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21.
C. Benito F. J. Gallego C. Zaragoza J. M. Frade A. M. Figueiras 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(1):27-32
Summary The segregation of different isozymic loci was investigated in backcrosses and F2s in rye. The leucin aminopeptidase-1 (Lap-1), Aconitase-1 (Aco-1), Esterase-6 (Est-6), Esterase-8 (Est-8), and Endopeptidase-1 (Ep-1) loci were linked. The Aco-1, Est-6, and Est-8 loci have been previously located on the 6RL chromosome arm. The Lap-1 locus has been located on the 6RS chromosome arm. The results favor the gene order: Lap-1... (centromere)... Aco-1... Est-8... Est-6... Ep-1. The isoelectric focusing separations of aqueous extracts from mature embryo tissue of wheat-rye addition and substitution lines involving the chromosomes of cereal rye Secale cereale L. confirmed the gene location of locus Ep-1 on the 6RL chromosome arm. Screening of wheat-rye addition lines involving the chromosomes of Secale montanum revealed that Ep-1 locus is not located on chromosome 6R of S. montanum. These results are the first biochemical evidence of the translocation between chromosome arms 6RL/7RL in the evolution of S. cereale from S. montanum. 相似文献
22.
Rita Baraldi Francesca Fasolo Fabbri Malavasi Stefano Predieri Marco Castagneto 《Plant Cell, Tissue and Organ Culture》1991,24(3):187-191
The effects of humic substances on in vitro culture of Golden Delicious apple are reported. Potassium humate (KH) when used in proliferation showed a negative interaction with BA while it enhanced rooting when IBA was not present in the culture medium. In the presence of IBA, KH increased root number and reduced root growth. The highest concentration tested, 500 mg l-1, caused a drastic reduction in root system development. 50 mg l-1 KH hastened rooting and plants grew more rapidly when transferred to soil. 相似文献
23.
An acyl coenzyme A:cholesterol acyltransferase activity which directly incorporates palmitoyl coenzyme A into cholesterol esters using endogenous cholesterol as substrate was demonstrated in microsomal preparations from neonatal chick brain. The enzyme showed, at pH 7.4, about 2-fold greater activity than that observed at pH 5.6. Nearly 10-times higher esterifying activity was found in brain microsomes using palmitoyl coenzyme A than that with palmitic acid. The acyltransferase activity was clearly different from the other cholesterol-esterifying enzymes previously found in brain, which incorporated free fatty acids into cholesterol esters and did not require ATP or coenzyme A as cofactors. Chick brain microsomes also incorporated palmitoyl coenzyme A into phospholipids and triacylglycerols. However, most of the radioactivity from this substrate was found in the fatty acid fraction, due to the presence of an acyl coenzyme A hydrolase activity in the enzyme preparations. Therefore, the formation of palmitate was tested during all the experiments. The brain acyltransferase assay conditions were optimized with respect to protein concentration, incubation time and palmitoyl coenzyme A concentration. Microsomal activity was independent of the presence of dithiothreitol in the incubation medium and microsomes can be stored at -40 degrees C for several weeks without losing activity. Addition of fatty acid-free bovine serum albumin to brain microsomal preparations produced a considerable increase in the acyltransferase activity, while acyl coenzyme A hydrolase was clearly inhibited. Results obtained show the existence in neonatal chick brain of an acyl coenzyme A:cholesterol acyltransferase activity similar to that found in a variety of tissues from different species but not previously reported in brain. 相似文献
24.
G Semenzato C Agostini R Zambello L Trentin M Chilosi G Pizzolo G Marcer A Cipriani 《Journal of immunology (Baltimore, Md. : 1950)》1986,137(4):1164-1172
Cells recovered from bronchoalveolar lavage (BAL) and tissue sections from transbronchial lung biopsies were studied in 16 patients with symptomatic hypersensitivity pneumonitis (HP) and in six subjects with a similar history of exposure but without features of disease by using a series of monoclonal antibodies (MoAb) detecting different lymphocyte subpopulations, including T and T subsets, B lymphocytes, and natural killer (NK) cells. Their functional activities in cytotoxic and suppressor assays and the microenvironment in the lung by using immunohistological techniques were also evaluated. It has been demonstrated that the majority of cells recovered from BAL of HP patients are represented by T8 lymphocytes, with a relevant imbalance of the T4/T8 ratio (p less than 0.001). HNK-1+ cells were markedly increased (p less than 0.001), whereas the frequency of cells bearing other NK-related markers (NK-15, VEP 13, Ab8.28, T10, M1, and Fc gamma R) were not significantly increased with respect to controls. Immunohistological study confirmed that the majority of cells infiltrating lung parenchyma are T8+ lymphocytes. The number of HNK-1+ cells detected on lung biopsies was very low in all cases, even in patients with the highest values on BAL suspensions. The evidence of cells bearing the proliferation-associated markers (Tac and T9 antigens) seems to support the hypothesis of a local proliferation in the lung. In terms of phenotypic analysis, the results observed in the group of asymptomatic individuals are qualitatively superimposable on those observed in the HP group, but the magnitude of the phenomenon is less prominent and therefore the data are not as statistically significant as that produced by the comparison between HP patients and the same controls. Functional analysis of BAL T cells from both HP patients and asymptomatic individuals showed suppressor activity in vitro, as determined by the ability to influence a pokeweed mitogen (PWM)-driven B cell differentiation assay. BAL cells from HP patients were also able to display a definite cytotoxic function in vitro, whereas BAL lymphocytes from asymptomatic subjects did not. Taken together, these data demonstrated that cells responsible for the alveolitis in patients with HP are characterized by the expansion of T cells with the phenotype and functions of both suppressor and/or cytotoxic lymphocytes. This expansion is likely to be related to a local immunologic response to the antigenic stimulus and may provide new insights into the pathogenetic mechanisms of this disease, its pathological pattern, and its management. 相似文献
25.
Role of mevalonate-5-pyrophosphate decarboxylase in the regulation of chick intestinal cholesterogenesis 总被引:2,自引:0,他引:2
D Gonzalez-Pacanowska C Marco J Garcia-Martinez E Garcia-Peregrin 《Biochimica et biophysica acta》1985,833(3):449-455
The response to different dietary conditions of the enzymes responsible for the transformation of mevalonic acid to isopentenyl pyrophosphate has been studied for the first time in the small bowel of the chick to elucidate the role of these enzymes in the regulation of intestinal cholesterogenesis. Feeding a 2% cholesterol diet from hatching resulted in a small but significant inhibition of mevalonate-5-pyrophosphate decarboxylase, while mevalonate kinase and mevalonate-5-phosphate kinase remained unaltered. Similar results were obtained for the three enzymes when 13-day-old chicks fed a standard fat-free diet were switched to a 5% cholesterol diet. Starved chicks exhibited lower intestinal decarboxylase activity than chicks fed a standard diet, while refeeding resulted in levels of activity similar or slightly greater than controls. None of the enzymes effecting the conversion of mevalonate to isopentenyl pyrophosphate in the small intestine presented diurnal variations. Results obtained suggest that mevalonate-5-pyrophosphate decarboxylase may play a significant role in the regulation of cholesterol synthesis in the small intestine. 相似文献
26.
Summary A voltage-dependent anion-selective channel, VDAC, is found in outer mitochondrial membranes. VDAC's conductance is known to decrease as the transmembrane voltage is increased in either the positive or negative direction. Charged groups on the channel may be responsible for this voltage dependence by allowing the channel to respond to an applied electric field. If so, then neutralization of these charges would eliminate the voltage dependence. Channels in planar lipid bilayers which behaved normally at pH 6 lost much of their voltage dependence at high pH. Raising the pH reduced the steepness of the voltage dependence and raised the voltage needed to close half the channels. In contrast, the energy difference between the open and closed state in the absence of a field was changed very little by the elevated pH. The groups being titrated had an apparent pK of 10.6. From the pK and chemical modification, lysine epsilon amino groups are the most likely candidates responsible for VDAC's ability to respond to an applied electric field. 相似文献
27.
Summary Southern Corn Leaf Blight is caused by a toxin produced by a virulent form ofHelminthosporium maydis (Race T). The toxin has been shown to uncouple oxidative phosphorylation and dissipate Ca2+ gradients in mitochondria isolated from susceptible, but not resistant, corn. The possibility that the toxin acted by increasing the permeability of membranes to ions was tested using a planar bilayer membrane system. Addition of the toxin to the bilayer system, under voltage-clamp conditions, resulted in stepwise increases in current across the phospholipid bilayer, a response characteristic for channel formers. Single-channel conductance in 1m KCl is 27 pS which corresponds to 1.7×107 ions sec–1 channel–1 at 100 mV applied potential. The toxin channels are: (i) fairly uniform in conductance, (ii) ideally selective for K+ over Cl–, and (iii) most conductive to H+. The channel showed the following selectivity for alkali metal cations: Rb+>K+>Cs+>Na+>Li+ (169731) based on the most frequently observed conductance in 1m chloride salts. The toxin showed no voltage dependence over the range of –100 to +100 mV. Channel formation was also a property of a synthetic analog (Cmpd IV) of the toxin. The ability of the native toxin to form channels may be a mode of toxin action on mitochondrial membranes from susceptible corn. 相似文献
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