scholarly journals Ca2+-sequestering smooth endoplasmic reticulum in an invertebrate photoreceptor. I. Intracellular topography as revealed by OsFeCN staining and in situ Ca accumulation.

1982 ◽  
Vol 93 (3) ◽  
pp. 839-848 ◽  
Author(s):  
B Walz
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Osmium Tetroxide ◽  
Photoreceptor Cell ◽  
Smooth Endoplasmic Reticulum ◽  
Photoreceptor Cells ◽  
Submicrovillar Cisternae ◽  
Invertebrate Photoreceptor ◽  
Ca Oxalate

Two ultrastructural approaches were used in photoreceptor cells of the leech, Hirudo medicinalis, to (a) investigate the intracellular topography of the smooth endoplasmic reticulum (SER) and (b) identify among the various subregions of the SER those which might function as Ca-sequestering sites. When the cells are prefixed with CaCl2-containing glutaraldehyde and postfixed with osmium tetroxide-ferricyanide (OsFeCN), only a part of the total SER is specifically stained. The stained SER cisternae include the submicrovillar cisternae (SMC), subsurface cisternae (SSC), the nuclear envelope, Golgi-associated SER, paracrystalline SER, and SER associated with glycogen areas. An extensive tubular SER cisternal system always remains unstained. When the cells are permeabilized by saponin and subsequently incubated with Ca2+, MgATP, and oxalate, the SMC (Walz, 1979, Eur. J. Cell Biol. 20:83-91), the SSC and the nuclear envelope contain electron-opaque Ca-oxalate precipitates indicating their ability to function as an effective Ca2+ sink. The results show that the very elaborate SER in this photoreceptor cell includes many functionally heterogeneous subregions. Of special physiological significance are those components (SMC and SSC) which are effective in Ca2+-buffering in the immediate vicinity of the plasma membrane.

scholarly journals Inositol 1,4,5 trisphosphate releases calcium from specialized sites within Limulus photoreceptors

1987 ◽  
Vol 104 (4) ◽  
pp. 933-937 ◽  
Author(s):  
R Payne ◽  
A Fein
Keyword(s):  
Endoplasmic Reticulum ◽  
Injection Site ◽  
Intracellular Calcium ◽  
Subcellular Distribution ◽  
Smooth Endoplasmic Reticulum ◽  
Image Intensifier ◽  
Photoreceptor Cells ◽  
Calcium Stores ◽  
Inositol 1,4,5 Trisphosphate ◽  
Probable Site

We have investigated the subcellular distribution and identity of inositol trisphosphate (InsP3)-sensitive calcium stores in living Limulus ventral photoreceptor cells, where light and InsP3 are known to raise intracellular calcium. We injected ventral photoreceptor cells with the photoprotein aequorin and viewed its luminescence with an image intensifier. InsP3 only elicited detectable aequorin luminescence when injected into the light-sensitive rhabdomeral (R)-lobe where aequorin luminescence induced by light was also confined. Calcium stores released by light and InsP3 are therefore localized to the R-lobe. Within the R-lobe, InsP3-induced aequorin luminescence was further confined around the injection site, due to rapid dilution and/or degradation of injected InsP3. Prominent cisternae of smooth endoplasmic reticulum are uniquely localized within the cell beneath the microvillar surface of the R-lobe (Calman, B., and S. Chamberlain, 1982, J. Gen. Physiol., 80:839-862). These cisternae are the probable site of InsP3 action.

scholarly journals The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking in Drosophila

2018 ◽  
Vol 29 (13) ◽  
pp. 1640-1651 ◽  
Author(s):  
Haifang Zhao ◽  
Jing Wang ◽  
Tao Wang
Keyword(s):  
Animal Model ◽  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Photoreceptor Cell ◽  
Photoreceptor Cells ◽  
Secretory Vesicle ◽  
Light Sensitivity ◽  
Model System ◽  
Genetic Screen ◽  
Reduced Light

Synthesis and maturation of the light sensor, rhodopsin, are critical for the maintenance of light sensitivity and for photoreceptor homeostasis. In Drosophila, the main rhodopsin, Rh1, is synthesized in the endoplasmic reticulum and transported to the rhabdomere through the secretory pathway. In an unbiased genetic screen for factors involved in rhodopsin homeostasis, we identified mutations in vha68-1, which encodes the vacuolar proton-translocating ATPase (V-ATPase) catalytic subunit A isoform 1 of the V1 component. Loss of vha68-1 in photoreceptor cells disrupted post-Golgi anterograde trafficking of Rh1, reduced light sensitivity, increased secretory vesicle pH, and resulted in incomplete Rh1 deglycosylation. In addition, vha68-1 was required for activity-independent photoreceptor cell survival. Importantly, vha68-1 mutants exhibited phenotypes similar to those exhibited by mutations in the V0 component of V-ATPase, vha100-1. These data demonstrate that the V1 and V0 components of V-ATPase play key roles in post-Golgi trafficking of Rh1 and that Drosophila may represent an important animal model system for studying diseases associated with V-ATPase dysfunction.

scholarly journals Immunocytochemical localization of lysosomal beta-galactosidase in rat liver.

1983 ◽  
Vol 97 (5) ◽  
pp. 1559-1565 ◽  
Author(s):  
P M Novikoff ◽  
N F La Russo ◽  
A B Novikoff ◽  
R J Stockert ◽  
A Yam ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Protein A ◽  
Intracellular Sorting ◽  
Specialized Region ◽  
Beta Galactosidase ◽  
Specific Polyclonal Antibody ◽  
Galactosyl Residues

beta-galactosidase is a ubiquitous lysosomal hydrolase that specifically cleaves terminal beta-galactosyl residues from glycoproteins, glycosaminoglycans, oligosaccharides, and glycolipids. To study the intracellular distribution of this enzyme, we prepared a specific polyclonal antibody to lysosomal beta-galactosidase by immunizing rabbits with a highly purified preparation of beta-galactosidase from rat liver. Using this antibody we employed an immunocytochemical technique (protein A coupled to horseradish peroxidase and diaminobenzidine cytochemistry) and showed that beta-galactosidase is present in all hepatocytes of the rat liver. All types of lysosomes, the rough endoplasmic reticulum, and the specialized region of smooth endoplasmic reticulum known as GERL showed immunoreactivity. This in situ distribution suggests that these organelles are involved in the biosynthesis and intracellular sorting of this lysosomal enzyme.

scholarly journals Properties of membrane-bound bilirubin UDP-glucuronyltransferase in rough and smooth endoplasmic reticulum and in the nuclear envelope from rat liver

1989 ◽  
Vol 259 (3) ◽  
pp. 659-663 ◽  
Author(s):  
F Vanstapel ◽  
L Hammaker ◽  
K Pua ◽  
N Blanckaert
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Membrane System ◽  
Permeability Barrier ◽  
Membrane Bound ◽  
Marker Studies ◽  
High Degree ◽  
Regulatory Properties

We examined regulatory properties of bilirubin UDP-glucuronyltransferase in sealed RER (rough endoplasmic reticulum)- and SER (smooth endoplasmic reticulum)-enriched microsomes (microsomal fractions), as well as in nuclear envelope from rat liver. Purity of membrane fractions was verified by electron microscopy and marker studies. Intactness of RER and SER vesicles was ascertained by a high degree of latency of the lumenal marker mannose-6-phosphatase. No major differences in the stimulation of UDP-glucuronyltransferase by detergent or by the presumed physiological activator, UDPGlcNAc, were observed between total microsomes and RER- or SER-enriched microsomes. Isolated nuclear envelopes were present as a partially disrupted membrane system, with approx. 50% loss of mannose-6-phosphatase latency. The nuclear transferase had lost its latency to a similar extent, and the enzyme failed to respond to UDPGlcNAc. Our results underscore the necessity to include data on the integrity of the membrane permeability barrier when reporting regulatory properties of UDP-glucuronyltransferase in different membrane preparations.

scholarly journals Ca2+-sequestering smooth endoplasmic reticulum in an invertebrate photoreceptor. II. Its properties as revealed by microphotometric measurements.

1982 ◽  
Vol 93 (3) ◽  
pp. 849-859 ◽  
Author(s):  
B Walz
Keyword(s):  
Endoplasmic Reticulum ◽  
Uptake Rate ◽  
Smooth Endoplasmic Reticulum ◽  
High Specificity ◽  
Optical Signal ◽  
Uptake Mechanism ◽  
Intact Cells ◽  
Rate Of Increase ◽  
Ca Uptake ◽  
Ca Oxalate

Microphotometric measurements are used to investigate the functional properties of Ca2+-sequestering smooth endoplasmic reticulum (SER) in leech photoreceptors. 10-30 intact cells are mounted in a perfusion chamber, placed between crossed polarizers in a microphotometer, and permeabilized by saponin treatment. Subsequent perfusion with solutions containing Ca2+, MgATP, and oxalate leads to Ca uptake by SER. When the solubility product of Ca-oxalate is exceeded in the SER, birefringent Ca-oxalate precipitates form in the cisternae, leading to a large increase in the optical signal recorded from the preparation. The rate of increase in light intensity is used to measure the rate of Ca uptake. Ca uptake rate is linear with time over much of its course, can be switched on/off by the addition/withdrawal of Ca2+, ATP, or oxalate to/from the medium, and is inhibited by mersalyl and tetracaine. The Ca uptake mechanism has a high specificity for MgATP (KM,MgATP is approximately 0.8 mM). Uptake rates observed with dATP, GTP, UTP, ITP, and CTP are only 20-30% of the rate measured in ATP. The Ca pump has a high affinity for Ca2+ ions: the threshold for activation of the pump is approximately 5 x 10(-8) M, the apparent KM,Ca is approximately 4 x 10(-7) M. When Na+ or Li+ is substituted for K+, Ca uptake rate is decreased by 40-50%. The results show that the Ca2+-sequestering SER in leech photoreceptors shares some basic properties with skeletal muscle sarcoplasmic reticulum and supports the idea that certain subregions of the SER in invertebrate photoreceptors function as effective Ca2+ sinks/buffers close to the plasmalemma.

scholarly journals STUDIES ON THE BIOGENESIS OF SMOOTH ENDOPLASMIC RETICULUM MEMBRANES IN LIVERS OF PHENOBARBITAL-TREATED RATS

1972 ◽  
Vol 55 (2) ◽  
pp. 282-298 ◽  
Author(s):  
Joan A. Higgins ◽  
Russell J. Barrnett
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Specific Activity ◽  
Smooth Endoplasmic Reticulum ◽  
Normal Liver ◽  
Subsequent Treatment ◽  
Cell Fractionation ◽  
Acyltransferase Activity ◽  
Normal Rat

The localization of acyltransferases involved in acylation of α-glycerophosphate, during phenobarbital induced proliferation of smooth endoplasmic reticulum (ser) membranes, has been investigated using cytochemical and cell fractionation techniques. In cytochemical studies of normal rat liver, reaction product marking acyltransferase activity was associated to the greatest extent with the rough endoplasmic reticulum (rer) membranes and to a lesser extent with ser membranes. In liver from phenobarbital-treated rats, reaction product was largely restricted to ser membranes. The specific activity of the acyltransferases of rough microsomes from normal rat liver was higher than that of the smooth microsomes. On injection of phenobarbital, this fell rapidly after three injections to a low level, at which it remained during subsequent treatment. The specific activity of the smooth microsomes, on injection of phenobarbital, rose to a peak 12 hr after the first injection, after which it fell to a level at an activity above that of smooth microsomes of normal liver. A mechanism is postulated for the biogenesis of smooth membranes in which the phospholipid is synthesized in situ and the protein is synthesized in the rer and moves to the site of newly synthesized phospholipid, where it is inserted to produce a whole membrane.

scholarly journals Retention of membrane proteins by the endoplasmic reticulum.

1985 ◽  
Vol 101 (5) ◽  
pp. 1724-1732 ◽  
Author(s):  
R Brands ◽  
M D Snider ◽  
Y Hino ◽  
S S Park ◽  
H V Gelboin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibody ◽  
Endoplasmic Reticulum ◽  
Cytochrome P450 ◽  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Smooth Endoplasmic Reticulum ◽  
Membrane Glycoprotein ◽  
Glucosidase Ii ◽  
Er Membrane

We have used a monoclonal antibody specific for a hydrocarbon-induced cytochrome P450 to localize, by electron microscopy, the epitope-specific cytochrome P450. The cytochrome was found in the rough and smooth endoplasmic reticulum (ER) and the nuclear envelope of hepatocytes. Significant quantities of cytochrome P450 were not found in Golgi stacks. We also could not find any evidence of Golgi-associated processing of the Asn-linked oligosaccharide chains of two well-characterized ER membrane glycoprotein enzymes (glucosidase II and hexose-6-phosphate dehydrogenase), or of the oligosaccharides attached to the bulk of the glycoproteins of the ER membrane. We conclude that these ER membrane proteins are efficiently retained during a process of highly selective export from this organelle.

A quantitative morphological study of the pineal organ in the goldfish, Carassius auratus

1981 ◽  
Vol 59 (7) ◽  
pp. 1312-1325 ◽  
Author(s):  
John A. McNulty
Keyword(s):  
Endoplasmic Reticulum ◽  
Pineal Organ ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Photoreceptor Cells ◽  
Nerve Fibers ◽  
Substantial Part ◽  
Electron Microscopic ◽  
Goldfish Carassius Auratus ◽  
Supportive Cells

Stereological techniques applied to a light and electron microscopic study of the pineal organ of the goldfish indicated that photoreceptor and supportive cells were comparable in their number and cell volume and that approximately 500 nerve cells were present in the pineal end vesicle. There were approximately 310 nerve fibers descending the distal part of the pineal tract. Quantitative analysis of organelles in photoreceptor cells revealed that the endoplasmic reticulum and Golgi bodies, in the vicinity of which were situated both clear and dense-cored vesicles, formed a substantial part of the cytoplasmic volume. Other new observations reported for this species include a close association between mitochondria and parts of the smooth endoplasmic reticulum, a characteristic feature of photoreceptor cells, and the presence of subsurface cisternae formed from profiles of endoplasmic reticulum. Moreover, specialized contacts were found between both photoreceptor and supportive cells. Some of these ultrastructural features are similar to those reported in the secretory pinealocytes of mammals. These findings suggest that (1) the pineal organ in this species has a high degree of photosensitivity as evidenced by the large number of photoreceptor cells related to each nerve cell, and (2) photoreceptor cells are metabolically active possibly having functions other than photoreception.

scholarly journals THE RABBIT ZYGOTE

1972 ◽  
Vol 55 (3) ◽  
pp. 533-541 ◽  
Author(s):  
Bela J. Gulyas
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Smooth Endoplasmic Reticulum ◽  
Annulate Lamellae ◽  
Nuclear Pores ◽  
Late Anaphase ◽  
Dense Nucleus

The formation of the blastomere nucleus was examined in the rabbit zygote with the electron microscope. In late anaphase the chromosomes are bare and vesicles of the smooth endoplasmic reticulum are numerous in the vicinity of the chromosomes. In early telophase individual chromosomes attain their own nuclear envelope and they are called karyomeres. The envelope of the karyomeres contains small gaps within it at several places where the chromatin is exposed to the cytoplasm. Nuclear pores are also observed. In the cytoplasm short annulate lamellae appear adjacent to the karyomeres, and clusters of punctate substance are also present. From early telophase onward the karyomeres extend pseudopod-like structures, called karyopods, which extend toward other karyomeres or karyopods, and consequently fuse together and serve as chromosomal bridges. Eventually all of the karyomeres fuse into a dense nucleus and decondensation of the chromosomes occurs.

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