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151.
Pazos AJ Sánchez JL Román G Luz Pérez-Parallé M Abad M 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,134(2):367-380
Seasonal variations in lipid classes and fatty acid composition of triacylglycerols and phospholipids in the digestive gland of Pecten maximus were studied over a period of 16 months. Acylglycerols predominated (19-77% of total lipids), in accordance with the role of the digestive gland as an organ for lipid storage in scallops. Seasonal variations were mainly seen in the acylglycerol content, while phospholipids (2.5-10.0% of total lipids) and sterols (1.9-7.4% of total lipids) showed only minor changes. The most abundant fatty acids were 14:0, 16:0, 18:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 18:4(n-3), 20:5(n-3) and 22:6(n-3) and these showed similar seasonal profiles in both, triacylglycerol and phospholipid fractions. In contrast to the phospholipid fraction, the triacylglycerol fraction contained more 20:5(n-3) than 22:6(n-3). In three phospholipid samples we noted a high percentage of a 22-2-non-methylene-interrupted fatty acid, previously described to have a structural role in several bivalve species. The main polyunsaturated fatty acids displayed important seasonal variations parallel to those of the acylglycerols, suggesting good nutritional conditions. A positive correlation existed between the level of saturated fatty acids and temperature, whereas the levels of polyunsaturated fatty acids correlated negatively with temperature. 相似文献
152.
Hai-Sheng?Li Kuntala?Shome Raúl?Rojas Mark?A?Rizzo Chandrasekaran?Vasudevan Eric?Fluharty Lorraine?C?Santy James?E?Casanova Guillermo?RomeroEmail author 《BMC cell biology》2003,4(1):13
Background
Phospholipase D (PLD) is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF) family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs) of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin. 相似文献153.
Lucas M Rodríguez MC Gata JM Zayas MD Solano F Izquierdo G 《Neurochemistry international》2003,42(1):67-71
The activation of lymphocytes and monocytes and the concentration of reduction equivalents in serum were studied in a cohort of multiple sclerosis (MS) patients undergoing weekly treatment with 30 microg intramuscular interferon beta-1a for 2 years. The degree of activation of monocytes and lymphocytes and reactive oxygen species (ROS) production was higher in MS patients than in healthy controls and decreased in the course of interferon beta-1a treatment approaching control values. The concentration of reduced sulfhydryls in the serum of MS patients was lower than in healthy controls and the treatment with interferon beta-1a (IFNbeta-1a) raised the levels approaching the values of healthy controls. 相似文献
154.
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are important neuropeptides in the control of lung physiology. Both of these commonly bind to specific G protein coupled receptors named VPAC(1)-R and VPAC(2)-R, and PAC(1)-R (with higher affinity for PACAP). VIP and PACAP have been implicated in the control of cell proliferation and tumor growth. This study examined the presence of VIP and PACAP receptors in human lung cancer samples, as well as the functionality of adenylyl cyclase (AC) stimulated by both peptides. Results from RT-PCR and immunoblot experiments showed the expression of VPAC(1)-, VPAC(2)- and PAC(1)-R in lung cancer samples. Immunohistochemical studies showed the expression of VPAC(1) and VPAC(2) receptors. These receptors were positively coupled to AC, but the enzyme activity was impaired as compared to normal lung. There were no changes in Galpha(s) or Galpha(i) levels. Present results contribute to a better knowledge of VIP/PACAP actions in lung cancer and support the interest for the development of VIP/PACAP analogues with therapeutic roles. 相似文献
155.
T1alpha/podoplanin deficiency disrupts normal lymphatic vasculature formation and causes lymphedema 总被引:25,自引:0,他引:25
Schacht V Ramirez MI Hong YK Hirakawa S Feng D Harvey N Williams M Dvorak AM Dvorak HF Oliver G Detmar M 《The EMBO journal》2003,22(14):3546-3556
Within the vascular system, the mucin-type transmembrane glycoprotein T1alpha/podoplanin is predominantly expressed by lymphatic endothelium, and recent studies have shown that it is regulated by the lymphatic-specific homeobox gene Prox1. In this study, we examined the role of T1alpha/podoplanin in vascular development and the effects of gene disruption in mice. T1alpha/podoplanin is first expressed at around E11.0 in Prox1-positive lymphatic progenitor cells, with predominant localization in the luminal plasma membrane of lymphatic endothelial cells during later development. T1alpha/podoplanin(-/-) mice die at birth due to respiratory failure and have defects in lymphatic, but not blood vessel pattern formation. These defects are associated with diminished lymphatic transport, congenital lymphedema and dilation of lymphatic vessels. T1alpha/podoplanin is also expressed in the basal epidermis of newborn wild-type mice, but gene disruption did not alter epidermal differentiation. Studies in cultured endothelial cells indicate that T1alpha/podoplanin promotes cell adhesion, migration and tube formation, whereas small interfering RNA-mediated inhibition of T1alpha/podoplanin expression decreased lymphatic endothelial cell adhesion. These data identify T1alpha/podoplanin as a novel critical player that regulates different key aspects of lymphatic vasculature formation. 相似文献
156.
Micromolar Ca2+ from sparks activates Ca2+-sensitive K+ channels in rat cerebral artery smooth muscle 总被引:3,自引:0,他引:3
Perez Guillermo J.; Bonev Adrian D.; Nelson Mark T. 《American journal of physiology. Cell physiology》2001,281(6):C1769
The goal of the present study was to testthe hypothesis that local Ca2+ release events(Ca2+ sparks) deliver high local Ca2+concentration to activate nearby Ca2+-sensitiveK+ (BK) channels in the cell membrane of arterial smoothmuscle cells. Ca2+ sparks and BK channels were examined inisolated myocytes from rat cerebral arteries with laser scanningconfocal microscopy and patch-clamp techniques. BK channels had anapparent dissociation constant for Ca2+ of 19 µM and aHill coefficient of 2.9 at 40 mV. At near-physiological intracellularCa2+ concentration ([Ca2+]i; 100 nM) and membrane potential (40 mV), the open probability of a singleBK channel was low (1.2 × 106). A Ca2+spark increased BK channel activity to 18. Assuming that 1-100% of the BK channels are activated by a single Ca2+ spark, BKchannel activity increases 6 × 105-fold to 6 × 103-fold, which corresponds to ~30 µM to 4 µM sparkCa2+ concentration.1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acidacetoxymethyl ester caused the disappearance of all Ca2+sparks while leaving the transient BK currents unchanged. Our resultssupport the idea that Ca2+ spark sites are in closeproximity to the BK channels and that local[Ca2+]i reaches micromolar levels to activateBK channels. 相似文献
157.
Engineering the Escherichia coli outer membrane protein OmpC for metal bioadsorption 总被引:1,自引:0,他引:1
Norberto Cruz Sylvie Le Borgne Georgina Hernández-Chávez Guillermo Gosset Fernando Valle Francisco Bolivar 《Biotechnology letters》2000,22(7):623-629
The outer membrane protein, OmpC, from Escherichia coli was used to display metal-binding poly-histidine peptides on the surface of this bacterium. SDS-PAGE analysis of outer membrane protein preparations confirmed the expression of the metal-binding epitopes inserted in position 162 of the mature OmpC protein. Display of these epitopes was confirmed by epifluorescence microscopy of cells bound to Ni2+-NTA-agarose beads and metal adsorption experiments. The cells harboring one or two copies of the metal binding epitope were able to adsorb 3 to 6 times more Zn2+ (13.8 mol g–1 cell), Fe3+ (35.3 mol g–1 cell), and Ni2+ (9.9 mol g–1 cell) metallic ions than control cells expressing the wild-type OmpC. 相似文献
158.
Gil A. Enríquez-Obregón Roberto I. Vázquez-Padrón Dmitri L. Prieto-Samsonov Gustavo A. De la Riva Guillermo Selman-Housein 《Planta》1998,206(1):20-27
The presence of undesirable plants in sugarcane (Saccharum officinarum L.) plantations reduces crop yields. Using genetic engineering as a complement for traditional breeding methods it is possible
to introduce herbicide-resistant traits into Saccharum germplasm. Transgenic sugarcane plants resistant to phosphinothricine (PPT), the active compound of the commercial herbicide
BASTA were generated by Agrobacterium tumefaciens-mediated transformation. Meristematic sections of sugarcane were treated with anti-necrotic compounds to minimize oxidative
bursts and used as explants. Four transformation protocols were assessed and the transformation frequencies reached 10–35%.
The regeneration rate was high and did not appear to be affected by the transformation procedure. Southern blot analysis of
several transformed plants indicated the integration per genome of one or two intact copies of the bar gene which encodes PPT acetyltransferase and confers resistance to BASTA. The levels of BASTA resistance were evaluated under
greenhouse and small-plot conditions.
Received: 8 November 1997 / Accepted: 22 November 1997 相似文献
159.
Nitrogen availability influences the biochemical composition and photosynthesis of tank-cultivated Ulva rigida (Chlorophyta) 总被引:5,自引:0,他引:5
Juan Luis Gómez Pinchetti Elena del Campo Fernández Paula Moreno Díez Guillermo García Reina 《Journal of applied phycology》1998,10(4):383-389
Physiological and biochemical changes in relation to inorganic nitrogen availability were studied for tank-cultivated Ulva
rigida grown under nitrogen- enriched and nitrogen-depleted seawater. U. rigida was initially cultivated in nitrogen-enriched
seawater (daily concentrations of NH4+ and NO3- + NO2- ranged between 0.5–1.7 and 0.06–0.15 mg L-1, respectively), then transferred
to nitrogen-depleted seawater where photosynthetic capacity decreased to zero after 23 d. At the time (14 d) when photosynthetic
rates were lower than 2.0 μmol O2 g-1 FW min-1 and strong bleaching had occurred, some algae were returned to the initial
nitrogen-enriched seawater to study recovery from N-limited growth. Data on biochemical composition (chlorophylls, ash, caloric
content, fatty acids and dietary fibres) and colouration varied significantly depending on the nitrogen conditions. C:N ratios
correlated significantly with biochemical parameters. Fatty acid (FA) synthesis continued during the N-starvation period;
saturated and mono-unsaturated FA increased to a maximun of 72.2%, while poly-unsaturated fatty acids (PUFA) decreased to
27.7%. During the N-enriched recovery period, the reverse was found. C:N ratios above 10 correlated with carbohydrate synthesis
as shown by the dietary fibre level. Under nitrogen enriched conditions, C:N ratios decreased along with a decrease in fibre
level. Under controlled conditions, nitrogen represents a major influence on the development of intensive tank cultivation
of Ulva rigida, not only by affecting parameters closely related to nitrogen metabolism but also some clearly influenced by
carbon uptake.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
160.