at high voltages, which grows progressively with either deeper oxidation of oxygen at higher potential or extended cycling. In contrast to what is reported on layered LMR oxides, extensive TM reduction is observed but phase transition is not detected in the cycled oxide. A densification/degradation mechanism is proposed accordingly which elucidates how a unique combination of extensive chemical reduction of TM and reduced quality of the Li percolation network in cation‐disordered rock‐salts can lead to performance degradation in these newer cathodes with 3D Li migration pathways. Design strategies to achieve balanced capacity and stability are also discussed.  相似文献   
3.
Toxin–antitoxin (TA) systems are small genetic elements that typically encode a stable toxin and its labile antitoxin. These cognate pairs are abundant in prokaryotes and have been shown to regulate various cellular functions. Vibrio cholerae, a human pathogen that is the causative agent of cholera, harbors at least thirteen TA loci. While functional HigBA, ParDE have been shown to stabilize plasmids and Phd/Doc to mediate cell death in V. cholerae, the function of seven RelBE-family TA systems is not understood. In this study we investigated the function of the RelBE TA systems in V. cholerae physiology and found that six of the seven relBE loci encoded functional toxins in E. coli. Deletion analyses of each relBE locus indicate that RelBE systems are involved in biofilm formation and reactive oxygen species (ROS) resistance. Interestingly, all seven relBE loci are induced under the standard virulence induction conditions and two of the relBE mutants displayed a colonization defect, which was not due to an effect on virulence gene expression. Although further studies are needed to characterize the mechanism of action, our study reveals that RelBE systems are important for V. cholerae physiology.  相似文献   
4.
Rubredoxin was purified from Desulfovibrio vulgaris Miyazaki. It was sequenced and some of its properties determined. Rubredoxin is composed of 52 amino acids. It is highly homologous to that from D. vulgaris Hildenborough. Its N-methionyl residue is partially formalated. The millimolar absorption coefficients of the rubredoxin at 489 nm and 280 are 8.1 and 18.5, respectively, and the standard redox potential is +5 mB, which is slightly higher than those of other rubredoxins. Rubredoxin, as well as cytochrome c-553, was reduced with lactate by the action of lactate dehydrogenase of this organism, and the rection was stimulated with 2-methyl-1, 4-naphthoquinone. It is suggested that rubredoxin, in collaboration with membraous quinone, functions as natural electron carrier for cytoplasmic lactate dehydrogenase of this organism, whereas cytochrome c-553 plays the same role for periplasmic lactate dehydrogenase.  相似文献   
5.
In the aphidophagous syrphid species,Betasyrphus serarius (Wiedemann),Metasyrphus frequens Matsumura andSyrphus vitripennis (Meigen), females in search of oviposition sites assess the qualitative and quantitative value of pea aphid colonies for securing the successful development of their offspring. They select, as their oviposition sites, young and “promising” aphid colonies consisting of nymphs and/or adult aphids including few winged adults. They neglect large, older colonies of 4th-instar nymphs and/or winged adult aphids. The 3 syrphid species adopt “buy-futures” ovipositional tactic as doesEpisyrphus balteatus (de Geer), although some tinge of “spot-transaction” is noticed inM. frequens andS. vitripennis.  相似文献   
6.
7.
Summary Cytotoxicity was induced in lymphocytes (CL) from 10 out of 15 patients by autologous mixed lymphocyte tumor cell culture and further cultivation with recombinant interleukin-2. In cells from 3 of the 10 patients, cytotoxicity was suppressed by more than 50% when autologous peripheral blood mononuclear cells (PBMC) from the patients with large tumors were added to the autologous killing system. The cells responsible for suppressing the cytotoxicity in the effector phase were adherent or nonadherent to plastic depending on the patient examined. The T cell fraction from 1 patient significantly suppressed the cytotoxic activity, and this suppression was seen only in the autologous system. On the other hand, plastic adherent cells but not T cells from PBMC of 2 subjects suppressed the cytotoxic activity of CL. The reason why the main cell population suppressing the CL activity differed among the patients is unclear. However, the findings that the suppression was mostly abrogated following resection of the tumor mass suggested that suppressor cells, either of macrophage lineage or T cells, are induced in patients with a large tumor mass. This speculation is supported by the finding that the PBMC from a patient with tumor recurrence regained the suppressive activity.  相似文献   
8.
In rodents, SR 95191 [3-(2-morpholinoethylamino)-4-cyano-6-phenylpyridazine] has been shown to be active in animal models of depression. The profile of activity of SR 95191 suggests that the compound is a selective and short-acting type A monoamine oxidase (MAO) inhibitor (MAOI) in vivo. In the present study, the interaction of SR 95191 with MAO-A and MAO-B activity was further examined in vivo and in vitro. In brain, liver, and duodenum of pretreated rats, SR 95191 selectively inhibited MAO-A (ED50 = 3-5 mg/kg, p.o.), whereas MAO-B was only weakly inhibited for doses as high as 300 mg/kg, p.o. In vivo, SR 95191 (1-100 mg/kg, p.o.) antagonized, in a dose-dependent fashion, the irreversible inhibition of brain and liver MAO-A induced by phenelzine. Finally, dopamine and 5-hydroxytryptamine depleted from their striatal stores by tetrabenazine were able to displace SR 95191 from the active site of MAO-A. However, ex vivo, kinetic studies showed that the inhibitory effect of SR 95191 (1-10 mg/kg) towards MAO-A was noncompetitive and was unchanged after dilution or dialysis. In vitro, the inhibition of brain MAO-A, but not MAO-B, by SR 95191 was time dependent, with a 19-fold decrease in the IC50 values being observed over a 30-min incubation period (140 to 7.5 microM). At this time, the SR 95191-induced inhibition of MAO-A was not removed by repeated washings. When the reaction was started by adding the homogenate without prior preincubation with SR 95191, the inhibition of brain MAO-A was fully competitive (Ki = 68 microM).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
9.
Complete or partial monosomy 7 is a recurring cytogenetic abnormality in acute myelogenous leukemia (AML) and myeloproliferative syndromes (MPS) and is particularly common in patients with Fanconi's anemia and in secondary AML. A familial form of monosomy 7 has been recognized in which two or more siblings develop MPS or AML before age 20. We tested the hypothesis that a recessive cancer susceptibility locus on chromosome 7 was important in the pathogenesis of leukemia in familial monosomy 7 by determining the parental origins of the chromosome 7 retained in the bone marrows of three pairs of affected siblings. We found no overlapping region where all three pairs retained DNA derived from the same paternal or maternal chromosome. These data suggest that inactivation of a single allele of a putative tumor-suppressor gene may be sufficient to contribute to leukemic transformation in familial monosomy 7.  相似文献   
10.
Among several approaches to augment the therapeutic effect of adoptive immunotherapy, we focused the antitumor synergy between transferred killer cells and host's fresh lymphocytes. Immunotherapy models using murine tumors or clinical experiments revealed that preadministration of immunostimulator such as OK-432, followed by chemotherapeutic agents such as cyclophosphamide, can induce host's non-cytotoxic fresh lymphocytes that act synergistically with cultured killer cells against autologous tumor cells. Immuno-chemo-lymphocytotherapy (a sequential treatment with OK-432, chemotherapy and adoptive immunotherapy) is useful to treat the patients with advanced cancer even if the number of transferred lymphocytes is limited.  相似文献   
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