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1.
Martinez-Cortina Carmen; Ullrich Cornelia I.; Sanz Amparo 《Plant & cell physiology》1992,33(8):1165-1170
The effect of IAA, GA3 and ABA on transmembrane potential difference(Em) and on sucrose-induced depolarization has been studiedin young Citrus leaves. The addition of any of these hormonesto the perfusion solution (short-term experiments) did not affectEm or sucrose-induced depolarization. Hormonal treatments ofyoung leaves on the tree resulted, after 4 to 16 days (long-termexperiments), in an increase of Em for GA3- and ABA-treatedleaves, while in IAA-treated ones no hyperpolarization was found.Only in ABA treated leaves this membrane hyperpolarization couldbe related to an enhancement of sucrose uptake. (Received April 28, 1992; Accepted September 21, 1992) 相似文献
2.
Mónica Lowinger-Seoane Josep M. Torres-Rodríguez Neus Madrenys-Brunet Salvador Aregall-Fusté Pere Saballs 《Mycopathologia》1992,120(3):143-146
Retrospective studies have shown the occurrence of episodes of deep or superficial fungal infections in 58 to 81% of HIV/AIDS patients as a result of impairment of cell immunity. We describe a case of disseminated cutaneous dermatophytoses caused by Trichophyton mentagrophytes and Microsporum canis in a patients with AIDS. Diagnostic and therapeutic problems in relation to this unsual presentation are emphasized as well as the importance of an early mycologic diagnosis to prescribe antifungal therapy. 相似文献
3.
Paulo E. Oliveira Peter E. Gibbs Ana Angélica Barbosa Salvador Talavera 《Plant Systematics and Evolution》1992,179(3-4):207-219
The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens. 相似文献
4.
José L. García-Martínez Manuel Martí Teresa Sabater Amparo Maldonado Yolanda Vercher 《Physiologia plantarum》1991,83(3):411-416
The histological development of fertilized ovules during fruit-set and development in pea ( Pisum sativum L. cv. Alaska) has been investigated. Killing the ovules on day 0 (anthesis) or day 1 prevented fruit-set and resulted in ovary degeneration. When the ovules were destroyed at later stages the ovaries developed, though the rate of growth of the pod was reduced significantly. Pollination in pea occurs normally the day before anthesis, and fertilization of the egg cell 32 to 48 h later. The first divisions of the zygote and endosperm nuclei started simultaneously (ca 48 h after pollination) but the endosperm developed more rapidly than the embryo; the embryo sac cavity was lined with free endosperm nuclei at the time of beginning suspensor elongation. Extracts of endosperm and ovule coats from ovules at day 7 after anthesis showed fruit-set activity in pea, the latter material having about 3 times more activity than the former per ovule basis. These results indicate that fertilization of the ovule is necessary for fruit-set in pea, and that compounds which induce fruit-set are probably synthesized in the ovules following fertilization. 相似文献
5.
Reduction potential of iron in transferrin 总被引:1,自引:0,他引:1
D C Harris A L Rinehart D Hereld R W Schwartz F P Burke A P Salvador 《Biochimica et biophysica acta》1985,838(3):295-301
The reduction potential of Fe3+ in transferrin was measured spectrophotometrically by equilibration with methyl viologen in the presence of sodium dithionite. For an ionic strength near 0.1 M at 25 degrees C and pH 7.3 under 0.048 atm. CO2, half of the iron is reduced at a potential near -0.40 V (vs. standard hydrogen electrode). At least one disulfide bond of the protein is partially reduced at a potential of -0.44 V, as evidenced by reaction with [14C]iodoacetate. 相似文献
6.
John A. Salmon Lorna C. Tilling Salvador Moncada 《Prostaglandins & other lipid mediators》1985,29(3):377-385
The effect on arachidonate metabolism of two compounds (BW755C and benoxaprofen) which have been reported to inhibit 5′ lipoxygenase in leukocytes has been evaluated in human polymorphonuclear leukocytes (PMN) stimulated with the calcium ionophore A23187 and serum-treated zymosan (STZ). The syntheses of leukotriene B4 (LTB4) and thromboxane B2 (TXB2) from endogenous substrate were determined by specific radioimmunoassays as indicators of 5′ lipoxygenase and cyclo-oxygenase activity in the PMN respectively. Benoxaprofen inhibited the synthesis of leukotriene B4 by human PMN stimulated with the calcium ionophore A23187, but it was approximately 5 times less potent than BW755C. However, benoxaprofen (IC50 1.6 × 10−4M) was approximately 100 times less potent than BW755C (IC50 1.7 × 10−6M) at inhibiting leukotriene B4 synthesis induced by serum-treated zymosan. Both drugs inhibited thromboxane synthesis by leukocytes stimulated with A23187 or serum-treated zymosan at similar concentrations (approximately 5 × 10−6M). The data obtained using STZ as stimulus are consistent with previous
studies and indicate that benoxaprofen is a relatively selective inhibitor of cylco-oxygenase. However, this selectivity was far less apparent when A23187 was used as a stimulus to release the eicosanoids which suggests that this inhibition could be via an indirect mechanism and therefore A23187 should be used with caution as a stimulus of 5′ lipoxygenase for evaluating inhibitors of eicosanoid synthesis. 相似文献
7.
Ramón F. Pinilla Amparo Cano Luis Boto Angel Pestan˜a 《Biochemical and biophysical research communications》1984,119(3):1141-1146
A transitory increase in ornithine decarboxylase activity has been observed soon after food removal from Dictyostelium discoideum amoeba. This increase can be prevented by supplementation of the differentiation buffer with the 11 amino acids known for their ability to retard the development of this slime mold. Lysine can replace the amino acid mixture with an apparent inhibition constant of 50 micromolar. This inhibition by lysine, which was only observed in vivo, took place within 5 min and was readily reversed upon lysine removal. 相似文献
8.
Nieves M. Aparicio-Pagés Hein W. Verspaget Salvador A. Peña Cornelis B. H. W. Lamers 《Cancer immunology, immunotherapy : CII》1989,28(4):301-304
Summary The present study was undertaken to study natural killer (NK) cell activity in patients with colorectal cancer at peripheral and local levels. Mononuclear cells were isolated from uninvolved colorectal mucosa, tumor tissue and peripheral blood, and tested against the colon carcinoma cell line CaCo-2 and the erythroleukemia cell line K-562. Peripheral blood NK cell activity from the patients showed similar levels compared with healthy controls, whereas, mononuclear cells of tumor tissue were found to have a significantly decreased NK cell activity compared to the normal intestinal mucosa (P<0.01). No relation was found between the NK cell activity and the advancement of the disease according to the Duke's stage. Interferon- (IFN-) stimulated the NK cell activity of the mononuclear cells from blood, mucosa and tumor. However, the increase of NK cell activity after IFN- stimulation was lower in the tumor compared to the mucosa (P<0.02). The lectin, phytohaemagglutinin, increased the cytotoxicity of mononuclear cells from blood, mucosa and tumor to a similar level. These results suggest that patients with colorectal tumors exhibit a normal NK cell activity in peripheral blood and intestinal mucosa; however, a diminished NK cell activity exists at the tumor level. Although mononuclear cells isolated from the tumor have a normal response to lectin stimulation they show hyporesponsiveness to IFN- stimulation with regard to their NK cell activity. 相似文献
9.
Uptake rate of calcium, potassium, nitrate-N and phosphorus were measured in a second order Mediterranean temporary stream, in February and March 1992. This study analyzed a period of continuous surface flow between two hydrologic disturbance events (flood and drought) of an annual hydrological cycle (1991–92).The lowest values of uptake length were recorded for nitrate-N in February 92 and calcium in March 92. Nitrate had the highest uptake rate in both release performances, and potassium showed the lowest uptake rate values. The increase of calcium and nitrate uptake rate between February 92 and March 92 suggested a higher ecosystem efficiency in nutrient retention with a higher temperature and light intensity and slower water velocity, discharge and water depth. These results obtained were similar to those reported in permanent streams, indicating that in periods of continuous surface flow (without extreme hydrologic disturbance), abiotic factors can influence nutrient retention in temporary streams. 相似文献
10.
Digeneans of the family Campulidae occur exclusively in marine mammals, particularly in cetaceans. Their taxonomy is confused, being based on adult morphology only. We used a multivariate discriminant analysis of morphometric data to provide new evidence on the taxonomy of the Campulidae. Measurements of 217 specimens from 21 species of all seven genera of the family were taken. The percentage of specimens correctly assigned into their own species was 96.3%. The first three discriminant functions accounted for most of the variation between the species, which were grouped together in suprageneric groups along the first and the second function. The ordination pattern observed conforms partly with the established taxonomy of the Campulidae. Variation along the first discriminant function can be interpreted as a gradient of the vitelline extension and the maximum width to length ratio. This function separates three groups of species, corresponding to the Hunterotrematinae, Orthosplanchninae and Campulinae-Lecithodesminae. The last two subfamilies are separated along the second axis, the Lecithodesminae having longer bodies and suckers than the Campulinae. This study also provides some evidence at the generic and specific level. 相似文献