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71.
Antonio Campos-Neto Fernanda W. M. Lima Arnaldo F. B. Andrade 《The Journal of eukaryotic microbiology》1985,32(1):84-88
A rapid and simple method for the purification of amastigotes of Trypanosoma cruzi from spleens of infected mice is described. A protein A-Scpharose 4B immunoadsorbent column bound with antisera to epimastigotes of T. cruzi was used to purify the tissue forms of this parasite. Host cells and debris are not retained, and parasites can be eluted in high yields and purity. Studies of surface glycoproteins and glycolipids of the purified amastigotes with 18 lectins of various specificities revealed the presence on the parasites of receptors for N-acetylglucosamine, N-acetylgalactosamine, D-galactose, and D-mannose binding lectins. 相似文献
72.
F. J. Silva 《Genetica》1984,63(2):147-152
The3H-uridine labelling patterns in J and U polytene chromosomes ofDrosophila subobscura were determined. The analysis was carried out in two developmental stages and in two strains proceeding from the same geographical origin whose genotypes were: Jst/Jst; U1+2/U1+2 and J1/J1; U1+2+8/U1+2+8 respectively. It was observed that the labelling pattern coincided very approximately with the puffing pattern in the same stages and chromosomal arrangements. Comparison of the3H-Uridine incorporation patterns between chromosomal arrangements showed light quantitative differences. These results are discussed in relation to the inversion effect. 相似文献
73.
Mixing patterns in Amazon lakes 总被引:2,自引:2,他引:0
Jose G. Tundisi Bruce R. Forsberg Allan H. Devol Thomas M. Zaret Takako M. Tundisi Antonio Dos Santos Jorge S. Ribeiro Elsa R. Hardy 《Hydrobiologia》1984,108(1):3-15
The diel mixing patterns of two small floodplain lakes, Lago Jacaretinga in the Amazon drainage, and Lago Cristalino in the Rio Negro system, were investigated during both the high-water and low-water states of the Amazon River hydrograph. Measurements included temperature, oxygen, ammonia, phosphate, and chlorophyll. In both lakes thermal stratification developed during the day and was eroded at night. During the low-water period when the lakes were shallow, nocturnal circulation extended to the lake bottom, whereas when the lakes were deeper (greater than about 5 m), circulation did not reach the bottom and an anoxic hypolimnion developed. During the low-water period, percent of oxygen concentrations were relatively high but always less than saturation. Low oxygen concentrations were observed during the high-water period. At all times nocturnal mixing supplied a significant amount of oxygen to the lake ecosystems. Nighttime upward mixing of recycled nitrogen and phosphorus also appeared to be important nutrient sources for algal productivity. 相似文献
74.
Rita Delgado J. J. R. Fraústo Da Silva M. Cndida T. A. Vaz 《Inorganica chimica acta》1984,90(3):185-190
Enthalpy changes for the complexation of alkaline-earth and transition metals with three cyclic tetra-aza-tetracetic acids (cDOTA, cTRITA and cTETA) were obtained by continuous titration calorimetry. From these values and free energy data, the entropy changes for the same reactions were derived. The results show that these complexes are stabilised by both favourable enthalpy and entropy changes, except those of Mg2+ and those of Sr2+ and Ba2+ with cTETA. Generally, the entropy changes for the reactions of the alkaline-earth metals are higher than for the reactions of the non cyclic polyaminocarboxylic acids, but for the reactions of the transition metals the entropy changes are comparable for the cyclic and non cyclic ligands. These results are discussed in terms of a model of ‘cage’ coordination of the metals.The enthalpy changes decrease with the increase in size of the tetra-aza ring (except in the case of Cu2+) but no specific cavity size effect is noticeable. Consideration of the temperature-dependent and temperature-independent contributions to ΔH supports the idea that the number of coordinated nitrogen atoms and carboxylate groups vary along the series. 相似文献
75.
Antonio Gomez Sanchez Manuel Mancera Francisco Rosado Manuel Rico 《Carbohydrate research》1984,134(1):75-82
3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-1-nitro-d-gluco-hept-1-enitol reacts with methyl acetoacetate in an unusual Michael reaction, giving the normal adduct (6), and a bicyclic derivative (9) that arises from quasi-dimerization of the former when a high concentration of the base is used. Acetylation of compound 9 gives the hydroxylamine O-acetate (10).From the reactions of 3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-nitro-d-galacto-hept-1-enitol with ethyl and tert-butyl acetoacetate, the normal adducts (7 and 8) were isolated. The structures of compounds 6 to 10 were established on the basis of their spectral properties (u.v., i.r., mass, and 1H- and 13C-n.m.r.) 相似文献
76.
77.
High density of transmembrane glycoproteins on the flagellar surface of boar sperm cells 总被引:3,自引:2,他引:1 下载免费PDF全文
Membrane halves of boar sperm flagella were produced by freeze-fracture and labeled in situ with concanavalin A and wheat germ agglutinin; the lectins were visualized with protein-gold complexes. Concanavalin A and wheat germ agglutinin binding sites partition with both protoplasmic and exoplasmic halves of the membrane. A high density of lectin marking was found on protoplasmic membrane halves; we conclude that the label corresponds to transmembrane glycoproteins that, on freeze-fracture, are dragged across the outer (exoplasmic) half of the phospholipid bilayer. Our demonstration of numerous transmembrane proteins in sperm flagella offers the structural setting for previous models on flagellar surface motility that postulate accessibility of motile membrane components to the submembranous cytoskeleton. 相似文献
78.
Summary
Aspergillus sp strains from decaying lemons were tested for extracellular pectinase production, testing differently pretreated lemon peel as the carbon source instead of pectin. It was found that the production of extracellular polygalacturonase was about the same and that of pectinesterase substantially higher when unwashed fresh lemon peel was used instead of pectin. The culture filtrate obtained showed a clarifying capacity similar to that of a commercial pectinase preparation, but the vitamin C of the juice was less affected by the treatment. 相似文献
79.
I T Toledo e Souza B L Wajchenberg F Prestes Cesar J S Almeida Neto 《Hormones et métabolisme》1983,15(12):575-580
Insulin and C-peptide (free insulin and C-peptide in insulin-treated patients) were measured after glucose stimulation in nine Type II diabetics on chlorpropamide, eleven insulin-treated maturity-onset diabetics and in 8 normal controls. Dissociation between C-peptide and insulin response to glucose was observed in several diabetics. The relation between incremental molar areas under C-peptide and insulin curves, after glucose challenge (delta CPR - delta IRI/delta CPR) were used to evaluate the hepatic insulin extraction in all but the insulin-treated diabetics. The lower insulin requirements and better control of the short-duration insulin-treated maturity-onset diabetics in relation to the long-term ones could not be explained either by the residual insulin secretion or by the level of "insulin antibodies". The chlorpropamide-responsive patients presented higher insulin levels after the glucose challenge and a lower hepatic insulin extraction than the non-responsive ones. 相似文献
80.
J R Holtman A L Buller A M Taveira Da Silva P Hamosh R A Gillis 《Life sciences》1983,32(20):2313-2320
The effects of taurine (0.8-64.8 mumol) were studied on respiratory activity following intracisternal (cisterna magna) and intracerebroventricular (lateral ventricle) injections in cats anesthetized with alpha-chloralose. Respiratory activity was measured by using a Fleisch pneumotachograph and monitoring tracheal airflow. The flow signal was integrated to obtain tidal volume (VT) and respiratory rate (f) was obtained by counting the number of VT excursions over one minute. Inspiratory (TI), expiratory (TE) and total (TTOT) cycle durations were also determined during this time period. In addition, end-tidal CO2 was continuously monitored. Associated changes in arterial pressure (femoral artery cannula) and heart rate were also determined. After injections into the cisterna magna, taurine caused dose-related decreases in minute ventilation (VE). The maximal decrease in VE was from 495 +/- 59 to 64 +/- 14 ml/min (p less than 0.05), and was due to both decreases in VT (from 27 +/- 3 to 5 +/- 1 ml; p less than 0.05) and f (from 18 +/- 1 to 12 +/- 2 breaths/min; p less than 0.05). TE and TTOT were increased from 2.4 +/- 0.4 to 4.5 +/- 0.6 sec (p less than 0.05) and from 3.7 +/- 0.4 to 6.4 +/- 0.8 sec (p less than 0.05), respectively. Mean inspiratory flow (VT/TI), a measure of inspiratory drive, was decreased from 21 +/- 4 to 4 +/- 2 ml/sec (p less than 0.05). Apnea occurred in 5 of 6 animals after the 64.8 mumol dose. This respiratory depression occurred without any significant change in arterial pressure. After lateral ventricle injections, taurine also caused dose-related, but not as pronounced, decreases in respiratory activity. In addition, taurine caused significant decreases (p less than 0.05) in arterial pressure in doses that decreased VE. Taurine administered intravenously had no significant cardiorespiratory depressant effects. These data indicate that centrally administered taurine produces respiratory depression and, depending on the route of CNS administration, also produces hypotension. 相似文献