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161.
E P Beem J J W Lisman G J Van Steijn C J Van Der Wal L A W Trippelvitz B Overdijk H Van Halbeek J H G M Mutsaers J F G Vliegenthart 《Glycoconjugate journal》1987,4(1):33-42
Acid -l-fucosidase (EC 3.2.1.51) was obtained from human liver and purified to homogeneity. The enzyme consists of four subunits; each of these has a molecular mass of 50 kDa and bears oneN-linked carbohydrate chain. The structures of these chains were studied at the glycopeptide level by methylation analysis and 500-MHz1H-NMR spectroscopy. Oligomannoside-type chains andN-acetyllactosamine-type chains are present in an approximate ratio of 31. While the oligomannoside-type chains show some heterogeneity in size (Man5–8GlcNAc2), theN-acetyllactosaminetype chains are exclusively bi-(2–6)-sialyl, bi-antennary in their structure.These observations on the carbohydrate moieties of -l-fucosidase substantiate our hypothesis [Overdijket al. (1986) Glycoconjugate J 3:339–50] with respect to the relationship between the oligosaccharide structure of lysosomal enzymes and their residual intracellular activity in I-cell disease. For the series of enzymes examined so far, namely, -N-acetylhexosaminidase, -l-fucosidase and -galactosidase, the relative amount ofN-acetyllactosamine-type carbohydrate increases, while the residual intracellular activity in I-cell disease tissue decreases in this order. The system which is responsible for preferentially retaining hydrolases with (non-phosphorylated) oligomannoside-type chains both in I-cells and in normal cells has yet to be identified. 相似文献
162.
P J McAlpine N Van Cong C Boucheix A J Pakstis R C Doute T B Shows 《Cytogenetics and cell genetics》1987,46(1-4):29-101
163.
The distribution of low density lipoprotein (LDL) receptors marked with colloidal gold-conjugated low density lipoproteins has been mapped on the surfaces of cultured human skin fibroblasts and bovine aortic endothelial cells viewed whole in the transmission electron microscope. A dispersed or scattered population of LDL receptors, in addition to and clearly distinct from clustered receptors was detected on the surfaces of both fibroblasts and dividing endothelial cells. No LDL receptors could be detected on contact-inhibited endothelial cells. Clustered receptors imaged in whole-mount preparations were often arranged in rings with an approximate diameter of 250 nm. In ultra-thin sections of marked cells, clustered receptors were localised in coated pits while the few dispersed receptors seen were restricted to non-coated membrane regions. Clustered receptors often appeared localised on the rims of coated pits whose central areas were not marked. The dispersed population of receptors was usually distributed diffusely amongst the clusters on dividing endothelial cells and normal fibroblasts. Only the dispersed population appeared on LDL receptor internalisation-defective mutant fibroblasts. The marginal zones of both fibroblasts and dividing endothelial cells were populated by dispersed receptors. Clusters appeared further "inland" and were rarely seen near the cell margins. These results indicate that LDL receptors on dividing endothelial cells and fibroblasts may be dispersed on the cell surface upon or soon after their insertion during recycling. 相似文献
164.
In the present study, we have localized immunohistochemically S-100 protein, glial fibrillary acidic (GFA) protein, and neuron-specific enolase (NSE) by the unlabelled antibody peroxidase-antiperoxidase technique. Special attention was paid to the influence of fixation and of pretreatment of sections with proteolytic enzymes. It appeared that the final immunostaining of a given antigen largely depends on the fixative and on the species used. Moreover, pepsin pretreatment proved to be necessary to unmask S-100 protein in quail and GFA protein in rat. S-100 protein (rat, human) and GFA protein (human) immunoreactivities were detected in the folliculo-stellate (FS) cells. In quail, S-100 protein was also found in cells, which were not arranged around a follicular lumen and, in rat, the endothelial cells were immunostained for GFA protein. Clusters of granular cells were weakly immunostained for NSE in all species. An exclusive relationship between FS cells and S-100 protein could not be ascertained from this study. 相似文献
165.
166.
167.
M. W. A. Verstegen A. Siegerink W. Van der Hel R. Geers C. Brandsma 《Journal of thermal biology》1987,12(4):257-261
The aim of the experiments was to investigate the effect of air velocity on the temperature preferred by growing pigs 12–14 weeks old. Pigs displayed a temperature preference by means of operant supplemental heating. They pushed a button connected to heating lamps. Six experiments of three weeks each and with two treatments with a group of 8 pigs each were made. Animals were housed in groups and weighed 14–20 kg at the start of the experiments. Air velocity was 0.08, 0.25 and 0.40 m/s. At each air velocity four replicates were made. Mean temperatures preferred were 17.9°C at 0.08 m/s, 20.5°C at 0.25 m/s and 21.7°C at 0.40 m/s. Within a day temperature preference fluctuated with 5.7 K at 0.08 m/s, 4.3 K at 0.25 m/s and 4.2 K at 0.4 m/s. Temperatures preferred were highest during day time. 相似文献
168.
C J Van Noorden W M Frederiks D C Aronson F Marx K Bosch G N Jonges I M Vogels J James 《Virchows Archiv. B, Cell pathology including molecular pathology》1987,52(6):501-511
Extrahepatic cholestasis induced by ligation and transsection of the common bile duct caused a change in the parenchyma/stroma relationship in rat liver. Two weeks after ligation, the periportal zones of the parenchyma were progressively invaded by expanding bile ductules with surrounding connective tissue diverging from the portal areas. Parenchymal disarray developed and small clumps of hepatocytes or isolated hepatocytes were scattered within the expanded portal areas. These cells showed normal activity of lactate, succinate and glutamate dehydrogenase and may, therefore, be considered to be functionally active. After cholestasis the remainder of the liver parenchyma showed adaptational changes with respect to glucose homeostasis, as demonstrated by histochemical means. Glycogen stores disappeared completely whereas glycogen phosphorylase activity increased about ten fold. The increased glycogen phosphorylase activity and glycogen depletion indicate a greater glycogenolytic capacity in liver parenchyma after bile duct ligation to maintain as far as possible a normal plasma glucose concentration. The parenchymal distribution pattern of glucose-6-phosphatase activity did not change significantly after bile duct ligation. The isolated hepatocytes within the expanded portal tracts showed a high activity of this enzyme whereas the pericentral parenchyma was only moderately active. The distribution patterns of glucose-6-phosphate dehydrogenase and lactate dehydrogenase activity in the liver parenchyma were also largely unchanged after bile duct ligation, but the histochemical reaction for glucose-6-phosphate dehydrogenase activity demonstrated infiltration of the remainder of the parenchyma by non-parenchymal cells, possibly Küpffer cells and leucocytes as part of an inflammatory reaction. Under normal conditions the mitochondrial enzymes succinate and glutamate dehydrogenase show an opposite heterogenous distribution pattern in liver parenchyma. Following cholestasis both enzymes became uniformly distributed. The underlying regulatory mechanism for these different changes in distribution patterns of enzyme activities is not yet understood. 相似文献
169.
Human elongation factor 1α: a polymorphic and conserved multigene family with multiple chromosomal localizations 总被引:1,自引:0,他引:1
170.
Gynodioecy, the coexistence of hermaphrodites and male steriles, is frequent in populations of Plantago lanceolata L. A condition for the maintenance of gynodioecy in an obligatory outbreeding species like this is an increase in female fitness in male steriles compared with hermaphrodites. One of the possible underlying mechanisms, a lower cyanide-resistant respiration in male steriles, which could lead to a higher metabolic efficiency, was investigated. For the experiments adult plants were used, because the effects which compensate for male sterility have been found in characters like seed production and longevity. No general correlation between sex phenotype and cyanide-resistant respiration capacity, or with any other respiration component, was found. Only in a single cross a strong correlation between cyanide-resistant respiration activity and sex phenotype was established, male steriles possessing the higher activity. The conclusion from these experiments is that there is no pleiotropic relationship between respiration levels and sex phenotype. The strongly significant correlation mentioned is ascribed to chromosomal linkage. 相似文献