Rows Of Vesicles Research Articles

Reclassification of Gyrodinium flavescens Kofoid & Swezy as Torquentidium flavescens comb. nov. (Ceratoperidiniaceae, Dinophyceae), based on morphology and phylogeny

ABSTRACTA Cochlodinium-like species was isolated from the Korean coast and examined by light microscopy and scanning electron microscopy (SEM). The species was characterised by cellular torsion, cingulum with 1.25 turns and sulcus with 0.25 turn, and a hemispherical hypocone. The nucleus was curved, and sausage-shaped, and there were small, dark grains distributed at the cell periphery, which were also reported in the original description of Gyrodinium flavescens by Kofoid & Swezy (1921). SEM observations revealed that the apical structure complex of the species formed a complete circle surrounding the cell apex, consisting of three parallel rows of vesicles; and that the outer rows, composed of small vesicles, were visible along the sides of cingulum. These morphological features were identical to those of Torquentidium convolutum. Phylogeny-based on small subunit and large subunit rDNA sequences, confirmed that the species was closely related to T. convolutum within the family Ceratoperidiniaceae. However, the species was distinct from T. convolutum by differences in cingulum and sulcus turn numbers, shape of hypocone in dorsal view and size. Based on morphological and phylogenetic analyses, we propose Torquentidium flavescens comb. nov. nested within the family Ceratoperidiniaceae.

Characterization of the unarmored dinoflagellate Pseliodinium pirum (Ceratoperidiniaceae) from Jiaozhou Bay, China

SUMMARYA strain of Pseliodinium pirum was isolated from Jiaozhou Bay, China, identified based on a recently emended classification, and further characterized for its morphology using light, scanning electron, and transmission electron microscopy, and phylogeny based on SSU and partial LSU rDNA sequences. The pigment composition, life history, and potential effects on aquatic animals were also examined. We observed the typical characteristics of Ceratoperidiniaceae, in which its apical structure complex (ASC) formed a circular loop, and the ASC of our isolate comprised four to five rows of vesicles, and connected with sulcal intrusion. Epifluorescence and transmission electron microscopy revealed a bean‐shaped, centrally located nucleus, with at least 76 chromosomes. Numerous rod‐shaped chloroplasts were in connection to the irregularly shaped pyrenoids. Pigment analysis showed that peridinin was the most abundant among all carotenoids and other pigments. Phylogenetic analyses using maximum likelihood and Bayesian inference indicated that our isolate is conspecific with the entity Cochlodinium cf. helix (accession No. KF245459), but different from Ceratoperidinium, Kirithra, and other unidentified species of the family Ceratoperidiniaceae. Pseliodinium pirum could produce sexual, thin‐walled cyst, with subspherical and spherical shape and smooth surface (without spines or rough projections). The cyst could germinate within 3 days. Bioassays did not show adverse effects of P. pirum on the finfish Oryzias melastigma and the rotifer Brachionus plicatilis, indicating it may not be a harmful species.

Molecular phylogeny and morphology of Torquentidium gen. et comb. nov. for Cochlodinium convolutum and allied species (Ceratoperidiniaceae, Dinophyceae)

ABSTRACT Although the genus Pseliodinium within the family Ceratoperidiniaceae includes Ceratoperidinium falcatum, Cochlodinium cf. convolutum, C. cf. helix and unidentified Cochlodinium species, it is in need of reclassification because of the morphological differences and lack of morphological details of the species within the genus. A Cochlodinium-like species was isolated from a Korean coastal area and examined by light and scanning electron microscopy, as well as by the analysis of nuclear-encoded small subunit (SSU) and large subunit (LSU) rDNA. The Korean isolate was morphologically characterized by cellular torsion, and outer rows consisting of small rectangular and polygonal vesicles were visible along the sides of the cingulum. The apical structure complex (ASC) formed a complete circle surrounding the cell apex, consisting of three parallel rows of vesicles. In the ASC, the upper row was sometimes hidden and very small knobs were present on the central row. Morphological characteristics separated the Korean isolate from Ce. margalefii, Pseliodinium fusus(=Ce. falcatum), Kirithra asteri and Gymnodinium species (Gymnodinium sp. 1 and sp. 2) within the family Ceratoperidiniaceae. However, the morphological characteristics coincided with those of the previously recorded C. convolutum, C. cf. helix and other Cochlodinium species within the same family. Phylogeny based on SSU and LSU rDNA sequences revealed that the Korean isolate forms a clade independent from P. fusus, although they have high sequence similarity. Based on the morphological and phylogenetic analyses, we propose the new genus Torquentidium gen. nov. and a new combination for C. cf. helix and the Korean isolate Torquentidium convolutum erected within the family Ceratoperidiniaceae.

Ultrastructure and Phylogeny of Kirithra asteri gen. et sp. nov. (Ceratoperidiniaceae, Dinophyceae) — a Free-Living, Thin-Walled Marine Photosynthetic Dinoflagellate from Argentina

A gymnodinioid photosynthetic dinoflagellate was isolated from Argentina and examined by light and electron microscopy and analysis of nuclear-encoded LSU rDNA. Kirithra asteri gen. et sp. nov. was proposed as morphology and molecular phylogeny separated this dinoflagellate from others within the family Ceratoperidiniaceae. Cells were surrounded by a hyaline amphiesma comprising polygonal vesicles. Each vesicle contained a honeycomb and a trilaminar structure. An anterior sulcal extension ending in a complete circle formed the apical structure complex (ASC), which characterizes Ceratoperidiniaceae. The ASC comprised three rows of vesicles. The nucleus was located in the hypocone, and several large, irregularly shaped vesicles were present in the epi- and hypocone. Chloroplasts were surrounded by three membranes, and grana-like arrangements of thylakoids were observed in one strain used for ultrastructural study. The cell centre contained 1-3 multiple-stalked pyrenoids and membrane-bound vesicles containing tile-like structures surrounded each pyrenoid. Two pusules with collecting chambers and associated vesicles branched off each of the flagellar canals. The flagellar apparatus featured a ventral connective between the amphiesma and the R1 root, and almost opposite basal bodies, rarely seen in dinoflagellates. This was the first ultrastructural study of a species within Ceratoperidiniaceae.

Ultrastructural morphogenesis of a virus associated with lymphocystis-like lesions in parore Girella tricuspidata (Kyphosidae: Perciformes).

The morphogenesis of large icosahedral viruses associated with lymphocystis-like lesions in the skin of parore Girella tricuspidata is described. The electron-lucent perinuclear viromatrix comprised putative DNA with open capsids at the periphery, very large arrays of smooth endoplasmic reticulum (sER), much of it with a reticulated appearance (rsER) or occurring as rows of vesicles. Lysosomes, degenerating mitochondria and virions in various stages of assembly, and paracrystalline arrays were also present. Long electron-dense inclusions (EDIs) with 15 nm repeating units split terminally and curled to form tubular structures internalising the 15 nm repeating structures. These tubular structures appeared to form the virion capsids. Large parallel arrays of sER sometimes alternated with aligned arrays of crinkled cisternae along which passed a uniformly wide (20 nm) thread-like structure. Strings of small vesicles near open capsids may also have been involved in formation of an inner lipid layer. Granules with a fine fibrillar appearance also occurred in the viromatrix, and from the presence of a halo around mature virions it appeared that the fibrils may form a layer around the capsid. The general features of virogenesis of large icosahedral dsDNA viruses, the large amount of ER, particularly rsER and the EDIs, are features of nucleo-cytoplasmic large DNA viruses, rather than features of 1 genus or family.

Two new genera and five new species of Tullbergiidae (Collembola) from the southern Appalachian Mountains of North America, with redescription of Tullbergia clavata Mills.

Two new genera and five new species of Tullbergiidae (Collembola) are described from the North American Appalachian zone in eastern Tennessee and western North Carolina. Ameritulla n. gen. is established for species with 15 setae on the middle tibiotarsus, blunt papilla A on the labial palpus, two long rows of vesicles in the postantennal organ (PAO), two dorsal sensilla on the third antennal segment and crescentic pseudocelli. Ameritulla clavata (Mills, 1934) n. comb. (=Tullbergia clavata Mills, 1934) is designated as type species and redescribed from type specimens, and A. obscura n. sp. is described. On Mixturatulla ozwini n. gen., n. sp. papillae A and B of the labial palpus are thick and blunt, the second row of the PAO is laterally broken into numerous spherical vesicles, and the dorsum of Abd. VI has two rows of large, coalesced tubercles. Psammophorura miniclavata n. sp. lacks pseudocelli on the third abdominal segment, which are present in previously described species. Stenaphorura shaconage n. sp. is the first species of its genus reliably recorded from North America. It differs from its Palaearctic relatives in having 2+2 pseudocelli on most body segments. Tullbergia nearctica n. sp. resembles T. arctica (Wahlgren, 1900) but differs in several chaetotaxic characters. Sensilliform setae traditionally considered as ordinary pointed setae are recognized and charted. A new setal nomenclature is proposed for the ventral setae of the sixth abdominal segment.

Structural organization of the presynaptic density at identified synapses in the locust central nervous system

In a synaptic active zone, vesicles aggregate around a densely staining structure called the presynaptic density. We focus on its three-dimensional architecture and a major molecular component in the locust. We used electron tomography to study the presynaptic density in synapses made in the brain by identified second-order neuron of the ocelli. Here, vesicles close to the active zone are organized in two rows on either side of the presynaptic density, a level of organization not previously reported in insect central synapses. The row of vesicles that is closest to the density's base includes vesicles docked with the presynaptic membrane and thus presumably ready for release, whereas the outer row of vesicles does not include any that are docked. We show that a locust ortholog of the Drosophila protein Bruchpilot is localized to the presynaptic density, both in the ocellar pathway and compound eye visual neurons. An antibody recognizing the C-terminus of the Bruchpilot ortholog selectively labels filamentous extensions of the presynaptic density that reach out toward vesicles. Previous studies on Bruchpilot have focused on its role in neuromuscular junctions in Drosophila, and our study shows it is also a major functional component of presynaptic densities in the central nervous system of an evolutionarily distant insect. Our study thus reveals Bruchpilot executes similar functions in synapses that can sustain transmission of small graded potentials as well as those relaying large, spike-evoked signals. J. Comp. Neurol. 520:384–400, 2012. © 2011 Wiley Periodicals, Inc.

Ultrastructural observations of efferent terminals in the crista ampullaris of the toadfish, Opsanus tau.

The present study was conducted to visualize the ultrastructural features of vestibular efferent boutons in the oyster toadfish, Opsanus tau. The crista ampullaris of the horizontal semicircular canal was processed for and examined by routine transmission electron microscopy. The results demonstrate that such boutons vary in size and shape, and contain a heterogeneous population of lucent vesicles with scattered dense core vesicles. Efferent contacts with hair cells are characterized by local vesicle accumulations in the presynaptic terminal and a subsynaptic cistern in the postsynaptic region of the hair cell. Serial efferent to hair cell to afferent synaptic arrangements are common, particularly in the central portion of the crista. However, direct contacts between efferent terminals and afferent neurites were not observed in our specimens. The existence of serial synaptic contacts, often with a row of vesicles in the efferent boutons lining the efferent-afferent membrane apposition, suggests that the efferent influence on the crista may involve both synaptic and nonsynaptic, secretory mechanisms. Further, it is suggested that differences in more subtle aspects of synaptic architecture and/or transmitter and receptor localization and interaction may render the efferent innervation of the peripheral crista less effective in influencing sensory processing.

Ultrastructural observations of efferent terminals in the crista Ampullaris of the toadfish, opsanus tau.

The present study was conducted to visualize the ultrastructural features of vestibular efferent boutons in the oyster toadfish, Opsanus tau. The crista ampullaris of the horizontal semicircular canal was processed for and examined by routine transmission electron microscopy. The results demonstrate that such boutons vary in size and shape, and contain a heterogeneous population of lucent vesicles with scattered dense core vesicles. Efferent contacts with hair cells are characterized by local vesicle accumulations in the presynaptic terminal and a subsynaptic cistern in the postsynaptic region of the hair cell. Serial efferent to hair cell to afferent synaptic arrangements are common, particularly in the central portion of the crista. However, direct contacts between efferent terminals and afferent neurites were not observed in our specimens. The existence of serial synaptic contacts, often with a row of vesicles in the efferent boutons lining the efferent-afferent membrane apposition, suggests that the efferent influence on the crista may involve both synaptic and nonsynaptic, secretory mechanisms. Further, it is suggested that differences in more subtle aspects of synaptic architecture and/or transmitter and receptor localization and interaction may render the efferent innervation of the peripheral crista less effective in influencing sensory processing.

The Cytostome of Trypanosoma cruzi Epimastigotes Is Associated with the Flagellar Complex

Okuda, K., Esteva, M., Segura, E. L., and Bijovsky, A. T. 1999. The cytostome of Trypanosoma cruzi epimastigotes is associated with the flagellar complex. Experimental Parasitology92, 223–231. Proliferative forms of Trypanosoma cruzi, amastigotes and epimastigotes, have a cytostome, a specialized structure formed by an invagination of the flagellar pocket's membrane surrounded by microtubules and frequently followed by a row of vesicles. All this assemblage penetrates deeply into the cytoplasm overpassing the nucleus. This structure, together with the flagellar pocket, appears to play an important role in the nutrition of the parasite. We demonstrated that the monoclonal antibody 2C4, made-up against isolated flagellar complex of T. cruzi epimastigotes, recognizes a protein doublet of 76 and 87 kDa in total epimastigotes homogenate. The 76-kDa polypeptide is enriched in the detergent-soluble fraction whereas the 87-kDa polypeptide is highly represented in the insoluble fractions and the purified flagella. Immuno-fluorescence assays show the antigen as a small spot at the flagellar pocket region. Immunogold labeling of ultrathin sections of epimastigote forms reveals gold particles at the opening of flagellar pocket, concentrated in the cytostome region. Immunocytochemistry of epimastigote whole-mount cytoskeletons reveals the labeling on an array of three to four microtubules that appears attached to flagellum, running in the direction of the nucleus. Ultrastructural observations have shown that the posterior region of isolated flagella, corresponding to the level of the flagellar pocket, possesses a microtubular structure compatible with that from the cytostome. The relationship between the cytostome, an endocytic organelle, and the flagellum is here described for the first time.

Ultrastructural study of Trichinella spiralis with emphasis on adult male reproductive organs

The ultrastructure of the reproductive system of adult male Trichinella spiralis has been examined, particularly to assist in recent advances such as the localization of target antigens of protective immunity and the mode of immune attack. The male reproductive system consists of a single tube with a hairpin-like bend, composed of a basal lamina, epithelial cells, rachis, circumferential and constrictor muscles, and germinal cells. The organs were surrounded by basal lamina and haemolymph. Germinal cells in different stages of maturation were found on the wall of the testis along its entire length. As the maturation of germinal cells proceeded, the cells moved towards the lumen of the testis. The germinal cells had a row of vesicles (cup-shaped structures) at the cell periphery. The mature sperm, lacking flagella and an acrosome, were stored in the seminal vesicle. The cytoplasm of the epithelial cells of the seminal vesicle and ejaculatory duct was filled with distended rough endoplasmic reticulum (rER) and exocrine granules which appeared homogenous and of medium electron density. The granules appeared to discharge to the lumen.

The formation of annulate lamellae in the human Sertoli cell.

The formation of annulate lamellae (AL) has been studied in human Sertoli cells. Sertoli cells of infants did not show AL. Sertoli cells of 9- to 11-year-old boys showed incompletely circumferentially arranged cisternae of endoplasmic reticulum (ER), alternating with rows of vesicles, 200-300 nm in diameter, with a weakly osmiophilic content. The ER cisternae displayed both pores and attached ribosomes at a few sites. These membranous structures were also observed beside true concentrically arranged AL in pubertal Sertoli cells (11-13 years of age). Both types of membranous formations were continuous with parallel, rough endoplasmic reticulum cisternae (RER) that interconnected them. Adult Sertoli cells showed only AL, not the other peculiar membranous formation. These features suggest that the RER plus associated vesicles originate the AL in human Sertoli cells.

Fine structure of the afferent synapse of the hair cells in the saccular macula of the goldfish, with special reference to the anastomosing tubules.

The fine structure of the afferent synapse has been studied in the hair cells of the goldfish saccular macula. A spherical dense body which is surrounded by synaptic vesicles is observed in association with the presynaptic membrane. An alternating, parallel arrangement of dense bars and of rows of synaptic vesicles is observed on the presynaptic membrane beneath the dense body. Each row consists of five to six immediately available synaptic vesicles, and five to six such rows of vesicles are observed per synapse. Sometimes anastomosing tubules are found around the dense body. The tubules are formed by direct infolding of the plasma membrane. Many coated vesicles are found at the periphery of the anastomosing tubules. A possible role of the anastomosing tubules in the turnover of the synaptic vesicle membrane is discussed.

Cytokinesis during early development of a teleost embryo: Brachydanio rerio

During early development of the teleost Brachydanio rerio , both furrow cleavage and vesicle cleavage were found in the same blastula. Furrow cleavage, characterized by an “in-pinching” of the plasma membrane with a fine deposit on the cytoplasmic side of the encroaching furrow, and vesicle cleavage, characterized by a row of vesicles across the plane of daughter cell separation, are found until one-third epiboly stage embryos, when only furrow cleavage was found.

Ultrastructure of the prawn nerve sheaths. Role of fixative and osmotic pressure in vesiculation of thin cytoplasmic laminae.

The sheaths from freshly teased nerve fibers of the prawn exhibit a positive radial birefringence, consistent with their EM appearance as highly organized laminated structures composed of numerous thin cytoplasmic sheets or laminae bordered by unit membranes and arranged concentrically around the axon. The closely apposed membranes in these sheaths are fragile and often break down into rows of vesicles during fixation. Desmosome-like attachment zones occur in many regions of the sheath. The membranes within these zones resist vesiculation and thereby provide a "control" region for relating the type of vesicles formed in the fragile portions of the sheaths to the specific fixation conditions. It is proposed that during fixation the production of artifactual vesicles is governed by an interplay of three factors: (a) direct chemical action of the fixative on the polar strata of adjacent unit membranes, (b) osmotic forces applied to membranes during fixation, and (c) the pre-existing natural relations between adjacent membranes. It is found that permanganate best preserves the continuity of the membranes but will still produce vesicles if the fixative exerts severe osmotic forces. These results support other reports (19) of the importance of comparing tissues fixed by complementary procedures so that systematic artifacts will not be described as characteristic of the natural state.

ARTIFACTUAL LOCALIZATION OF FERRITIN IN THE CILIARY EPITHELIUM IN VITRO

The accumulation of ferritin by the ciliary epithelium of the adult albino rabbit has been studied by electron microscopy. The experiments have been carried out under in vitro conditions, such that any uptake observed should be the result of passive diffusion of the tracerparticles rather than the product of active metabolic processes. The cells were fixed in osmium tetroxide and embedded in Araldite. Ferritin was found localized in three areas: in rows of apparent vesicles, free in the cytoplasmic matrix, and in the basement membrane. Some of the conclusions reached are as follows. The appearance of tracer in rows of vesicles is not in itself an adequate demonstration of pinocytosis. The permeability of the plasma membrane is drastically increased by osmium tetroxide fixation, so that tracer particles are free to diffuse across the membrane and wander through the cytoplasm. These results indicate the serious danger of being misled by artifacts when colloidal particles are used as tracers.

Electron microscopy of the formation of the cellular blastoderm in Drosophila melanogaster

1. 1. The transition from the syncytial to the cellular blastoderm has been studied in Drosophila melanogaster embryos with the electron microscope. 2. 2. The ultrastructure of the syncytial blastoderm is described during the first stage of membrane growth. Before cell membranes form between the nuclei located at the surface of the embryo, the nuclei are spherical and lack nucleoli. Flattened cisternae of ER are present below the nuclei, but most of the basophilia of the cytoplasm is due to the presence of many unattached ribosomes. As the cell membranes form, a nucleolus appears in the nuclei which elongate and withdraw from the surface. 3. 3. Tubular extensions of the outer nuclear membrane occur near the membrane furrows, and these tubules, or vesicles from the tubules, may fuse with the furrow. However, rows of vesicles along the future site of the cell membranes are not found. 4. 4. The cytoplasmic side of the furrow bears filamentous material, 500 Å in thickness. This material is lacking on other membranes and it is possibly related to the formation of new cell membrane material.

Fine structure of the ciliary epithelium of the rabbit, with particular reference to "infoldedmembranes," "vesicles," and the effects of Diamox.

The structure of the ciliary epithelium of the adult albino rabbit has been studied by electron microscopy. Material was fixed in osmium tetroxide and embedded in epoxy resins. Two hitherto unappreciated features of the non-pigmented epithelial layer are described. First, the "infolded plasma membranes" described by previous workers are shown by serial sections to be projections or interdigitations from adjacent cells. Second, the "rows of vesicles" described by previous workers are shown by serial sections to be part of an unusual form of smooth-surfaced tubular endoplasmic reticulum. The tubules are highly convoluted and extensively interconnected. They are arranged in sheets, so that a cross-section through a sheet gives the appearance of a row of vesicles. The other structural features of the ciliary epithelium are also described. Previous workers have reported that Diamox, which inhibits the secretory activity of the epithelium, causes profound structural changes. An effort has been made to confirm these reports under carefully controlled experimental conditions. It was found that secretion could be inhibited by a maximally effective dose of Diamox without the occurrence of any detectable structural changes. The physiological significance of these findings is discussed.

Electron microscope study on the regenerative process of peripheral nerves of mice.

An electron microscope study of the reactive process taking place in the proximal segment of sectioned dorso-spinal nerves of white mice was carried out in about 50 animals. Attention was mainly directed to the study of the earliest changes (30′) observable in the neuroplasm but the series of experiments included the study of nerves fixed up to 20 days after section. Most of the facts found (existence of microvesicles, multiplication of mitochondria, and presence of multivesicular bodies) confirmed the observation done in a preceding investigation, plus some non-described new findings. Early after section (30′) the nerve membrane is seen, in some cases, masked by the presence of microvesicles which seem to take origine from the membrane which also shows deep infoldings. These coalesce in many places taking thus the appearance of rows of vesicles. At later stages (60′, 80′) this reactive process is more general in the nerve stumps and vast areas of microvesicles are seen in the fiber neuroplasm. This kind of reaction (membrane infolding and coalescence) decrease later on and is rarely observable at 100′. Microvesicles are nevertheless increasing in number and many of them change their round profile for an elongated shape. Elongation leads to the formation of tubuli of progressively thinner diameter. This process is described as a possible way of neurofilament formation.

An electron microscope study of sarcotubules and related structures in the leech muscle

Longitudinal body muscles from five leech species have been examined in the electron microscope. The contractile cortex contains many sectors of myofilaments, separated by sarcotubules, and encloses the sarcoplasmic core that lodges the nucleus, the mitochondria, and several membranous formations. A single row of vesicles are lined up under the sarcolemma. The sarcotubules are fairly straight elements with an extension mainly in the radial direction. There are two types of sarcotubules that alternate in a regular fashion; they have been called compact and hollow sarcotubules, respectively. The total number of sarcotubules in a cell may be in the order of 500,000. The hollow sarcotubules show similarities to the transverse sarcotubules of striated muscles with respect to their reactions toward some impregnating substances, their location, and their fine morphology. It is proposed that these sarcotubules are responsible for the conduction of the contraction stimulus. The sarcotubular systems of the leech muscle apparently lacks of longitudinal portion.