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PubMed1989

Morphology of the lingual apparatus of the domestic chicken, Gallus gallus, with special attention to the structure of the fasciae.

A detailed redescription of the mechanically interacting structural elements of the lingual apparatus of the domestic chicken, Gallus gallus, revealed the functional and constructional role of organized connective tissue (i.e., ligaments and fasciae) as structural elements that ensure the proper biomechanical interactions among the various structures within the lingual apparatus (e.g., cartilaginous and bony skeletal elements, muscles, salivary glands, epithelial structures). Fasciae, together with extrinsic muscles, also connect the lingual apparatus to the other components of the feeding apparatus, such as the skull, jaw apparatus, and larynx. For example, the hyoid apparatus is attached to the skull by a sheath-like fascia (F. vaginalis), the internal structure of which is described here for the first time. Thus, the hyoid suspension in birds differs fundamentally from that in mammals. This study is the first to examine all biomechanically functioning structural elements that are part of the galliform lingual apparatus in a systematic and comprehensive manner. It also provides a set of novel characters that may be useful for future comparative studies in evolutionary and functional morphology.

Animals↗
PubMed1994

Anatomy of the hyoid apparatus in Odontoceti (toothed whales): specializations of their skeleton and musculature compared with those of terrestrial mammals.

BACKGROUND: The hyoid apparatus of odontocetes (toothed whales) serves as a major attachment point for many of the muscles and ligaments subserving breathing, swallowing, and sound production. METHODS: This study examines the hyoid apparatus in 48 specimens of ten odontocete genera (Phocoena, Lagenorhynchus, Stenella, Delphinus, Tursiops, Grampus, Globicephala, Mesoplodon, Physeter, and Kogia) collected post mortem from beach strandings. RESULTS: The odontocete hyoid apparatus, as that of their closest terrestrial relatives, the artiodactyls, is divisible into a basal portion (basihyal, paired thyrohyals) and a suspensory portion (paired ceratohyals, epihyals, stylohyals, and tympanohyals) connecting the basal portion to the skull base. Unlike other terrestrial mammals, the basal portion lies inferior to the laryngeal aditus, is flattened dorso-ventrally, and is relatively large, thus providing a broad surface area for muscle attachments. The suspensory elements are not as flattened and are joined by synovial joints (except for epihyal-stylohyal fusion). Muscular specializations include enlargement of those which retract the hyoid apparatus (e.g., sternohyoid) or control the tongue (e.g., styloglossus, hyoglossus). These muscles may be particularly important in a specialized prey capture behavior called suction feeding. In addition, the hyoid apparatus has a tilted placement, which allows asymmetrical enlargement of the piriform sinuses. Asymmetry is also seen in the muscular attachments between the larynx and the hyoid apparatus. The most pronounced differences from the basic pattern are observed in two families: Physeteridae and Ziphiidae. CONCLUSIONS: The derived position and shape of the odontocete hyoid apparatus may have evolved to subserve several specialized upper respiratory/digestive tract functions, such as simultaneous feeding (suction and swallowing) and sound production.

Anatomy, Comparative↗
PubMed2003

Reproductive barriers between congeneric monogenean parasites (Dactylogyrus: Monogenea): attachment apparatus morphology or copulatory organ incompatibility?

Morphometrical parameters of the attachment apparatus and copulatory organs of 52 Dactylogyrus species parasitizing 17 species of cyprinid fishes were analysed to test for the existence of reproductive barriers among congeneric species. The minimal spanning tree (MST) method was applied in the analyses. The position of "real" parasite communities, based on (1) observed infracommunities, (2) a checklist of parasites for a given host in the morphological space, was compared to the position of randomly generated communities using all Dactylogyrus species. The distribution of species similarity within infracommunities (using both attachment and copulatory measurements) was not significantly different from that obtained by simulation, and this trend was similar for both the checklist and observed infracommunities. When real infracommunities were separated according to host specificity (specialists versus generalists), we found differences reflecting similarities in the shapes of attachment and copulatory organs. Within specialists, more similarities in the shape of the attachment apparatus can be found than within generalists, whereas the similarity in copulatory organ shape seems to be random. When generalists are considered, parasite infracommunities with the greater differences in attachment apparatus are also more different in terms of the shape of their copulatory apparatus. We conclude that specialist parasites possess more similarity in attachment apparatus due to specialisation to their host, whereas the species similarity in copulatory organs within infracommunities exhibits a random pattern, but with the copulatory organs being more variable than the attachment apparatus (which may be due to reproductive isolation). The morphology of the copulatory apparatus seems not to be the single factor explaining reproductive isolation among species.

Animals↗
PubMed2003

Comparison of dissolution profiles for albendazole tablets using USP apparatus 2 and 4.

The in vitro dissolution of albendazole from three different commercially available products (200 mg tablets) was studied using U.S. Pharmacopeia (USP) Apparatus 2 and USP Apparatus 4 in order to compare the release performance of the drug in two essentially different dissolution systems. For both cases, 0.1 N HCl was used as dissolution medium. Only the reference product and one of the generic products studied met the 80% USP 24 specification for albendazole dissolved at 30 min, using USP Apparatus 2. Although the reference product reached 80% of albendazole dissolved at 30 min when Apparatus 4 was used, the generic products' dissolution performance was markedly reduced in this system. Though dissolution rate was slower using Apparatus 4, the total quantity of albendazole dissolved from the reference product, represented by area under the dissolution profile, was practically the same regardless of the system used. Dissolution kinetics of albendazole was adequately described by Weibull's function for all the products. The dissolution time (t(d)) derived from data fitting to this function showed significant differences among the products studied. Data analysis based on analysis of variance (ANOVA) showed nonequivalence among the dissolution profiles of generic products compared with the reference product either with the dissolution vessel system or the flow-through cell, as well as nonequivalence among the dissolution profiles using both apparatuses with the same product. Though differences in the dissolution profiles for generic products against the reference product in both systems were found, USP Apparatus 4 showed higher discriminative capacity in differentiating the release characteristics of the products tested.

Albendazole↗
PubMedDate not supplied

In vitro strength of the suspensory apparatus in training and resting horses.

Forty-eight limbs of 12 freshly euthanized horses were used to generate data on the strength of the equine suspensory apparatus. The point of failure of the suspensory apparatus of each limb was determined. Immediately before euthanasia, 6 of the 12 horses (thoroughbreds and standardbreds) had been engaged in active training or racing, and six horses in stall and/or pasture activity. In the actively training or racing horses, the point of acute failure of the suspensory apparatus was within the proximal sesamoid bones in 20 (83%) limbs (resulting in 17 apical fractures, 2 basilar fractures, and 1 midbody fracture). In the pasture exercised or stalled horses, the point of failure of the suspensory apparatus was either acutely within the suspensory ligament (10 horses, 42%) or, if no acute failure occurred, insidiously within the suspensory ligament (12 horses, 50%). Active training appeared to have a strengthening effect on the suspensory ligament, causing the weakest point in the suspensory apparatus to become the sesamoid bones rather than the suspensory ligament. An average force of 1338 kg (between 1082 and 1673 kg) was needed to fail the suspensory apparatus in this group of horses. In nontraining horses, the site of failure was most often the suspensory ligament. An average force of 1100 kg (between 918 and 1241 kg) used to fail the suspensory apparatus in this group of horses was significantly (p less than 0.5) less than in the first group.

Animals↗
PubMed1997

Contractile apparatus and sarcoplasmic reticulum function: effects of fatigue, recovery, and elevated Ca2+.

This investigation tested the notion that fatiguing stimulation induces intrinsic changes in the contractile apparatus and sarcoplasmic reticulum (SR) and that these changes are initiated by elevated intracellular Ca2+ concentration ([Ca2+]i). Immediately after stimulation of frog semitendinosus muscle, contractile apparatus and SR function were measured. Despite a large decline in tetanic force (Po), maximal Ca2+-activated force (Fmax) of the contractile apparatus was not significantly altered. However, Ca2+ sensitivity was increased. In conjunction, the rate constant of Ca2+ uptake by the SR was diminished, and the caffeine sensitivity of Ca2+ release was decreased. During recovery, Po, contractile apparatus, and SR function each returned to near-initial levels. Exposure of skinned fibers to 0.5 microM free Ca2+ for 5 min depressed both Fmax and Ca2+ sensitivity of the contractile apparatus. In addition, caffeine sensitivity of Ca2+ release was diminished. Results suggest that fatigue induces intrinsic alterations in contractile apparatus and SR function. Changes in contractile apparatus function do not appear to be mediated by increased [Ca2+]i. However, a portion of the change in SR Ca2+ release seems to be due to elevated [Ca2+]i.

Animals↗
PubMed1993

Effect of disrupting the mitral apparatus on left ventricular function in dogs.

BACKGROUND: The importance of the mitral apparatus to left ventricular function has been suggested in clinical studies. The effect of disruption of the mitral apparatus on left ventricular diastolic and systolic properties has not been fully documented. METHODS AND RESULTS: We investigated the end-diastolic and end-systolic pressure-volume and stroke work-end-diastolic volume relations and measured the isovolumic relaxation time constant (tau infinity) during nonfilling beats before and after disruption of the mitral apparatus under different loading conditions in 14 dogs using our recently developed volume-clamping technique for the in situ left ventricle. Disruption of the mitral apparatus increased left ventricular diastolic equilibrium volume (V0d) without changing the slope of the end-diastolic pressure-volume relation (Sd) and increased end-systolic pressure-volume relation dead volume (V0s) and volume-axis intercept of stroke work-end-diastolic volume relation (V0sw) without changing the slopes of these relations (maximum elastance, Ees, and Ssw). Disruption of the mitral apparatus increased tau infinity. CONCLUSION: Disruption of the mitral apparatus increases the equilibrium volume without changing left ventricular diastolic stiffness or contractility and slows left ventricular relaxation. These results support and help explain the clinical observation that it is desirable to maintain the mitral apparatus during mitral valve replacement surgery.

Animals↗
PubMed1991

Remodelling of the contractile apparatus of striated muscle stimulated electrically in a shortened position.

The aim of this study was to examine reorganisation of the contractile apparatus during adaptation to function when the length of a muscle is decreased. The rat soleus muscle was maintained in a shortened position and simultaneously stimulated electrically at a low frequency for 1-45 h. This experimental model decreased the length of the muscle and made the contractile apparatus irregular. The length of the sarcomeres decreased and became variable. The Z-line appeared wavy or fragmented. Foci, within which the sarcomeric organisation was lacking, often appeared within the contractile apparatus. These changes, occurring during the initial hours of stimulation, increased in number during the following hours. Their frequency and intensity depended on the degree of muscle shortening. In muscle moderately shortened during stimulation (up to 20%) the contractile apparatus recovered its normal appearance within 12 h of the experiment. In the muscle considerably shortened (by about 30%) the process of normalisation took much longer, in spite of recovery of sarcomere length. We conclude from these results that these changes are related to the accelerated work-induced reorganisation of the contractile apparatus whenever sarcomere number is reduced and/or when elimination of portions of the contractile apparatus occurs. These anomalies, occurring transiently in normal mature muscle when stimulated electrically in a shortened position, should be considered as adaptive phenomena. They resemble abnormalities appearing in the contractile apparatus of myopathic muscle.

Animals↗
PubMed1990

[Fundamental study of alveolar bone measurements in the hamster using an apparatus for intraoral radiography].

Morphometry of bone resorption in experimental periodontitis is performed primarily by radiography after sacrificing the animal or by microscopy of histopathologic specimens prepared from resected jaw bones. Both techniques are recognized as effective examinations. However, these are cross-sectional procedures involving resection of specimens, and for evaluation of changes in symptoms from reversible to irreversible, which are characteristic of periodontal diseases, or for follow-up of the aging process, application of standard radiography and a method to properly interpret the images obtained are needed. The author designed an apparatus that allows in site radiographic evaluation of individual animals, which has not been considered in conventional morphometric analyses of periodontal bone resorption. With this apparatus, radiograms are obtained by placing a soft X-ray film in the oral cavity and exposing it with a soft X-ray projector. As a fundamental study of the usefulness of this apparatus, author evaluated the optimal conditions of radiography for imaging of soft tissues, the accuracy of the measurements, and the method for bone measurement. Experimental bone resorption was induced in the mandibular alveolar bone of the hamster, the changing lesion was radiographed daily with this apparatus by the standard procedure, and measurements were attempted by the length measuring method and densitometry method. The following results were obtained: 1) The intraoral apparatus was designed to allow radiography of both sides of the mandibular molar regions of the hamster. The apparatus consisted basically of a film cartridge, an opening, and a fixing portion. The projection angle can be adjusted by the fixing portion so that soft X-ray is always projected orthoradially on the surface of the film, and the soft X-ray film can be kept attached to the hamster mandibular molar region by microadjustment of the opening and the calibrations for angle adjustment. With this apparatus, the percent enlargement was minute at 0.43%, and the reproduced image showed a correlation of 0.998 with the standard. (2) The radiographic conditions of a focus-film distance of 30 cm. acceleration potential of 40 kV, current of 2.5 mA, and projection time of 20 sec. were considered to be optimal in hamsters with regard to the quality of the image and stress to the animals. 3) Palladium used as a reference for densitometry was highly manipulatable with a maximum thickness of 0.1 mm and was appropriate for estimation of the mineral content of the hamster mandibular bone. 4) According to morphometry of the hamster lower jaw alveolar region by the length measuring method and the densitometry method in serial standard soft X-ray images, bone absorption was greater in the order of the diet + inoculation group, diet group and control group in a decreasing order. In the control group, the growth of the bilateral alveolar region reached a peak 23 weeks (about 165 days) after birth, and bone resorption probably due to aging was thereafter observed at the apex of the alveolar bone.

Alveolar Bone Loss↗
PubMed1982

A cytochemical study of the Golgi apparatus of the spermatid during spermiogenesis in the rat.

The reactivity of the various components of the Golgi apparatus of rat spermatids for three phosphatase activities (nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase) and the incorporation of 3H-fucose by the spermatids was analyzed at the 19 steps of spermiogenesis, i.e., during and after this organelle elaborated the glycoprotein-rich acrosomic system. During steps 1-3, the Golgi apparatus produced, in addition to the proacrosomic granules, multivesicular bodies that became associated with the chromatoid body. NADPase was located within the four of five intermediate saccules of Golgi stacks, and TPPase was found in the last one or two saccules on the trans aspect of the stacks from steps 1 to 17 of spermiogenesis. CMPase was located within the thick saccular GERL elements found in the trans region of the Golgi apparatus from steps 1 to 7 of spermiogenesis, but the CMPase-positive GERL disappeared from the Golgi apparatus after its detachment from the acrosomic system at step 8. Th acrosomic system itself was reactive from CMPase and TPPase but was negative for NADPase, while the multivesicular bodies were CMPase and NADPase positive but unreactive for TPPase. Tritiated-fucose was readily incorporated within the Golgi apparatus of steps 1-17 spermatids; in steps 1-7 it was subsequently incorporated within the acrosomic system and multivesicular bodies. These various data indicated (1) that the Golgi apparatus of spermatids, although it loses its CMPase-positive GERL element in step 8, retains evidence of functional capacity until it degenerates in step 17; (2) that in early spermatids the various saccular components of the Golgi are specialized with respect to enzymatic activities; and (3) that each Golgi region may contribute in a coordinated fashion to the formation of the acrosomic system and multivesicular bodies.

Animals↗
PubMed1985

Glycoprotein synthesis in the Golgi apparatus of spermatids during spermiogenesis of the rat.

During steps 1-7 of spermiogenesis the Golgi apparatus contributes to the formation of the acrosomic system which develops at the surface of the nucleus. Later, in step 8, the Golgi apparatus detaches from the acrosome and remains suspended in the elongated cytoplasm until it degenerates during step 16. Using 3H-fucose as a tracer and the radioautographic technique, we observed that the Golgi apparatus incorporates the tracer and delivers the labeled glycoproteins to the developing acrosomic system during steps 1-7 of spermiogenesis, to multivesicular bodies during steps 1-9, and to the remaining cytoplasm and plasma membrane during steps 1-15. Throughout these steps of spermiogenesis the Golgi apparatus does not show major changes in structure; it is composed of a cortex made up of connected stacks of saccules and a medulla showing a loose aggregate of vesicular profiles. Glycoprotein synthesis in this Golgi apparatus, before and after it contributes lysosomal glycoproteins to the growing acrosomic system, was quantitatively assessed in electron microscope EM radioautographs of tissue sections from animals sacrificed at 1, 4, 8, and 24 h of 3H-fucose injection. The incorporation of the labeled sugar was found to remain quantitatively similar during steps 1-15 of spermiogenesis, and therefore, no shift in glycoprotein synthesis took place following separation of the Golgi apparatus from the acrosomic system. Throughout these steps, fucose molecules are first incorporated in the cortex of the organelle and subsequently transported to the medulla, where they temporarily accumulate before being delivered, depending on the step of spermiogenesis, to the acrosomic system, to the multivesicular bodies, and also, presumably, to the plasma membrane.

Animals↗
PubMed1995

Relation between the trans-Golgi network and the Golgi stack on development of the Golgi apparatus of the ameloblast in developing rat molar tooth germs.

BACKGROUND: The problem of how the functional compartments of the Golgi apparatus organizes during cell differentiation to become a well-formed Golgi apparatus is as yet an unresolved issue. This study was designed to define the involvement of the trans-Golgi network (TGN) and the Golgi stack in organizing the Golgi apparatus. METHODS: The distribution of the TGN marker enzyme was examined in the ameloblast of developing rat molar tooth germs using cytochemistry with Co-enzyme A phosphatase (CoA Pase) and cytidine monophosphatase (CMPase). RESULTS: Typically formed Golgi apparatus was observed in the secretory ameloblast but not in the presecretory ameloblast. Organization of the Golgi apparatus through the presecretory ameloblast was noted. In the presecretory ameloblast, Golgi stacks of different sizes and clusters of small vesicles were located in the cytoplasm lateral to the nucleus. The saccules with enzymes marked for TGN were also observed in the cytoplasm lateral to the nucleus. These saccules were adjacent to the cluster of small vesicles and/or the Golgi stack. Upon cell differentiation, Golgi stacks were seen in line along the long axis of the cell, and the file of the stacks in the cytoplasm lateral to the nucleus was formed. The positive saccule was seen in a parallel line equal to the length of the Golgi stacks. CONCLUSIONS: In organizing the Golgi apparatus, the development process of the TGN and the Golgi stack appear to be different, and new Golgi stacks seem to be formed through the accumulation of small vesicles near the pre-existing TGN.

Ameloblasts↗
PubMed1991

Disruption of the Golgi apparatus with brefeldin A does not destabilize the associated detyrosinated microtubule network.

Stable subsets of microtubules (MTs) are often enriched in detyrosinated alpha-tubulin. Recently it has been found that the Golgi apparatus is associated with a subset of relatively stable MTs and that detyrosinated MTs colocalize spatially and temporally with the Golgi apparatus in several cell lines. To determine whether the Golgi apparatus actively stabilizes associated MTs and thus allows their time-dependent detyrosination, we have used the drug brefeldin A (BFA) to disrupt the Golgi apparatus and have monitored changes in the Golgi apparatus and MT populations using simultaneous immunofluorescence and fluorescent lectin microscopy. We found that although BFA caused the Golgi apparatus to completely redistribute to the endoplasmic reticulum (ER), the detyrosinated MTs were not disrupted and remained in a juxtanuclear region. By Western blot analysis we found that even after 6 h of continuous exposure of cells to BFA, there was no detectable reduction in the level of detyrosinated alpha-tubulin. Simultaneous treatment with nocodazole and BFA led to a complete disruption of all MTs and normal Golgi structure/organization. Upon removal of nocodazole in the continued presence of BFA, we found that the detyrosinated MTs reformed in a compact juxtanuclear location in the absence of an intact Golgi complex. Finally, we found that the detyrosinated MTs colocalized precisely with a BFA-resistant structure that binds to the lectin, wheat germ agglutinin. We conclude that the juxtanuclear detyrosinated MTs are not actively stabilized by association with BFA-sensitive Golgi membranes. However, another closely associated structure which binds wheat germ agglutinin may serve to stabilize the juxtanuclear MTs. Alternatively, the MT organizing center (MTOC) and/or MT-associated proteins (MAPs) may organize and stabilize the juxtanuclear detyrosinated MTs.

Animals↗
PubMed1991

Traffic through the Golgi apparatus as studied by radioautography.

The ability to radiolabel biological molecules, in conjunction with radioautographic or cell fractionation techniques, has brought about a revolution in our knowledge of dynamic cellular processes. This has been particularly true since the 1940's, when isotopes such as 35S and 14C became available, since these isotopes could be incorporated into a great variety of biologically important compounds. The first dynamic evidence for Golgi apparatus involvement in biosynthesis came from light microscope radioautographic studies by Jennings and Florey in the 1950's, in which label was localized to the supranuclear Golgi region of goblet cells soon after injection of 35S-sulfate. When the low energy isotope tritium became available, and when radioautography could be extended to the electron microscope level, a great improvement in spatial resolution was achieved. Studies using 3H-amino acids revealed that proteins were synthesized in the rough endoplasmic reticulum, migrated to the Golgi apparatus, and thence to secretion granules, lysosomes, or the plasma membrane. The work of Neutra and Leblond in the 1960's using 3H-glucose provided dramatic evidence that the Golgi apparatus was involved in glycosylation. Work with 3H-mannose (a core sugar in N-linked side chains), showed that this sugar was incorporated into glycoproteins in the rough endoplasmic reticulum, providing the first radioautographic evidence that glycosylation of proteins did not occur solely in the Golgi apparatus. Studies with the tritiated precursors of fucose, galactose, and sialic acid, on the other hand, showed that these terminal sugars are mainly added in the Golgi apparatus. With its limited spatial resolution, radioautography cannot discriminate between label in adjacent Golgi saccules. Nonetheless, in some cell types, radioautographic evidence (along with cytochemical and cell fractionation data) has indicated that the Golgi is subcompartmentalized in terms of glycosylation, with galactose and sialic acid being added to glycoproteins only within the trans-Golgi compartment. In the last ten years, radioautographic tracing of radioiodinated plasma membrane molecules has indicated a substantial recycling of such molecules to the Golgi apparatus.

Animals↗
PubMed1985

Repeated furrow formation from a single mitotic apparatus in cylindrical sand dollar eggs.

The methods used previously to demonstrate the ability of a single mitotic apparatus to elicit multiple furrows involved considerable cell distortion and did not permit the investigator to control the positioning of the parts or to observe satisfactorily the early stages of furrow development. In this investigation, Echinarachnius parma eggs were confined in 82 microns i.d. transparent, silicone rubber-walled capillaries, and the mitotic apparatus was moved by pushing the poles inward with 55-microns-diameter glass balls. When the mitotic apparatus was shifted immediately after the furrow first appeared, a new furrow appeared in the normal relation to the new position in 1-2 minutes. The same mitotic apparatus could elicit up to 13 furrows as it was shifted back and forth by alternately pushing in the poles. The previous furrow regressed as the new furrow developed. The operations protracted the furrow establishment period to as long as 24.5 minutes after establishment of the first furrow. The characteristics of furrow regression were related to the distance the mitotic apparatus was moved. It is unlikely that regression was caused either by stress imposed on the surface or the removal of the mitotic apparatus from the vicinity of the furrow.

Animals↗
PubMed1982

In 'undifferentiated' PC12 cells, GERL is not segregated from the Golgi apparatus.

The present study examines the endocytosis of conjugates of horseradish peroxidase (HRP) with ricin and wheat germ agglutinin (WGA) in rat adrenal pheochromocytoma cells (PC 12 line) cultured in the absence of nerve growth factor (NGF). In these cells acid phosphatase (ACPase) activity is not confined to a single cisterna and vesicles at the transaspect (mature face) of the Golgi apparatus which correspond to GERL of cultured neurons, neuroblastoma and other cell types. But ACPase is found in several cisternae of the Golgi apparatus as well as in lysosomes. On the other hand, thiamine pyrophosphatase activity, is found in a typical location within two or three cisternae of the Golgi apparatus near its transaspect. Following adsorptive endocytosis of HRP-labelled lectins (ricin-HRP or WGA-HRP) into PC12 cells, a reaction product is seen in dense bodies as well as in small vesicles and tubules throughout the cytoplasm, at the periphery of large vacuoles, in smooth and coated vesicles and tubules near the Golgi apparatus and in anastomosing tubules. The cisternae of the Golgi apparatus are not involved in the endocytosis of lectin-HRP. We conclude that in PC12 cells grown without NGF, unlike the case of cultured neurons and neuroblastoma cells, GERL is not segregated from the Golgi apparatus by either ACPase cytochemistry, or by the functional criterion of endocytosis of lectin-HRP conjugates.

Adrenal Gland Neoplasms↗
PubMed1990

Influence of antimicrotubular drugs on the Golgi apparatus of stomach secretory mucoid cells and small intestine absorptive cells.

The effects of vinblastine and colchicine on the Golgi apparatus of stomach surface mucoid and absorptive intestinal cells were compared by cytochemical analysis. The two epithelial cells were chosen because of their different specific functions in the formation of secretory granules, the production of lysosomes and the intensity of membrane traffic in the cytoplasm. For the analysis, adult mice were injected with 1 mg/100 g b.w. of vinblastine and 1 mg/100 g b.w. of colchicine. For the demonstration of cis and trans cisternae of the Golgi apparatus, prolonged osmification, thiamine pyrophosphatase and acid phosphatase activity identification were applied. After treatment with vinblastine or colchicine, polarity of stacks in the Golgi apparatus of surface mucoid cells is preserved although the number of cisternae with thiamine pyrophosphatase or acid phosphatase activity decreases. However, the Golgi apparatus of intestinal absorptive cells completely disintegrates and only a few separated cis or trans cisternae can be identified. The main effect seems to be a reduction of vesicles which can be cytochemically identified as parts of the Golgi apparatus and an accumulation of vesicles which probably originate from budding ER. Communication between the ER and the Golgi apparatus seems to be interrupted.

Animals↗
PubMedDate not supplied

Cell-free analysis of Golgi apparatus membrane traffic in rat liver.

Cell-free systems for the analysis of Golgi apparatus membrane traffic rely either on highly purified cell fractions or analysis by specific trafficking markers or both. Our work has employed a cell-free transfer system from rat liver based on purified fractions. Transfer of any constituent present in the donor fraction that can be labeled (protein, phospholipid, neutral lipid, sterol, or glycoconjugate) may be investigated in a manner not requiring a processing assay. Transition vesicles were purified and Golgi apparatus cisternae were subfractionated by means of preparative free-flow electrophoresis. Using these transition vesicles and Golgi apparatus subfractions, transfer between transitional endoplasmic reticulum and cis Golgi apparatus was investigated and the process subdivided into vesicle formation and vesicle fusion steps. In liver, vesicle formation exhibited both ATP-independent and ATP-dependent components whereas vesicle fusion was ATP-independent. The ATP-dependent component of transfer was donor and acceptor specific and appeared to be largely unidirectional, i.e., ATP-dependent retrograde (cis Golgi apparatus to transitional endoplasmic reticulum) traffic was not observed. ATP-dependent transfer in the liver system and coatomer-driven ATP-independent transfer in more refined yeast and cultured cell systems are compared and discussed in regard to the liver system. A model mechanism developed for ATP-dependent budding is proposed where a retinol-stimulated and brefeldin A-inhibited NADH protein disulfide oxidoreductase (NADH oxidase) with protein disulfide-thiol interchange activity and an ATP-requiring protein capable of driving physical membrane displacement are involved. It has been suggested that this mechanism drives both the cell enlargement and the vesicle budding that may be associated with the dynamic flow of membranes along the endoplasmic reticulum-vesicle-Golgi apparatus-plasma membrane pathway.

Animals↗