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21.
Two gametocyte-forming clones, HB-3 and 3D7, were used. Concentrates of late stage parasites were mixed with bloods containing different proportions of young erythrocytes, and the parasitemia and proportion of gametocytes determined after 2, 3 or 4 days of culture. Significantly more gametocytes were formed in light cells than in heavy cells separated from the same normal blood samples. Up to seven times more gametocytes were formed in reticulocyte-rich bloods from patients with sickle cell anemia than in normal control blood. 相似文献
22.
The rat major histocompatibility complex class I antigens RT1.Au and RT1.Eu from the u haplotype and RT1.An from the n haplotype were labeled with 14C-asparagine or with 3H-fucose, mannose, galactose, and N-acetylglucosamine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed complete removal of radioactivity from the sugar-labeled antigen heavy chains by digestion with glycopeptidase F, an enzyme that removes N-linked glycans completely. High performance liquid chromatography analysis of the tryptic digests of the mixed sugar-labeled and asparagine-labeled antigens demonstrated that all the sugar-labeled peptides were coincident with asparagine-labeled peptides. The An antigen showed three glycopeptides, each of which had different amounts of sugar radioactivity. The antigens Au and Eu showed two glycopeptides with different amounts of radioactivity but at identical positions in the two antigens. Antigen Eu had an additional glycopeptide with a lower amount of radioactivity. The positions of the glycopeptides from the Au and Eu antigens were different from those of the An antigen. The peptide profiles of the 14C-asparagine-labeled Au and Eu antigens demonstrated distinct differences between the molecules. The results of this study show that: (a) all the glycans on rat class I antigens are N-linked, as they are on H-2 and HLA class I antigens; (b) there are compositional differences among the glycans in each of the three antigens; (c) the glycosylation pattern of the rat class I antigens is similar to that of the mouse class I antigens, which contain two or three glycans, in contrast to that of the human class I antigens, which contain only one glycan; and (d) the antigens Au and Eu from the same haplotype are more closely related to each other than they are to the An antigen. 相似文献
23.
The precursor of the major light-harvesting chlorophylla/b-proteins of photosystem II was synthesizedin vitro from a gene fromLemna gibba. When the labelled precursor was incubated with developing barley plastids, the precursor and the processed polypeptide were incorporated in the thylakoids in proportions that varied depending on the developmental stage of plastids. At early stages of development most of the precursor associated with the thylakoids could be removed by washing with 0.1 M NaOH, while in more mature plastids most of its was resistant to a NaOH wash. Insertion of the precursor into thylakoids required the presence of a stromal factor and Mg-ATP. The stromal factor is probably a protein. The insertion reaction has an optimal temperature of 25°C and a pH of 8. The appearance of the stromal factor and the thylakoid membrane's receptivity for the insertion of the precursor depended on the stage of plastid development. These observations are consistent with the hypothesis that the insertion of the precursor into the thylakoid prior to its proteolytic processing, is one of the steps involved in the assembly of the light-harvesting complex of photosystem II. 相似文献
24.
25.
A Parody-Morreale C H Robert G A Bishop S J Gill 《The Journal of biological chemistry》1987,262(23):10994-10999
Two high precision techniques, titration microcalorimetry and thin-layer optical binding measurements, have made possible the evaluation of enthalpy changes for the overall oxygenation reactions for human hemoglobin (HbAo). Although the heat of adding three oxygen molecules could not be evaluated due to the indeterminate contribution of this species to the oxygen binding curve of the protein (Gill, S. J., Di Cera, E., Doyle, M. L., Bishop, G. A., and Robert, C. H. (1987) Biochemistry, 26, 3995-4002), the heats for binding two and four oxygen molecules were found to be simple multiples of the first binding heat. A direct consequence of equal stepwise heats is invariance of the shape of the binding curve with temperature, as pointed out by Wyman (Wyman, J. (1939) J. Biol. Chem. 127, 581-599). Titration microcalorimetry was also performed for the binding of carbon monoxide to hemoglobin. While the tight binding of CO precludes high-precision binding measurements, it does allow one to accurately determine the heat of ligation as a function of the CO bound. In these titrations a uniform heat of reaction is not observed, but the heat of binding increases markedly near the end point. This implies that the stepwise binding enthalpy for adding the third CO molecule is anomalously endothermic and for adding the fourth strongly exothermic. A similar phenomenon cannot be ruled out in the case of oxygen because of imprecision intrinsic in the analysis of the weaker ligand binding. 相似文献
26.
N J Pressman J K Frost P K Gupta R L Showers G W Gill D L Cook J K Frost R K Traub 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1987,9(4):291-302
Cellular dynamics often involve extremely low concentrations of biologically active substances, which can be radiolabeled and detected, localized and quantitated by autoradiography. The latter may require exposures from a few days to many months. The objective of this research was to demonstrate the feasibility of reducing this long period of data collection by one to two orders of magnitude, while maintaining or improving the spatial resolution and localization in tissues and the quantitative characteristics inherent in autoradiography. A mathematical model describing the complete system was generated using energy partition calculations to estimate photon production via scintillant per H3 beta particle emission and to estimate the subsequent photon capture based upon imaging system parameters and microscope geometry. Calculations showed that, typically, a single tritium beta particle produces a maximum of 5.8 X 10(3) photons. A photon-limited camera and microscope imaging system were selected and optimized in conjunction with a specially developed physical scintillation model. Results showed that the number of detected photoevents increases monotonically with both signal integration time and, independently, with the concentration of the radionuclide. Consequently, this work demonstrates that video microscopy imaging methods can spatially and temporally quantify very low concentrations of radiolabeled substances and can reduce data acquisition times. 相似文献
27.
Cytolytic activity and immunological similarity of the Bacillus thuringiensis subsp. israelensis and Bacillus thuringiensis subsp. morrisoni isolate PG-14 toxins. 总被引:5,自引:5,他引:0
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The parasporal bodies of the mosquitocidal isolates of Bacillus thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 were compared with regard to their hemolytic and cytolytic activities and the immunological relatedness of the 28- and 65-kilodalton (kDa) proteins that occur in both subspecies. The alkali-solubilized parasporal bodies of B. thuringiensis subsp. israelensis caused 50% lysis of human erythrocytes at 1.14 micrograms/ml, whereas those of B. thuringiensis subsp. morrisoni caused similar lysis at 1.84 micrograms/ml. Preincubation of solubilized parasporal bodies with dioleolyl phosphatidylcholine significantly inhibited the hemolytic activity of both supspecies. In cytolytic assays against Aedes albopictus cells, the toxin concentrations causing 50% lysis for B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni were 1.87 and 11.98 micrograms/ml, respectively. Polyclonal antibodies raised separately against the 25-kDa protein (a tryptic digest of the 28-kDa protein) or the 65-kDa protein of B. thuringiensis subsp. israelensis cross-reacted, respectively, with the 28- and the 65-kDa proteins of B. thuringiensis subsp. morrisoni. However, neither of these antibodies cross-reacted with the 135-kDa protein of either subspecies. These results indicate that the mosquitocidal and hemolytic properties of B. thuringiensis subsp. israelensis and B. thuringiensis subsp. morrisoni isolate PG-14 are probably due to the biologically related proteins that are present in the parasporal bodies of both subspecies. The lower hemolytic activity of the B. thuringiensis subsp. morrisoni may be due to the presence of lower levels of the 28-kDa protein in that subspecies.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
28.
L R Gill K J Mayberry-Carson B Tober-Meyer F Hodin D W Lambe B G Painter 《Microbios》1989,58(235):113-126
Ciprofloxacin concentrations were determined in serum, bone and bone marrow of rabbits. Four experimental groups of animals were examined: group A (n = 6) received a dosage of 60 mg/kg/day intramuscularly for 4 weeks, groups B (n = 6), C (n = 15) and D (n = 15) received dosages of 120 mg/kg/day subcutaneously for 2 days, 2 weeks, and 4 weeks, respectively. In the kinetic portion of the study, peak serum concentrations of ciprofloxacin measured at the 15 min sampling time were: 2.61 +/- 0.27 micrograms/ml in the 60 mg/kg/day group (group A) and 3.24 +/- 0.78 micrograms/ml in the 120 mg/kg/day group (group B). At necropsy, rabbits in group A had mean ciprofloxacin concentrations of 3.60 +/- 2.27 micrograms/ml in serum, 2.24 +/- 1.19 micrograms/g in marrow and 1.19 +/- 0.44 micrograms/g in bone. Rabbits in group B achieved mean levels of 4.02 +/- 1.23 micrograms/ml in serum, 2.48 +/- 0.79 micrograms/g in marrow, and 1.35 +/- 0.40 micrograms/g in bone. Rabbits in group C achieved mean levels of 5.65 +/- 2.16 micrograms/ml in serum, 3.74 +/- 1.33 micrograms/g in marrow and 1.92 +/- 0.94 micrograms/g in bone. Rabbits in group D achieved mean levels of 7.24 +/- 2.50 micrograms/ml in serum, 4.48 +/- 1.68 micrograms/g in marrow, and 1.93 +/- 0.54 micrograms/g in bone. Differences between mean values for the four experimental groups were not statistically significant. 相似文献
29.
Heinz W. Kunz Andrea L. Cortese Hassett Tetsuo Inomata D. N. Misra Thomas J. Gill III 《Immunogenetics》1989,30(3):181-187
A new antigenic system in the rat homologous to theQa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations
that were matched for theRT1. A, B, D, E loci in the major histocompatibility complex (MHC): (R11×BN)F1 anti-BN.1L(LEW), (R18×BN)F1 anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic and
recombinant strains identified three alleles,RT1.G
a
,G
b
,G
c
, of whichG
c
is a null allele. The strain distribution of these alleles was determined, using 37 strains of rats representative of all
of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains
showed that theRT1.G locus was linked to the MHC and that the most probable gene order wasA-E-G. Testcross analysis showed that the map distance betweenA andG was 1.4 cM(4/285 recombinants). The RT1.G antigen has a heavy chain ofM
r 46 000 and is present on both T and B cells. 相似文献
30.
The 25-kilodalton toxin of Bacillus thuringiensis subsp. israelensis binds irreversibly to Aedes albopictus cells, Choristoneura fumiferana cells, and erythrocytes. The binding to cells increased with both toxin concentration and time and when the cells were first preincubated with unlabeled toxin. Binding data indicated a two- to threefold increase in the rate of binding after the amount of the membrane-bound toxin reached approximately 3.5 fmol/3 x 10(5) A. albopictus cells or 3.3. fmol/2 x 10(5) C. fumiferana cells. When this level of bound toxin was reached, the toxins also began forming aggregates at the cell membrane. The toxin aggregates were extracted with 10% Triton X-100 and separated from the monomers with a 5 to 20% sucrose density gradient. The toxin aggregates isolated from A. albopictus and C. fumiferana cell membranes were ca. 400 kilodaltons, while those isolated from human erythrocytes were significantly smaller. The proportion of the toxin found in aggregate form increased rapidly with the amount of toxin bound; however, the molecular size of the aggregates remained constant. Eleven monoclonal antibodies raised against the native form of the toxin blocked 80 to 97% of the toxin binding to cells. The epitope of one of these monoclonal antibodies was mapped to a domain which included the cysteine, suggesting the importance of the domain around this amino acid to binding. Toxin binding and cell lysis were also inhibited by treating the toxin with HgCl2, further indicating the importance of the C-terminal hydrophobic cysteine-containing domain in cytolytic activity of the 25-kilodalton protein. 相似文献