Number Of Cisternae Research Articles

A Quantitative Subarachnoid Hemorrhage Grading System, Including Supratentorial and Infratentorial Cisterns, With Multiplanar Computed Tomography Reformations.

BackgroundSubarachnoid hemorrhage (SAH) grading scales typically evaluate a limited number of cisterns on the axial plane. The goal of our study is to apply a simple quantitative yet comprehensive SAH grading scale to all major intracranial cisterns, including the infratentorial cisterns, with multiplanar computed tomography (CT) reformations.MethodologyWe performed a retrospective review of 94 consecutive cases of spontaneous SAH presenting within 72 hours of onset. SAH was categorized into five grades based on the short-axis thickness of SAH in 20 intracranial cisterns measured on the axial, coronal, and sagittal planes. Statistical analysis was performed for inter-rater agreement with kappa statistics, for inter-plane agreement by Spearman correlation statistics, and for inter-rater and inter-plane agreement by Pearson correlation statistics.ResultsThe extended kappa coefficient for the three reviewers across all 20 cisterns varied from 0.38 (0.27, 0.50) to 0.59 (0.52, 0.65) on the axial plane. The kappa coefficient for two reviewers varied from 0.46 (0.33, 0.59) to 0.70 (0.60, 0.80) on the coronal plane and from 0.35 (0.20, 0.49) to 0.87 (0.77, 0.96) on the sagittal plane. The average grade of cisterns per case demonstrated mostly excellent correlation between the imaging planes with Spearman correlation statistics (≥0.70). Pairwise concordance correlation coefficient of the total SAH score revealed agreement ranging from 0.81 to 0.90 in all three planes. Pearson correlation statistics of the average total SAH scores revealed excellent correlation among the three planes (≥0.91).ConclusionA simple quantitative SAH grading scale can be successfully applied to the supratentorial and infratentorial cisterns in three standard CT imaging planes.

Glycan processing in the Golgi as optimal information coding that constrains cisternal number and enzyme specificity

Many proteins that undergo sequential enzymatic modification in the Golgi cisternae are displayed at the plasma membrane as cell identity markers. The modified proteins, called glycans, represent a molecular code. The fidelity of this glycan code is measured by how accurately the glycan synthesis machinery realizes the desired target glycan distribution for a particular cell type and niche. In this article, we construct a simplified chemical synthesis model to quantitatively analyse the trade-offs between the number of cisternae, and the number and specificity of enzymes, required to synthesize a prescribed target glycan distribution of a certain complexity to within a given fidelity. We find that to synthesize complex distributions, such as those observed in real cells, one needs to have multiple cisternae and precise enzyme partitioning in the Golgi. Additionally, for a fixed number of enzymes and cisternae, there is an optimal level of specificity (promiscuity) of enzymes that achieves the target distribution with high fidelity. The geometry of the fidelity landscape in the multidimensional space of the number and specificity of enzymes, inter-cisternal transfer rates, and number of cisternae provides a measure for robustness and identifies stiff and sloppy directions. Our results show how the complexity of the target glycan distribution and number of glycosylation enzymes places functional constraints on the Golgi cisternal number and enzyme specificity.

The effect of selected immunostimulants on hemocytes of the false black widow Steatoda grossa (Theridiidae) spiders under chronic exposition to cadmium

The aim of this study was to analyze whether, and to what extent, long–term exposure to cadmium, administered in sublethal concentrations by the oral route, caused changes in the immune potential of hemocytes in adult female Steatoda grossa spiders. We used artificial and natural immunostimulants, namely phorbol 12–myristate 13–acetate (PMA) and bacterial cell suspension based on Gram–positive (G+, Staphylococcus aureus) and Gram–negative (G−, Pseudomonas fluorescens) bacteria, to compare the status of hemocytes in nonstimulated individuals and those subjected to immunostimulation. After cadmium exposure, the percentage of small nongranular hemocytes in response to G+ cell suspension and PMA mitogen was decreased. Furthermore, in the cadmium–intoxicated spiders the percentage of plasmatocytes after immunostimulation remained lower compared to the complementary control group. Exposure to cadmium also induced several degenerative changes, including typical apoptotic and necrotic changes, in the analyzed types of cells. Immunostimulation by PMA mitogen and G+ bacterial suspension resulted in an increase in the number of cisterns in the rough endoplasmic reticulum of granulocytes, in both the control group and cadmium–treated individuals. These changes were accompanied with a low level of metallothioneins in hemolymph. Chronic cadmium exposure may significantly weaken the immune defense system of spiders during infections.

Efficiency of technologies to live with drought in agricultural development in Brazil's semi-arid regions

Vulnerability to water stress brings challenges to water resources management in arid and semi-arid regions and it is an obstacle to socioeconomic development. In this sense, some technologies are used to overcome this bottleneck. The present study sought to investigate the insertion of cisterns and public irrigation schemes in seven sub-basins in Brazil's semi-arid regions, to verify their effects on family farming agricultural development and their suitability according to water availability trend. These technologies were spatialized and agricultural production trend lines, between 1995 and 2017, were generated in order to indicate these technologies efficiency. Finally, the precipitation, surface and subsurface runoff trend was evaluated for all sub-basins. Trend analysis in agricultural production showed that a large part of the municipalities had a decrease in agricultural production and municipalities that had a larger number of cisterns did not achieve good agricultural development, while agricultural irrigation systems brought better results. Regarding physical-natural conditions, subsurface runoff has decreased and an increase in surface runoff was identified, which can be collected through the installation of new cisterns. However, for this purpose, future investigations are important to identify the factors that are affecting cisterns performance.

Dynamics of ultrastuctural changes in the secretory apparatus of thyrocytes in the conditions of an experimental blastomogenesis.

Background. Secretion of thyroid hormones considerably decreases at development of tumoral pathology of various localization and significantly affects efficiency of treatment and the forecast of a disease. Development of a hypothyroid state can be connected with disturbance of secretory activity thyrocytes of a thyroid gland and contributes to the development of system thyroid deficiency. Definition of structural bases of development of thyroid deficiency at tumoral pathology at the subcellular level in distance interaction of a thyroid gland and a tumor will allow to define molecular and cellular mechanisms of interaction of an organism and a tumor in the a blastomogenesis. Objective. The purpose of the research was studying of a state and dynamics of changes of a lamellar complex of thyrocytes in the course of distance interaction with a tumor in an experiment. Methods. As the experimental model of tumor we have used a model of the slightly differentiated solid adenocarcinoma of Guerin. Experiment carried out on the rats - the males of the line of Vistar as far as the mass 120 - 160 g. animals were divided beside 2 groups. First group - control. To the second group - translanted the strain of the cells of Guerin's carcinoma by hypodermic injection beside the region thighs. Animals derived based on the experiment on 2, 4 and 12 weeks. Cytotopographical and ultramicroscopic studying of dynamics of changes of dictyosomes, their distribution in cytoplasm of thyrocytes and a condition of structural components of a lamellar complex is carried out. Results. On the 2nd week of an experimental blastomogenesis reduction of number of cisterns of a lamellar complex to 3 - 4 is observed, cis - cisterns are considerably expanded, distances between cisterns are increased when comparing with control group, length of cisterns of trans - compartment is reduced when comparing with control group. On the 4th week of growth of a transplanted tumor the significant changes of a lamellar complex connected with fragmentation of cisterns, loss of polarity of dictyosomes and lack of vesicles and vacuoles around a lamellar complex are noted. On the 12th week of growth of a carcinoma of Guerin in thyrocytes reduction of length of cisterns of a lamellar complex, their mutually parallel and dense arrangement, lack of ampullar expansions, insignificant increase in volume of cisterns of trans - compartment dictyosome is observed. Conclusion. Changes of ultrastructure of a lamellar complex of Golgi of thyricytes of a thyroid gland in the course of distance interaction with the transplanted tumor demonstrate early disturbance of processes of secretion and vesicular transport with possible development of apoptosis due to activation of a caspase system.

3D electron tomographic and biochemical analysis of ER, Golgi and trans Golgi network membrane systems in stimulated Venus flytrap (Dionaea muscipula) glandular cells

BackgroundThe insect-trapping leaves of Dionaea muscipula provide a model for studying the secretory pathway of an inducible plant secretory system. The leaf glands were induced with bovine serum albumin to secrete proteases that were characterized via zymogram activity gels over a 6-day period. The accompanying morphological changes of the endoplasmic reticulum (ER) and Golgi were analyzed using 3D electron tomography of glands preserved by high-pressure freezing/freeze substitution methods.ResultsSecretion of multiple cysteine and aspartic proteases occurred biphasically. The majority of the Golgi was organized in clusters consisting of 3–6 stacks surrounded by a cage-like system of ER cisternae. In these clusters, all Golgi stacks were oriented with their cis-most C1 cisterna facing an ER export site. The C1 Golgi cisternae varied in size and shape consistent with the hypothesis that they form de novo. Following induction, the number of ER-bound polysomes doubled, but no increase in COPII vesicles was observed. Golgi changes included a reduction in the number of cisternae per stack and a doubling of cisternal volume without increased surface area. Polysaccharide molecules that form the sticky slime cause swelling of the trans and trans Golgi network (TGN) cisternae. Peeling of the trans-most cisternae gives rise to free TGN cisternae. One day after gland stimulation, the free TGNs were frequently associated with loose groups of oriented actin-like filaments which were not seen in any other samples.ConclusionsThese findings suggest that the secretory apparatus of resting gland cells is “overbuilt” to enable the cells to rapidly up-regulate lytic enzyme production and secretion in response to prey trapping.

Self-Assembled "Breathing" Grana-Like Cisternae Stacks.

Membranes in cells display elaborate, dynamic morphologies intimately tied to defined cellular functions. Cisternae stacks are a common membrane morphology in cells widely found in organelles. However, compared with the well-studied spherical cell membrane mimics, cisternae stacks as organelle membrane mimics are greatly neglected because of the difficulty of fabricating this unique structure. Herein, the grana-like cisternae stacks are assembled via the reorganization of stacked microsized bicelles to mimic grana functions. The cisternae stacks are connected by fusion regions between adjacent cisternae. The number of cisternae can be controlled from ≈4 to 15 by the variation of ethanol volume percentage. Under the stimulation of solvent or negatively charged nanoparticles, the cisternae stacks can reversibly compress and expand, similar to the "breathing" property of natural grana. During the "breathing" process, nanoparticles are reversibly captured and released. Frequency resonance energy transfer is realized on the cisternae stacks trapped with two kinds of quantum dots. The cisternae stacks provide advanced membrane model for cell biotechnology, and clues for the shaping of organelles composed of cisternae. The ability of the cisternae stacks to capture materials enables them to possibly be applied in biomimetics and the design of advanced functional materials.

The Byzantine cisterns of Constantinople

Abstract The most unusual aspect of Byzantine Constantinople's water system was the large number of cisterns throughout the city. This research integrates the two most recent in-depth studies of the cisterns to determine that there have been at least 211 cisterns attributed to the Byzantine city. The distribution of the cisterns indicates that the size and number of cisterns constructed reduced over time, with more and larger cisterns developed prior to the 7th century. Cisterns are concentrated in the older area of the city and sparser on the periphery, but with later ones more common in the peripheral areas, suggesting that water provision was extended over time, and although the majority of cisterns are small, most storage volume is concentrated in the three largest open-air cisterns. The extended, detailed list produced will allow more in-depth investigations to proceed. Analysis of the distribution of cisterns across the city creates a framework for understanding the development and functioning of Byzantine Constantinople's complex water supply system.

Brefeldin A affects the system of contractile vacuoles in Mesostigma viride (Streptophyta)

Brefeldin A was used to disrupt the contractile vacuoles (CVs) of the streptophyte green flagellate Mesostigma viride. Treatment of M. viride with BFA caused enlarged CVs, as well as a decrease in the number of CVs, and finally the cells burst. In addition, BFA treated cells revealed the typical changes in Golgi structure (decrease in number of cisternae and Golgiassociated COP1 vesicles) observed in other systems. It is well known that treatment with BFA inhibits the formation of COP1-coated vesicles and some types of clathrin-coated vesicles (CCV). Clathrin coated pits (CCPs) and clathrin coated vesicles are associated with the CVs in Mesostigma viride. However, electron microscopically analysis revealed that the number of CCVs did not decrease upon treatment with BFA. We conclude that the molecular cause for BFA effect on the CV must be localized at the Golgi, probably due to the inhibition of transport of proteins from the Golgi to the CV.

Changes in the ultrastructure of Capsicum annuum L. seedlings roots under aluminum stress conditions

The effect of aluminum was investigated on the cell ultrastructure of roots of fourteen-day-old 'Trapez' red pepper seedlings grown in water culture. Disorders in the cell structure were observed using transmission electron microscopy (TEM). An analysis of longitudinal sections of the apical region of the control plants' roots showed that cells of the cap and cells of the meristematic region had an arrangement and shape typical for these root regions, and cell organelles were properly developed. Changes in the cell structure under the influence of aluminum involved a reduction in the number of starch grains in the leucoplasts of the cap, the formation of lobate nuclei and a reduction in the number of cisternae in the dictyosomes as well as the damage of the cell membranes. Moreover, the swelling of mitochondria was observed with a simultaneous reduction in the number of mitochondrial cristae or the bursting of the membrane of these structures. In the vacuoles of the investigated root section, the presence of numerous electron-opaque large-sized formations was found, being most probably aluminum deposits. The cell wall, often thickened, was wavy or the formation of two walls in close distance was observed. The obtained results prove the high sensitivity of the studied red pepper cultivar to aluminum stress.

The JIP3 scaffold protein UNC‐16 regulates RAB‐5 dependent membrane trafficking at C. elegans synapses

How endosomes contribute to the maintenance of vesicular structures at presynaptic terminals remains controversial and poorly understood. Here, we have investigated synaptic endosomal compartments in the presynaptic terminals of C. elegans GABAergic motor neurons. Using RAB reporters, we find that several subsynaptic compartments reside in, or near, presynaptic regions. Loss of function in the C. elegans JIP3 protein, UNC-16, causes a RAB-5-containing compartment to accumulate abnormally at presynaptic terminals. Ultrastructural analysis shows that synapses in unc-16 mutants contain reduced number of synaptic vesicles, accompanied by an increase in the size and number of cisternae. FRAP analysis revealed a slow recovery of RAB-5 in unc-16 mutants, suggestive of an impairment of RAB-5 activity state and local vesicular trafficking. Overexpression of RAB-5:GDP partially suppresses, whereas overexpression of RAB-5:GTP enhances, the synaptic defects of unc-16 mutants. Our data demonstrate a novel function of UNC-16 in the regulation of synaptic membrane trafficking and suggest that the synaptic RAB-5 compartment contributes to synaptic vesicle biogenesis or maintenance.

ZFPL1, a novel ring finger protein required for cis-Golgi integrity and efficient ER-to-Golgi transport

The Golgi apparatus occupies a central position within the secretory pathway, but the molecular mechanisms responsible for its assembly and organization remain poorly understood. We report here the identification of zinc finger protein-like 1 (ZFPL1) as a novel structural component of the Golgi apparatus. ZFPL1 is a conserved and widely expressed integral membrane protein with two predicted zinc fingers at the N-terminus, the second of which is a likely ring domain. ZFPL1 directly interacts with the cis-Golgi matrix protein GM130. Depletion of ZFPL1 results in the accumulation of cis-Golgi matrix proteins in the intermediate compartment (IC) and the tubulation of cis-Golgi and IC membranes. Loss of ZFPL1 function also impairs cis-Golgi assembly following brefeldin A washout and slows the rate of cargo trafficking into the Golgi apparatus. Effects upon Golgi matrix protein localization and cis-Golgi structure can be rescued by wild-type ZFPL1 but not mutants defective in GM130 binding. Together, these data suggest that ZFPL1 has an important function in maintaining the integrity of the cis-Golgi and that it does so through interactions with GM130.

How Many Ways Through the Golgi Maze?

The secretory route in eukaryotic cells has been regarded as one common pathway from the endoplasmic reticulum (ER) through the Golgi cisternae to the trans Golgi network where recognition, sorting and exit of cargo molecules are thought to occur. Morphologically, the ribosome-coated ER is observed throughout the cytoplasm, while the Golgi apparatus usually is confined to a perinuclear position in mammalian cells. However, Golgi outposts have been observed in neuronal dendrites and dispersed Golgi elements in skeletal muscle myofibers. In insects, like in Drosophila melanogaster imaginal disc cells and epidermal cells of Tobacco and Arabidopsis leafs, individual Golgi stacks are distributed throughout the cytoplasm. Golgi stacks do not only differ in their intracellular localization but also in the number of stacks from one to several hundreds. Each stack consists of closely aligned, flattened, membrane-limited cisternae. The number of cisternae in a Golgi stack is also variable, 2-3 in some ciliates, 10 in many plant cell types and up to 30 in certain euglenoids. The yeast Saccharomyces cerevisiae has a Golgi structure of minimal complexity with scattered solitary cisternae. It is assumed that the number of Golgi cisternae reflects the overall complexity of the enzymatic reactions that occur in their lumen, while the number of stacks reflects the load of macromolecules arriving at the cis side. In this review, we will focus on how the available morphological and biochemical data fit with the current view of protein sorting in the secretory pathway, particularly in polarized cells like neuronal and epithelial cells.

The Golgi-associated Protein GRASP65 Regulates Spindle Dynamics and Is Essential for Cell Division

At the onset of mitosis, the pericentriolar Golgi apparatus of mammalian cells is converted into small fragments, which are dispersed throughout the cytosol. The Golgi-associated protein GRASP65 is involved in this process. To address the role of GRASP65 in mitotic Golgi fragmentation, we depleted the protein from HeLa cells by RNAi. In the absence of GRASP65, the number of cisternae per Golgi stack is reduced without affecting the overall organization of Golgi membranes and protein transport. GRASP65-depleted cells entered mitosis, but accumulated in metaphase with condensed chromatin and multiple aberrant spindles and eventually died. Although Centrin2 and g-tubulin were detected in two of the spindle poles, the other spindle poles contained g-tubulin, but not Centrin2. Furthermore, we provide evidence that the expression of the C-terminus of GRASP65 interferes with entry of cells into mitosis. Our results suggest the requirement for GRASP65 in the regulation of spindle dynamics rather than a direct role in the stacking of Golgi cisternae. This novel function is in addition to the previously established negative role of GRASP65 at the G2/M transition, which is mediated by its C-terminus.

Calmodulin and Its Role in the Secretory Apparatus of the DesmidClosterium

Closterium acerosum is a large bipolar desmid that has an extensive secretory apparatus. Two major secretory complexes that are produced by this green alga are a glucuronic acid–rich mucilage that is key in the gliding mechanism and a cell wall consisting of multiple polysaccharide and protein components. These substances are synthesized and processed for secretion through an elaborate endomembrane system and are transported around the cell and to the cell surface via actin‐mediated cyclosis. In this study, an analysis of the role of calmodulin with regard to the secretory apparatus was conducted. Whole‐cell extracts and Western blot analysis show the existence of calmodulin. Immunogold labeling reveals calmodulin in the peripheral cytoplasm near the plasmamembrane and cell wall region. Calmodulin antagonists cause significant disruption to the morphology of the Golgi apparatus. On application of the antagonists W7, W13, TMB‐8, and TFP, the Golgi body exhibits reduction in the number of cisternae per stack, significant curling of cisternae, and formation of unusual multiperforate vesicles. In addition, there is alteration of the cytoplasmic streaming network and limited disturbance to the peripheral vacuole system. Immunogold labeling with an antibody specific to the mucilage shows that mucilage processing is still apparent in the altered Golgi bodies and remnants after treatment.

Plant cells show an acquired insensitivity to Brefeldin A

Hawes, 1993). Often these compartments are surrounded by remnants of Golgi stacks, where the trans-cisternum The parameters of Brefeldin A (BFA) action in plant faces into the BFA compartment, suggesting that vesiculacells have been further investigated in maize root tips. tion of the stack is a controlled event. These BFA Incubation of maize root tip cells with 100 m gm l’1 BFA compartments can be specifically and heavily stained for for 2 h induces the vesiculation and aggregation of secretory products, indicating an accumulation of secretGolgi membrane to form BFA compartments; an effect ory products at the Golgi after BFA treatment (Satiatthat is reversed by incubation of the cells in BFA-free Jeunemaitre and Hawes, 1993). medium. In this paper, the effects of prolonged incuba- For the majority of plant cell types investigated, a tion with BFA are reported, revealing that Golgi stacks response to BFA has been observed. Reported ultrastrucspontaneously re-form in the presence of this drug tural eVects include an increase in cisternal length after incubation for 12 h or 24 h. The observation that ( Kimura et al., 1993; Yasuhara et al., 1995), or reduction the same BFA solution is still able to induce the forma- in the number of cisternae per stack (Schindler et al., tion of BFA compartments in fresh roots suggests that 1994), and vesiculation of the trans -o rcis-cisternae this recovery is not due to metabolism, detoxification (Satiat-Jeunemaitre and Hawes, 1992; Driouich et al., or depletion of the drug. Furthermore, incubation of 1993; Kimura et al., 1993; Rutten and Knuiman, 1993; maize roots with a fresh 100 m gm l’1 BFA solution for Schindler et al., 1994; Dairman et al., 1995). The well2 h following 24 h BFA treatment fails to induce the documented response of mammalian cells to BFA, the reformation of BFA compartments. Thus, an acquired retrograde adsorption of Golgi proteins into the endoinsensitivity to BFA in plant cells, that has not been plasmic reticulum (Lippincot-Schwartz et al., 1989) may observed in mammalian cells to date, is indicated. occur in some plant cell types. ER-Golgi connections

The effect of castanospermine on embryonic mouse cerebellar neurons in culture.

This study examines ultrastructural changes in explants of fetal mouse cerebellum following exposure to castanospermine, an inhibitor of N-linked glycosylation and therefore likely to interfere with cell-cell interactions in the developing nervous system. Explants were grown in castanospermine enriched medium for a period of 10 days and compared with identical explants maintained in control culture medium. Both control and treated explants contained many neurons and numerous synaptic profiles. A detailed analysis of 75 thin sections from each group of explants did however reveal highly significant differences between the two. The castanospermine-treated cells contained smaller numbers of cisternae in each Golgi stack; much larger numbers of secretory vesicles which were also substantially larger in size and four times as many coated vesicles per section as control cells. In addition, at 10 days in culture the first changes in the rough endoplasmic reticulum were observed, with individual profiles of reticulum occasionally associated with large vacuoles. Thus, although cerebellar neurons in culture are able to survive prolonged exposure to castanospermine, there are marked ultrastructural changes in subcellular organelles associated with glycoprotein synthesis, packaging and secretion.

Structure, differentiation, and multiplication of Golgi apparatus in fungal hyphae

Golgi apparatus in subapical regions of hyphae consist of paranuclear dictyosomes with 4–5 cisternae each. Transverse and tangential sections provide ultrastructural evidence for a three-dimensional architectural model of the Golgi apparatus and a stepwise mechanism for dictyosome multiplication. The dictyosomes are polarized, with progressive morphological and developmental differentiation of cisternae from the cis to the trans pole. Small membrane blebs and transition vesicles provide developmental continuity between the nuclear envelope and the adjacent dictyosome cisterna at the cis face. Cisternae are formed as fenestrated plates with extended tubular peripheries. The morphology of each cisterna depends on its position in the stack, consistent with a developmental gradient of progressive maturation and turnover of cisternae. Mature cisternae at the trans face are dissociated to produce spheroid and tubular vesicles. Evidence in support of a schematic sequence for increasing the numbers of dictyosomes comes from images of distinctive and unusual forms of Golgi apparatus in hyphal regions where nuclei and dictyosomes multiply, as follows: (a) The area of the nuclear envelope exhibiting “forming-face” activity next to a dictyosome expands, which in turn increases the size of cisternae subsequently assembled at the cis face of the dictyosome. (b) As subsequent large cisternae are formed and mature as they pass through the dictyosome, an entire dictyosome about twice normal size is built up. The number of cisternae per stack remains the same because of continuing turnover and loss of cisternae at the trans face, (c) This enlarged dictyosome becomes separated into two by a small region of the nuclear envelope next to the cis face that acquires polyribosomes and no longer generates transition vesicles, (d) As a consequence, assembly of new dictyosomes is physically separated into two adjacent regions, (e) As.the enlarged cisternae are lost to vesiculation at the trans pole, they are replaced by two separate stacks of cisternae with typical “normal” diameters, (f) The net result is two adjacent dictyosomes where one existed previously. Dictyosome multiplication is thus accomplished as part of the normal developmental turnover of cisternae, without interrupting the functioning of the Golgi apparatus as it continues to produce new secretory vesicles from mature cisternae at the trans face. Coordination of Golgi apparatus multiplication with nuclear division ensures that each daughter nucleus receives a complement of paranuclear dictyosomes.

Ultrastructural and cytochemical study of the Golgi complex of molluscan (Mytilus galloprovincialis) digestive cells

The present study has been performed to investigate the ultrastructure and subcellular distribution of several marker enzymes within the Golgi complex of digestive cells of the mussel, Mytilus galloprovincialis. This cell type is involved in the intracellular digestion of food and contains a well-developed lysosomal-vacuolar system and a characteristic cup-shaped Golgi complex. The number and degree of compaction of the tubulo-filamentous structures extending across the distended regions of the cisternae, the number of Golgi stacks per cell and the number of cisternae per stack vary with season and nutritional status of the animals. The degree of compaction of the tubulo-filamentous structures defines the cis- and trans-portions of the Golgi apparatus, the less compacted structures being associated with the cis-portion. Acid phosphatase and arylsulphatase activities are located within some tubules and vesicles in the trans-Golgi network and in some membrane-bounded organelles comprising the lysosomal-vacuolar system. The tubulo-filamentous structures of the dilated rims are reactive for arylsulphatase activity only when located in the trans-portion. Osmium impregnation techniques label all the cisternae of the Golgi complex. No nicotinamide adenine dinucleotide phosphatase activity is present in Golgi bodies or other associated structures in digestive cells. Thiamine pyrophosphatase activity only rarely occurs in some elongate tubules that are interpreted as belonging to trans-cisternae.

The Pathway of Golgi Cluster Formation in Okadaic Acid-Treated Cells

Using stereology and immunoelectron microscopy we examined the pathway of Golgi duster formation during treatment with the phosphatase inhibitor okadaic acid. During the first hour the Golgi stack of suspension HeLa cells lost 90% of its membrane without appreciable reduction in the number of cisternae. During this time clusters of tubules and vesicles (Golgi clusters) appeared and these contained only a fraction of the Golgi membrane present in untreated cells. Despite the overall reduction in membrane the total amount of immunolabeling for galactosyltransferase over the Golgi clusters of a typical cell was maintained, indicating that galactosyltransferase had been retained in Golgi membranes. The observation that, after 40 min okadaic acid treatment, labeling density for galactosyltransferase within trans Golgi cisternae increased 1.6-fold (n = 3, CE 10%) suggests that membrane loss from trans cisternae was selective. Careful evaluation of immunolabeled clusters showed that most of the galactosyltransferase labeling was located over complex tubular profiles and not vesicular profiles. Tubular structures were also observed during disassembly and these were found both connected to disassembling cisternae and within forming Golgi clusters, indicating that they were intermediates in cluster formation. We also investigated the role of vesicular transport in cluster formation. During disassembly we found no accumulation of COP-coated buds and vesicles over Golgi membrane. However, aluminium fluoride, previously found to arrest transport in the Golgi stack, completely inhibited membrane depletion and stack disassembly. Taken together, our results indicate that during Golgi cluster formation, membrane leaves the Golgi but galactosyltransferase is retained within a tubular reticulum which is a direct descendant of trans-Golgi cisternae. Membrane depletion may require ongoing vesicular transport and we postulate that it arises because of an imbalance in membrane traffic into and out of the Golgi apparatus.