The ultrastructure of the zoospore of Hyphochytrium catenoides

1985 ◽  
Vol 63 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Elizabeth W. Cooney ◽  
Donald J. S. Barr ◽  
William E. Barstow
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Transition Zone ◽  
Multivesicular Bodies ◽  
Dense Matrix ◽  
Flagellar Membrane ◽  
Membrane Bound

The ultrastructure of the zoospore of Hyphochytrium catenoides Karling is described. The zoospore has a single, anterior, tinsel flagellum. The nucleus is elongate and convoluted with an indentation at the anterior end in which the Golgi cisternae are located. There are large lipid globules in the posterior end of the cell. The ribosomes are loosely enclosed by endoplasmic reticulum, the nuclear envelope, and mitochondria. The mitochondria have tubular cristae in a dense matrix. Microbodies are found appressed to the nuclear envelope and also free in the ribosomal region. Endoplasmic reticulum sheets traverse the ribosome region. The vesiculate cytoplasm has several distinct types of membrane-bound inclusions: (i) multivesicular bodies, (ii) vesicles containing presumptive mastigonemes, (iii) vesicles having an electron-dense cortex with an electron-transparent center, and (iv) electron-opaque vesicles whose contents seem condensed and only partially fill the vesicles. The transition zone from the flagellum to the kinetosome has three segments: a distal set of struts extending from the axonemal doublets into the axoneme core, a midsection of electron-opaque rings, and a distinctive "disclike" terminal plate with a thickened portion between the doublets and the flagellar membrane. The three-part rootlet system has (i) a "ribbed" pair of microtubules on one side of the kinetosome, (ii) a curved "ribbed," single microtubule with electron-opaque backing which originates near the nonfunctional centriole, and (iii) a straight doublet of microtubules without ribs extending from the nonfunctional centriole posteriorly to the midregion of the zoospore.

Zoospore ultrastructure of Olpidium cucurbitacearum (Chytridiales)

1977 ◽  
Vol 55 (24) ◽  
pp. 3063-3074 ◽  
Author(s):  
D. J. S. Barr ◽  
V. E. Hadland-Hartmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Transition Zone ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Flagellar Apparatus ◽  
Multivesicular Bodies ◽  
Taxonomic Relationship ◽  
Anterior Nucleus

Zoospore ultrastructure of Olpidium cucurbitacearum Barr & Dias is described. Isolates from Ontario and Japan are alike. The elliptical zoospore has an anterior nucleus partially surrounded by lobed and branched mitochondria. In the central part an interconnecting network consisting ofsmooth and rough endoplasmic reticulum, a Golgi complex, microbodies, and multivesicular bodies predominates. Vacuoles are abundant in the posterior. Ribosomes occur throughout the cytoplasm. The flagellar apparatus consists of the following: a short fibrillar rhizoplast connecting both kinetosome and nonfunctional centriole to an electron-opaque bar on the nuclear envelope; an elongated transition zone; and a 9 + 2 flagellum axoneme running much of the length of the zoospore through to the posterior end. Props do not connect the kinetosome to the plasmalemma; however, prop parts connect to the kinetosome, and prop parts connect to the plasmalemma at the posterior end of the zoospore. The taxonomic relationship to other chytrids is discussed; the zoospore is similar to that of O. brassicae (Woronin) Dang, and Rhizophlyctis rosea (deBary &Woronin) Fischer, and somewhat similar to that of Rozella allomycis Foust.

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

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

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

scholarly journals Das endoplasmatische Retikulum in der Mitose — ein wandelbares Netz

BIOspektrum ◽  
2020 ◽  
Vol 26 (7) ◽  
pp. 739-742
Author(s):  
Anne Schlaitz
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Molecular Mechanisms ◽  
Detailed Understanding ◽  
Membrane Bound

AbstractIn order to divide successfully, cells need to reorganize their interior including membrane-bound organelles such as the endoplasmic reticulum (ER). The ER serves as sink and source for the nuclear envelope and undergoes distinct transformations in its morphology and dynamics during cell division. To fully appreciate the functions of ER remodeling during cell division it will be essential to first achieve a detailed understanding of the underlying molecular mechanisms.

scholarly journals Cisternal Organization of the Endoplasmic Reticulum during Mitosis

2009 ◽  
Vol 20 (15) ◽  
pp. 3471-3480 ◽  
Author(s):  
Lei Lu ◽  
Mark S. Ladinsky ◽  
Tom Kirchhausen
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Three Dimensional ◽  
Freeze Substitution ◽  
High Resolution Electron Microscopy ◽  
Animal Cells ◽  
Resolution Electron ◽  
Major Transformation ◽  
Membrane Bound

The endoplasmic reticulum (ER) of animal cells is a single, dynamic, and continuous membrane network of interconnected cisternae and tubules spread out throughout the cytosol in direct contact with the nuclear envelope. During mitosis, the nuclear envelope undergoes a major rearrangement, as it rapidly partitions its membrane-bound contents into the ER. It is therefore of great interest to determine whether any major transformation in the architecture of the ER also occurs during cell division. We present structural evidence, from rapid, live-cell, three-dimensional imaging with confirmation from high-resolution electron microscopy tomography of samples preserved by high-pressure freezing and freeze substitution, unambiguously showing that from prometaphase to telophase of mammalian cells, most of the ER is organized as extended cisternae, with a very small fraction remaining organized as tubules. In contrast, during interphase, the ER displays the familiar reticular network of convolved cisternae linked to tubules.

scholarly journals FINE STRUCTURE OBSERVATIONS OF THE UPTAKE OF INTRAVENOUSLY INJECTED PEROXIDASE BY THE RAT CHOROID PLEXUS

1967 ◽  
Vol 15 (3) ◽  
pp. 160-165 ◽  
Author(s):  
NORWIN H. BECKER ◽  
ALEX B. NOVIKOFF ◽  
H. M. ZIMMERMAN
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cerebrospinal Fluid ◽  
Choroid Plexus ◽  
Smooth Endoplasmic Reticulum ◽  
Multivesicular Bodies ◽  
Adult Rats ◽  
Dense Bodies ◽  
Pinocytotic Vesicles ◽  
Membrane Bound

The uptake by the choroid plexus of adult rats of intravenously injected horseradish peroxidase has been investigated by electron microscopy. Within 4 min, the injected protein passes the capillary and is rapidly distributed through extracellular space and choroidal cells. Peroxidase enters the choroidal cells within coated vesicles which act as pinocytotic vesicles. At 15 min, peroxidase activity is present in numerous membrane-bound vesicles, multivesicular bodies, dense bodies and what appear to be segments of smooth endoplasmic reticulum. None of the peroxidase-containing organelles is seen to empty to the ventricular surface. Egress of the extracellular peroxidase into the cerebrospinal fluid is apparently blocked by apical zonulae occludentes between the choroidal cells.

Localization of various phosphatase activities within the golgi apparatus and lysosomes of rat leydig cells

1986 ◽  
Vol 44 ◽  
pp. 294-295
Author(s):  
M. F. Lalli ◽  
V. Lacroix ◽  
L. Hermo ◽  
Y. Clermont ◽  
C. E. Smith
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Leydig Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Fluid Phase ◽  
Multivesicular Bodies ◽  
Golgi Stack ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Adsorptive Endocytosis

The testosterone-secreting Leydig cells contain an abundance of smooth endoplasmic reticulum, peroxisomes, mitochondria as well as a large, spheroidal, juxtanuclear Golgi apparatus composed of interconnected stacks of saccules (Figs. 1,2). Each Golgi stack appears to be composed of between 5 to 7 saccules or sacculo-tubular elements (Figs.1,2). These cells also possess pale and dense multivesicular bodies and dense membrane-bound bodies identified assecondary lysosomes, all of which have been shown to be involved in fluid phase and adsorptive endocytosis as well as in receptor mediated endocytosis. The purpose of the present study was to characterize the reactivity of Golgi saccules, multivesicular bodies and lysosomes of Leydig cells for different phosphatases.

Ultrastructure of Spermatogenesis of Syndisyrinx-Punicea (Hickman, 1956) (Platyhelminthes, Rhabdocoela, Umagillidae)

1992 ◽  
Vol 40 (2) ◽  
pp. 153 ◽  
Author(s):  
MM Li ◽  
NA Watson ◽  
K Rohde
Keyword(s):  
Endoplasmic Reticulum ◽  
Multivesicular Bodies ◽  
Dense Bodies ◽  
Cytoplasmic Bridges ◽  
Membrane Bound ◽  
Concentric Circles

Spermatogenesis of Syndisyrinx punicea is described. Spermatogonia are little differentiated, with few organelles and inclusions: polyribosomes, ribosomes, small round mitochondria with few cristae and some endoplasmic reticulum. Primary spermatocytes are large and contain multivesicular bodies that are also found in the cytoplasm of spermatids in greater numbers. Spermatids contain Golgi complexes consisting of a series of concentric circles, and numerous membrane-bound, rod-shaped electron-dense bodies. A zone of differentiation develops with peripheral microtubules, followed by the appearance of a prominent intercentriolar body. Two axonemes grow out in opposite directions from centrioles adjacent and perpendicular to the intercentriolar body. The area of differentiation protrudes and elongates to form the sperm shaft into which the nucleus and mitochondria migrate. Typical rootlets were not observed, although rod-shaped structures situated on each side of the nucleus, seen in one section, may be rudimentary rootlets. Spermatocytes and spermatids are linked by different kinds of cytoplasmic bridges. Spermatogenesis of S. punicea is compared with that in other groups of turbellarians and Neodermata.

Compound Symbiosis in Peridinium Balticum

1973 ◽  
Vol 31 ◽  
pp. 500-501
Author(s):  
R. N. Tomas
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
The Other ◽  
Exact Nature ◽  
Symbiotic Relationship

Peridinium balticum appears to be unusual among the dinoflagellates in that it possesses two DNA-containing structures as determined by histochemical techniques. Ultrastructurally, the two dissimilar nuclei are contained within different protoplasts; one of the nuclei is characteristically dinophycean in nature, while the other is characteristically eucaryotic. The chloroplasts observed within P. balticum are intrinsic to an eucaryotic photosynthetic endosymbiont and not to the dinoflagellate. These organelles are surrounded by outpocketings of endoplasmic reticulum which are continuous with the eucaryotic nuclear envelope and are characterized by thylakoids composed of three apposed lamellae. Girdle lamellae and membranebounded interlamellar pyrenoids are also present. Only the plasmalemma of the endosymbiont segregates its protoplast from that of the dinophycean cytoplasm. The exact nature of this symbiotic relationship is at present not known.

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

Temporal and spatial interrelationships of confronting cisternae to nuclear envelope

1992 ◽  
Vol 50 (1) ◽  
pp. 930-931
Author(s):  
John R. Palisano
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Tumor Cells ◽  
Hela Cells ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Serial Sections ◽  
Electron Microscopic ◽  
Fetal Rat ◽  
Temporal And Spatial

Although confronting cistemae (CC) have been observed in a variety of tumor cells and normal fetal rat, mouse, and human epithelial tissues, little is known about their origin or role in mitotic cells. While several investigators have suggested that CC arise from nuclear envelope (NE) folding back on itself during prophase, others have suggested that CC arise when fragments of NE pair with endoplasmic reticulum. An electron microscopic investigation of 0.25 um thick serial sections was undertaken to examine the origin of CC in HeLa cells.

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