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51.
Stephen M. Henry Per-?ke Jovall Sohbat Ghardashkhani Mikael L. Gustavsson Bo E. Samuelsson 《Glycoconjugate journal》1995,12(3):309-317
Total non-acid glycosphingolipids were isolated from the plasma of a healthy red blood cell group O Le(a-b-) salivary ABH secretor individual. Glycolipids were fractionated by HPLC and combined into eight fractions based on chromatographic and immunoreactive properties. These glycolipid fractions were analysed by thin-layer chromatography and tested for Lewis activity with antibodies reactive to the type 1 precursor (Lec), H type 1 (Led), Lea and Leb epitopes. Fractions were structurally characterized by mass spectrometry (EI-MS and LSIMS) and proton NMR spectroscopy. Expected blood group glycolipids, such as H type 1, (Fuc1-2Gal1-3GlcNAc1-3Gal1-4Glc1-1Cer) were immunochemically and structurally identified. Inconsistent with the red cell phenotype and for the first time, small quantities of Leb blood group glycolipids (Fuc1-2Gal1-3(Fuc1-4)GlcNAc1-3Gal1-4Glc1-1Cer) were immunochemically and structurally identified in the plasma of a Lewis-negative individual. These findings confirm recent immunological evidence suggesting the production of small amounts of Lewis antigens by Lewis negative individuals.
Abbreviations: HPLC, high performance liquid chromatography; TLC, (high performance) thin layer chromatography; EI-MS, electron impact ionisation mass spectrometry; LSIMS, liquid secondary ion mass spectrometry; NMR, nuclear magnetic resonance spectroscopy. The sugar types are abbreviated to Hex for hexose, HexNAc forN-acetylhexosamine and dHex for deoxyhexose (fucose). The ceramide types are abbreviated to d for dihydroxy and t for trihydroxy base, n for non-hydroxy and h for hydroxy fatty acids; LCB, long chain base. 相似文献
52.
A method for the estimation of chlorophyll turnover in wheat leaves is presented. This is based on the inhibition of chlorophyll synthesis by treatment of the cut leaves with laevulinic acid (LA), a competitive inhibitor of δ-aminolaevulinic acid dehydratase. The turnover of chlorophyll in young, greening leaves, given short periods of light was a relatively rapid process. However, in seedlings exposed to light for longer periods the turnover became progressively slower, and was measured in days rather than hours. 相似文献
53.
Microcysts of the myxomycete Didymium iridis were induced to excyst by transfer to 5mM potassium phosphate buffer. After 1 h in suspension, 90% of the microcysts had germinated into myxamoebae distinguishable by phase contrast microscopy and staining with Lugol's iodine. Both pH and osmolarity affected the kinetics of excystment. The rate and extent of excystment were decreased by cycloheximide but remained unaffected by actinomycin D, suggesting a requirement for protein synthesis but not RNA synthesis. Initially, the outer wall layers separated from the inner layer, which gradually expanded and loosened. The protoplast rehydrated and reverted to a vegetative morphology. Excysting cells were characterized by nucleolar inclusions, changes in the nuclear envelope and plasma membrane, appearance of ringed cisternal elements and microbodies in the cytoplasm, and formation of a densely fibrous zone adjacent to the site of emergence. Excysting populations have been classified into characteristic stages: mature, initiated, swollen, and pre-emergent microcysts.Florida Agricultural Experiment Station Journal Series No. 2407 相似文献
54.
Marsh white seedless grapefruit were treated with the 2-diethylaminoethanol esters of the following acids: benzoic, phenylacetic, hydrocinnamic, 4-phenylbutyric, 5-phenylvaleric, valeric, hexanoic, heptanoic, octanoic, nonanoic, 5-chlorovaleric, cyclohexanecarboxylic, phenoxyacetic, p-chlorophenoxyacetic, 3-phenoxypropionic, cinnamic and p-chlorocinnamic. Several of these esters, in particular the hexanoate, 4-phenylbutyrate and cinnamate, caused the accumulation of large amounts of β-carotene. The effects of the hexanoate and of 2-phenoxytriethylamine, which causes only lycopene accumulation, were studied as functions of time. The hexanoate caused the rapid accumulation of lycopene during the first day. The amount of lycopene then began to decrease and that of β-carotene increased until, after 14 days, β-carotene was the major pigment. 2-Phenoxytriethylamine caused rapid lycopene accumulation during the first day and a slow steady increase afterwards. Thus, the mode of action of the β-carotene inducers may be similar to that of the lycopene inducers except that the former are probably rapidly hydrolysed by the esterase(s) in the flavedo, so that they no longer inhibit the cyclase(s), and β-carotene is accumulated at the expanse of lycopene. 相似文献
55.
A method has been developed for the measurement of DNA synthesis in vivo using the incorporation of multilabeled, non-radioactive thymidine. Simultaneous intraperitoneal injection of hexalabeled thymidine and tritiated thymidine into a normal adult rat resulted in the incorporation of both labeled nucleosides into the DNA of cells undergoing replication. The DNA of several tissues and organs was analysed, including liver, thymus, spleen, bone marrow, and small intestine. Following extraction with hot trichloroacetic acid, acid hydrolysis, and thin-layer chromatography of the hydrolysates, the isotopic compositions of the thymine products were determined by field ionization mass spectrometry and by scintillation counting. The relative incorporation of radioactive and stable isotope-labeled thymidine was similar in all tissues, and corresponded to the ratio of the two labeled nucleosides in the injected material. These results indicate the feasibility of utilizing thymidine multilabeled with stable isotopes for measurement of cellular proliferation rates in conjunction with cancer therapy. 相似文献
56.
Anne T. Truesdale David A. Johnson Hendrick G. Bedigian Henry C. Outzen George A. Carlson 《Cellular immunology》1982,74(1):120-125
C57BL/6J-bgJ mice are reported to be less susceptible to tumor induction by threshold doses of Moloney murine sarcoma virus than their +/bg littermates, and there are no significant differences between and +/bg mice in which tumors were induced with respect to tumor latency, size, and regression rate. The difference in tumor frequency cannot be accounted for by M-MSV boosting of activity in mice or by depression of activity in +/bg animals. 相似文献
57.
Role of siderophores in the biocontrol of Pseudomonas tolaasii by fluorescent pseudomonad antagonists 总被引:1,自引:1,他引:0
A number of pseudomonad bacteria were investigated for their in vitro antagonism on agar against Pseudomonas tolaasii , the causative agent of bacterial blotch of the cultivated mushroom. Addition of FeCl3 to the culture medium suppressed the antagonism in 14 of the 20 bacteria tested and the production of a substance with an absorption peak at 400 nm by all antagonists was eliminated by the presence of Fe3+ . Both observations indicated that siderophores could be involved in the mode of action of some antagonists. The addition of the iron chelators EDTA and bipyridyl to the medium used for culture of antagonists and pathogens did not generally prevent growth. Siderophore production is not essential for the in vivo activity of antagonists. 相似文献
58.
Effects of chilling on tomato fruit texture 总被引:1,自引:0,他引:1
The effects of chilling on tomato ( Lycopersicon esculentum Mill cv. Caruso) texture were investigated using fruit stored at 22°C (nonchilled) or 5°C (chilled) for 28 days. or at 5°C for 15 days before transfer to 22°C to facilitate ripening during and additional 13 days (prechilled). Prechilled fruit exhibited symptoms of slight chilling injury, i.e. development of mealiness, accelerated softening relative to that of nonchilled fruit and nonuniform surface colour development. The firmness of all fruit decreased during ripening and chilled storage when measured by flat plate compression and puncture, especially during the early stages of ripening of nonchilled and prechilled fruit. The compression firmness of pericarp tissue similarly decreased during ripening of nonchilled and prechilled fruit, but was maintained during chilling. Total moisture content (ca 94%) of tissue, uronide content (32-35% w/w) and extracted β-galactosidase activity did not differ significantly ( P > 0.05) among fruit during ripening and chilled storage. The degree of uronide methyl esterification in ethanol-insoluble solids prepared from pericarp tissue (EIS) was relatively low for all fruit. i.e. <40%. EIS from which greater levels of pectinesterase were extracted (i.e. nonchilled>chilled>prechilled) exhibited decreased levels of uronide methyl esterification. Markedly elevated levels of β-glucosidase activity were extracted from prechilled EIS. Total polygalacturonase activity (mainly as PGI) and autolysis of enzyme-extracted EIS were inversely correlated ( P ≤ 0.05) only with the loss of nonchilled fruit and tissue firmness and prechilled fruit firmness. Results suggest a possible role for β-glucosidase in textural changes of prechilled fruit and tissue (e.g. loss of firmness, development of mealiness) and also implicate loss of skin strength in the softening of whole fruit during chilling. 相似文献
59.
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