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31.
T C Madhok C C Chao S G Matta A Hong B M Sharp 《Biochemical and biophysical research communications》1989,165(1):151-157
Polyclonal antibodies were raised against a synthetic decapeptide (designated S3) predicted from a segment of the alpha-3 subunit cDNA (amino acid residues 130-139) encoding the rat brain nicotinic cholinergic receptor. This segment was selected because it may be proximate to the nicotine/acetylcholine-binding site of the receptor (1). By radioligand binding assays and sucrose density gradient centrifugation, these monospecific antibodies were shown to inhibit the binding of [3H]nicotine to both the large molecular weight rat brain receptor (240 kDa) and to an SDS-disaggregated nicotine-binding subunit species (80 kDa), in a dose-dependent manner. The neutralizing effect of the anti-S3 antibodies supports the view that this region of the protein is closely related to the agonist binding site. 相似文献
32.
33.
人体小卫星DNA探针的制备 总被引:3,自引:2,他引:1
根据人体小卫星DNA核心顺序,化学合成长23碱基寡核苷酸探针,筛选人体基因组文库,旨在获得能用作遗传分析探针的小卫星顺序。结果得到15个含小卫星的阳性重组子。随机取其一(C_(35.9))作探针,试做群体分析。所有个体均可检出多条杂交带。其中某些带具有多态性。在一定检测条件下,检出的DNA图谱在有限的个体内具有个体特异性。结果表明筛选文库得到的小卫星顺序可用于小卫星多态性的检测。其它小卫星探针的筛选和应用性研究正在进行。 相似文献
34.
异育淇鲫及其双亲同工酶的比较研究 总被引:14,自引:0,他引:14
用4.5%聚丙烯酰胺凝胶平板电泳研究了异育淇鲫及其母本淇鲫和父本兴国红鲤的肌可溶性蛋白以及肾、肝、眼、背白肌和心等五种组织的乳酸脱氢酶(LDH)、苹果酸脱氢酶(MDH)和酯酶(EST)。结果发现:异育淇鲫的肌可溶性蛋白以及同工酶的电泳图谱与母本淇鲫相同而与父本兴国红鲤显著不同,因而认为异育淇鲫是淇鲫雌核发育的产物,父本基因对子代基本无影响。在此基础上,本文对异源精子在雌核发育中所起的生物学作用进行了初步探讨。 相似文献
35.
36.
A field study with barley was conducted in 1984 and 1985 to provide data on uptake rates of N, P, K and Mg and their variation as the growing season progressed. Two varieties were grown: Galt in 1984 and Otal in 1985. Soil fertility was maintained at or near optimum conditions. Samples were obtained approximately every 10 days for shoot dry weight, nutrient content and root length measurements. The approximate method (Williams, 1948) traditionally used for calculating uptake rates was found to be invalid for most of the nutrients studied. The method used for measuring uptake rates was the functional approach proposed by Hunt (1973). Inflow,i.e. uptake rate per unit root length, of plant nutrients, decreased with time. However, maximum uptake rates measured in kg ha–1d–1 occurred at about 50 days from sowing because of increasing root length density with time. Inflow or uptake rates were low in 1985 because of moisture deficiency, and grain yield (0.89 t ha–1) was severely depressed. This study demonstrated that Hunt's method is superior and more advantageous than the traditional, approximate method. 相似文献
37.
C5 convertase of the alternative complement pathway: covalent linkage between two C3b molecules within the trimolecular complex enzyme 总被引:3,自引:0,他引:3
T Kinoshita Y Takata H Kozono J Takeda K S Hong K Inoue 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(11):3895-3901
C5 convertase of the alternative C pathway is a complex enzyme consisting of three C fragments--one molecule of a major fragment of factor B (Bb) and two molecules of a major fragment of C3 (C3b). Within this C3bBbC3b complex, the first C3b binds covalently to the target surface, and Bb, which bears a catalytic site, binds noncovalently to the first C3b. In the present investigation, we studied the nature of the convertase that is assembled on E surfaces and obtained evidence that the second C3b binds directly to the alpha'-chain of the first through an ester bond rather than to the target surface. Thus, the alternative pathway C5 convertase could be described as a trimolecular complex in which Bb binds noncovalently to a covalently linked C3b dimer. We also obtained evidence that not only the second C3b but also the first C3b participates in binding C5, that is, covalently-linked C3b dimer acts as a substrate-binding site. Because of this two-site binding, the convertase has a much higher affinity for C5 than the surrounding monomeric C3b molecules. Based on this evidence, a new model of the alternative pathway C5 convertase is proposed. Covalent association of two subunits and the bivalent binding of the substrate are then common properties of the alternative and classical pathway C5 convertases. 相似文献
38.
Monoclonal antibodies to mouse complement receptor type 1 (CR1). Their use in a distribution study showing that mouse erythrocytes and platelets are CR1-negative 总被引:14,自引:0,他引:14
T Kinoshita J Takeda K Hong H Kozono H Sakai K Inoue 《Journal of immunology (Baltimore, Md. : 1950)》1988,140(9):3066-3072
mAb to murine C receptor type 1 (CR1) were produced and three of them were characterized. One antibody, designated as 8C12, immunoprecipitated a protein of 190,000 Mr from a detergent extract of surface-labeled spleen cells and stained spleen B but not T lymphocytes in fluorescent flow cytometry. It inhibited both CR1-mediated rosette formation and the cofactor activity of CR1 for factor I-mediated cleavage of C3b, suggesting that it recognizes the ligand-binding site of CR1. The two other antibodies, designated as 7G6 and 7E9, recognized different epitopes from that recognized by 8C12, and they cross-reacted with a protein of 150,000 Mr that is present in a spleen extract. The distribution of CR1 in murine hemopoietic cells was studied by binding experiments with radiolabeled 8C12 and fluorescent flow cytometry. When CR1 was not detected by 8C12 alone, the two other antibodies were used in combination with 8C12 to confirm the negative results. Almost all B lymphocytes from the spleen, lymph nodes, and peripheral blood were CR1 positive. Most of the Thy-1-positive lymphocytes from these tissues were CR1 negative. Thymus lymphocytes were also CR1 negative. Peritoneal macrophages and chemotactic factor stimulated but not unstimulated peripheral blood granulocytes were CR1 positive. In contrast to human E, mouse E were CR1 negative. This pattern of distribution was consistent with previous results obtained by rosette assays. Although mouse platelets cause immune adherence hemagglutination with C3b-bearing SRBC, they are CR1 negative. Three other lines of evidence also indicated that platelets are CR1 negative. First, no band of CR1 was demonstrated by immunoprecipitation with 8C12 of an extract of surface-labeled platelets. Second, 8C12, which inhibited rosette formation by lymphocytes, alone or in combination with 7G6 and 7E9, did not inhibit immune adherence between platelets and C3b-bearing SRBC. Third, polyclonal rabbit IgG prepared from anti-mouse CR1 antiserum did not inhibit immune adherence by platelets. These results strongly suggest that the C3b-binding factor(s) on mouse platelets is different from CR1 and that processing of C3b-bearing immune complexes in mouse blood may be mediated by a new and as yet unidentified C3b-binding factor(s). 相似文献
39.
从“湖北光敏感核不育水稻”的未受精子房和花药培养出单倍体植株 总被引:10,自引:0,他引:10
采用10种诱导培养基,培养湖北光敏感核不育水稻农垦58品种的未受精子房和花药。共培养未受精子房2790个,获得胚囊愈伤组织17块,最高诱导频率达3.33%,其中2块分化出绿苗。培养花药16740个,获得花药愈伤组织15块,最高诱导频率为0.92%,其中3块分化出苗,2丛白苗,1株绿苗。胚囊植株和花粉植株经根尖染色体检查为单倍体,2n=x=12。实验证明,液体培养、2,4-D0.2-0.5 mg/1、低温预处理对诱导胚囊愈伤组织及花粉愈伤组织的形成具良好效果。 相似文献
40.
Observation was made on early ontogeny of vascular cambium in the developing root ofGinkgo biloba L. After completion of root elongation, the vascular meristem gradually acquires cambial characteristics. Strips of the periclinal
division of cells in transverse section are observed on the inner side of phloem when the primary xylem and phloem in the
stele have been established. The strips are united into a continuous layer between phloem and xylem. In tangenital section,
the procambium shows a homogeneous structure, which is initially composed of short cells with transverse end walls and subsequently,
of long cells with tapering ends. Then, the procambium is organized into two systems of cells; axial strands of short cells
with transverse end walls resulting from the sporadic transverse divisions of long cells, and long cells with tapering ends.
Still later, the short cells are divided frequently in a trasverse plane exhibiting one or a few cells in width and several
decades of cells in height, while the long cells are elongated. The frequency of transverse divisions of the short cells decreases
in subsequent stages. Eventually, the short cells in axial strands are vertically separated from one another by the elongation
of neighboring long cells and by the decrease in the frequency of transverse divisions of short cells themselves. Cambial
initials occur in two forms; ray initials a few cells in height and one cell in width derived from the short cells, and fusiform
initials with tapering ends derived from the long cells. 相似文献