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21.
Kuo Huang Ling Bai Jiun Chen Yun Wen Peng Shih Chong Tsai Fu Chuo Peng Chung Kuang Yang 《Mycotoxin Research》1987,3(2):58-64
The chemical reaction of cleavaging territrem B to give 3,4,5-trimethoxy benzoic acid by alkaline hydrogen peroxide was investigated. The method was applied for confirmation of the chemical structure of the aromatic moiety of territrem A, A’, B, and B’. The physicochemical properties of the aromatic cleavage product of territrem Aindicated the structure as 3,4-methylendioxy, 5-methoxy benzoic acid (or 4-methoxy, 6-carboxy, 1, 3-benzodioxole). The experiment also gave the evidences that territrem A and A’, on the other hand territrem B and B’ have the identical aromatic moieties on their structures. 相似文献
22.
Summary The regulation of extracellular amylase production by the basidiomycetous yeast Filobasidium capsuligenum CCY 64-5-1 was characterized using growing and resting cells. A basal level of amylolytic activity was produced with various carbon sources including glucose. Amylase secretion was repressed by glucose and, more severely, by 2-deoxy-d-glucose, whereas compounds with -1,4-linked glucose, such as methyl glucoside, maltose, -cyclodextrin and soluble starch, served as inducers. Repression was not relieved by exogenously added cAMP. The effects of several metabolic inhibitors on amylase secretion were studied. Following UV-mutagenesis a mutant strain (FC-5) capable of growing in a 2-deoxy-d-glucose supplemented corn starch medium was selected for further characterization. This strain produced more amylase, had acquired an increased resistance against repression by glucose, and retained a growth rate comparable to the wild type. FC-5 was also characterized by a reduced glucokinase activity and an increased hexokinase activity. 相似文献
23.
拟异蚖和古蚖精子的超微形态和精子形成的研究(原尾目:古蚖科) 总被引:2,自引:2,他引:0
余山拟异蚖和3种古蚖的精子均为扁圆形,未见顶体,线粒体集中在一侧;核呈环形、边位、中部由膜状体分布其间.领结古蚖的早期精细胞为球形,染色质凝集成团,继而核中裂并沿细胞赤道逐渐围绕成环,染色质呈细沙状,胞间有“桥”相通.核膜一端开始内陷,出现黑点.待发育到中期精细胞,这些黑点逐渐形成奇特的管状核膜陷体;染色质变成短线形,随后排成4—5行.线粒体颗粒状,细胞间仍有“桥”连通.晚期精细胞的染色质凝集成粗带,最后形成光滑质密的核,而多余的核物质,一段一段从精子一端脱离,形成一串孢囊状体夹在精子之间,待精子成熟游离时,这些孢状体分散开来.从观察结果表明拟异蚖精子与古蚖的非常相近. 相似文献
24.
25.
在125只呼吸受戊巴比妥钠抑制并切断双侧颈迷走神经的家兔,分析了利他林(MP)呼吸效应的中枢部位及可能的递质。静脉注射 MP(2mg/kg)引起呼气时程显著缩短和呼吸频率显著增加。去除颈动脉体不影响 MP 兴奋呼吸的效应。将浸有2%MP 溶液的滤纸(2×2mm~2)贴敷在第四脑室底闩附近,或微量注射2%MP 2μl 到延髓 NTS 区,均可引起上述效应,但 NA区、NPBM 区和皮层体感运动区则无效。第四脑室或 NTS 区微量注射酚妥拉明均可阻断 MP兴奋呼吸的效应,但第四脑室注射心得安却不能阻断。结果提示,MP 可能作用于 NTS 区,在肾上腺素能α受体的参与下,受戊巴比妥钠抑制的家兔发生呼吸频率增快的效应。 相似文献
26.
Peter Kaastrup René J. M. Stet Albert J. Tigchelaar Egbert Egberts Willem B. van Muiswinkel 《Immunogenetics》1989,30(4):284-290
In this study, experiments are described that were designed to investigate whether fish have an immune regulatory systems
similar to the major histocompatibility complex (MHC) in higher vertebrate species. From combinations of gynogenetic carp
showing either slow of fast rejection of skin transplants, the latter were chosen for alloantiserum production by hyperimmunization
with peripheral blood leucocytes. The resulting alloantisera were analyzed for hemagglutinating reactivity with gynogenetic
siblings and proved to be operationally monoscpecific in absorption experiments. The serologically determined carp erythrocyte
specificites were shown to correspond to two codominantly expressed allelic products of a single locus and were designated
K1 and K2, respectively. Flow cytometer analysis revealed that the same products are also present on leucocytes from peripheral
blood, thymus, spleen, and pronephros.K1-andK2-homozygous second-generation gynogenetic siblings were used to study the histocompatibiligy nature of the K locus products.
Skin transplants between K-allogeneic gynogenetic siblings were rejected significantly faster than within K-syngeneic combinations.
Taken together, these data suggest that theK locus incorporates MHC class I-like characteristics. 相似文献
27.
Lymphocyte-specific Ca2+-binding protein LSP1 is associated with the cytoplasmic face of the plasma membrane. 总被引:2,自引:0,他引:2
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D P Klein J Jongstra-Bilen K Ogryzlo R Chong J Jongstra 《Molecular and cellular biology》1989,9(7):3043-3048
The gene for LSP1 is a lymphocyte-specific gene previously isolated by us using a subtractive hybridization technique. LSP1 mRNA is found in normal and transformed B lymphocytes and in normal T lymphocytes but not in transformed T lymphocytes. To study the expression of the mouse LSP1 protein, we prepared a polyclonal antiserum specific for the LSP1 protein. Here we report that the gene for LSP1 was expressed in transformed B-lymphoma cell lines and in normal mouse thymocytes as a protein doublet with apparent molecular masses of 52 and 50.5 kilodaltons when analyzed on a sodium dodecyl sulfate-10% polyacrylamide gel. BW5147 cells transfected with an LSP1 cDNA clone expressed only the 52-kilodalton protein. No LSP1 protein was expressed in nine T-lymphoma cell lines tested. Immunofluorescence studies of intact and permeabilized cells and subcellular fractionation experiments showed that the LSP1 protein was associated with the cytoplasmic side of the plasma membrane in transformed B-lymphoma cell lines and in normal thymocytes. Using a simple filter-binding assay, we showed that recombinant LSP1 protein was Ca2+ binding, as predicted on the basis of its deduced amino acid sequence. On the basis of the particular expression pattern, the subcellular localization, and the Ca2+-binding property of the LSP1 protein, we hypothesize that the LSP1 protein is a lymphocyte-specific component of a signal transduction pathway involved in the regulation of lymphocyte growth. 相似文献
28.
Calorimetric studies of the effects of cholesterol on the phase transition of C(18):C(10) phosphatidylcholine. 总被引:1,自引:1,他引:0
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Differential scanning calorimetry (DSC) has been employed to study the effects of cholesterol on the phase transition of C(18):C(10) phosphatidylcholine (C(18):C(10)PC). C(18):C(10)PC is an asymmetric mixed-chain phosphatidylcholine known to form mixed-interdigitated structures below the transition temperature and form partially interdigitated lipid bilayers above the transition. Three types of samples were used. The treated sample is the lipid dispersion that had undergone three freeze-thaw cycles and stored at 4 degrees C for more than 48 h. The untreated sample was made by vortexing the dry lipid in 50 mM KCl, without the above-mentioned pretreatment. The cold-treated sample was prepared by incubating the treated sample at -20 degrees C for 15 d. There is no apparent difference in the DSC curves between the treated and cold-treated samples. The data derived from the treated samples seem to be more reproducible. The DSC curves between the cholesterol/C(18):C(10)PC and cholesterol/symmetric diacylphosphatidylcholine mixtures are different in three aspects: overall appearance, the cholesterol dependence of delta H, and the effect of cholesterol on the maximal transition temperature Tm, the onset temperature To, and the completion temperature Tc. for both the treated and untreated samples, the total enthalpy change delta H of the phase transition of C(18):C(10)PC decreases with increasing cholesterol content, approaching zero at approximately 25 mol%. This level is lower than the total enthalpy changes reported previously for the cholesterol/symmetric diacylphosphatidylcholine mixtures. Both the heating and cooling thermograms show that Tm, To, and Tc decrease with increasing cholesterol content. The decreasing rates of these temperatures with cholesterol are in the neighborhood of -0.24 degree per mol% of cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
29.
Joel K. Phillips J. Michael Chong John F. Andersen Wendell E. Burkholder 《Entomologia Experimentalis et Applicata》1989,51(2):149-153
The enantiomeric composition of sitophilate, the granary weevil [Sitophilus granarius (L.)] male-produced aggregation pheromone [(R*,S*)-1-ethylpropyl 2-methyl-3-hydroxypentanoate)], was determined by three methods: (1) bioassaying the synthetic (2S,3R) and (2R,3S) enantiomers of the active (R*,S*) diastereomer; (2) 1H NMR spectroscopy of Mosher ester derivatives of the natural pheromone and synthetic (2S,3R)-and (2R,3S)-sitophilate; and (3) capillary GLC comparisons of the retention times of derivatized natural pheromone and the two synthetic enantiomers. The combined methods confirmed the (2S,3R) enantiomer as the active form of sitophilate. Male granary weevils were shown to produce >96% (2S,3R)-sitophilate. No significant attraction of S. granarius by the (2R,3S) enantiomer was observed. Rice and maize weevils [S. oryzae (L.) and S. zeamais Motschulsky] were not attracted by (2S,3R)-sitophilate.
S. granarius L. est un déprédateur important des grains stockés. Le (R*,S*)-1-éthylpropyl 2-méthyl-3-hydroxypentanoate a été identifié en 1987 comme le principal composé du sitophilate, la phéromone mâle d'agrégation de S. granarius. La composition énantiométrique du sitophilate a été déterminée par 3 méthodes:
La combinaison des 3 méthodes confirme que le (2S,3R) énantiomère est la forme active du sitophilate. Le mâle produit >96% de l'énantiomère (2S,3R). Il n'y a pas eu attraction de S. granarius par le (2R,3S) sitophilate. S. oryzae L. et S. zeamais Motsch n'ont pas été attirés par le (2S,3R)-sitophilate. L'utilisation du (2S,3R)-1-éthylpropyl 2-méthyl-3-hydroxypentanoate dans les pièges devrait permettre une détection précoce de la présence de S. granarius dans des stocks de grains. 相似文献
1) | tests biologiques des énantiomères synthétiques (2S,3R) et (2R,3S) du diastéréomère actif (R*,S*); |
2) | spectrométrie RMN 1H des esters Mosher dérivés de la phéromone naturelle et des sitophilates de synthèse (2S*,3R*)-et (2R*,3S*); |
3) | comparaison en capillarité GLC des temps de rétention des dérivés naturels de la phéromone et des 2 éniantiomères de synthèse. |
30.
Nora Goosen Harold P. A. Horsman René G. M. Huinen Arjan de Groot Pieter van de Putte 《Antonie van Leeuwenhoek》1989,56(1):85-91
From a gene bank of theAcinetobacter calcoaceticus genome a plasmid was isolated that complements four different classes of PQQ- mutants. Subclones of this plasmid revealed that the four corresponding PQQ genes are located on a fragment of 5 kilobases. The nucleotide sequence of this 5 kb fragment was determined and by means of Tn5 insertion mutants the reading frames of the PQQ genes could be identified. Three of the PQQ genes code for proteins of Mr 29700 (gene I), Mr 10800 (gene II) and Mr 43600 (gene III) respectively. In the DNA region where gene IV was mapped however the largest possible reading frame encodes for a polypeptide of only 24 amino acids. A possible role for this small polypeptide will be discussed. Finally we show that expression of the four PQQ genes inAcinetobacter lwoffi andEscherichia coli lead to the synthesis of the coenzyme in these organisms. 相似文献