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91.
Rod and cone photoreceptors project from the outer retinal surface into a
carbohydrate-rich interphotoreceptor matrix (IPM). Unique IPM
glycoconjugates are distributed around rods and cones. Wheat germ
agglutinin (WGA) strongly decorates the rod matrix domains and weakly
decorates the cone matrix domains. This study characterizes the major
WGA-binding glycoprotein in the human IPM, which we refer to as SPACR
(sialoprotein associated with cones and rods). SPACR, which has a molecular
weight of 147 kDa, was isolated and purified from the IPM by lectin
affinity chromatography. A polyclonal antibody to SPACR was prepared that
colocalizes in tissue preparations with WGA-binding domains in the IPM.
Sequential digestion of SPACR with N- and O- glycosidases results in a
systematic increase in electrophorectic mobility, indicating the presence
of both N- and O-linked glycoconjugates. Complete deglycosylation results
in a reduction in the relative molecular mass of SPACR by about 30%.
Analysis of lectin binding allowed us to identify some of the structural
characteristics of SPACR glycoconjugates. Treatment with neuraminidase
exposes Galbeta1- 3GalNAc disaccharide as indicated by positive peanut
agglutinin (PNA) staining, accompanied by the loss of WGA staining. Maackia
amurensis agglutinins (MAA-1 and MAA-2), specific for sialic acid in
alpha2-3 linkage to Gal, bind SPACR, while Sambucus nigra agglutinin (SNA),
specific for alpha2-6 linked sialic acid, does not, indicating that the
dominant glycoconjugate determinant on SPACR is the O-linked carbohydrate,
NeuAcalpha2-3Galbeta1-3GalNAc. The abundance of sialic acid in SPACR
suggests that this glycoprotein may contribute substantially to the
polyanionic nature of the IPM. The carbohydrate chains present on SPACR
could also provide sites for extensive crosslinking and participate in the
formation of the ordered IPM lattice that surrounds the elongate
photoreceptors projecting from the outer retinal surface.
相似文献
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Functional aspects of peritoneal macrophages in endometriosis of women 总被引:11,自引:0,他引:11
G A Dunselman M G Hendrix P X Bouckaert J L Evers 《Journal of reproduction and fertility》1988,82(2):707-710
Peritoneal fluid was collected in the periovulatory phase of the cycle from 25 women undergoing laparoscopy. Endometriosis was diagnosed in 13 patients (AFS score 1, N = 9; AFS score 2, N = 4) and 12 patients without endometriosis served as controls. In endometriosis patients the total peritoneal fluid cell number and cell concentration was significantly higher than in controls, indicating peritoneal irritation by endometrial implants. Peritoneal fluid macrophages in patients with endometriosis showed significantly increased erythrophagocytosis and lower chemiluminescence than in controls, suggesting an advanced differentiation of the macrophages in endometriosis patients. The macrophages in this stage of differentiation may interfere with gametes and embryos and thus contribute to endometriosis-associated subfertility. 相似文献
96.
Binding of 5S estradiol receptor to poly-deoxynucleotides 总被引:2,自引:0,他引:2
M Sluyser S G Evers T Nijssen 《Biochemical and biophysical research communications》1974,61(1):380-388
Calf uterus cytosol was incubated with (3H)estradiol and fractionated on Sephadex G-200. Two (3H)estradiol-binding protein fractions were obtained with sedimentation coefficients of 5.1 S and 3.5 S, respectively. The 5.1 S fraction bound to poly dT, poly dA:dT and poly dG:dC to a higher extent than to calf thymus DNA. The 3.5 S fraction did not bind to DNA. 相似文献
97.
K E Creek V P Walter D Evers E Yeo W L Elliott P F Heinstein D M Morré D J Morré 《Biochimica et biophysica acta》1984,793(2):133-140
Previous studies indicated a reproducible pattern of altered glycosphingolipid biosynthesis accompanying late stages of liver tumorigenesis in the rat induced by the carcinogen 2-acetylaminofluorene. The sequence began with a dramatic elevation in CMP-sialic acid:lactosylceramide sialyltransferase and was followed by sequential elevations and eventual depressions in other enzymes catalyzing sugar transfers to glycolipid acceptors. The present study focused on the early events of glycolipid biosynthesis during the first 11 weeks of 2-acetylaminofluorene administration according to the same feeding schedule as used previously. Transient elevations in CMP-sialic acid synthetase and elevations in neutral glycosphingolipid precursors to gangliosides were found to precede the major elevations in CMP-sialic acid:lactosylceramide sialyltransferase (GM3 synthetase) noted earlier. Two cycles of response were observed prior to the initiation of the sustained enhancement of biosynthesis of precursor ganglioside, GM3, and/or a significant increase in total or lipid-soluble sialic acid. In vitro rates of sialyl transfer from CMP-sialic acid to endogenous protein acceptors were not altered. The results suggest that the previous observations of altered ganglioside biosynthesis following 2-acetylaminofluorene administration are not an isolated occurrence but may represent late events in a sequence or 'cascade' of biochemical change involving, as well, biosynthesis of ganglioside precursors, CMP-sialic acid and neutral glycosphingolipids. 相似文献
98.
Giardia lamblia cysts were harvested from Mongolian gerbils and exposed to free chlorine in buffered water at pH 5, 7, and 9 at 15 degrees C. The contact times required to obtain a 2-log reduction in cyst survival (i.e., a 99% kill) were interpolated from survival curves generated at fixed concentrations of chlorine in the range of 0.25 to about 16 mg/liter. Concentration-time (C.t') products for 99% inactivation ranged from about 120 to nearly 1,500 mg.min/liter. These values are higher than those reported previously for free chlorine using G. lamblia cysts from infected humans. The cysts isolated from gerbils, as with other Giardia cysts, were unusually sensitive to chlorine in alkaline solutions. 相似文献
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