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101.
102.
Elimrani I Lahjouji K Seidman E Roy MJ Mitchell GA Qureshi I 《American journal of physiology. Gastrointestinal and liver physiology》2003,284(5):G863-G871
l-Carnitine is derived both from dietary sources and biosynthesis. Dietary carnitine is absorbed in the small intestine and then distributed to other organs. Previous studies using Caco-2 cells demonstrated that the transport of l-carnitine in the intestine involves a carrier-mediated system. The purpose of this study was to determine whether the uptake of l-carnitine in Caco-2 cells is mediated by the recently identified organic cation/carnitine transporter (OCTN2). Kinetics of l-[(3)H]carnitine uptake were investigated with or without specific inhibitors. l-Carnitine uptake in mature cells was sodium dependent and linear with time. K(m) and V(max) values for saturable uptake were 14.07 +/- 1.70 micro M and 26.3 +/- 0.80 pmol. mg protein(-1). 6 min(-1), respectively. l-carnitine uptake was inhibited (P < 0.05-0.01) by valproate and other organic cations. Anti-OCTN2 antibodies recognized a protein in the brush-border membrane (BBM) of Caco-2 cells with an apparent molecular mass of 60 kDa. The OCTN2 expression was confirmed by double immunostaining. Our results demonstrate that l-carnitine uptake in differentiated Caco-2 cells is primarily mediated by OCTN2, located on the BBM. 相似文献
103.
Functional organization of adult motor cortex is dependent upon continued protein synthesis 总被引:5,自引:0,他引:5
Kleim JA Bruneau R Calder K Pocock D VandenBerg PM MacDonald E Monfils MH Sutherland RJ Nader K 《Neuron》2003,40(1):167-176
The functional organization of adult cerebral cortex is characterized by the presence of highly ordered sensory and motor maps. Despite their archetypical organization, the maps maintain the capacity to rapidly reorganize, suggesting that the neural circuitry underlying cortical representations is inherently plastic. Here we show that the circuitry supporting motor maps is dependent upon continued protein synthesis. Injections of two different protein synthesis inhibitors into adult rat forelimb motor cortex caused an immediate and enduring loss of movement representations. The disappearance of the motor map was accompanied by a significant reduction in synapse number, synapse size, and cortical field potentials and caused skilled forelimb movement impairments. Further, motor skill training led to a reappearance of movement representations. We propose that the circuitry of adult motor cortex is perpetually labile and requires continued protein synthesis in order to maintain its functional organization. 相似文献
104.
Chemical synthesis, functional reconstitution, and electron paramagnetic resonance (EPR) have been used to analyze the structure and function of phospholamban (PLB), a 52-residue integral membrane protein that regulates the calcium pump (Ca-ATPase) in cardiac sarcoplasmic reticulum (SR). PLB exists in equilibrium between monomeric and pentameric forms, as observed by SDS-PAGE, EPR, and fluorescence. It has been proposed that inhibition of the pump is due primarily to the monomeric form, with both pentameric stability and inhibition dependent primarily on the transmembrane (TM) domain. To test these hypotheses, we have studied the physical and functional properties of a synthetic null-cysteine PLB analogue that is entirely monomeric on SDS-PAGE, and compared it with the synthetic null-cysteine TM domain (residues 26-52). The TM domain was found to be primarily oligomeric on SDS-PAGE, and boundary lipid spin label analysis in lipid bilayers verified that the isolated TM domain is more oligomeric than the full-length parent molecule. These results indicate that the stability of the PLB pentamer is due primarily to attractive interactions between hydrophobic TM domains, overcoming the repulsive electrostatic interactions between the cationic cytoplasmic domains (residues 1-25). When reconstituted into liposomes containing the Ca-ATPase, the null-cysteine TM domain had the same inhibitory function as that of the full-length parent molecule. We conclude that the TM domain of PLB is sufficient for inhibitory function, the oligomeric stability of PLB does not determine its inhibitory activity, and the three Cys residues in the TM domain are not required for inhibitory function. 相似文献
105.
Ollmann M Young LM Di Como CJ Karim F Belvin M Robertson S Whittaker K Demsky M Fisher WW Buchman A Duyk G Friedman L Prives C Kopczynski C 《Cell》2000,101(1):91-101
The importance of p53 in carcinogenesis stems from its central role in inducing cell cycle arrest or apoptosis in response to cellular stresses. We have identified a Drosophila homolog of p53 ("Dmp53"). Like mammalian p53, Dmp53 binds specifically to human p53 binding sites, and overexpression of Dmp53 induces apoptosis. Importantly, inhibition of Dmp53 function renders cells resistant to X ray-induced apoptosis, suggesting that Dmp53 is required for the apoptotic response to DNA damage. Unlike mammalian p53, Dmp53 appears unable to induce a G1 cell cycle block when overexpressed, and inhibition of Dmp53 activity does not affect X ray-induced cell cycle arrest. These data reveal an ancestral proapoptotic function for p53 and identify Drosophila as an ideal model system for elucidating the p53 apoptotic pathway(s) induced by DNA damage. 相似文献
106.
Pesticidal activity of Bacillus thuringiensisδ-endotoxins, Cry1Aa, Cry1Ab, Cry1Ac, and Cry2A, was determined by using the force-feeding bioassay method to 4th instar larvae of Helicoverpa zea. H. zea was susceptible to Bt toxins in the order Cry1Ac > Cry1Ab > Cry1Aa > Cry2A with 63.60, 89.04, 159.65, and 375.78 ng/larvae
respectively. The abilities of selected Bacillus thuringiensis toxins to inhibit short circuit current (ISC) in midgut epithelia of H. zea were also investigated by voltage clamp assay. The voltage-clamp studies were conducted on isolated midguts, measuring the
inhibition of short circuit current (ISC) by activated toxin. A Cry1Aa toxin dilution of 33.3 and 500 ng/ml resulted in inhibition of ISC of −2.29 μA/min (lag time 15 min) and −4.48 μA/min (lag time, 2 min) respectively. The Cry1Ab dilution of 25 ng/ml inhibited
ISC to −1.39 μA/min, a lag time of 14 min, and 333.3 ng/ml dilution resulted in decay of ISC−2.49 μA/min, lag time 1 min respectively. The Cry1Ac lower dilution 16.7 ng/ml inhibited ISC to −1.39 μA/min, lag time 4 min, and a high dilution 333.3 ng/ml decay ISC to −2.44 μA/min, lag time 1 min. The inhibition of ISC (−1.10 μA/min, lag time 25) at lower dilution (33.3 ng/ml) and high dilution (500 ng/ml), decay (−2.38 μA/min, lag time 5
min), showed a correlation between toxin concentration and inhibitory response with Cry2A toxin. The lag time decreased with
increasing concentration of toxin applied, which is additional evidence of dose response besides direct correlation of toxicity
assays and ISC.
Received: 7 April 2000 / Accepted: 2 May 2000 相似文献
107.
From December of 1980 to May of 1998, 390 male-to-female transsexuals underwent vaginoplasty by inversion of the penile skin and a triangular perineoscrotal flap. Although minor modifications were made throughout the years, the basic surgical technique remained the same over this 17.5-year period. In 86 of the 390 patients (22 percent), secondary corrections of the vulva were deemed necessary. A total of 130 corrections were performed in these 86 patients. In the same 17.5-year period, the authors performed 26 secondary corrective procedures in 19 patients in whom the initial vaginoplasty had been done elsewhere. Bilateral Z-plasties were performed 69 times to center the labia in instances when the ventral part of the labia majora remained too far apart. This is not advisable, primarily because it will reduce the vascular supply of the penile skin flap. Introital widening by five-flap advancement was performed in 40 cases in which a dorsal skin fold obstructed the introitis. The use of the triangular perineoscrotal flap favors the vaginal and introital width, but its base should be close to the anal ring to prevent such a skin fold. Secondary construction of the labia minora was performed 27 times, and a skin reduction of the labia majora was performed 20 times. So far, the authors have been unable to develop a satisfactory method for primary construction of the labia minora. Because the appearance of the vulva may charge gradually during the first postoperative year, secondary vulvar corrections should not be performed in that period. 相似文献
108.
109.
110.
Imed Hassen Yassine M'Rabet Chaouki Belgacem Ons Kesraoui Hervé Casabianca Karim Hosni 《化学与生物多样性》2015,12(4):637-651
The chemical composition of the volatile oils obtained from the roots, leaves, flowers, and stems of Thapsia garganica of Tunisian origin was investigated by GC‐FID and GC/MS analyses. Sesquiterpene hydrocarbons and oxygenated monoterpenes were predominant in the oils of all plant parts. Bicyclogermacrene (21.59–35.09%) was the main component in the former compound class, whereas geranial (3.31–14.84%) and linalool (0.81–10.9%) were the most prominent ones in the latter compound class. Principal‐component (PCA) and hierarchical‐cluster (HCA) analyses revealed some common constituents, but also significant variability amongst the oils of the different plant parts. This organ‐specific oil composition was discussed in relation to their biological and ecological functions. For the evaluation of the intraspecific chemical variability in T. garganica, the composition of the flower volatile oils from four wild populations was investigated. Bicyclogermacrene, linalool, and geranial were predominant in the oils of three populations, whereas epicubenol, β‐sesquiphellandrene, and cadina‐1,4‐diene were the most prominent components of the oil of one population. PCA and HCA allowed the separation of the flower oils into three distinct groups, however, no relationship was found between the volatile‐oil composition and the geographical distribution and pedoclimatic conditions of the studied populations. 相似文献