Endoplasmic reticulum cisternae

M (dilation of rough endoplasmic reticulum cisternae of thyroid of weanling rats)... 

Intermediate-duration oral studies in humans for mirex are lacking. A review of the animal oral intermediate toxicity data for mirex indicates that the available studies are not adequate to derive intermediate oral MRL for mirex. The most suitable study provides a LOAEL of 0.25 mg/kg/day for endocrine effects-dilation of rough endoplasmic reticulum cisternae of the thyroid of weanling Sprague-Dawley rats (Singh et al. 1985). Adjusting the LOAEL of 0.25 mg/kg/day determined from this study with a total uncertainty factor of 1,000 (10 for use of a LOAEL, 10 for animal to human extrapolation, and 10 for interspecies variability) yields an intermediate oral MRL of 0.0003 mg/kg/day, which is lower than the chronic-duration oral MRL of 0.0008 mg/kg/day derived from an NTP (1990) study in rats (see chronic-duration MRL). Therefore, no oral intermediateduration MRL was developed for mirex. 

Fig. 102. Conspicuous dilatation of the rough endoplasmic reticulum cisternae in a type II pneumocyte of a 228 g female rat (breeder Winkehnann, Borchen-Kirchborchen) 30 min after a subcutaneous injection of 1 mg pilocarpine HCl per kg body weight. Fixed under methitural anaesthesia by intratracheal instillation of 2.5 % glutarmdehyde in phosphate buffer (pH 7.4) before opening the thorax. Postfixation with 1 % osmium tetroxide in phosphate buffer (pH 7.4). Contrasted en bloc for 12 h with 0.5 % uranyl acetate in 70% ethanol. Embedded in a 2 8 mixture of methyl and butyl methacrylate. Sectioned at 50 nm. Lead citrate after Reynolds (1963). Plate 26/06...

Oligodendrocytes do not show anoxic damage as rapidly as the astrocytes (Hills 1964). A few hours after the anoxic episode, the endoplasm reticulum cisternae and mitochondria may swell shghtly. In the later periods of hypoxia ohgodendrocytes showed marked dilatation of the cisternae of the endoplasmic reticulum, partly in the peripheral zone of the perikarya (Yu et al. 1972). 

Albumin (69 kDa) is the major protein of human plasma (3.4-4.7 g/dL) and makes up approximately 60% of the total plasma protein. About 40% of albumin is present in the plasma, and the other 60% is present in the extracellular space. The liver produces about 12 g of albumin per day, representing about 25% of total hepatic protein synthesis and half its secreted protein. Albumin is initially synthesized as a preproprotein. Its signal peptide is removed as it passes into the cisternae of the rough endoplasmic reticulum, and a hexapeptide at the resulting amino terminal is subsequently cleaved off farther along the secretory pathway. The synthesis of albumin is depressed in a variety of diseases, particularly those of the liver. The plasma of patients with liver disease often shows a decrease in the ratio of albumin to globulins (decreased albumin-globuhn ratio). The synthesis of albumin decreases rela-... 

FIGURE 1-5 Detail of the nuclear envelope showing a nuclear pore (single arrow) and the outer leaflet connected to the smooth endoplasmic reticulum (ER) (double arrows). Two cisternae of the rough ER with associated ribosomes are also present. X80,000. 

The process of infection of lupine nodule cells by Rhizobia was examined by the thin-section electron microscopic technique, as well as the freeze-fracture technique. Different membranes such as infection thread membranes, peribacterioid membranes, plasma membranes, membranes of cytoplasmic vesicles, and membranes of the Golgi bodies and ER were stained with uranium-lead, silver, phosphotungstic acid, and ZIO (31). ZIO stained the membranes of the proximal face of the Golgi bodies and endoplasmic reticulum. ZIO staining has given good contrast in thick sections such as a cotyledon cell, a root cell, and an aleurone layer for ER, dictyosomes cisternae, mitochondria, and nuclear envelopes (17,32-37). 

Fig. 3. Intracellular transport route of the SFV spike glycoproteins from the endoplasmic reticulum (ER), over the Golgi apparatus, to the plasma membrane (PM). The cis cisternae do not react positively for add phosphatase or thiamin pyrophosphatase, and do not label with ridn in thin frozen sections. The medial cisternae do not react positively for thiamin pyrophosphatase or acid phosphatase, but label with ridn. The trans cisternae are positive for all of these markers.

It seems likely that the enzyme complexes for hemicelluloses, pectins and cellulose are constructed, at least in part, on the endoplasmic reticulum and then transferred to the Golgi apparatus, where they are modified and sorted so that they can be segregated within the compartments of the Golgi cisternae (30,31). The complex for cellulose synthesis is not normally active within the Golgi apparatus and it is transported to active sites at the plasma membrane (1). The hemicelluloses and pectins are formed within vesicles and cisternae of the Golgi apparatus and the vesicles are transported to the plasma membrane, where fusion occurs and the polysaccharides are packed into the wall (1). It is not known whether particular polysaccharides such as the xylans of the hemicellulose and the arabinogalactans of the pectins are transported in separate vesicles or together in one vesicle. Nor is it known if the complex for cellulose synthesis is transported by vesicles which carry hemicellulose and pectin polysaccharides. 

Enantiotopic atoms or groups 479 Endergonic reactions 286 Endo ring conformation 212 Endocytosis 13,425-427 Endoderm 23 Endoglucanases 602 Endoglycanases 593, 602 Endonexin SeeAnnexin Endoplasmic reticulum (ER) 10,13,14, 521 cisternae of 14 definition of 14 in micrograph 13 rough 14 smooth 14 Endosomes 13, 426 Endosperm 30... 

Schematic diagram showing the relative locations of nucleus, endoplasmic reticulum (ER), Golgi complex, trans-Golgi network, and plasma membrane. Glycoproteins synthesized in the lumen of the ER pass to the cis cisterna of the Golgi complex by a sequential membrane budding and fusion mechanism. The Golgi cisternae are classified into cis, medial, and trans in the order of increasing...

The Golgi complex is in a constant state of flux279. Cisternal membranes arising from the rough endoplasmic reticulum change to smooth endoplasmic reticulum and become the Golgi cisternae. Those cisternae then break down to vesicles which can fuse with and extend the plasmalemma. 

This is an interconnected network of flattened or spherical vesicles and tubules found in the cytoplasm of eukaryotic cells. These structures are enveloped by a membrane that separates the endoplasmic reticulum cavities or cisternae. The cisternae constitute a network of channels that go through the cytoplasm and regulate the transport of various cell products, generally to the exterior environment. In some cells the cisternae also serve as a storage area. There are two types of endoplasmic reticulum granular (or rough) and smooth. 

Ribosomes are spherical cell structures enriched with ribonucleoprotein and with a diameter of 15-20 nm. Each ribosome is formed by two subunits of different sizes, only visible through high resolution electron microscopy. Ribosomes connected to the rough endoplasmic reticulum are involved in the biosynthesis of proteins that are temporarily stored or transported to the cell s outer environment. Proteins synthesized by ribosomes connected to membranes accumulate in the cisternae before passage to the plasma membrane for secretion. 

At the EM level, our work indicates that dysbindin-1 in neuronal cell bodies is often found on the chromatin of the nucleus, along membranes of the endoplasmic reticulum, and over the cisterna and... 

Other organelles include the rough endoplasmic reticulum, the subsurface cisternae, and the mitochondria. As in other cell types, the rough endoplasmic reticulum is the primary site of protein synthesis. In neurons, this granular organelle studded with ribosomes is also known as the Nissl substance, due to its chromophilic nature. It is highly developed in neurons and reflects the active protein synthesis that is constantly occurring in these cells. Few of the proteins synthesized at the Nissl bodies are secreted and the majority of them remain within the cell or are incorporated into the cell membrane. After ribosomal translation, many of the proteins are transported... 

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