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111.
112.
The presynaptic dopamine (DA) D2 receptor-mediated regulation of ATP-sensitive potassium (K+
ATP) channels was examined in slices of the rat caudate-putamen. When slices were incubated with the specific D2 receptor antagonist (–)-sulpiride (SLP), a concentration-dependent increase of extracellular DA release was observed. SLP-induced enhancement was completely antagonized by coincubation with the K+
ATP channel opener diazoxide (DIA). Treatment of slices with the D2 receptor agonist quinpirole (QUI) almost completely inhibited DA outflow induced by the K+
ATP channel blocker butanedione-monoxime (BDM). Coincubation of SLP and guanosine triphosphate (GTP) or its non-hydrolizable analogue guanylyl-5-imidodiphosphate [Gpp(NH)p], significantly reduced the SLP-induced effect on DA levels. Furthermore, we observed that BDM-induced DA outflow was markedly inhibited by G protein activators suggesting an additional receptor-independent regulation of K+
ATP channel gating. Our results suggest that PTX-sensitive G proteins are involved in the signal transduction between D2 receptors and K+
ATP channels. Furthermore, K+
ATP channels can be modulated in a receptor-independent mechanism by G protein activators. 相似文献
113.
Cross-Reactions between the Cytotoxic T-Lymphocyte Responses of Human Immunodeficiency Virus-Infected African and European Patients 总被引:13,自引:5,他引:8 下载免费PDF全文
Deniz Durali Jacques Morvan Franck Letourneur Doris Schmitt Nelly Guegan Marc Dalod Sentob Saragosti Didier Sicard Jean-Paul Levy Elisabeth Gomard 《Journal of virology》1998,72(5):3547-3553
The great variability of protein sequences from human immunodeficiency virus (HIV) type 1 (HIV-1) isolates represents a major obstacle to the development of an effective vaccine against this virus. The surface protein (Env), which is the predominant target of neutralizing antibodies, is particularly variable. Here we examine the impact of variability among different HIV-1 subtypes (clades) on cytotoxic T-lymphocyte (CTL) activities, the other major component of the antiviral immune response. CTLs are produced not only against Env but also against other structural proteins, as well as some regulatory proteins. The genetic subtypes of HIV-1 were determined for Env and Gag from several patients infected either in France or in Africa. The cross-reactivities of the CTLs were tested with target cells expressing selected proteins from HIV-1 isolates of clade A or B or from HIV type 2 isolates. All African patients were infected with viruses belonging to clade A for Env and for Gag, except for one patient who was infected with a clade A Env-clade G Gag recombinant virus. All patients infected in France were infected with clade B viruses. The CTL responses obtained from all the African and all the French individuals tested showed frequent cross-reactions with proteins of the heterologous clade. Epitopes conserved between the viruses of clades A and B appeared especially frequent in Gag p24, Gag p18, integrase, and the central region of Nef. Cross-reactivity also existed among Gag epitopes of clades A, B, and G, as shown by the results for the patient infected with the clade A Env-clade G Gag recombinant virus. These results show that CTLs raised against viral antigens from different clades are able to cross-react, emphasizing the possibility of obtaining cross-immunizations for this part of the immune response in vaccinated individuals. 相似文献
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115.
Stange Claudia Prehn Doris Arce-Johnson Patricio 《Plant Molecular Biology Reporter》1998,16(4):366-366
A protocol is presented for Pinus radiata genomic DNA isolation based on an alkyltrimethyl-ammonium bromide (CTAB) method described for other woody species. The method involves mortar grinding of tissue, a modified CTAB extraction employing high salt concentrations and polyvinyl pyrrolidone, a RNase A treatment and successive isoamyl alco- hol-chloroform extractions. The yield was approximately 15 g DNA per 100 mg of initial fresh plant material. The genomic DNA obtained by this method was suitable to be used in simple sequence repeat and random-amplified-polymorphic DNA reactions. This extraction method would allow the molecular analysis of shoots from different clones within P. radiata families. 相似文献
116.
Brigitte Hirner Wolf N. Fischer Doris Rentsch Marion Kwart Wolf B. Frommer 《The Plant journal : for cell and molecular biology》1998,14(5):535-544
Long distance transport of amino acids is mediated by several families of differentially expressed amino acid transporters. The two genes AAP1 and AAP2 encode broad specificity H+-amino acid co-transporters and are expressed to high levels in siliques of Arabidopsis, indicating a potential role in supplying the seeds with organic nitrogen. The expression of both genes is developmentally controlled and is strongly induced in siliques at heart stage of embryogenesis, shortly before induction of storage protein genes. Histochemical analysis of transgenic plants expressing promoter-GUS fusions shows that the genes have non-overlapping expression patterns in siliques. AAP1 is expressed in the endosperm and the cotyledons whereas AAP2 is expressed in the vascular strands of siliques and in funiculi. The endosperm expression of AAP1 during early stages of seed development indicates that the endosperm serves as a transient storage tissue for organic nitrogen. Amino acids are transported in both xylem and phloem but during seed filling are imported only via the phloem. AAP2, which is expressed in the phloem of stems and in the veins supplying seeds, may function in uptake of amino acids assimilated in the green silique tissue, in the retrieval of amino acids leaking passively out of the phloem and in xylem-to-phloem transfer along the path. The promoters provide excellent tools to study developmental, hormonal and metabolic control of nitrogen nutrition during development and may help to manipulate the timing and composition of amino acid import into seeds. 相似文献
117.
Whole‐cell biotransformation of oleanolic acid by free and immobilized cells of Nocardia iowensis: Characterization of new metabolites 下载免费PDF全文
Benjamin Ludwig Doris Geib Christiane Haas Juliane Steingroewer Thomas Bley Kai Muffler Roland Ulber 《Engineering in Life Science》2015,15(1):108-115
In this study, Nocardia iowensis was used to transform oleanolic acid (OA) into oleanane derivatives. The first derivative, which was found after 24 h of cultivation, was the known and already described OA methyl ester. After 1 week, two other derivatives (oleanonic acid methyl ester and an unknown metabolite) were identified as new products of a biotransformation by N. iowensis. These oleanane metabolites were characterized by HPLC, HPLC‐ESI‐MS, and HPLC‐1H NMR spectroscopy. The biotransformation was performed by suspended and immobilized cells (ICs) of N. iowensis. Cells immobilized in alginate beads were used in order to prepare a continuous process. The substrate uptake of free and ICs was similar, whereas the peak area of OA methyl ester of the ICs was only about 10% of the native cells. However, the final product (oleanonic acid methyl ester) concentrations were similar in both approaches, whereas the unknown metabolite 3 was only detected transiently in the medium of ICs. Based on these results, a new biosynthetic pathway for the biotechnological production of oleanonic acid methyl ester is proposed. 相似文献
118.
Daniela Wojta-Stremayr Alina Neunkirchner Bharani Srinivasan Doris Trapin Klaus G. Schmetterer Winfried F. Pickl 《PloS one》2015,10(5)
A variety of adjuvants fostering humoral immunity are known as of today. However, there is a lack of adjuvants or adjuvant strategies, which directly target T cellular effector functions and memory. We here determined whether systemically toxic cytokines such as IL-2 can be restricted to the site of antigen presentation and used as ‘natural adjuvants’. Therefore, we devised antigen-presenting virus-like nanoparticles (VNP) co-expressing IL-2 attached to different membrane-anchors and assessed their potency to modulate CD8+ T cell responses in vitro and in vivo. Efficient targeting of IL-2 to lipid rafts and ultimately VNP was achieved by fusing IL-2 at its C-terminus to a minimal glycosylphosphatidylinositol (GPI)-anchor acceptor sequence. To identify optimal membrane-anchor dimensions we inserted one (1Ig), two (2Ig) or four (4Ig) immunoglobulin(Ig)-like domains of CD16b between IL-2 and the minimal GPI-anchor acceptor sequence of CD16b (GPI). We found that the 2IgGPI version was superior to all other evaluated IL-2 variants (IL-2v) in terms of its i) degree of targeting to lipid rafts and to the VNP surface, ii) biological activity, iii) co-stimulation of cognate T cells in the absence of bystander activation and iv) potency to induce differentiation and acquisition of CD8+ T cell effector functions in vitro and in vivo. In contrast, the GPI version rather favored memory precursor cell formation. These results exemplify novel beneficial features of membrane-bound IL-2, which in addition to its mere T cell stimulatory capacity include the induction of differential effector and memory functions in CD8+ T lymphocytes. 相似文献
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120.
Sahar Hassani Anja Schou Lindman Doris Tove Kristoffersen Oliver Tomic Jon Helgeland 《PloS one》2015,10(9)