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Query: UNIPROT:Q9UIJ5 (Rec)
 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The morphology and development of junctional complexes between blastomeres of the preimplantation rabbit embryo were investigated using several approaches. Electron microscopic examination of embryos stained en bloc with uranyl acetate, and the study of junction permeability using horseradish peroxidase and lanthanum nitrate provided information on structure, intermembrane spacing and permeability of the junctional complexes. In addition, the freeze fracture technique was used with day 5 and day 6 blastocysts, since the large size of these embryos facilitated use of this method. These experiments showed that although rudimentary junctions were present between blastomeres of the early cleavage stages, effective tight junctions were not present until the blastocyst stage. Electron microscopic examination of thin sections revealed apical foci of membrane approximation or "fusion" between trophoblast cells by day 4. Freeze fracturing revealed a lattice of interconnecting ridges (on the A face) and grooves (on the B face) in the apical region between trophoblast cells of the day 5 blastocyst. This lattice formed a continuous band along the apical margin of each cell, and therefore constituted a zonula occludens. The zonula occludens of the day 5 blastocyst averages 2-3 ridges per lattice, while day 6 blastocysts had lattices that averaged 5-6 ridges. Also seen in the freeze fracture replicas from the day 5 and day 6 blastocysts were local accumulations of intramembranous particles on the A face. These particles were often observed in aggregates similar to those of previously described gap junctions. It could not be determined whether these small regions of particles were true gap junctions or a possible primitive form of gap junction because the complementary pitted surfaces (B face pits) were not demonstrated.
Anat Rec 1975 Jan
PMID:Junctional complexes in the preimplantation rabbit embryo. 4 78

A procedure for differential staining of decalcified bone with silver nitrate showed major histological features which appeared to correspond closely to microradiographic images. The extent to which this is actually the case was investigated directly by preparing microradiographs of ground sections of baboon and dog radii and then decalcifying and staining the same sections. The many detailed similarities indicate that this staining procedure is a useful adjunct to microradiography. Thus, poorly mineralized osteons or layers of circumferential lamellae are darker stained by silver nitrate, and the variably mineralized layers of circumferential lamellae are closely duplicated by light and dark bands in the stained sections. These similarities imply that there is a relationship between the mineral density of bone and some condition of the organic matrix which is probably related to maturation changes in the collagen.
Anat Rec 1975 Jun
PMID:Correspondence of silver nitrate staining patterns in decalcified bone withe the microradiographic image. 5 Jul 53

The comparative cytogenetic and mutagenic effects between trivalent and hexavalent chromium were investigated. Five chromium compounds, K2Cr2O7 and K2CrO4 containing Cr6+, and Cr(CH3COO)3, Cr(NO3)3 and CrCl3 containing Cr3+, were examined for their ability to induce chromosomal damage in cultures of human leukocytes, for their reactivity with DNA by a rec-assay system and for mutagenicity in the E. coli Hs30R test system. Chromosome-breaking activity was significantly higher for the compounds with hexavalent than trivalent chromium, the efficiency being in the decreasing order K2Cr2OM greater than K2CrO4 greater than Cr(CHCOO)3 greater than Cr(NO3)3, CrCl3. In the rec-assay and mutation assay, hexavalent (K2Cr2O7 and K2CrO4) and trivalent Cr(CH3COO)3) compounds gave positive results, their mutagenic potential being higher in the same order of clastogenic magnitude.
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PMID:Comparative studies of chromosomal aberration and mutagenicity of the trivalent and hexavalent chromium. 74 15

The fine structure of the rete testis was examined in several primates, domestic animals and rodents. The rete testis consists of a series of interconnected wide channels lined with a simple cuboidal to columnar epithelium, resting on a thick basal lamina. Beneath the basal lamina dense bundles of collagen fibrils and a few blood vessels, lymphatics or nerve tissue are found. The epithelial cells are characterized by large, deeply indented nuclei, spherical or short rod-shaped mitochondria, supranuclear Golgi profiles, some cisterns of rough endoplasmic reticulum, free ribosomes and numerous micropinocytotic vesicles in the ectoplasmic regions. Smooth endoplasmic reticulum, secretory granules, lysosomes or other types of dense bodies are rarely seen. The apical surface of the cells bears numerous microvilli and a single very long flagellum which is presumed to be motile. Ajoining lateral cell membranes exhibit a juxtaluminal tight junction, elaborate interdigitations and desmosomes. The basal plasma membrane is highly irregular greatly increasing its surface area of contact with the underlying interstitium. The nuclei of the rete epithelial cells contain pale-staining, spherical structure, 2 mum in diameter, composed of circularly oriented fine filaments. The significance of the nuclear structures remains unknown. Thorotrast was injected into the lumen of the hamster and rat rete testis and 30 minutes later the proximal portion of the excurrent duct system of the testis was prepared for electron microscopy. Whereas the ductuli efferentes and first part of the epididymis possessed numerous apical vesicles filled with the thorotrast, this electron opaque substance was rarely found in the epithelium of the rete testis. Thus, incorporation of particulate matter into the lining cells of the rete from its lumen is apparently less active than in the epithelium of the ductuli and epididymis. Vascularly introduced intercellular tracer compounds such as lanthanum nitrate or horseradish peroxidase did not enter the lumen of the rete testis from the interstitium. The tracer molecules appeared to be blocked by the juxtaluminal tight junction separating adjacent epithelial cells. This latter observation suggests that a blood-testis barrier exists at the level of the rete testis epithelium. Although physiological studies have indicated that the composition of fluid secreted in the seminiferous epithelium is considerably modified in the rete testis, the present morphological study does not provide additional evidence to support a secretory or absorptive function for this region of the excurrent duct system of the testis.
Anat Rec 1976 Dec
PMID:The mammalian rete testis--a morphological examination. 82 16

The surface coat of syncytial trophoblast from term human placentas was studied using cytochemical methods (colloidal iron, alcian blue-lanthanum nitrate, dialyzed iron) in coordination with tissue enzyme digestions (trypsin, neuraminidase) and sialic acid analyses. The presence of at least two highly acidic anionic components that contribute significantly to the surface negativity of trophoblast has been demonstrated. The first of these, sialic acid, was removed with neuraminidase. Tissue digestion with this glycosidase was accompanied by a decrease in trophoblast surface staining with colloidal iron, a decrease in tissue sialic acid, and an increase in the concentration of sialic acid in the incubating medium. Results from methylation experiments were consistent with the presence of sialic acid. The second anionic component(s) was identified by removal with trypsin of a glycocalyx constituent that stained with both colloidal iron and lanthanum. After trypsinization, tissue sialic acid levels were not significantly different from control values, and no detectable sialic acid was present in the incubating medium. The identity of this anionic component has not been established. Both sialic acid and nonsialic acid acidic components are distributed in higher density on membrane of microvilli than on intermicrovillous surface membrane. In addition, the sialic acid moieties appear to be clustered in the glycocalyx.
Anat Rec 1976 Feb
PMID:The nonuniform distribution of acidic components on the human placental syncytial trophoblast surface membrane: a cytochemical and analytical study. 124 83

The genotoxicity of beryllium, gallium and antimony compounds was studied with the rec, Salmonella mutagenicity and SCE assays. In the rec assay, all the salts of the metals, BeCl2, Be(NO3)2, GaCl3, Ga(NO3)3, SbCl3, SbCl5, and an oxide, Sb2O3, had DNA-damaging activity. None of the compounds was mutagenic to Salmonella. In the SCE assays using V79 cells, 2 antimony(III) compounds, SbCl3 and Sb2O3, and 2 beryllium compounds, BeCl2 and Be(NO3)2, induced SCEs significantly. Sb2O3, slightly soluble in water, was positive in both the rec assay and the SCE assay at very low doses.
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PMID:Genotoxicity of beryllium, gallium and antimony in short-term assays. 172 93

Ultrastructural and histochemical techniques have been utilized to study selected aspects of the fine structure of the three-hooked sperm head of the plains mouse, Pseudomys australis. The peripheral layer of the two ventral hooks was found to consist of a continuation of the postacrosomal dense lamina. Parallel ridges connected the dense lamina and plasma membrane in the postacrosomal region and ventral hooks. Both these regions stained intensely with silver nitrate. The distribution of actin filaments in the hooks was investigated using NBD-phallacidin. Fluorescence was more intense in the apical regions of the ventral hooks, and two bands of fluorescence extended caudally from their base. It was also shown that the equatorial segment of the acrosome extended onto the dorsal hook. The structural features of the three hooks are discussed in relation to their possible functional significance.
Anat Rec 1987 Mar
PMID:Further ultrastructural observations on the sperm head of the plains mouse, Pseudomys australis (Rodentia: Muridae). 243 33

The ultrastructural distribution of complex carbohydrates in an early formation stage of rat incisor enamel was investigated by staining with the periodic acid-thiocarbohydrazide-silver proteinate reaction (PA-TCH-SP) for vicinal glycol-containing glycoconjugates, the phosphotungstic acid-chromic acid mixture (PTA) for glycoproteins, and the cationic dyes alcian blue or bismuth nitrate for sulfated glycoconjugates. In order to remove selectively sulfated complex carbohydrates, half of the serial sections obtained were digested with a bovine testicular hyaluronidase prior to staining. Far fewer electron-dense deposits were observed with the PA-TCH-SP method on hyaluronidase-treated sections, especially those subsequently treated for 48 hours with TCH. On the other hand, the minimal staining obtained with PTA was much more intense on sections treated with hyaluronidase where linear fiberlike structures were observed. With cationic dyes, staining of dotlike alignment structures and ground substance was obtained but was completely abolished by hyaluronidase treatment. Cuprolinic blue in a critical electrolyte concentration, ruthenium hexamine trichloride used with aldehyde during fixation, as well as rapid-freezing followed by freeze-substitution validate that this dotlike distribution is not an artefact of processing. The staining results demonstrated that the glycoproteins and sulfated complex carbohydrates in developing rat incisor enamel each display a specific distribution pattern. The glycoproteins were present as fiberlike structures and the sulfated carbohydrates appeared as dotlike formations located close to the surface of the fiberlike structures, and/or in the spaces between them.
Anat Rec 1986 Oct
PMID:Ultrastructural location of complex carbohydrates in developing rat incisor enamel. 377 50

A new light microscopic staining technique allows the visualization of satellite cells on the surface of myofibers. Either prior to or during fixation, whole frog sartorius muscles are bathed in an acidic buffered solution containing lead nitrate and subsequently exposed to ammonium sulfide. The staining of the satellite cells resulting from this procedure reveals their positions, and the outlines of their cell processes which occasionally branch. Electron microscopy shows that the staining is due to lead deposits localized between apposing membranes of satellite cells and associated myofibers. Prior exposure to N-ethyl-maleimide (NEM) does not alter the formation of the lead deposits on the satellite cell, but reduces the amount of Pb deposits on the muscle surface and connective tissue. This technique has been applied to determine the effects of denervation on the satellite cells of frog sartorius muscles. Four weeks after denervation, the number of satellite cells is essentially the same in both denervated muscles and the intact muscles of the contralateral side. However, denervation results in a subpopulation of satellite cells with altered shapes. They have elongated cytoplasmic processes which often branch. It is suggested that these supernumerary cytoplasmic processes represent an intermediate phase in the transition of satellite cells to myoblasts.
Anat Rec 1980
PMID:The visualization of myosatellite cells in normal and denervated muscle: a new light microscopic staining technique. 615 10

The occurrence of a suspected mixed ammonia and nitrate fertiliser poisoning that led to acute illness and fatalities in cattle is described. The circumstances leading to the incident included the method of application of the fertiliser, low rainfall and the absence of subsequent irrigation of the fertilised pastures. The clinical and gross post mortem findings, principally dehydration and fluid distension of the rumen, were not pathognomonic. The complex of nitrate, nitrite and ammonia toxicity is discussed.
Vet Rec 1982 May 15
PMID:Suspected ammonium nitrate fertiliser poisoning in cattle. 628 85


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