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11.
Degradation of heparin in mouse mastocytoma tissue 总被引:8,自引:6,他引:2
1. Heparin was prepared from mouse mastocytoma tissue by mild procedures, including extraction of mast-cell granules with 2m-potassium chloride, precipitation of the extracted polysaccharide with cetylpyridinium chloride from 0.8m-potassium chloride and finally digestion of the isolated material with testicular hyaluronidase. The resulting product (fraction GE(H)) represented approx. 40% of the total heparin content of the tissue. 2. Fraction GE(H) was fractionated by gel chromatography on Sepharose 4B into three subfractions, with average molecular weights ( M(w)) of approx. 60000-70000 (highly polydisperse material), 26000 and 9000 respectively. Treatment of each of the subfractions with alkali or with papain did not affect their behaviour on gel chromatography. Amino acid and neutral sugar analyses indicated that the two low-molecular-weight fractions consisted largely of single polysaccharide chains lacking the carbohydrate-protein linkage region. It was suggested that these heparin molecules had been degraded by an endopolysaccharidase. 3. Pulse labelling in vivo of mastocytoma heparin with [(35)S]sulphate showed initial labelling of large molecules followed by a progressive shift of radioactivity toward fractions of lower molecular weight. Further, heparin-depolymerizing activity was demonstrated by incubating (35)S-labelled heparin in vitro with a mastocytoma 10000g-supernatant fraction. Appreciable degradation of the polysaccharide occurred, as demonstrated by gel chromatography. In contrast, no depolymerization was observed on subjecting (14)C-labelled chondroitin sulphate to the same procedure. 相似文献
12.
1. Electrophoresis of chondroitin sulphate, before and after partial degradation with testicular hyaluronidase, revealed charge heterogeneity of the degraded but not of the intact polymer. 2. Hyaluronidase-treated chondroitin sulphate was fractionated by gel chromatography. Two subfractions which were essentially monodisperse with regard to molecular weight (values of 8600 and 4800, respectively) were separated further by chromatography on Dowex 1. The resulting subfractions differed considerably with respect to their sulphate/disaccharide molar ratios. 3. Amino acid and neutral-sugar analyses of the Dowex 1 subfractions showed that the less sulphated fragments contained the carbohydrate-protein linkage region, whereas the high-sulphated fragments essentially lacked this constituent. It was concluded that chondroitin sulphate contains relatively less sulphate in the vicinity of the carbohydrate-protein linkage region than in the more peripheral portion of the polysaccharide chain. 相似文献
13.
Distribution of sulphate and iduronic acid residues in heparin and heparan sulphate 总被引:12,自引:12,他引:0 下载免费PDF全文
1. A method was developed for determination of the uronic acid composition of heparin-like glycosaminoglycans. Polymers or oligosaccharides are degraded to monosaccharides by a combination of acid hydrolysis and deamination with HNO2. The resulting uronic acid monosaccharides (accounting for about 70% of the uronic acid contents of the starting materials) are isolated and converted into the corresponding aldono-1,4-lactones, which are separated by g.l.c. The calculated ratios of glucuronic acid/iduronic acid are reproducible within 5%. 2. Samples of heparin from pig intestinal mucosa (molar ratio of sulphate/disaccharide unit, 2.40) and heparan sulphate from human aorta (sulphate/disaccharide ratio, 0.46) were subjected to uronic acid analysis. l-Iduronic acid constituted 77% and 19% respectively of the total uronic acid contents. 3. The correlation between the contents of sulphate and iduronic acid indicated by this finding also applied to the fractionated deamination products of the two polymers. The sulphated fragments varied in size from disaccharide to octasaccharide (or larger) and showed sulphate/disaccharide molar ratios in the range of 0.05–2.0. The proportion of iduronic acid increased with increasing ester sulphate contents of the oligosaccharides. 4. Previous studies on the biosynthesis of heparin in a cell-free system have shown that l-iduronic acid residues are formed by C-5 epimerization of d-glucuronic acid units at the polymer level; the process requires concomitant sulphation of the polymer. The results obtained in the present structural study conform to these findings, and suggest further that similar mechanisms may operate in the biosynthesis of heparan sulphate. The epimerization reaction appears to be linked to the sulphation of hydroxyl groups but does not seem to require sulphation of the target uronic acid residues. The significance of sulphamino groups in relation to the formation of iduronic acid is unknown. 相似文献
14.
15.
The Ultrastructure of a Cyanophage Attack on Anabaena variabilis 总被引:2,自引:0,他引:2
Cyanophages multiplying on the nitrogen fixing blue-green alga Anabaena variabilis Kütz. were revealed by electron microscopy. Severe ultrastructural changes have been observed in the vegetative cells, whereas the heterocysts appeared resistant to the cyanophage. A lytic cycle was observed from adsorption to lysis. 相似文献
16.
Summary Cyclical changes in bovine endometrial gland cells were investigated in six heifers, three at estrus and three at day twelve of the estrous cycle in the luteal phase. The epithelium is generally low at estrus but high in the luteal phase. There are ciliated and non-ciliated cells. The ciliated cells are fewer and lighter and show inconspicuous cyclical changes.The secretory cells show more prominent changes. At estrus, their free border is flat with short microvilli. The conspicuous rough-surfaced endoplasmic reticulum may synthesize protein for later secretion. The Golgi complex seems inactive. The high number of cytosegresomes and dense bodies might express cell regression caused by endocrine changes.In the luteal phase, the cells are lighter with long microvilli. The Golgi apparatus shows vacuoles and immature secretory droplets. Secretory vacuoles with light contents occur in the apical cytoplasm. Some of them appear to discharge their contents into the lumen. This is interpreted as evidence of merocrine secretion. Accumulations of tubular, smooth-surfaced endoplasmic reticulum, masses of glycogen granules, and several fat droplets are present.Some lymphocytes and degranulated granulocytes are seen near the basement membrane, more frequently at estrus.Financial support for this study was received from Anslaget för främjande av medicinsk forskning vid Veterinärhögskolan.The authors express their gratitude to Prof. A. Bane and Dr. J.-E. E. Ringmar, Department of Obstetrics and Gynecology, for their help with the selection and clinical control of the animals and for keeping them in good condition.Post doctoral fellow, No. 43-KO-52 (1968) from the Educational Ministry of Japan. 相似文献
17.
18.
Thymocyte growth peptide (TGP) initiates DNA synthesis in immature thymocytes and has previously been characterized as an acidic peptide isolated from calf thymus. We now report the isolation of TGP from sheep thymus and show it to be a nonapeptide with a large N-terminal blocking moiety characterized by high UV absorbance. The amino acid composition is identical to FTS, consisting of 2 Gly, 2 Ser, 2 Glx, 1 Ala, 1 Lys, 1 Asx. In contrast to FTS, TGP is acidic with an apparent isoelectric point of 4.2 and a high UV absorbance at 270–280 nm. Reverse phase chromatography of TGP at an acidic pH results in a change of the molecule and the appearance of two new compounds TGP-A and TGP-B, both with less than 50% of the original TGP activity. Full activity could be restored by the addition of ZnCl2 to TGP-A. Both TGP-A and B have some amino acid composition and high UV absorbance as native TGP. We propose that TGP consists of a non-peptide moiety bound to the N-terminal of the nonapeptide Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn and that the active molecule is stabilized by Zn2+. 相似文献
19.
Ephyra larvae and small medusae (1.795 mm diameter, 0.01350mg ash-free dry wt, AFDW) of the scyphozoan jellyfish Aureliaaurita were used in predation experiments with phytoplankton(the flagellate Isochrysis galbana, 4 µm diameter, {smalltilde}6 x 106 µg AFDW cell1), ciliates (theoligotrich Strombidium sulcatum, 28 µm diameter, {smalltilde}2 x 103 µg AFDW), rotifers (Synchaeta sp.,0.5 µg AFDW individual1) and mixed zooplankton(mainly copepods and cladocerans, 2.13.1 µg AFDWindividual1). Phytoplankton in natural concentrations(50200 µg C I1) were not utilized by largemedusae (4495 mm diameter). Ciliates in concentrationsfrom 0.5 to 50 individuals ml"1 were consumed by ephyra larvaeand small medusae (314 mm diameter) at a maximum predationrate of 171 prey day1, corresponding to a daily rationof 0.42%. The rotifer Synchaeta sp., offered in concentrationsof 100600 prey I1, resulted in daily rations ofephyra larvae (25 mm diameter) between 1 and 13%. Mixedzooplankton allowed the highest daily rations, usually in therange 540%. Large medusae (>45 mm diameter) consumedbetween 2000 and 3500 prey organisms day"1 in prey concentrationsexceeding 100 I1. Predation rate and daily ration werepositively correlated with prey abundance. Seen over a broadsize spectrum, the daily ration decreased with increased medusasize. The daily rations observed in high abundance of mixedzooplankton suggest a potential scope for growththat exceeds the growth rate observed in field populations,and this, in turn, suggests that the natural populations areusually food limited. The predicted predation rate at averageprey concentrations that are characteristic of neritic environmentscannot explain the maximum growth rates observed in field populations.It is therefore suggested that exploitation of patches of preyin high abundance is an important component in the trophodynamicsof this species.
1Present address: University of Bergen, Department of MarineBiology, N-5065 Blomsterdalen, Norway 相似文献
20.
Evolution takes place in an ecological setting that typically involves interactions with other organisms. To describe such
evolution, a structure is needed which incorporates the simultaneous evolution of interacting species. Here a formal framework
for this purpose is suggested, extending from the microscopic interactions between individuals – the immediate cause of natural
selection, through the mesoscopic population dynamics responsible for driving the replacement of one mutant phenotype by another,
to the macroscopic process of phenotypic evolution arising from many such substitutions. The process of coevolution that results
from this is illustrated in the context of predator–prey systems. With no more than qualitative information about the evolutionary
dynamics, some basic properties of predator–prey coevolution become evident. More detailed understanding requires specification
of an evolutionary dynamic; two models for this purpose are outlined, one from our own research on a stochastic process of
mutation and selection and the other from quantitative genetics. Much of the interest in coevolution has been to characterize
the properties of fixed points at which there is no further phenotypic evolution. Stability analysis of the fixed points of
evolutionary dynamical systems is reviewed and leads to conclusions about the asymptotic states of evolution rather different
from those of game-theoretic methods. These differences become especially important when evolution involves more than one
species.
Received 10 November 1993; received in revised form 25 July 1994 相似文献