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A novel algorithm for multiple alignment of biological sequences is suggested. At the first step the DotHelix procedure is employed for construction of motifs, i.e. continuous fragments of local similarity of various “thickness” and strength, and then these motifs are concatenated into chains consistent with the order of letters in the sequences. The algorithm is implemented in the MA-Tools program of the GeneBee package. An example illustrating the effectivity of the algorithm is presented. 相似文献
3.
Tick-borne encephalitis virus (TBEV) is transmitted to vertebrates by taiga or forest ticks through bites, inducing disease of variable severity. The reasons underlying these differences in the severity of the disease are unknown. In order to identify genetic factors affecting the pathogenicity of virus strains, we have sequenced and compared the complete genomes of 34 Far-Eastern subtype (FE) TBEV strains isolated from patients with different disease severity (Primorye, the Russian Far East). We analyzed the complete genomes of 11 human pathogenic strains isolated from the brains of dead patients with the encephalitic form of the disease (Efd), 4 strains from the blood of patients with the febrile form of TBE (Ffd), and 19 strains from patients with the subclinical form of TBE (Sfd). On the phylogenetic tree, pathogenic Efd strains formed two clusters containing the prototype strains, Senzhang and Sofjin, respectively. Sfd strains formed a third separate cluster, including the Oshima strain. The strains that caused the febrile form of the disease did not form a separate cluster. In the viral proteins, we found 198 positions with at least one amino acid residue substitution, of which only 17 amino acid residue substitutions were correlated with the variable pathogenicity of these strains in humans and they authentically differed between the groups. We considered the role of each amino acid substitution and assumed that the deletion of 111 amino acids in the capsid protein in combination with the amino acid substitutions R16K and S45F in the NS3 protease may affect the budding process of viral particles. These changes may be the major reason for the diminished pathogenicity of TBEV strains. We recommend Sfd strains for testing as attenuation vaccine candidates. 相似文献
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5.
Identification and characterization of two novel lymphocyte function-associated antigens, L24 and L25 总被引:12,自引:0,他引:12
C Clayberger A M Krensky B W McIntyre T D Koller P Parham F Brodsky D J Linn E L Evans 《Journal of immunology (Baltimore, Md. : 1950)》1987,138(5):1510-1514
We describe the function and cell distribution of two novel cell surface antigens, L24 and L25. These antigens are broadly distributed on human lymphocytes. Monoclonal antibodies specific for these molecules block lysis by Class I- and II-specific cytotoxic T lymphocytes, but do not affect any other T cell functions tested. Anti-L24 antibody immunoprecipitates a molecule composed of two disulfide-linked monomers of 140 kd each. Anti-L25 antibody immunoprecipitates three proteins of 150, 85, and 75 kd. The study of these and other function associated molecules may provide insight into mechanisms of cytotoxic T lymphocyte recognition and/or function. 相似文献
6.
In vivo environmental temperature and the in vitro pattern of luminal acidification in turtle bladders. Evidence for HCO3 ion reabsorption 下载免费PDF全文
In this study, it is shown how to transfer tared aliquots of (HCO3 + CO2)-containing luminal fluids directly into the mercury-sealed chamber of a modified Van Slyke apparatus and how to obtain direct as well as indirect manometric determinations of dissolved CO2 ([CO2]f) in each aliquot of such fluids. It is next shown that the pattern of in vitro luminal acidification in an isolated turtle bladder sac depends upon the prior in vivo ambient temperature to which the donor turtle had become adapted. Under in vivo conditions, the food intake, physical activity, and acid excretion of 32 degrees C-adapted turtles are greater than those of 21 degrees C or 26 degrees C-adapted turtles. Under in vitro conditions of incubating isolated bladder sacs (from 21, 26, and 32 degrees C turtles) in (HCO3 + CO2)-containing Ringer media at a single temperature (21 degrees C), the patterns of luminal acidification are as follows: (a) The rate of depletion of luminal [HCO3] is greatest in bladders from the 32 degrees C-adapted turtles. (b) Concomitant decreases in luminal [CO2]f, [HCO3], and pH (the 'CO2-decreasing patterns' of luminal acidification) develop in all bladders from 32 degrees C turtles, in half of those from 26 degrees C turtles, but in less than one-fifth of those from 21 degrees C-adapted turtles: and (c) a CO2-increasing pattern of luminal acidification is found in most of the bladders from 21 degrees C-adapted turtles. A postulated bicarbonate ion-reabsorbing pump is consistent with all of these patterns of luminal acidification. 相似文献
7.
Novel peripheral blood-derived human cell lines with properties of megakaryocytes 总被引:1,自引:0,他引:1 下载免费PDF全文
For 18 mo, we derived 18 cell lines from 11 donors with various clinical profiles ranging from normal to leukemic. Suspension cultures were initiated with 1 X 10(6) mononuclear blood cells/ml of nutrient medium containing 10% human serum and 10% lectin-stimulated human lymphocyte conditioned medium. The cultures were monitored weekly by morphological analyses of Wright-Giemsa-stained cell preparations. All successful cultures showed a significant decline in viability during the first 3-4 wk with rate "lymphoid" cells observed in mitosis. Within the next 2 wk, the proliferating cells gave rise to a rapidly expanding population of mononuclear cells. As the cultures expanded, cell morphology became heterogeneous with respect to cell size and nuclear ploidy, with an accumulation of giant multinuclear cells that were suggestive of megakarocytes. Even though the cells did not have the classical morphology of mature platelet-forming megakaryocytes, 90% of the cells within a cell line were positive by direct or indirect immunofluorescence for the platelet membrane glycoproteins IIb and IIIa; for surface markers HLA-Dr and B2-microglobulin; for intracellular platelet-derived growth factor and platelet factor IV; and for membrane affinity or binding with serum platelet-derived growth factor and platelet factor IV. These results suggest that a blood precursor cell, most likely a primitive megakaryoblast, was isolated from the peripheral blood and was provided with an optimal culture environment for sustained growth. These cells did not mature to a more differentiated stage, perhaps owing to regulatory factor deficiencies in this in vitro system. The remarkable frequency of obtaining cell lines with megakaryocyte properties from normal peripheral blood and the capacity of some normal donors to repeatedly yield these cell lines make this cell culture system indeed unique by being selective for putative megakaryocyte precursors. 相似文献
8.
The number of myocytes and the percentage of cells with a high degree of ploidy increased in the heart ventricles of fast-growing mice compared with slow-growing ones. The mean incidence of octa- and hexadecaploid (by summary DNA content) myocytes was 7% in the slow-growing and 23% in the fast-growing, weaned mice. In these groups, the total myocyte number varied by 20%. There were 43% more myocyte genomes in the heart ventricles of the fast-growing mice than in those of the slow-growing mice. The same differences in cell number and ploidy persist in 90-day-old mice in spite of feeding ad libitum after weaning. 相似文献
9.
Experiments have been carried out on Chinese hamster fibroblasts. Cultures at the log-stage of growth were incubated at 15 or 25° C for 24 hrs. In two groups of experiments the cells were labeled with H3-TdR for 6 hrs at the respective temperature, washed and further incubated at 37° C. In each group of experiments cultures labeled with H3-TdR at 37° C for 20 min were used as a control. It was found: 1. the delay in the onset of cell passage through the mitotic cycle at 37° in cultures exposed to 15 or 25° C was about equal to 1,5-1 hr resp. and cells proceeded through the life cycle without blockages at any phase of the cycle; 2. the patterns of chromosome reproduction during the second half of the S-phase were the same after labeling at 15, 25 and 37° C. — In the third group the cells were labelled with HP-TdR for 10–60 min and 6 hrs resp. at 25° C. The patterns of reproduction of chromosome pairs 1–4 and small metacentrics were found to be the same in cells labeled briefly and those labeled for 6 hrs. After brief labeling asynchronous reduplication of different segments in many chromosomes became evident. It was masked because of heavy labeling after 6 hrs treatment. 相似文献
10.
The calcium-binding site of clathrin light chains 总被引:4,自引:0,他引:4
I N?thke B L Hill P Parham F M Brodsky 《The Journal of biological chemistry》1990,265(30):18621-18627
Clathrin light chains are calcium-binding proteins (Mooibroek, M. J., Michiel, D. F., and Wang, J. H. (1987) J. Biol. Chem. 262, 25-28) and clathrin assembly can be modulated by calcium in vitro. Thus, intracellular calcium may play a regulatory role in the function of clathrin-coated vesicles. The structural basis for calcium's influence on clathrin-mediated processes has been defined using recombinant deletion mutants and isolated fragments of the light chains. A single calcium-binding site, formed by residues 85-96, is present in both mammalian light chains (LCa and LCb) and in the single yeast light chain. This sequence has structural similarity to the calcium-binding EF-hand loops of calmodulin and related proteins. In mammalian light chains, the calcium-binding sequence is flanked by domains that regulate clathrin assembly and disassembly. 相似文献