Cytochemical staining of multivesicular body and golgi vesicles

Progeny Varicella-Zoster Virus Capsids Exit the Nucleus but Never Undergo Secondary Envelopment during Autophagic Flux Inhibition by Bafilomycin A1

Varicella-zoster virus (VZV) is an alphaherpesvirus that lacks the herpesviral neurovirulence protein ICP34.5. The underlying hypothesis of this project was that inhibitors of autophagy reduce VZV infectivity. We selected the vacuolar proton ATPase inhibitor bafilomycin A1 for analysis because of its well-known antiautophagy property of impeding acidification during the late stage of autophagic flux. We documented that bafilomycin treatment from 48 to 72 h postinfection lowered VZV titers substantially (P ≤ 0.008). Because we were unable to define the site of the block in the infectious cycle by confocal microscopy, we turned to electron microscopy. Capsids were observed in the nucleus, in the perinuclear space, and in the cytoplasm adjacent to Golgi apparatus vesicles. Many of the capsids had an aberrant appearance, as has been observed previously in infections not treated with bafilomycin. In contrast to prior untreated infections, however, secondary envelopment of capsids was not seen in the trans-Golgi network, nor were prototypical enveloped particles with capsids (virions) seen in cytoplasmic vesicles after bafilomycin treatment. Instead, multiple particles with varying diameters without capsids (light particles) were seen in large virus assembly compartments near the disorganized Golgi apparatus. Bafilomycin treatment also led to increased numbers of multivesicular bodies in the cytoplasm, some of which contained remnants of the Golgi apparatus. In summary, we have defined a previously unrecognized property of bafilomycin whereby it disrupted the site of secondary envelopment of VZV capsids by altering the pH of the trans-Golgi network and thereby preventing the correct formation of virus assembly compartments.IMPORTANCE This study of VZV assembly in the presence of bafilomycin A1 emphasizes the importance of the Golgi apparatus/trans-Golgi network as a platform in the alphaherpesvirus life cycle. We have previously shown that VZV induces levels of autophagy far above the basal levels of autophagy in human skin, a major site of VZV assembly. The current study documented that bafilomycin treatment led to impaired assembly of VZV capsids after primary envelopment/de-envelopment but before secondary reenvelopment. This VZV study also complemented prior herpes simplex virus 1 and pseudorabies virus studies investigating two other inhibitors of endoplasmic reticulum (ER)/Golgi apparatus function: brefeldin A and monensin. Studies with porcine herpesvirus demonstrated that primary enveloped particles accumulated in the perinuclear space in the presence of brefeldin A, while studies with herpes simplex virus 1 documented an impaired secondary assembly of enveloped viral particles in the presence of monensin.

Serum Deprivation of Mesenchymal Stem Cells Improves Exosome Activity and Alters Lipid and Protein Composition

Exosomes can serve as delivery vehicles for advanced therapeutics. The components necessary and sufficient to support exosomal delivery have not been established. Here we connect biochemical composition and activity of exosomes to optimize exosome-mediated delivery of small interfering RNAs (siRNAs). This information is used to create effective artificial exosomes. We show that serum-deprived mesenchymal stem cells produce exosomes up to 22-fold more effective at delivering siRNAs to neurons than exosomes derived from control cells. Proteinase treatment of exosomes stops siRNA transfer, indicating that surface proteins on exosomes are involved in trafficking. Proteomic and lipidomic analyses show that exosomes derived in serum-deprived conditions are enriched in six protein pathways and one lipid class, dilysocardiolipin. Inspired by these findings, we engineer an “artificial exosome,” in which the incorporation of one lipid (dilysocardiolipin) and three proteins (Rab7, Desmoplakin, and AHSG) into conventional neutral liposomes produces vesicles that mimic cargo delivering activity of natural exosomes.

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Source cell stress augments exosome activity but reduces microvesicle activity

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Source cell stress alters exosome lipid and protein composition

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DSP, Rab7, AHSG an dilysocardiolipin enhances exosome activity

MicroRNA Shuttle from Cell-To-Cell by Exosomes and Its Impact in Cancer

The identification of exosomes, their link to multivesicular bodies and their potential role as a messenger vehicle between cancer and healthy cells opens up a new approach to the study of intercellular signaling. Furthermore, the fact that their main cargo is likely to be microRNAs (miRNAs) provides the possibility of the transfer of such molecules to control activities in the recipient cells. This review concerns a brief overview of the biogenesis of both exosomes and miRNAs together with the movement of such structures between cells. The possible roles of miRNAs in the development and progression of breast, ovarian and prostate cancers are discussed.

Extracellular vesicles round off communication in the nervous system

Functional neural competence and integrity require interactive exchanges among sensory and motor neurons, interneurons and glial cells. Recent studies have attributed some of the tasks needed for these exchanges to extracellular vesicles (such as exosomes and microvesicles), which are most prominently involved in shuttling reciprocal signals between myelinating glia and neurons, thus promoting neuronal survival, the immune response mediated by microglia, and synapse assembly and plasticity. Such vesicles have also been identified as important factors in the spread of neurodegenerative disorders and brain cancer. These extracellular vesicle functions add a previously unrecognized level of complexity to transcellular interactions within the nervous system.

Vesicular glutamate transporters: spatio-temporal plasticity following hearing loss

An immunocytochemical comparison of vGluT1 and vGluT3 in the cochlear nucleus (CN) of deafened versus normal hearing rats showed the first example of vGluT3 immunostaining in the dorsal and ventral CN and revealed temporal and spatial changes in vGluT1 localization in the CN after cochlear injury. In normal hearing rats vGluT1 immunostaining was restricted to terminals on CN neurons while vGluT3 immunolabeled the somata of the neurons. This changed in the ventral cochlear nucleus (VCN) 3 days following deafness, where vGluT1 immunostaining was no longer seen in large auditory nerve terminals but was instead found in somata of VCN neurons. In the dorsal cochlear nucleus (DCN), while vGluT1 labeling of terminals decreased, there was no labeling of neuronal somata. Therefore, loss of peripheral excitatory input results in co-localization of vGluT1 and vGluT3 in VCN neuronal somata. Postsynaptic glutamatergic neurons can use retrograde signaling to control their presynaptic inputs and these results suggest vGluTs could play a role in regulating retrograde signaling in the CN under different conditions of excitatory input. Changes in vGluT gene expression in CN neurons were found 3 weeks following deafness using qRT-PCR with significant increases in vGluT1 gene expression in both ventral and dorsal CN while vGluT3 gene expression decreased in VCN but increased in DCN.

Ultrastructure of the bone marrow in HIV infection: evidence of dyshaemopoiesis and stromal cell damage

The ultrastructure of bone marrow cells was studied in nine patients infected with the human immunodeficiency virus (HIV). Two of these (cases 1 and 3) were thrombocytopenic, had never suffered from opportunistic infections and had not received any drugs prior to the time of study. A number of ultrastructural abnormalities were found in a variable proportion of the affected cell types in all nine patients. These were: (a) an increased prevalence of multivesicular bodies within several cell types and of abnormalities of the nuclear membrane in neutrophil granulocytes, (b) an increase in the size of the Golgi apparatus and in the quantity of endoplasmic reticulum in neutrophil granulocytes, (c) dysplastic features, including multiple long intranuclear clefts and large cytoplasmic vacuoles in some erythroblasts and (d) vacuolation of the plasma cells. Other abnormalities seen in a proportion of the patients were: (a) cylindrical confronting cisternae (CCC) in some of the lymphocytes, macrophages (phagocytic reticular cells), non-phagocytic reticular cells (including adventitial cells) and endothelial cells of marrow sinusoids, (b) tubuloreticular structures (TRS) in some lymphocytes, plasma cells, monocytes and endothelial cells and (c) precipitates of protein within occasional erythroblasts and marrow reticulocytes. There was also a striking and hitherto undescribed abnormality of the structure of the nucleus in intersinusoidal and perisinusoidal non-phagocytic reticular cells. This was seen in six patients, including case 3, and was characterized by the extensive detachment of masses of abnormally electron-dense heterochromatin from the nuclear membrane, the presence of a uniformly thin layer of electron-dense material at the inner surface of the areas of nuclear membrane denuded of heterochromatin masses and an abnormal electron lucency of areas containing euchromatin. The CCC and TRS were found in the six patients with the lowest number of circulating CD4-positive T cells. The precipitation of protein within erythroid cells may have been caused by the oxidant effect of dapsone or high doses of co-trimoxazole. The abnormalities in the stromal cells and in particular the nuclear changes seen in the non-phagocytic reticular cells support the possibility that one of the mechanisms underlying the cytopenia in patients infected with HIV may be a disturbance of the microenvironmental regulation of haemopoiesis.

Membrane recycling in secretory cells: pathway to the Golgi complex

The pathway taken by membrane that is recovered by endocytosis from the surface of secretory cells was investigated with electron-dense tracers 9dextrans and cationized ferritin). The cell types examined included exocrine cells of the parotid and lacrimal glands, endocrine cells of the anterior pituitary gland, and immunoglobulin-secreting cells from lymph nodes or myeloma cell lines. In all cases, when the cells were incubated at 37 degrees C the tracers were initially taken up by endocytosis and they later appeared in the stacked Golgi cisternae, in immature secretion granules or vacuoles and in lysosomes. Similar results were obtained after covalent labelling of surface membrane constituents when myeloma cells were radioiodinated and the fate of the labelled components was followed by autoradiography. Initially only the cell surface was labelled, and the autoradiographic grains were concentrated over the plasmalemma. After incubation at 37 degrees C some of the labelled components were internalized (by endocytosis), and the majority of the internal autoradiographic grains were found over Golgi cisternae and over associated secretory vacuoles, which were the only organelles significantly labelled. The findings indicate the existence of considerable membrane traffic from the plasmalemma to the stacked Golgi cisternae and forming secretion granules or vacuoles in all these cell types. Membrane is thus continually recovered from the cell surface of secretory cells and funnelled through the Golgi complex; moreover, the plasmalemma-to-Golgi traffic appears to represent a major route of membrane traffic in secretory cells. A large portion of this traffic appears to be associated with the recycling of the membrane containers used in the packaging of secretory products.

The Golgi apparatus: roles for distinct 'cis' and 'trans' compartments

The Golgi apparatus seems to consist of distinct cis and trans compartments that are proposed to act sequentially to refine the protein export of the endoplasmic reticulum by removing escaped endoplasmic reticulum proteins. Refinement may be a multi-stage process that employs a principle akin to fractional distillation; the stack of cisternae comprising the cis Golgi may be the plates in this distillation tower. The trans Golgi, consisting of the last one or two cisternae, may be the receiver that collects from the cis Golgi only its most refined fraction for later distribution to specific locations throughout the cell.

CHMP1 functions as a member of a newly defined family of vesicle trafficking proteins

A multivesicular body is a vesicle-filled endosome that targets proteins to the interior of lysosomes. We have identified a conserved eukaryotic protein, human CHMP1, which is strongly implicated in multivesicular body formation. Immunocytochemistry and biochemical fractionation localize CHMP1 to early endosomes and CHMP1 physically interacts with SKD1/VPS4, a highly conserved protein directly linked to multivesicular body sorting in yeast. Similar to the action of a mutant SKD1 protein, overexpression of a fusion derivative of human CHMP1 dilates endosomal compartments and disrupts the normal distribution of several endosomal markers. Genetic studies in Saccharomyces cerevisiae further support a conserved role of CHMP1 in vesicle trafficking. Deletion of CHM1, the budding yeast homolog of CHMP1, results in defective sorting of carboxypeptidases S and Y and produces abnormal, multi-lamellar prevacuolar compartments. This phenotype classifies CHM1 as a member of the class E vacuolar protein sorting genes. Yeast Chm1p belongs to a structurally-related, but rather divergent family of proteins, including Vps24p and Snf7p and three novel proteins, Chm2p, Chm5p and Chm6p, which are all essential for multivesicular body sorting. These observations identify the conserved CHMP/Chmp family as a set of proteins fundamental to understanding multivesicular body sorting in eukaryotic organisms.

Glycoprotein reglucosylation and nucleotide sugar utilization in the secretory pathway: identification of a nucleoside diphosphatase in the endoplasmic reticulum

UDP is generated in the lumen of the endoplasmic reticulum (ER) as a product of the UDP-glucose-dependent glycoprotein reglucosylation in the calnexin/calreticulin cycle. We describe here the identification, purification and characterization of an ER enzyme that hydrolyzes UDP to UMP. This nucleoside diphosphatase is a ubiquitously expressed, soluble 45 kDa glycoprotein devoid of transmembrane domains and KDEL-related ER localization sequences. It requires divalent cations for activity and hydrolyzes UDP, GDP and IDP but not any other nucleoside di-, mono- or triphosphates, nor thiamine pyrophosphate. By eliminating UDP, which is an inhibitory product of the UDP-Glc:glycoprotein glucosyltransferase, it is likely to promote reglucosylation reactions involved in glycoprotein folding and quality control in the ER.

Ultrastructure and lectin cytochemistry of the cloacal ventral glands in the male newt Triturus marmoratus marmoratus

Ventral glands are found in the cloacal walls of male urodele amphibians except for sirenids. These glands are mucous, and secrete substances that will form part of the spermatophore used in transfer of sperm during fertilization. Ventral glands are formed by secretory and ductal portions; both possess epithelial and myoepithelial cells with different characteristics. Urodeles have cyclic reproduction, and cloacal ventral glands show seasonal differences with electron microscopy. The glycoproteins secreted by these glands have been studied by means of lectin histochemistry. The labeling was detected mainly in the nuclei, rough endoplasmic reticulum, Golgi complex, and cytosol. Secretory granules in these glands are composed by mucous glycoproteins that bind PNA lectin (which binds galactose) and SBA and HPA lectins (N-acetylgalactosamine), UEA-I (fucose), and LcA (glucose and/or mannose). These findings suggest that the mucins secreted by ventral glands contain both N- and O-linked oligosaccharides. Ventral glands secrete higher quantity and more diverse mucous substances in the reproductive period, as confirmed by lectin-histochemical reactions. Based on these results, the major similarity between ventral cloacal glands and accessory mammalian glands, can be established with bulbourethral glands.

The Golgi apparatus: 100 years of progress and controversy

Research on the Golgi apparatus has resulted in major advances in understanding its structure and functions, but many important questions remain unanswered. The history of the Golgi apparatus has been marked by arguments and controversies, some of which have been resolved, whereas others are still ongoing. This article charts progress in understanding the role of the Golgi apparatus during the 100 years since it was discovered, highlighting major milestones and discoveries that have led to the concepts of the organization and functions of this organelle that we have today.

Sequestration of mitotic (M-phase) chromosomes in autophagosomes: mitotic programmed cell death in human Chang liver cells induced by an OH* burst from vanadyl(4)

BACKGROUND

Fragmentation of genomic DNA in apoptosis/programmed cell death (PCD) is a characteristic hallmark in which both 2N and 4N DNA from G1, S, and G2/M cell cycle phases were seen degraded to the sub-2N Ao level in PCD such as from serum deprivation, glucocorticoid treatment, and gamma-radiation. However M-phase (mitotic) cells are said to perish only via non-programmed or necrotic cell death unless they were allowed to complete cytokinesis and re-enter interphase. The morphological criteria of PCD refer only to interphase cells with intact nuclear membranes, none seems applied to mitotic cells. We show here autophagic sequestration of mitotic chromosomes in a typical PCD response where G1, S, and G2/M DNA were replaced by a sub-2N Ao peak, suggesting that mitotic cells may yet have the option of PCD or suicide. Autophagy is absent in necrosis.

METHODS

Mitotic human Chang liver cells in normal monolayer culture were compared with apoptotic counterparts initiated by a burst of hydroxyl free radicals (OH*) generated from vanadium internalized by an NH4Cl prepulse containing vanadyl(4) ions. Total (free and bound) vanadium uptake was quantitated by elemental spectral analysis of single cells using a) Particle-Induced X-ray Emission (PIXE) profiling, and b) Scanning Transmission Ion Microscopy (STIM) in the nuclear microscope. The Coulter EPICS PROFILE II flow cytometer was used for a) the cell cycle analysis using propidium iodide-DNA binding, b) intracellular pH (pHi) evaluation in the acidification-and-recovery cycle, using ratiometric 2',7'-bis(2-carboxyethyl)-5 (and-6)-carboxyfluorescein (BCECF) fluorescence quantitation. Transmission electron microscopy examined the morphological changes. Vanadyl(4)- generated hydroxyl free radicals (OH*) were evaluated by measuring OH*-benzoic adduct fluorescence at 304/413 nm using the SPEX Fluoromax photon counting spectrofluorometer.

RESULTS

Nuclear microscopy showed that a 30 min acidification prepulse containing 4mM vanadyl(4) ions, V(4), had increased the total (free and bound) vanadium concentration of human Chang liver cells from normal ultratrace levels to 56,992 ppm of dry wt (1.1174 Eq per kg dry wt). After the prepulse, cells realkalinized in DMEM growth medium, recovering to the physiological pHi level in 30 min. At the physiological pH 7 level, V(4) generated a burst of OH* free radicals in the order of 15,000 folds above the prepulse (pH 4.5) level. In these conditions, spectrofluorometric evaluation showed loss of DNA intercalation with propidium iodide (PI-DNA binding) indicating DNA degradation. Cell-by-cell evaluation of the PI-DNA binding by flow cytometry showed abolition of G1, S, and G2/M phases and their replacement by a sub-2N Ao peak of fragmented DNA, emulating serum deprivation PCD in these cells. Immediately upon initiating an OH* burst ultrastructural profiles showed mitotic chromosomes (M-phase chromatin) being surrounded by rough endoplasmic reticulum (RER) and small vesicles, indicating their sequestration in autophagosomes. Autophagy was also seen to be a prominent feature in serum deprivation PCD.

CONCLUSION

Sequestration of mitotic chromosomes by autophagosomes in a typical PCD response showed a well-defined morphological pathway for direct degradation of M-phase chromatin without first completing cytokinesis. Mitotic cells could commit suicide via autophagy directed at its own chromatin. Autophagic sequestration of chromatin in PCD is novel.

Ultrastructural studies of neutral lipid localisation in Streptomyces

Triacylglycerol is accumulated by Streptomyces spp. when grown in submerged culture. Ultrastructural studies using transmission electron microscopy (TEM), staining and freeze-fracture/freeze-etch procedures, and light microscopy confirmed the accumulation of neutral lipid by S. lividans and S. coelicolor during the stationary phase and its storage within membrane-bound globular structures within the cytoplasm. These structures were of various sizes and occupied up to approximately 80% of the total cell volume at that time. There was no evidence of such material within cells examined during the early exponential phase of growth. The globules visualised by TEM were electron-transparent since they comprised lipids containing saturated fatty acids that did not react with osmium tetroxide. The globules appeared to be bounded by a single membrane.

Localization of lysosomal enzymes in the retina and retinal pigment epithelium of RCS rats

Using ultrahistochemical and immunohistochemical techniques, localization of acid phosphatase and cathepsin D was demonstrated in the retina and pigment epithelium of 1 to 42 day old RCS rats and its nonaffected congenic rat strain. Both enzymes are present in the pigment epithelium of the normal and dystrophic rat eye. As early as the age of 1 week, it was found that the lysosomes in the dystrophic rat retina are less stable in releasing acid phosphatase than those of control animals. Infiltration of cathepsin D into the subretinal space could first be detected with certainty in 2-week-old animals. The fragility of the lysosomal membrane and, therefore, the release of both enzymes became more pronounced as the animals aged. The findings of this study indicate that the instability of the lysosomal membrane in the RCS rat pigment epithelium may initiate degeneration of photoreceptors and pigment epithelium. The demonstration of cathepsin D activity has proved very helpful in revealing the physiological or pathophysiological condition of retinal pigment epithelium.

Internalization of type 1 complement receptors and de novo multivesicular body formation during chemoattractant-induced endocytosis in human neutrophils

Upon activation of human neutrophils by chemoattractants, functionally important proteins are rapidly transported from intracellular granules and storage vesicles to the plasma membrane. This is accompanied by a marked increase in the rate of endocytosis and by ligand-independent internalization of type 1 complement receptors (CR1). To define the pathway of endocytosis, we used gold-conjugated BSA in a pulse-chase protocol. This tracer was initially internalized into small endocytic vesicles which rapidly traversed the cytoplasm and coalesced to form large, conspicuous multivesicular bodies. Within 5 min after addition of the chemoattractant, multivesicular bodies contained > 60% of the cell-associated BSA-gold. CR1 colocalized with the endocytic tracer in both the early endosomes and multivesicular bodies. In unstimulated cells, there was much less uptake of BSA-gold and multivesicular bodies were rarely seen. Using the acidotropic amine, DAMP, and anti-DNP antibodies, we found that the multivesicular bodies were acidified but the early endosomes did not concentrate DAMP. Neither the early endosomes nor the multivesicular bodies initially contained the lysosomal membrane antigens hLAMP 1 or 2, but hLAMP-positive structures subsequently joined the multivesicular bodies. The rapid activation of the endocytic pathway upon stimulation of neutrophils allowed us to visualize the de novo formation and maturation of multivesicular bodies. Our observations suggest that vesicles containing ion pumps and acid hydrolases fuse with multivesicular bodies, giving them characteristics of lysosomes, and that these are the probable sites of degradation of CR1. The observations do not support models which would require transport of CR1 from multivesicular bodies to defined, pre-existing lysosomes for degradation.

Thiamine pyrophosphatase activity in secretory cells of the lateral prostate and seminal vesicle of normal and castrated guinea pigs and castrates treated with oestradiol

Ultrastructural localization of thiamine pyrophosphatase (TPPase) activity was studied in secretory cells of the lateral prostate and seminal vesicle of normal and castrated guinea pigs and castrates treated with 17 beta-oestradiol benzoate. The present study has demonstrated that TPPase reaction product is consistently localized in the three to four trans cisternae of Golgi complexes in both the lateral prostate and the seminal vesicle. The reaction was intense and the reaction product often filled the cisternae completely. After castration there was a decrease in TPPase activity in both glands as revealed by the reduction in the amount of the reaction product which was found mainly in one to two trans cisternae of the regressed Golgi complex. The reaction product changed from a dense to a more particulate or granular pattern or to discrete deposits of high electron-density. Administration of 17 beta-oestradiol benzoate to the castrates caused changes in the localization and patterns of distribution of TPPase. In the lateral prostate there was an apparent increase in TPPase activity. The reaction product was found in two to four trans cisternae and occasionally in the trans-most cisternae of the dilated Golgi complex. The reaction product appeared as discrete, dense coarse precipitates. In the seminal vesicle TPPase reaction product was consistently found in one to two trans cisternae in cells with larger Golgi complexes. However, almost all cisternae of the smaller Golgi complexes were TPPase-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of cytochemical properties in the Golgi apparatus during in vivo differentiation of the ameloblast in developing rat molar tooth germs

The cytochemical changes of the Golgi stacks occurring concomitantly with cell differentiation were examined in ameloblasts of developing rat molar tooth germs using osmium impregnation and cytochemistry with nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and acid phosphatase (Acpase). NADPase, TPPase, and Acpase activities were already present in the Golgi stacks of the inner enamel epithelial cells, the undifferentiated form of the ameloblast: NADPase activity existed in the medial Golgi cisternae, TPPase activity in the trans Golgi cisternae, and Acpase activity in almost all cisternae and strongly in the trans-most cisterna of the Golgi stack. At this stage, however, osmium deposits after impregnation were not observed in the cisterna of Golgi stacks but were present in some small vesicles. These vesicles were located throughout the cytoplasm. Osmiophilic cisternae in the Golgi stacks were apparent for the first time at the stage when the Golgi apparatus developed and migrated to the region distal to the nucleus with the progression of cell differentiation. These findings indicate that the cis subcompartment of the Golgi apparatus was incomplete in the inner enamel epithelial cells with regard to appearance of its cytochemical property, as compared with the medial and trans subcompartments. It is suggested that the cis compartment of the Golgi stack may be completed only in the last stage of the compartmentalized Golgi organization during differentiation of the ameloblast.

Structural differentiation of the epithelial cells of the testicular excurrent duct system of rats during postnatal development

The light and electron microscopic appearance of the various epithelial cells lining the efferent ducts and different regions of the epididymis were examined in rats on postnatal days 21, 39, 49, 56, and 90 to determine the role of androgens and/or spermatozoa, as well as other possible factors, on the structural differentiation of these cells. Five conclusions may be drawn from the observations made. First, on day 21 epithelial cells of all regions are structurally undifferentiated. Second, it was not until day 49 that nonciliated cells of the efferent ducts resembled those of adult animals, suggesting that more than one factor, such as androgens, testicular products, and/or spermatozoa, is needed for their full structural differentiation. Third, principal cells of the epididymis become structurally differentiated by day 39, i.e., these cells contained an elaborate Golgi apparatus, endoplasmic reticulum cisternae, and numerous 200-400 nm electron lucent secretory vesicles, as well as a full complement of endocytic organelles; this occurred in spite of the absence of spermatozoa in the epididymal lumen. The differentiation of these epididymal cells may be under the influence of androgens, which are known to be high at this time, but may also be due to specific secretions from Sertoli cells secreted directly into the efferent ducts. Fourth, clear cells of the cauda epididymidis are fully differentiated by day 39. The presence of degenerating germ cells in the lumen of the cauda epididymidis and various cellular debris, as well as high androgen levels, may be factors causing the differentiation of the cells of this region. Finally, clear cells of the corpus and cauda epididymidis only become fully differentiated by day 49, at a time when spermatozoa appear in the lumen, despite high levels of androgens at day 39; this observation indicates that the presence of spermatozoa in the lumen may be a necessary factor in causing their differentiation. Overall, these results suggest that a combination of different factors are necessary for the structural differentiation of the various epithelial cell types of the different regions of the epididymis.

Golgi apparatus of epithelial principal cells of the epididymal initial segment of the rat: structure, relationship with endoplasmic reticulum, and role in the formation of secretory vesicles

The initial segment of the epididymis of rats, fixed with glutaraldehyde, was postfixed with reduced osmium, a technique that clearly delineates the membranes of cisternae of the endoplasmic reticulum (ER) and the various elements of the Golgi apparatus, or with tannic acid to enhance the coats of vesicles and ribosomes on ER cisternae. The material was also treated to demonstrate various phosphatase activities (NADPase, TPPase, CMPase, G-6-Pase) or impregnated with osmium tetroxide. In osmium-impregnated material, the Golgi apparatus of the epithelial principal cells of the initial segment appeared in the light microscope as a branching, anastomosing ribbon forming a large network in the supranuclear region. In the electron microscope, ER were of two types: the heavily granulated, flattened, rough ER seen in the infranuclear and juxtanuclear regions and the distended, tubular, sparsely granulated ER, showing only few ribosomes, seen interlaced with the Golgi ribbon in the supranuclear region and at the apical pole of the cell. Of particular interest in this cell was the fact that the sparsely granulated ER approximated the Golgi stack on both its cis- and trans-faces. On the cis-face of the Golgi stack, the sparsely granulated ER cisternae showed the usual finger- or bud-like protrusions directed toward the cis element of the Golgi stack and around which numerous small 80 nm vesicles or membranous tubules were clustered. The Golgi stack consisted of the following elements in a cis-trans axis: the cis osmiophilic element, a first saccule slightly dilated, saccules two to four (S2-S4), which were NADPase-positive, and saccules five to seven and the eight Golgi element, which were TPPase-positive. On the trans-aspect of the Golgi stacks, several (up to four) CMPase-positive trans-Golgi networks were observed often in close apposition to the sparsely granulated ER cisternae. One of the trans-Golgi networks showed a "peeling-off" configuration, i.e. part of it was closely apposed to the overlying Golgi element of the stack, whereas the remaining part was separated from the stack by a space occupied by a cisterna of sparsely granulated ER. The other trans-Golgi networks were completely separated from the stack and were often seen sandwiched between sparsely granulated ER cisternae. Thus, ER cisternae showed extensive areas of close apposition but no continuity with the trans-Golgi networks. Although the saccules of the Golgi stacks showed NADPase and/or TPPase activity, the trans-Golgi networks displayed CMPase activity, thus facilitating their identification from the closely associated unreactive sparsely granulated ER cisternae.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparisons of Golgi structure and dynamics in plant and animal cells

The Golgi apparatus of both higher plant and animal cells sorts and packages macromolecules which are in transit to and from the cell surface and to the lysosome (vacuole). It is also the site of oligosaccharide and polysaccharide synthesis and modification. The underlying similarity of function of plant and animal Golgi is reflected in similar morphological features, such as cisternal stacking. There are, however, several fundamental differences between the Golgi of plant and animal cells, reflecting, in large part, the fact that the extracellular matrices and lysosomal systems differ between these kingdoms. These include 1) the form and replication of the Golgi during cell division; 2) the disposition of the Golgi in the interphase cell; 3) the nature of "anchoring" the Golgi in the cytoplasm; 4) the genesis, extent, and nature of membranes at the trans side of the stack; 5) targeting signals to the lysosome (vacuole); and 6) physiological regulation of secretion events (constitutive vs. regulated secretion). The degree of participation of the Golgi in endocytosis and membrane recycling is becoming clear for animal cells, but has yet to be explored in detail for plant cells.

The effects of monensin on Golgi complex of adrenal cortex and steroidogenesis

The ultrastructural and biochemical changes produced by monensin on zona fasciculata cells of the rat adrenal cortex are described. In this study we used adrenal cells in culture, adrenal slices and the intact animal. Monensin (1 microM) was added to the culture medium containing the cells, and to the incubation medium containing the adrenal slices, and was injected intravenously to the intact animal (0.65 mg/kg body weight). The ultrastructural alterations were similar in the three experimental conditions, and consisted of Golgi complex disorganization with dilated cisternae or large smooth vesicles. Quantitative analysis showed a significant increase of the relative volume of the Golgi area. The biochemical study demonstrated a significant decrease of corticosterone concentrations in culture medium after monensin addition, and in adrenal glands from treated rats. These results showed that monensin alters the fine structure of adrenal cortex Golgi complex and inhibits corticosteroidogenesis, which supports the probable role of the Golgi complex in the regulation of steroidogenesis.

The ultrastructure of signet-ring cell non-Hodgkin's lymphoma

New ultrastructural findings are reported from two lymphomas of vacuolar signet-ring cell morphology (SR+), one of B cell and one of T cell lineage. When these lymphomas were compared ultrastructurally a difference in the relationship of the endoplasmic reticulum (ER) to the vacuole was noted, although the fine structure of the vacuoles themselves was similar and they were interpreted as giant multivesicular bodies (mvbs). Smooth ER was found near the vacuoles in both cases. Dark mvbs with a complex, reticulate form are emphasised as readily identified but hitherto unreported cell components in these tumours. A further B cell lymphoma of centroblastic/centrocytic type which was SR- was found to be rich in mvbs and may be a transitional form between SR- and SR+ lymphomas. In addition, the occurrence of mvbs has been studied quantitatively in a number of other lymphomas and in B and T lymphocytes in reactive nodes. Although increased numbers of mvbs were found in neoplastic compared with reactive lymphocytes, and in T compared with B cell lymphomas, these differences were not statistically significant. The possible roles of endoplasmic reticulum and mvbs in the generation of SR+ change are discussed.

Multitubular bodies in intestinal cells of Amphiuma means/tridactylum (Urodela): ultrastructural characterization

The jejunal absorptive cells of the salamander Amphiuma, when examined using transmission electron microscopy, were found to possess a unique type of intracellular vacuole containing membranous tubules. These vacuoles, tentatively named multitubular bodies, were located in the cytoplasm between the nucleus and the brush-border membrane, and were seen with greatest frequency in the summer and fall. The vacuoles containing multitubular bodies had an average diameter of 0.6 microns, and the membranous tubules within had an average diameter of 30 nm. The tubules differed morphologically from the vesicles in the multivesicular bodies, and from the primary lysosomes in the polylysosomal vacuoles. The tubules did not exhibit acid phosphatase activity, and were of similar diameter and membrane thickness as the Golgi saccules. In contrast to the multivesicular bodies, the multitubular bodies did not take up exogenous horseradish peroxidase. Early forms of autophagosomes resembling these vacuoles were often seen in the para-Golgi region of the cell. The multitubular bodies may represent a distinct type of autophagosome. Although the exact origin of the tubules as well as their role in cellular activity is unclear, their seasonal appearance within the multitubular bodies of the absorptive cells suggests a unique means of selective down-regulation of Golgi-like organelles.

Electron-dense lipidic capillary deposits in Rett syndrome

Conjunctival, muscle, and peripheral artery biopsies were examined by light and electron microscopy in a patient with clinically diagnosed Rett syndrome. In capillaries, amorphous and membranous electron-dense deposits were observed (a) endoluminally attached to endothelial cell membranes, (b) within junctional clefts of adjacent endothelial cells, and (c) at abluminal sites of endothelial cells. In addition, electron-dense deposits lay isolated or inside multivesicular bodies in endothelial cells and pericytes. These findings have not been reported before in Rett syndrome. They were not seen in age-matched normal or pathological control cases and are suggested to indicate deposition of an as yet unknown lipidic plasma component possibly in association with impairment of the blood-tissue barrier.

Increased endocytosis and formation of multivesicular bodies in phorbol ester-stimulated human monoblastic U-937 cells

The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to arrest mitotic activity and induce macrophage differentiation in the U-937 monoblastic cell line. The acute effect of TPA on ultrastructural morphology and endocytic activity of U-937 cells was studied. TPA induced within 15 min a marked enlargement of multivesicular bodies (MVBs), comprising both volume and number of inclusion vesicles (other organelles appeared unchanged). At this stage the MBVs frequently showed tubular cytoplasmic extensions. Inclusion vesicles accumulated in MBVs with prolonged incubation (60 min). Horseradish peroxidase (HRP) and cationized ferritin (CF) added to the medium were routed preferentially to MVBs in TPA-stimulated cells. In contrast to MVBs of unstimulated cells many of the TPA-induced MVBs showed a positive cytochemical reaction to acid phosphatase. The MVBs in cells incubated with ionomycin, a calcium ionophore, did not differ from those of unstimulated cells. Cellular uptake of 125I-HRP was increased five times the control values already after 5 min of TPA stimulation. The uptake increased further with prolonged incubation (60 min), but at a slower rate. Together these indicate a TPA-induced transfer by endocytosis of portions of the plasma membrane to the lysosomal system via MVBs. Consideration of MVBs as part of the receptor-mediated endocytic pathway suggests that this effect of TPA might involve down-regulation of cell-surface receptors. The possibility of MVBs as a proton-sequestrating compartment, responsible for the cytoplasmic alkalinization previously reported for TPA-stimulated U-937 monoblastic cells, is discussed.

Light microscopical structure of the excurrent ducts and distribution of spermatozoa in the Australian rodents Pseudomys australis and Notomys alexis

The light microscopical structure of the male excurrent ducts and the distribution of spermatozoa were examined in two species of Australian rodents, the plains rat, Pseudomys australis, and the hopping mouse, Notomys alexis. In plains rats the microstructure of the ductus epididymidis and ductus deferens was similar to that of the common laboratory rodents, with the majority of the spermatozoa being found in the cauda epididymides. By contrast, in the hopping mouse, the structure of the cauda epididymidis differed significantly as the height of the epithelium and stereocilia did not decrease from the distal caput to the cauda region, and luminal diameter did not increase markedly along its length. In addition, few spermatozoa were stored in the cauda region of the tract, and as many as 60% were located in the ductus deferens, the distal portion of which displayed a highly infolded epithelium and underlying lamina propria. These differences in histological structure of the hopping mouse excurrent ducts presumably reflect divergence in function of the various regions of the tract. Although the functional implications of the present findings remain to be determined, this study demonstrates the considerable plasticity in the male excurrent ducts amongst the hydromyine rodents of Australia.

Convergence of the endocytic and lysosomal pathways in soybean protoplasts

Ultrastructural analysis of endocytosis of cationized ferritin (CF) has been combined with ultrastructural localization of acid phosphatases (AcPase) in soybean (Glycine max (L.) Merr.) protoplasts. While CF is an electron-dense marker of organelles of the endocytic pathway, ultrastructural histochemistry of AcPase identifies the organelles involved in the synthesis, transport, and storage of lytic-compartment enzymes, i.e. the lysosomal pathway. Acid phosphatases have been localized using both lead- and cerium-precipitation techniques. Protoplasts have been exposed to CF for 5 min, 30 min, or 3 h and processed for AcPase localization. At 5 min, smooth vesicles contain both CF and AcPase. By 30 min, Golgi cisternae and multivesicular bodies contain both labels. By 3 h, vacuoles become labelled with both CF and AcPase. The large central vacuoles contain intraluminal membranes which are associated with both AcPase and CF. These observations extend the analogy between plant vacuoles and animal lysosomes and demonstrate the points at which the endocytic pathway of plants converges with the lysosomal pathway.

Budding of small vesicles from the rough-surfaced endoplasmic reticulum in secretory ameloblasts of rat molar tooth germs

The budding of small vesicles from the rough-surfaced endoplasmic reticulum (rER) was examined in the secretory ameloblast of rat molar tooth germs by ordinary fixation or prolonged osmium fixation. The budding of small vesicles from the rER was observed not only at the special region (transitional region) of the rER system, which abutted on the cis-face of the Golgi apparatus, but also at other regions of the rER in the secretory ameloblast. Small vesicles (presumed to be transitional vesicles) were adjacent to the rER, which also showed budding of vesicles. After prolonged osmium treatment, osmium deposits appeared in small vesicles, as well as in the cisternae of the cis saccule of the Golgi apparatus. Small vesicles containing osmium deposits were located at various regions of the cell, including the cis-face of the Golgi apparatus. These findings indicate that the budding of small vesicles from the rER is not restricted to the transitional region of the rER system of the secretory ameloblast, but is found at various regions of the cell. This indicates that newly synthesized proteins may be transferred from the rER cisternae to the transitional vesicles not only in the transitional region of the rER system adjacent to the Golgi apparatus, but also in other regions of the secretory ameloblast.

Transcytosis in the epididymis studied by local arterial perfusion

The transport of protein across the cells of the epididymal epithelium was studied using horseradish peroxidase. Transient vascular perfusion of the epididymis of the rat and golden hamster was achieved by pulsatile retrograde infusion into the testicular artery. Peroxidase was found in the interstitium and in the epithelium, located in vesicles, vacuoles and multivesicular bodies of principal, clear and apical cells. Similar findings were obtained in mice after systemic injection of the tracer. In the rat, discharge to the lumen was confirmed by the appearance of enzyme activity in luminal fluid from the caput epididymidis after local injection. The extent of transport amounted to no more than what has been considered leakage in physiological experiments, and the time-course of appearance complemented that found by electron microscopy. The level of transcytosis after pulsatile administration of peroxidase in vivo, as judged from the occurrence of tracer in the epithelium, was much less than that obtained during constant immersion in vitro. The protein was present in multivesicular bodies of principal cells and in vesicles of clear cells at short times after presentation in vitro, when it could not have arrived by endocytosis from the lumen. This suggests that routing of basal endocytic vesicles to the lysosomal apparatus occurs.

Cytoplasmic assembly and accumulation of human immunodeficiency virus types 1 and 2 in recombinant human colony-stimulating factor-1-treated human monocytes: an ultrastructural study

Recombinant human colony-stimulating factor-1-treated human peripheral blood-derived monocytes-macrophages are efficient host cells for recovery of the human immunodeficiency virus (HIV) from blood leukocytes of patients with acquired immunodeficiency syndrome. These cells can be maintained as viable monolayers for intervals exceeding 3 months. Infection with HIV resulted in virus-induced cytopathic effects, accompanied by relatively high levels of released progeny virus, followed by a prolonged low-level release of virus from morphologically normal cells. In both acutely and chronically infected monocytes, viral particles were seen budding into and accumulating within cytoplasmic vacuoles. The number of intravacuolar virions far exceeded those associated with the plasma membrane, especially in the chronic phase, and were concentrated in the perinuclear Golgi zone. In many instances, the vacuoles were identified as Golgi elements. Fusion of virus-laden vacuoles with primary lysosomes were rare. The pattern of cytoplasmic assembly of virus was observed with both HIV types 1 and 2 and in brain macrophages of an individual with acquired immunodeficiency syndrome encephalopathy. Immunoglobulin-coated gold beads added to acutely infected cultures were segregated from the vacuoles containing virus; relatively few beads and viral particles colocalized. The assembly of HIV virions within vacuoles of macrophages is in contrast to the exclusive surface assembly of HIV by T lymphocytes. Intracytoplasmic virus hidden from immune surveillance in monocytes-macrophages may explain, in part, the persistence of HIV in the infected human host.

Cytochemical study of the Golgi apparatus and related organelles of the secretory ameloblasts of rat molar tooth germs cultured with and without colchicine

The Golgi apparatus and Golgi-associated endoplasmic reticulum lysosome (GERL) were examined in the ameloblasts with a cytochemical marker, osmium impregnation, and two enzyme markers, thiamine pyrophosphatase (TPPase) and acid phosphatase (ACPase). In control cultured germs, osmium deposit appeared in one to two immature side cisternae of Golgi stacks; TPPase activity was restricted in a few mature side cisternae and condensing vacuoles. ACPase activity existed in the GERL and, sometimes, in the mature side-cisternae and condensing vacuoles. These findings show that Golgi stacks of ameloblasts consist of several distinct compartments. In colchicine-treated tooth germs, there were morphological and cytochemical changes in both Golgi stacks and GERL. The Golgi apparatus was fragmented and its stacks were scattered throughout the supranuclear region. In some stacks, the number of osmium-positive cisternae was greater than normal; in others they were absent. TPPase and ACPase activity was absent or diminished. These findings suggest the importance of microtubules in the organization of Golgi complex and GERL in the secretory ameloblast.

Cytochemical studies on induced autophagocytosis in mouse exocrine pancreas

1. The origin of the limiting membranes of autophagic vacuoles (AVs) in mouse pancreatic acinar cells was studied in vinblastine-induced autophagocytosis. 2. The marker enzymes used were adenosine triphosphatase, lipase, inosine diphosphatase and thiamine pyrophosphatase. The following impregnation techniques were used: unbuffered osmium tetroxide impregnation, imidazole-buffered osmium tetroxide impregnation and uranyl-lead-copper impregnation. 3. Only a weak lipase activity was observed between the limiting membranes of a few AVs. The AV membranes were stained heavily with all impregnation techniques used. 4. The origin of AV membranes seems to be same in mouse liver and exocrine pancreas in vinblastine-induced autophagocytosis.

Fragmentation and partitioning of the Golgi apparatus during mitosis in HeLa cells

Osmium impregnation was used to determine the number of Golgi apparatus in both interphase and mitotic HeLa cells. The number was found to increase substantially during mitosis to the point where random partitioning alone would explain the nearly equal numbers found in each daughter cell.

Protein transport to the epididymal lumen

Experiments were performed to clarify the debate over the entry of circulating proteins into the epididymal lumen by use of the marker horseradish peroxidase (HRP). Epididymal tubules from the caput epididymidis of the rat were immersed in medium TC 199 containing HRP (3.5 mg/ml) for 5 min to 3 h at 33 degrees C. Sections were examined for the presence of tracer within the epithelial cells by electron microscopy. From 5 min to 3 h, vesicles containing peroxidase reaction products were found throughout the cytoplasm of the principal cells. Vesicles occurred close to both the basal and apical membranes, and many were found opening into the interstitial space and lumen, depending on the length of incubation. By 5 min labelled vesicles were infrequently found in the apical part of the cells. Reaction product was observed in the epididymal lumen adhering to the microvilli from 30 min of incubation onwards. At all periods of incubation peroxidase was present at the base of the epithelium and between the cells, but it was never found within the tight junctional complexes, and no reaction deposits were found within epithelial cells of tubules incubated in the absence of peroxidase. It is concluded that large molecules leaving the capillaries may enter the epididymal lumen in the caput by means of fluid-phase endocytosis.

Endocytic apparatus and transcytosis in epithelial cells of the vas deferens in the rat

The apex of the principal epithelial cells lining the vas deferens of the rat contains coated pits in continuity with the apical plasma membrane and large subsurface-coated vesicles (100-125 nm). In the apical cytoplasm, large, pale, uncoated vesicles (150-300 nm), small coated and uncoated vesicles (50-60 nm), uncoated vesicles about 75-90 nm, and membranous apical tubules are present, in addition to large, vacuolar, pale, multivesicular bodies, dense multivesicular bodies, and secondary lysosomes seen deeper in the cytoplasm amongst numerous ER cisternae, saccules of the Golgi apparatus, and mitochondria. The endocytic activity of these cells was investigated by using cationic ferritin (CF) as a marker of adsorptive endocytosis and native ferritin (NF) for demonstrating fluid-phase endocytosis. These tracers were injected separately into the lumen of the vas deferens, and the animals were killed at various time intervals thereafter from 2 to 90 minutes. At 2 minutes CF was seen bound predominantly to microvilli and to areas of the apical plasma membrane delimiting coated pits as well as in large, coated vesicles. At 5 and 15 minutes the tracers were seen in apical tubules and pale multivesicular bodies; at 30 minutes moderately dense multivesicular bodies were labeled. At 1 hour and longer time intervals dense multivesicular bodies and secondary lysosomes were labeled. NF followed the same pathway as CF; however, no binding to microvilli or areas delimiting coated pits was observed. The numerous other vesicular structures, i.e., the large uncoated vesicles (150-300 nm) and the small coated and uncoated vesicles (50-60 nm), never became labeled with the tracers and therefore were not involved in the endocytic process. There was, however, an exception in the case of several small (75-90 nm) uncoated vesicles seen deeper in the apical cytoplasm of these cells which were labeled exclusively with CF. With time such vesicles appeared along the lateral and basal surfaces of these cells and discharged their content of CF into the lateral intercellular space or the connective tissue space at the base of these cells. Thus the principal epithelial cells in addition to sequestering the endocytosed tracers within secondary lysosomes where they are presumably degraded also appear to be involved in the transcytosis of material from the lumen of the vas deferens to the underlying lamina propria.

Immunocytochemical localization of cathepsins B and H in rat liver

Light and electron microscopic localization of cathepsins B and H in rat liver was investigated by immunoenzyme and protein A-gold techniques. For light microscopy (LM), semi-thin sections of the Epon-embedded material were stained by the immunoenzyme technique after removal of epoxy resin. For electron microscopy (EM), ultra-thin sections of the Lowicryl K4M-embedded material were stained by the protein A-gold technique. By LM, reaction deposits for cathepsins B and H were present in the cytoplasmic granules of parenchymal cells and endothelial cells, and Kupffer cells. The sinus-lining cells and the parenchymal cells showed the similar staining intensity. By EM, gold particles were present exclusively in lysosomes of all the cell types cited above. The same results were obtained from quantitative analysis. In addition, Golgi complexes themselves were mostly negative but some small vesicles on the trans side of them were labeled for these proteinases. The results indicate that cathepsins B and H are present in the lysosomes of rat liver and that these enzymes seem to be transported by small vesicles from endoplasmic reticulum to lysosomes via tubuloreticular network of the trans Golgi region.

The relationship between the morphology of cell organelles and kinetics of the secretory process in male sex accessory glands of mice

Two male sex accessory glands of the mouse, seminal vesicle and coagulating gland, were compared with the aim of relating differences in the morphology of organelles to the kinetics of the secretory process. The epithelial cells of the two glands were assessed by morphometric analysis, cytochemical staining, and electron-microscopic autoradiography after administration of a labeled amino acid. The rough endoplasmic reticulum of the seminal vesicle comprised narrow parallel cisternae, while that of the coagulating gland was greatly distended and occupied a much larger percentage of the cytoplasmic volume. Radioactively labeled products were secreted much more rapidly in the seminal vesicle than in the coagulating gland. The primary point of difference in kinetics of intracellular transport between the two glands was in exit of material from the rough endoplasmic reticulum. The more rapid drainage of the rough endoplasmic reticulum may be related to its relatively greater membrane surface density and lesser internal volume. In contrast, similarities in size and cytochemical staining in the Golgi apparatus of the two glands were accompanied by similar kinetics of intracellular transport of secretory protein through this organelle.

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--II. Copper accumulation in the ileum and distal jejunum

High concentrations of copper were demonstrated histochemically in the enterocytes lining the ileum and distal jejunum of suckling rats. Copper was not detected in cells from the duodenum or proximal jejunum of these rats or from any region of the small intestine of rats in which "closure" had taken place. X-Ray microanalysis demonstrated copper, in equi-atomic association with sulphur, within discrete vesicles in the supranuclear cytoplasm of the enterocytes. Despite the high concentrations of these two elements no biochemical evidence was found for the presence of significant amounts of copper-binding metallothionein. The highest concentrations of copper (226 +/- 48 mg atoms/kg dry wt: +/- SD) were found in vesicles adjacent to the nucleus, which did not accumulate particulate tracers, or calcium from the lumen of the intestine. These vesicles probably result from the coalescence of Golgi-derived primary lysosomes followed by fusion with endocytic vacuoles. They may provide a mechanism of copper excretion from the neonatal rat.