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61.
The pollen content of eleven honey samples from ten different apiaries in the Baixa Limia – Serra do Xurés Nature Reserve and other honey commercialised by the cooperative as “Mel do Xurés” (north‐west Spain) was subjected to quantitative and qualitative melissopalynological analysis. The quantitative analysis found that ten samples belonged to Maurizio's Class III and one to Class IV. According to the qualitative analysis, four samples were classified as unifloral honey with Erica, four samples as multifloral honey with Erica pollen as the principal component and three samples as multifloral honey with Cytisus‐type pollen and Erica as the principal component pollen. The pollen spectra differ between the diverse honeys analysed, with a common denominator being Erica and Cytisus‐type pollen being abundant in all. For the rest of the samples, the pollen spectra were mainly the same, but with different relative percentages among secondary elements. Thus, either as a secondary or an important element, 91% of the honeys contained Quercus, 82% Castanea sativa Miller, 45% Rubus, 36% Cistus and 27% Lithodora prostrate (Loisel) Griseb,. In particular, we record for the first time the presence of Ribes and Ilex aquifolium L. pollen in Spanish honeys as an important minor or minor pollen component. 相似文献
62.
The chemokine receptor CCR7 and its ligands CCL19 and CCL21 play a crucial role for the homing of lymphocytes and dendritic cells to secondary lymphoid tissues. Nevertheless, how CCR7 senses the gradient of chemokines and how migration is terminated are poorly understood. In this study, we demonstrate that CCR7(-GFP) is endocytosed into early endosomes containing transferrin receptor upon CCL19 binding, but less upon CCL21 triggering. Internalization of CCR7 was independent of lipid rafts but relied on dynamin and Eps15 and was inhibited by hypertonic sucrose, suggesting clathrin-dependent endocytosis. After chemokine removal, internalized CCR7 recycled back to the plasma membrane and was able to mediate migration again. In contrast, internalized CCL19 was sorted to lysosomes for degradation, showing opposite fate for endocytosed CCR7 and its ligand. 相似文献
63.
J. Fábregas E. D. Morales N. Polanco M. Patiño A. Otero J. F. Tobar 《World journal of microbiology & biotechnology》1996,12(1):47-49
The marine microalga Phaeodactylum tricornutum was cultivated in semi-continuous culture under mixotrophic conditions with the soluble fractions of potato, rye and wheat flours that had been naturally fermented, at 2% or 4% (w/v). The rye flour produced the highest microalgal cellular density of 90×106 cells.ml-1 when supplemented with NaNO3 and NaH2PO4. The autotrophic control only gave 57×106 cells.ml-1. The value of agricultural surpluses, such as rye flour, can therefore be increased by its use in the production of valuable, microalgal biomass which is rich in protein, pigments and fatty acids. 相似文献
64.
Cutting edge: scavenging of inflammatory CC chemokines by the promiscuous putatively silent chemokine receptor D6 总被引:6,自引:0,他引:6
Fra AM Locati M Otero K Sironi M Signorelli P Massardi ML Gobbi M Vecchi A Sozzani S Mantovani A 《Journal of immunology (Baltimore, Md. : 1950)》2003,170(5):2279-2282
In an effort to define the actual function of the promiscuous putatively silent chemokine receptor D6, transfectants were generated in different cell types. Engagement of D6 by inflammatory CC chemokines elicited no calcium response nor chemotaxis, but resulted in efficient agonist internalization and degradation. Also in lymphatic endothelium, where this receptor is expressed in vivo, D6 did not elicit cellular responses other than ligand internalization and degradation. In particular, no evidence was obtained for D6-mediated transcytosis of chemokines in the apical-to-basal or basal-to-apical directions. These results indicate that D6 acts as an inflammatory chemokine scavenging nonactivatory decoy receptors and suggest that in lymphatic vessels D6 may function as a gatekeeper for inflammatory CC chemokines, by clearing them and preventing excessive diffusion via afferent lymphatics to lymph nodes. 相似文献
65.
Numerous bacterial functions, such as virulence and biofilm formation, are controlled by a cell densitydependent communication mechanism known as Quorum Sensing (QS), in which small diffusible molecules are released, allowing bacteria to coordinate their behavior once a minimal effective quorum has been reached. The interference with these signaling systems, also known as Quorum Quenching (QQ), represents a promising strategy to tackle bacterial infections. The growing interest in this approach is reflected by the increasing number of patents within the field (45 up to now), especially in the last few years, as shown by patent applications published since 2009. The fact that biofilm formation is also controlled by QS systems expands the application of QQ to clinically-relevant biofilms such as those responsible for periodontal disease. Moreover, since biofilms increase bacterial resistance to antimicrobials, QQ could represent a new way to fight some of the most recurrent human pathogens, such as nosocomial multiresistant strains, and this deserves further exploration, especially through more proofs of concept. In this article we review the best known QS and QQ systems to date and we describe recent patents on the interference with this type of bacterial communication. 相似文献
66.
Human chorionic gonadotropin (hCG) stimulates the uptake of eight different amino acids and four nucleosides by Xenopus laevis ovarian follicles. This hormone also stimulates amino acid uptake in the follicles of another amphibian, Callyptocephallela caudiverbera. The stimulation of uptake is due to a reduction in the amino acid concentration required for half-maximal uptake velocity and not to an increment in Vmax. The effect of hCG does not require protein synthesis but requires physiological conditions of temperature and pH. Incorporation of radioactive exogenous amino acid into proteins is also stimulated by the hormone, but high-resolution electrophoresis shows that there are no drastic qualitative changes in the pattern of proteins synthesized at early times after hCG treatment. The effect of hCG on the uptake of exogenous amino acids does not appear to be required for oocyte maturation because other hormones such as progesterone and testosterone which induce maturation do not increase amino acid uptake. Also the concentration of hCG required for oocyte maturation is significantly lower than that required for an effect on amino acid transport. Inhibitors of oocyte maturation such as theophylline and cycloheximide do not inhibit the action of hCG on amino acid uptake by the amphibian follicles. 相似文献
67.
Eitel Pastor Cristina Otero Antonio Ballesteros 《Biocatalysis and Biotransformation》1995,12(2):147-157
Mixtures of 1(3)-monostearin and distearin were prepared by direct esterification of glycerol with stearic acid or transesterification using ethyl stearate as acyl donor in the presence of Candida antarctica lipase (Novozym 435) using a variety of solvents of differing polarity. In all cases, the transesterification resulted in higher product yields. In n-heptane as reaction medium the addition of water (3%) was essential for high product yields, with mono- and distearin being produced in almost equal amounts. Using more polar solvents as reaction media, such as acetonitrile or acetone, again the highest yields were obtained in the transesterification mode; employing these solvents the reactions were much more selective towards the formation of monostearin. 相似文献
68.
Pseudomonas aeruginosa phosphorylcholine phosphatase (PChP), the product of the PA5292 gene, is synthesized when the bacteria are grown with choline,
betaine, dimethylglycine, or carnitine. In the presence of Mg2+, PChP catalyzes the hydrolysis of both phosphorylcholine (PCh) and p-nitrophenylphosphate (p-NPP). PCh saturation curve analysis of the enzyme with or without the signal peptide indicated that the peptide was the fundamental
factor responsible for decreasing the affinity of the second site of PChP for PCh, either at pH 5.0 or pH 7.4. PChP contained
three conserved motifs characteristic of the haloacid dehalogenases superfamily. In the PChP without the signal peptide, motifs
I, II, and III correspond to the residues 31DMDNT35, 166SAA168, and K242/261GDTPDSD267, respectively. To determine the catalytic importance of the D31, D33, T35, S166, K242, D262, D265, and D267 on the enzyme
activity, site-directed mutagenesis was performed. D31, D33, D262, and D267 were identified as the more important residues
for catalysis. D265 and D267 may be involved in the stabilization of motif III, or might contribute to substrate specificity.
The substitution of T35 by S35 resulted in an enzyme with a low PChP activity, but conserves the catalytic sites involved
in the hydrolysis of PCh (Km1 0.03 mM, Km2 0.5 mM) or p-NPP (Km 2.1 mM). Mutating either S166 or K242 revealed that these residues are also important to catalyze the hydrolysis of both substrates.
The substitution of lysine by arginine or by glutamine revealed the importance of the positive charged group, either from
the amino or guanidinium groups, because K242Q was inactive, whereas K242R was a functional enzyme. 相似文献
69.
Rosa Fandos Antonio Otero Ana Rodríguez Sara Suizo Pilar Terreros 《Inorganica chimica acta》2011,366(1):122-127
The reaction of [TiCp*Cl3] with [Fe(η5-C5H5)(η5-C5H4COOH)] in the presence of NEt3 yields [TiCp*{(OOC-C5H4)FeCp}3] (1), (Cp = η5-C5H5). The alkyl complex [TiCp*Me3] reacts with [FeCp(η5-C5H4-CH2COOH)] or anthranilic acid rendering the tris-carboxylate titanium complexes [TiCp*{(OOCCH2-C5H4)FeCp}3] (2) and [TiCp*{(OOCC6H4NH2)3] (3), respectively. Complex 3 can be protonated with triflic acid to render [TiCp*{(OOCC6H4NH2)3].HOTf (4). The reaction of [TiCp*Me3] with anthranilic acid in a 1:2 M ratio yields the alkyl carboxylate derivative [TiCp*Me{(OOCC6H4NH2)2] (5). Complex 5 reacts with tBuNC to render the iminoacyl complex [TiCp*(η2-MeCNtBu){(OOCC6H4NH2)2] (6). The reaction of [TiCp*Cl3] with the ferroceneacetic acid, gives [TiCp*Cl2{(OOCCH2-C5H4)FeCp}] (7). The [TiCp*Cl]2(μ-O)[(ΟΟC-C5H4)2Fe] (8) can be obtained by reaction of [TiCp*Cl3] with [Fe(η5-C5H4-COOH)2] in the presence of a base. The molecular structures of 1 and 8 have been established by X-ray diffraction methods. 相似文献
70.
Marcelo G. Cerdn Juan I. Young Esilda Zino Toms L. Falzone Vernica Otero Hctor N. Torres Marcelo Rubinstein 《Molecular reproduction and development》1998,49(3):236-245
The spatial, temporal, and hormonal pattern of expression of the β-casein gene is highly regulated and confined to the epithelial cells of the lactating mammary gland. Previous studies have shown that 1.7 kb of the bovine β-casein promoter were able to drive cell-specific and hormone-dependent expression to a mouse mammary cell line but failed to induce accurate expression to the mammary gland of transgenic mice. We investigated here the ability of 3.8 kb of the bovine β-casein gene promoter to drive the expression of the human growth hormone (hGH) gene in transgenic mice. A Northern blot analysis using total RNA obtained from different tissues of lactating and nonlactating females revealed the presence of hGH mRNA only in the mammary gland of lactating females. hGH mRNA was not detectable in the mammary gland of virgin females or males. A developmental analysis showed that hGH mRNA only peaked on parturition, resembling more closely the bovine β-casein temporal expression pattern rather than the murine. In situ hibridization studies performed on mammary gland sections showed that the cellular pattern of hGH expression was homogeneous in all lobules from heterozygous and homozygous transgenic mice. Silver grain counts on the tissue sections highly correlated with the hGH contents in the milk determined by radioimmunoassay (r = 0.996). Thus 3.8 kb of the bovine β-casein promoter direct a high-level expression of a reporter gene to the lactating mammary gland of transgenic mice in a tissue-specific and developmentally regulated manner. Mol. Reprod. Dev. 49:236–245, 1998. © 1998 Wiley-Liss, Inc. 相似文献