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61.
Reversal of Fv-1 host range by in vitro restriction endonuclease fragment exchange between molecular clones of N-tropic and B-tropic murine leukemia virus genomes. 总被引:10,自引:10,他引:0 下载免费PDF全文
L R Boone F E Myer D M Yang C Y Ou C K Koh L E Roberson R W Tennant W K Yang 《Journal of virology》1983,48(1):110-119
We molecularly cloned unintegrated viral DNA of the BALB/c endogenous N-tropic and B-tropic murine leukemia retroviruses and in vitro passaged N-tropic Gross (passage A) murine leukemia retroviruses. Recombinant genomes were constructed in vitro by exchanging homologous restriction enzyme fragments from N- or B-tropic parents and subsequent recloning. Infectious virus was recovered after transfection of these recombinant genomes into NIH-3T3 cells and cocultivation with the Fv-1 nonrestrictive SC-1 cells. XC plaque assays of recombinant virus progeny on Fv-ln and Fv-lb cells indicated that the Fv-l host range was determined by sequences located between the BamHI site in the p30 region of the gag gene (1.6 kilobase pairs from the left end of the map) and the HindIII site located in the pol gene (2.9 kilobase pairs from the left end of the map). 相似文献
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64.
聚乙二醇处理大豆种子子叶中几种酶活性和可溶性蛋白含量的变化 总被引:5,自引:0,他引:5
聚乙二醇处理的大豆种子的异柠檬酸裂解酶、苹果酸脱氢酶、过氧化氢酶、超氧物歧化酶、酸性磷酸酶、碱性磷酸酶的活性明显高于受低温吸胀冷害的种子子叶的活性,相关的酶活性协同地增长,而蛋白质的含量没有明显的变化。这些酶活性的提高可能是渗透调控处理对细胞膜系统修补的结果。 相似文献
65.
Dual action of anti-sporozoite antibodies in vitro 总被引:3,自引:0,他引:3
S Nudelman L Rénia Y Charoenvit L Yuan F Miltgen R L Beaudoin D Mazier 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(3):996-1000
With the use of a double staining technique that permits localization of the sporozoite during the process of entering a host cell, we studied the biologic effects of three mAb directed against determinants contained in the circumsporozoite of Plasmodium yoelii. These mAb, which included one IgM and two IgG3, were studied in primary cultures of rodent hepatocytes inoculated with sporozoites of P. yoelii. These results confirm previous reports of the extended action of antibodies on Plasmodium falciparum after entering hepatocytes by producing a strong intrahepatocyte inhibitory effect in addition to the inhibitory effect on sporozoite entry. As with P. falciparum the intracellular effects on P. yoelii liver stages are only observed when the antibodies are present at the time the sporozoite enters the cell. While carrying out experiments on this phenomenon, it was discovered that, at lowered antibody concentrations, an increase in number of maturing liver schizonts occurs, with the increase or enhancement of infection reaching up to 150% of that of controls. It was also observed that there was an inverse relationship between the antibody concentration that was inhibitory and that which enhanced parasite infectivity. 相似文献
66.
山东莒南发现的石制品 总被引:2,自引:1,他引:1
本文报道的128件人工石制品分别采自山东莒南县的石莲子乡烟敦岭和扁山乡九顶莲花山两个地点。石制品常见类型有边刮器,端刮器和砍斫器等,另有少量的雕刻器和尖状器,内含典型细石器。就石制品的组合及工艺水平而言,其时代可能属于旧石器时代末期。 相似文献
67.
Microtubule-dependent retrograde transport of proteins into the ER in the presence of brefeldin A suggests an ER recycling pathway 总被引:168,自引:0,他引:168
J Lippincott-Schwartz J G Donaldson A Schweizer E G Berger H P Hauri L C Yuan R D Klausner 《Cell》1990,60(5):821-836
Characteristics of brefeldin A (BFA)-induced redistribution of Golgi proteins into the endoplasmic reticulum (ER) and its relationship to an ER retrieval pathway were investigated. Retrograde movement of Golgi proteins into the ER occurred via long, tubulovesicular processes extending out of the Golgi along microtubules. Microtubule-disrupting agents (i.e., nocodazole), energy poisons, and reduced temperatures inhibited this pathway. In BFA-treated cells Golgi proteins appeared to cycle between the ER and an intermediate compartment marked by a 53 kd protein. Addition of nocodazole disrupted this dynamic cycle by preferentially inhibiting retrograde movement, causing Golgi proteins to accumulate in the intermediate compartment. In the absence of BFA, such an ER cycling pathway appeared to be followed normally by the 53 kd protein but not by Golgi proteins, as revealed by temperature shift experiments. We propose that BFA induces the interaction of the Golgi with an intermediate "recycling" compartment that utilizes a microtubule-dependent pathway into the ER. 相似文献
68.
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Yuan Han-min V. D. Keppenne P. S. Baenziger T. Berke G. H. Liang 《Plant Cell, Tissue and Organ Culture》1990,21(3):253-258
Four winter wheat (Triticum aestivum L.) and two spring wheat cultivars were evaluated in anther culture on three to four different media for their ability to initiate callus and green plants. Five media were used in the experiment: stored-potato medium with Ficoll 400, fresh-potato medium with Ficoll 400, fresh-potato medium with agar, fresh-potato liquid medium without agar or Ficoll 400, and a one tep 85D12-3 medium. Greatly different frequencies of calli and/or green plants were obtained from different cultivars and media. The callus initiation frequency varied from 2.7% for Arapahoe to 52% for Pavon, both on the stored potato medium with Ficoll 400. The frequency of green plant regeneration ranged from 0% for Arapahoe and Siouxland on the stored-potato medium with Ficoll 400 and 0% for Redland and Arapahoe in the fresh-potato medium with Ficoll 400 to 12% for Chris in the 85D12-3 medium (one-step procedure). Chris and Centurk 78, previously reported as having high levels of response, had significantly higher (P < 0.05) frequencies of green plant regeneration on the 851312-3 medium than the other cultivars. An unexpected observation is that wet MSC– medium enhanced callus regeneration more than a drier MSC– medium. 相似文献
70.
In order to study the effects of peptides on intrinsic cardiac neurons, substance P, bradykinin, oxytocin, calcitonin gene related peptide, atrial natriuretic peptide and vasoactive intestinal peptide were administered into canine atrial or ventricular ganglionated plexi. When substance P was injected into right atrial or cranial medial ventricular ganglionated plexi heart rate, atrial force and ventricular intramyocardial pressures were augmented. No cardiac changes occurred when similar volumes of saline (i.e., peptide vehicle) were injected into these ganglionated plexi. When bradykinin was injected into atrial or ventricular ganglionated plexi heart rate, atrial force and ventricular force were augmented in approximately 50% and depressor responses were elicited in approximately 50% of these animals. When oxytocin was injected into right atrial ventral ganglionated plexi heart rate and atrial forces were reduced in five of ten dogs studied. No cardiac changes occurred when oxytocin was injected into left atrial or ventricular ganglionated plexi. No responses were elicited when calcitonin gene related peptide, atrial natriuretic peptide or vasoactive intestinal peptide was administered into atrial or ventricular ganglionated plexi. Following acute decentralization of the heart, no significant responses were elicited by repeat administrations of substance P, bradykinin or oxytocin, implying that connectivity with central nervous system neurons was necessary for consistent responses to be elicited. It is concluded that substance P, bradykinin and oxytocin can affect neurons on the heart such that cardiodynamics are modified, these different peptides eliciting different cardiac responses. 相似文献