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1.
Halobacterial megaplasmids are negatively supercoiled 总被引:1,自引:0,他引:1
Purificación López-García Josefa Antón Jose Pascua Abad Ricardo Amils 《Molecular microbiology》1994,11(3):421-427
Several covalently closed circular halobacterial megaplasmids (up to more than 500 kb) from different strains of Halolerax mediterranei, have been resolved by orthogonal-field alternating gel electro-phoresis (OFAGE). These molecules seem to be negatively supercoiled in vivo, as deduced from the effect of intercalating agents affecting their topology and, therefore, their electrophoretic mobility. It has also been demonstrated that the topolsomerase II Inhibitor novobiocin affects the native topological state of halobacterial megaplasmids impeding their migration in OFAGE under standard conditions for resolution of large supercoiled molecules. 相似文献
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3.
The effect of short chain fatty acids on the cellular permeability of embryonic axis inGcer arietinum seeds was studied. Octanoic (OCT) and nonanoic (NON) adds, which reduce both germination and growth of the embryonic axis and raise the inhibitor effects of the supraoptimal temperatures (30?C), induce a greater ionic efflux into the medium (conductivity). NON reduces glucose (3-0-MG) and K+ (86Rb) uptake during the germinative process, this action being counteracted by fusicoccin (FC) at optimal (25?C) and supraoptimal temperatures (30 ?C). Tonoplast and plasmalemma increase their permeability to the K+ efflux when NON is present. Addition of NON+FC gives rise to higher values in the efflux rate, the vacuolar compartment being the most affected. Temperatures around zero (2 ?C) notably reduce the isotope efflux from cytosol and vacuole. NON acid does not significantly affect the efflux of3H-ABA, suggesting that it does not cause any important changes in the phytohormone compartmentation. 相似文献
4.
Vicent Casadó Carmen Lluis Enrique Canela Rafael Franco Josefa Mallol 《Neurochemical research》1992,17(2):129-139
Pig brain cerebral cortex was subfractionated by isopycnic centrifugation in sucrose gradients. In each subfraction the content of the agonist [3H]R-PIA binding, the activity of adenosine metabolizing enzymes (5-nucleotidase and adenosine deaminase) and the activity of membrane marker enzymes were determined. The fractions were also examined by electron microscope. In general, the results suggest a widespread distribution of A1 adenosine receptors in membranes from different origins. Marker enzyme profile characterization indicated an enrichment of A1 adenosine receptor in pre-synaptic membranes isolated from the crude synaptosomal fraction (P2B subfraction) as well as in membranes of glial origin such as myelin. The receptor is also present in the endoplasmic reticulum and in membranes isolated from the microsomal fraction that seem to have a post-synaptic origin (P3B). In subfractions having a high content of adenosine receptor the equilibrium binding paramters were obtained as well as the proportion of high- to low-affinity sites. From the values of the equilibrium constants it was not possible to find differences between the receptor in the different subfractions. Analysis of the affinity state distribution showed a diminished percentage of high-affinity sites in fraction P3A, which can be accounted by the existence of myelin membranes; in contrast the percentage of high-affinity states was higher in P2 and P3B, indicating that in these fractions the receptor is present in synaptosomal membranes. The close correlation shown between the enzyme 5-nucleotidase specific activity and the specific ligand binding distributions led us to postulate an important role for the enzyme in the regulation of adenosine action in pig brain cortex. 相似文献
5.
Effect of prolactin and glucocorticoids on P-enolpyruvate carboxykinase activity in liver and mammary gland from diabetic and lactating rats 总被引:1,自引:0,他引:1
María F. Lobato Mertxe Careche Manuel Ros Francisco J. Moreno Josefa P. García-Ruíz 《Molecular and cellular biochemistry》1985,67(1):19-23
Summary The administration of 2 bromo--ergocryptine, to reduce serum prolactin decreased the activity of cytosolic P-enolpyruvatc carboxykinase (GTP) (EC4.1.1.32) about 50% in both liver and mammary gland of lactating animals. Adrenalectomy had similar effects to those of bromo-a-ergocryptine. In contrast, there was a 50% increase in enzyme activity in the mammary gland of diabetic, lactating rats and a 10-fold increase in liver as compared with normal rats. P-enolpyruvate carboxykinase activity in mammary gland as liver is coordinately regulated by prolactin, glucocorticoids and insulin. 相似文献
6.
Josefa Salgado Jose Villalain Juan C. Gómez-Fernández 《European biophysics journal : EBJ》1993,22(2):151-155
-Tocopherol, ubiquinone-10 and ubiquinol-10 have been studied by high resolution magic angle samples spinning 13C-nuclear magnetic resonance in egg yolk phosphatidylcholine multilamellar vesicles model membranes in order to assess their location and the induced perturbations on this model system. -Tocopherol is placed in such a position that it is in close contact with the head group of the phospholipid and exposed to the solvent. In this position it significantly perturbs the phospholipid head group, the 5a-CH3 and the 7a-CH3 groups being the closest parts to the membrane surface. On the other hand, ubiquinol-10 perturbs the membrane surface more than ubiquinone-10, but neither compound significantly changed the phospholipid head group conformation. 相似文献
7.
Experiments were conducted to determine the optimum dose of luteinizing hormone-releasing hormone analogue (LHRHa) and pimozide (PIM) injected simultaneously to yield a high ovulation rate and produce sufficient eggs in the Asian catfish Clarias macrocephalus . In June 1990, injection of 0.05 or 0.10 μg LHRHa/g body weight (BW) + 1 μg PIM/g resulted in 100% ovulation, while only 80% of gravid catfish injected 0.025 μg LHRHa + 1 μg PIM/g ovulated. Most of the eggs stripped from 6 out of 8 control fish were not mature. Fertilization and hatching rates of LHRHa + PIM-induced fish (75–90% and 39–51%, respectively) were higher than those of control fish (36–39% and 0–1% respectively). In August and September 1990, at gravid catfish ovulated after injection of 0.05–0.10 μg LHRHa + 1 μg PIM/g BW. However, only 20% of the fish given 0.025 μg LHRHa/g + 1 μg PIM/g BW in August ovulated. No eggs could be striped from any of the control fish in August and September 1990. Techniques developed in this study, showed a simple and effective way of spawning captive catfish, C. macrocephalus . A simultaneous intramuscular injection of 0.05 μg LHRHa + 1 μg PIM/g and stripping of eggs at 16–20 h post-injection have been tested to yield high ovulation, fertilization and hatching rates. 相似文献
8.
Josefa Alamillo Concepción Almoguera Dorothea Bartels Juan Jordano 《Plant molecular biology》1995,29(5):1093-1099
Using antibodies raised against two sunflower small heat shock proteins (sHSPs), we have detected immunologically related proteins in unstressed vegetative tissues from the resurrection plant Craterostigma plantagineum. In whole plants, further accumulation of these polypeptides was induced by heat-shock or water-stress. In desiccation-intolerant Craterostigma callus tissue, we failed to detect sHSP-related polypeptides, but their expression, and the concurrent acquisition of desiccation tolerance was induced by exogenous abscisic acid (ABA) treatment. In untressed plants, the cross-reacting polypeptides were abundant in the roots and lower part of the shoots, where they showed homogeneous tissue-distributions. This constitutive expression is novel for vegetative tissues of higher plants, and resembles the expression patterns of sHSPs in desiccation-tolerant zygotic embryos and germinating seeds.J.A. and C.A. contributed equally to this work and are both considered to be first author 相似文献
9.
Juan S. Jiménez María J. Benítez Carmen G. Lechuga Manuel Collado Josefa González-Nicólas Francisco J. Moreno 《Molecular and cellular biochemistry》1995,152(1):1-6
In order to elucidate the relationship between hypertension and hypertrophy in the production of heat shock proteins, we studied the induction of the HSP72 synthesis by the heart and gracilis muscles of normo (WKY) and hypertensive (SHR) rats subjected to hyperthermia (42°C±0.5 for 15 min). Two age groups were investigated in each strain: young (2 months, with developing cardiac hypertrophy) and old (18 months, with fully developed chronic cardiac hypertrophy). The gracilis muscle never developed hypertrophy, independently of hypertension or aging. 72 kDa inducible protein was determined by Western blot analysis using a specific monoclonal antibody. We also used a commercial standard, loaded on each blot, to quantitate densitometrically the signal.The heart of young SHR responds to heat shock more than their normotensive age-matched control (298.8±24.7% vs 88.3 ±8.5%, p<0.001). This response is not maintained during aging as we did not find any significant difference between normo-and hypertensive old rats after exposure to hyperthermia (43.6±5.3% vs 65.3±10.4%).Unlike the heart, the gracilis muscle shows a basal spontaneous HSP72 synthesis in both the SHR (71.4±10.8%) and WKY (40.6±11.7%) animals. There was a significant increase in HSP72 synthesis in the gracilis muscle of young SHR with respect to their control (186.2±18.7% vs 115.8±9.9%, p<0.02) which was maintained also during aging (171.9±17.3% vs 95.2±10.5%, p<0.01).In conclusion, these data show that hypertension results in an increased synthesis of HSP72 both in cardiac and gracilis muscle in response to heat shock. This abnormal response is attenuated by aging in the heart but not in the gracilis muscle. Thus, the abnormality seems to be independent from hypertrophy and linked to genetic determination of the disease. 相似文献
10.
Identification and Characterization of a New Serotonergic Recognition Site with High Affinity for 5-Carboxamidotryptamine in Mammalian Brain 总被引:1,自引:0,他引:1
Ma. Elena Castro Tamara Romón Ma. Josefa Castillo Elena del Olmo Angel Pazos Carmen del Arco 《Journal of neurochemistry》1997,69(5):2123-2131
Abstract: We analyzed the existence of an additional serotonin (5-HT) receptor subtype, sensitive to 5-carboxamidotryptamine, in the mammalian brain. Radioligand binding studies with [3 H]5-HT were carried out in rat, guinea pig, and human brain membranes, in the presence of unlabeled drugs to mask the binding to all known 5-HT receptors, with the exception of 5-HT1E sites. Under these conditions, unlabeled 5-carboxamidotryptamine still showed a biphasic competition curve with a nanomolar affinity component. Saturation studies with 5-[3 H]carboxamidotryptamine were carried out in the presence of (±)-8-hydroxy-2-(di- n -propylamino)tetralin, mesulergine, and ergotamine, to mask the binding to all receptors known to be labeled by 5-carboxamidotryptamine. These studies showed the existence in cortex and hippocampus from guinea pig and human brain of a remaining binding site with high affinity ( pK D = 7.8–8.1) and a unique pharmacological profile. 5-HT and 5-carboxamidotryptamine showed nanomolar affinity, whereas 5-methoxytryptamine recognized this binding site with intermediate affinity. Other drugs exhibited low or very low potency in inhibiting this binding. The addition of 5'-guanylylimidodiphosphate significantly reduced the number of binding sites labeled by 5-[3 H]carboxamidotryptamine, in the presence of the masking drugs described above, indicating the interaction with a GTP-binding protein. Preliminary autoradiographic studies in human brain appear to indicate that this 5-HT binding site is present in areas such as the globus pallidus, neocortex, and hippocampus, among others. 相似文献