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151.
Eye primordia of young chick embryos (stage XII) were transplanted into lensectomized optic cups of older embryos (stage XVII) to analyze the influence of the host retina on the degree of morphological differentiation attained by the donor lens. Embryos were sacrificed 24-96 h later. The donor lens primordium showed a differentiation more in correlation with the host eye cup (stage XXIII) after 24-96 h of incubation. 相似文献
152.
Phospholipid turnover during phagocytosis in human polymorphonuclear leucocytes 总被引:1,自引:0,他引:1
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Merche García Gil Fernando Alonso Vicente Alvarez Chiva Mariano Sánchez Crespo José M. Mato 《The Biochemical journal》1982,206(1):67-72
We have previously observed that the phagocytosis of zymosan particles coated with complement by human polymorphonuclear leucocytes is accompanied by a time- and dose-dependent inhibition of phosphatidylcholine synthesis by transmethylation [García Gil, Alonso, Sánchez Crespo & Mato (1981) Biochem. Biophys. Res. Commun. 101, 740–748]. The present studies show that phosphatidylcholine synthesis by a cholinephosphotransferase reaction is enhanced, up to 3-fold, during phagocytosis by polymorphonuclear cells. This effect was tested by both measuring the incorporation of radioactivity into phosphatidylcholine in cells labelled with [Me-14C]choline, and by assaying the activity of CDP-choline:diacylglycerol cholinephosphotransferase. The time course of CDP-choline:diacylglycerol cholinephosphotransferase activation by zymosan mirrors the inhibition of phospholipid methyltransferase activity previously reported. The extent of incorporation of radioactivity into phosphatidylcholine induced by various doses of zymosan correlates with the physiological response of the cells to this stimulus. This effect was specific for phosphatidylcholine, and phosphatidyl-ethanolamine turnover was not affected by zymosan. The purpose of this enhanced phosphatidylcholine synthesis is not to provide phospholipid molecules rich in arachidonic acid. The present studies show that about 80% of the arachidonic acid generated in response to zymosan derives from phosphatidylinositol. A transient accumulation of arachidonoyldiacylglycerol has also been observed, which indicates that a phospholipase C is responsible, at least in part, for the generation of arachidonic acid. Finally, isobutylmethylxanthine and quinacrine, inhibitors of phosphatidylinositol turnover, inhibit both arachidonic acid generation and phagocytosis, indicating a function for this pathway during this process. 相似文献
153.
A. Delibes C. Otero F. García-Olmedo F. Dosba 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1981,60(1):5-10
Summary The distribution of three biochemical markers, U-1, CM-4 and Aphv-a, -b, among wheat-Aegilops addition lines carrying Mv chromosomes from Aegilops ventricosa (genomes DvMv) has been investigated. Addition lines which had been previously grouped together on the basis of common non-biochemical characters carried marker U-1, a protein component from the 2M urea extract. The added chromosome, in the appropriate genetic background, seems to confer a high level of resistance to the eyespot disease, caused by the fungus Cercosporella herpotrichoides. The other two markers were concomitantly associated with another similarly formed group of addition lines. Both CM-4, a protein component from the chloroform:methanol extract, and Aphv-a, -b, alkaline phosphate isozymes, have been previously shown to be associated with homoeologous chromosome group 4, which suggests that the added chromosome in the second group of addition lines is 4Mv. 相似文献
154.
The incorporation of radioactive phosphate into phosphatidylinositol was stimulated by epinephrine in hamster fat cells. This action was inhibited by alpha-adrenergic antagonists in the potency order: Prazosin?phentolamine>yohimbine. Methoxamine, but not clonidine, was able to mimic the effect of epinephrine. These data indicate that the phosphatidylinositol effect in fat cells is due to activation of alpha1 adrenoceptors. On the other hand, the accumulation of cyclic AMP due to epinephrine was potentiated by alpha-adrenergic antagonists in the potency order phentolamine>yohimbine ?prazosin, in hamster fat cells. Clonidine significantly decreased the accumulation of cyclic AMP due to isoproterenol or ACTH in hamster fat cells, suggesting that the alpha-adrenergic modulation of cyclic AMP levels in hamster fat cells is mediated by alpha2 adrenoceptors. Radioligand binding studies with plasma membranes from hamster adipocytes demonstrated the presence of both alpha1 and alpha2 adrenoceptors but about 90% of the binding sites were alpha2. These data support the hypothesis that alpha2 effects of catecholamines are due to inhibition of adenylate cyclase while the increases in phosphatidylinositol turnover that seem to be involved in the mobilization of calcium are linked exclusively to alpha1 adrenoceptor activation. 相似文献
155.
Summary Two 46,XY brothers were found to have a previously undescribed syndrome characterized by severe mental deficiency, proportionate dwarfism, and delayed sexual development. A recessive mode of inheritance, either autosomal or X-linked, is assumed. 相似文献
156.
Merche García Gil Fernando Alonso Mariano Sánchez-Crespo JoséM. Mato 《Biochemical and biophysical research communications》1981,101(3):740-748
Phagocytosis of zymosan particles coated with complement induces a time and dose dependent inhibition of the enzyme phospholipid methyltransferase in human polymorphonuclear cells. The extent of phospholipid methyltransferase inhibition induced by various concentrations of zymosan strongly correlates with the secretory process: liberation of platelet-activating factor (PAF) and β-glucuronidase. Zymosan also decreases the incorporation of 3H-methyl group into phospholipids in cells pre-labeled with (3H-methyl)-methionine. Finally, preincubation of cells with 3-deaza-adenosine and homocysteine thiolactone, inhibitors of phospholipid methyltransferase, decrease the incorporation of 3H-methyl group into phospholipids in cells pre-labeled with (3H-methyl)-methionine and modulate the release of PAF. These results suggest that phospholipid methylation plays an important role during the transduction of the secretory signal triggered by zymosan in human polymorphonuclear cells. 相似文献
157.
158.
159.
M. Cristina García Kirkbride 《Brittonia》1979,31(3):313-332
All neotropical genera previously included in the tribe Isertieae A. Rich. ex DC. are considered. The tribe Isertieae is here delimited by the following characters: absence of rhaphides, valvate aestivation of the corolla, cordiform or discoid placenta, fleshy indehiscent fruit, and seed coat cells with pitted walls. As so delimited, the tribe definitely includes the neotropical generaIsertia Schreb.,Gonzalagunia Ruiz & Pav.,Amphidasya Standl.,Raritebe Wernh.,Sabicea Aubl., andMussaenda L. as well as some paleotropical genera not here considered. The following neotropical genera are excluded from tribe Isertieae:Hippotis Ruiz & Pav.,Pentagonia Benth.,Sommera Schlecht.,Tammsia Karst.,Coccocypselum P. Browne,Schradera Vahl,Didymochlamys Hook, f., andXerococcus Oerst. The position of four genera,Striolaria Ducke,Patima Aubl.,Habroneuron Standl., andNeosabicea Wernh., remains uncertain due to a lack of material. 相似文献
160.