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1.
The gene encoding the circumsporozoite (CS) protein of the rodent malaria parasite Plasmodium berghei was cloned and characterized. A cDNA library made from P. berghei sporozoite RNA was screened with a monoclonal antibody for expression of CS protein epitopes. The resulting cDNA clone was used to isolate the CS protein gene from a lambda library containing parasite blood-stage DNA. The CS protein gene contains a central region encoding two types of tandemly repeated amino acid units, flanked by nonrepeated regions encoding amino- and carboxy-terminal signal and anchorlike sequences, respectively. One of the central repeated amino acid unit types contains the immunodominant epitopes.  相似文献   
2.
Leukotrienes cause eosinophil emigration into conjunctival tissue   总被引:5,自引:0,他引:5  
The ability of LTB4, LTC4, the 5S,6R and 5R,6S LTD4 stereoisomers, and LTE4 to evoke leukocyte infiltration into the conjunctiva was demonstrated in the guinea pig by histological and light microscopy techniques. LTD4 and LTE4 demonstrated a dose-dependent and predominantly eosinophilic infiltrate over the selected dose range (10 ng to 1000 ng), while there was only a minimal response to LTC4. LTB4 produced marked eosinophil infiltrates only at the highest dose; scattered neutrophil infiltrates were also noted at the high dose of LTB4. The 5R,6S LTD4 stereoisomer did not evoke any leukocyte infiltration. The SRS-A antagonist, FPL 55712, abolished peptidoleukotriene-induced eosinophil emigration, and indomethacin pre-treatment had no inhibitory effect, indicating direct mediation of this response by LTs. Histamine caused a comparable eosinophilia over a dose range of 10 micrograms to 1000 micrograms. LT-induced eosinophil emigration was directed to the conjunctival epithelium; the cells appeared intact and no tissue damage was observed. These results may have relevance in the areas of allergic conjunctivitis and asthma research.  相似文献   
3.
A preliminary genetic map of the dioecious species Asparagus officinalis L. (2n = 20) has been constructed on the basis of restriction fragment length polymorphism (RFLP) and isozyme marker data. With DNA samples digested with either EcoRI or HindIII 61 out of 148 probes (41%) identified RFLPs in six families of doubled haploid lines obtained through anther culture. A higher level of polymorphism (65%) was observed when a single family was screened for RFLPs using six distinct restriction enzymes. Segregation analysis of the BC progenies (40–80 individuals) resulted in a 418-cM extended map comprising 43 markers: 39 RFLPs, three isozymes and one morphological (sex). These markers are clustered in 12 linkage groups and four of them exhibited significant deviations from the expected 11 ratio. One isozyme and three RFLP markers were assigned to the sex chromosome.  相似文献   
4.
High mobility group 1 (HMG1) protein is an abundant and conserved component of vertebrate nuclei and has been proposed to play a structural role in chromatin organization, possibly similar to that of histone H1. However, a high abundance of HMG1 had also been reported in the cytoplasm and on the surface of mammalian cells. We conclusively show that HMG1 is a nuclear protein, since several different anti-HMG1 antibodies stain the nucleoplasm of cultured cells, and epitope-tagged HMG1 is localized in the nucleus only. The protein is excluded from nucleoli and is not associated to specific nuclear structures but rather appears to be uniformly distributed. HMG1 can bind in vitro to reconstituted core nucleosomes but is not stably associated to chromatin in live cells. At metaphase, HMG1 is detached from condensed chromosomes, contrary to histone H1. During interphase, HMG1 readily diffuses out of nuclei after permeabilization of the nuclear membranes with detergents, whereas histone H1 remains associated to chromatin. These properties exclude a shared function for HMG1 and H1 in differentiated cells, in spite of their similar biochemical properties. HMG1 may be stably associated only to a very minor population of nucleosomes or may interact transiently with nucleosomes during dynamic processes of chromatin remodeling.  相似文献   
5.
The coupling of the analysis of the absorption and circular dichroism (CD) spectra with that of the cholesteric mesophases induced in nematic liquid crystals indicated some interesting conformational features of bridged and nonbridged mono- and dialkylethers of optically active 2,2′-dihydroxy-1,1′-binaphthalene. Bridged derivatives are characterized by relatively small dihedral angles. Simple monoalkyl ethers are characterized by larger dihedral angles but they all assume an s-cis conformation, owing to the existence of intramolecular hydrogen bonds. Nonbridged dialkylethers prefer even larger dihedral angles and, depending on the bulkiness of the alkyl groups, the s-trans conformation can be found. Interestingly, the conformation of dialkylethers is strongly dependent on the structure of the liquid crystal solvent, because the intramolecular hydrogen bond is not possible there. © 1995 Wiley-Liss, Inc.  相似文献   
6.
VIP stimulates adenylate cyclase activity of male and female rat anterior pituitaries and human prolactinomas, while dopamine inhibits the enzyme activity of female rat pituitaries and prolactinomas. A dopamine inhibited cyclase can be detected also in male rats provided the enzyme activity is increased by VIP. The analysis of the dose-response curves for one agent (VIP or dopamine) in the absence or in the presence of the other indicates that the two agents exhibit a different pattern of interaction in the different systems. In fact, in female rat pituitaries and in human prolactinomas, the curves for dopamine±VIP and for VIP±dopamine were parallel, indicating that the two agents exherted their effects independently from one another. On the contrary, in male rat pituitaries, the curves were definitively non parallel, that is, the inhibitory effect of dopamine was greatly amplified by VIP. In no case was the apparent affinity (EC50) of one agent modified by the presence of the other. It is concluded that two different modes of interaction between stimulatory and inhibitory neurohormones might exist at the level of adenylate cyclase from anterior pituitary cells.  相似文献   
7.
The hsp 70 gene of Plasmodium cynomolgi was isolated and characterized. As expected the gene is highly similar to that of the hsp 70 gene of Plasmodium falciparum (98% at the protein level, 82% at the nucleotide level). Surprisingly, the hsp 70 gene appears to be present in a single copy in all the P. cynomolgi strains tested, a finding that has implications for the parasite's ability to undergo a heat shock response.  相似文献   
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