Ultrastructure of meiosis-inducing (heterotypic) and non-inducing (homotypic) cell unions in conjugation of Blepharisma

1978 ◽  
Vol 32 (1) ◽  
pp. 31-43
Author(s):  
C. Bedini ◽  
A. Lanfranchi ◽  
R. Nobili ◽  
A. Miyake
Keyword(s):  
Ultrastructural Level ◽  
Cell Junctions ◽  
Type I ◽  
Type Ii ◽  
Initiation Mechanism ◽  
Blepharisma Japonicum ◽  
Nuclear Changes ◽  
Cytoplasmic Bridges ◽  
Multicellular Organisms ◽  
20 Nm

Cells of mating types I and II of Blepharisma japonicum interact with each other and unite in heterotypic (type I-type II) or homotypic (type I-type I, type II-type II) pairs. Heterotypic pairs undergo meiosis and other nuclear changes of conjugation, while homotypic pairs remain united for days without the nuclear changes taking place. We compared cell unions of these two kinds of pairs at the ultrastructural level. In the homotypic union, cell membranes are closely juxtaposed, separated by a distance of about 20 nm. This arrangement is interrupted in some places by vacuoles and small cytoplasmic bridges. Saccule-like structures tend to be more abundant near the united surfaces. Microtubules running at right or slightly obtuse angles with the cell surface (PACM microtubules) are characteristically present at the united region of cells. These structures are very similar to those observed in earlier stages of the heterotypic union. However, in homotypic pairs, cells unite only at the anterior half of the peristome, while in heterotypic pairs cells unite also at the posterior half of the peristome, where the cell membrane totally disappears in later stages. PACM microtubules persist for at least 18 h in homotypic unions, while they disappear within a few hours in heterotypic unions. These differences between the two kinds of cell union are discussed in relation to the initiation mechanism of meiosis and other nuclear changes of conjugation. Similarities between homotypic union and cell junctions in multicellular organisms are also discussed.

Alternative Gene Expression in Type I and Type II Cells May Enable further Nuclear Changes during Conjugation of Blepharisma japonicum

Protist ◽  
2012 ◽  
Vol 163 (2) ◽  
pp. 204-216 ◽  
Author(s):  
Mayumi Sugiura ◽  
Yuri Tanaka ◽  
Toshinobu Suzaki ◽  
Terue Harumoto
Keyword(s):  
Gene Expression ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Blepharisma Japonicum ◽  
Nuclear Changes

Fine-Structural Changes in a Lepidopteran Nervous System During Metamorphosis

1974 ◽  
Vol 14 (2) ◽  
pp. 369-387
Author(s):  
BARBARA J. McLAUGHLIN
Keyword(s):  
Tight Junctions ◽  
Manduca Sexta ◽  
Structural Changes ◽  
Cell Layer ◽  
Adult Emergence ◽  
Cell Junctions ◽  
Type I ◽  
Type Ii ◽  
Type Ii Cell ◽  
I Cells

The fine structure of the metamorphosing abdominal nerve cord of Manduca sexta has been studied. In fifth instar larvae, the connectives are ensheathed by a complex, thickened neural lamella. The underlying perineurium at this stage consists of 2 layers. The outer layer consists of interdigitating type I cells which are attached to the overlying neural lamella by hemidesmosomes, and to each other by occasional gap and tight junctions which persist throughout development. They are attached by desmosomes to a thin underlying type II cell layer, which is joined by gap and tight junctions and which has desmosomal attachments with the underlying glial membranes. The larval axons are surrounded by multiple glial wrappings containing bundles of microtubules. During the first week after larval-pupal ecdysis, the neural lamella degenerates and is phagocytosed by invading haemocytes. The underlying perineurial I cells gradually become hypertrophied and vacuolated. At the same time the type II layer, which does not increase in size, appears to be composed of either one or two cells which form a continuous ‘bracelet’ around each connective. The cellular bracelet is joined at one or two places by extensive gap, tight and septate junctions, and gap junctions are also seen along its perineurial I and glial borders. The underlying axons are embedded in vast amounts of glial cytoplasm containing relatively few microtubules. During the second week after larval-pupal ecdysis, the neural lamella is reformed and the perineurium flattens again. Type I and II cell junctions remain as described in earlier stages. Before adult emergence, the axons are again wrapped by glial cells rich in microtubules.

Corticosteroid receptors in cells derived from rat brain microvessels: mRNA identification and aldosterone binding

1992 ◽  
Vol 262 (1) ◽  
pp. C156-C163 ◽  
Author(s):  
N. Loffreda ◽  
P. Eldin ◽  
G. Auzou ◽  
C. Frelin ◽  
M. Claire
Keyword(s):  
Rat Brain ◽  
Cell Clone ◽  
Rat Kidney ◽  
Type I ◽  
Type Ii ◽  
Brain Microvessels ◽  
A Cell ◽  
Glucocorticoid Receptor Mrna ◽  
The One ◽  
20 Nm

B7 is a cell clone derived from rat brain microvessels. Expression of an amiloride-sensitive cationic channel has been recently established in these cells. In this study, the polymerase chain reaction (PCR) was used to amplify definite segments of mineralocorticoid and glucocorticoid receptor mRNA in B7 cells. Aldosterone binding was also characterized. Two classes of sites were detected. Aldosterone exhibited a high affinity for type I sites [dissociation constant (Kd) approximately 0.3 nM] and a lower one for type II sites (Kd approximately 20 nM). RU 28362, a highly specific glucocorticoid agonist, did not compete for type I sites. RU 28362 and dexamethasone were better competitors for type II sites than aldosterone. The sedimentation coefficients of aldosterone type I and type II complexes were approximately 9S. These characteristics are close to the one exhibited by aldosterone type I and type II receptors in rat kidney and other target tissues. In intact B7 cells, aldosterone binding expressed as number of acceptor sites per cell was higher (approximately 41,000 for type II and 8,800 for type I) than in the soluble cellular extract (approximately 18,000 for type II and 1,000 for type I).

scholarly journals Gamones and mating types in the genus Blepharisma and their possible taxonomic application

1976 ◽  
Vol 27 (2) ◽  
pp. 267-275 ◽  
Author(s):  
Akio Miyake ◽  
Lea K. Bleyman
Keyword(s):  
The Other ◽  
Type I ◽  
Type Ii Cells ◽  
Mating Types ◽  
Type Ii ◽  
Type I Cells ◽  
Blepharisma Japonicum ◽  
Union Type ◽  
I Cells

SUMMARYMating types I and II of Blepharisma japonicum v. intermedium excrete gamones 1 (blepharmone J) and 2 (blepharismone) respectively. The gamone of one type transforms cells of the other type so that they can conjugate with each other. We found that three other species, B. americanum, B. musculus and B. stoltei, have two types of cells homologous to those in B. japonicum; one (type II) excretes a factor which has the same activity as gamone 2 of B. japonicum, the other (type I) responds to this gamone by cell union. Type I cells of these species also excrete a gamone which induces pairs in type II cells of particular strains. Complementarity for mating is observed in some combinations of the two types.These results indicate that each of the four species has at least one pair of complementary mating types, I and II, with the gamones of the type II's being the same molecule, blepharismone, while gamones of type I's are species- or syngen-specific blepharmone. These generic and specific gamones can be utilized to clarify existing taxonomic and evolutionary questions in the genus Blepharisma.

scholarly journals Мультипористые наночастицы кремнезема с углеродными наноточками: синтез, оптоэлектронные и биомедицинские применения

2021 ◽  
Vol 63 (10) ◽  
pp. 1680
Author(s):  
Д.А. Курдюков ◽  
Д.А. Еуров ◽  
А.В. Медведев ◽  
Д.А. Кириленко ◽  
М.В. Томкович ◽  
...  
Keyword(s):  
Propidium Iodide ◽  
Cell Structure ◽  
Carbon Nanodots ◽  
Type I ◽  
Type Ii ◽  
Dye Molecules ◽  
Spherical Nanoparticles ◽  
Size Type ◽  
Spectral Ranges ◽  
20 Nm

Spherical multiporous silica nanoparticles (MSNPs) with a diameter of 50 ± 15 nm containing two types of nanopores with sizes of 0.8–2 nm (type I) and 5–10 nm (type II) are synthesized. The film formed from MSNPs contains pores 10–40 nm in size (type III) as a result of spherical nanoparticles packing. Methods are developed for the selective introduction of dye molecules – propidium iodide (PI), carbon nanodots (CD) 3.5 nm in size, and Ag nanoparticles (20 nm) into pores of types I, II, and III, respectively. The possibility of using MSNP/CD and MSNP/CD/Ag films as phosphors for white light LEDs is demonstrated. It is shown that composite MSNP/CD and MSNP/CD/PI particles are non-toxic and allow visualization of the cell structure (by the example of HeLa) simultaneously in several spectral ranges.

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates

1984 ◽  
Vol 42 ◽  
pp. 250-251
Author(s):  
G. D. Gagne ◽  
M. F. Miller ◽  
D. A. Peterson
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Infection ◽  
Uranyl Acetate ◽  
Type I ◽  
Cellular Injury ◽  
Type Ii ◽  
Tubular Structures ◽  
Type Iii ◽  
Type Iv ◽  
Infected Chimpanzee

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.

Comparative surface and ultrastructural views of methylotrophic bacteria by TEM, STEM, SE, and freeze-etch electron microscopy.

1987 ◽  
Vol 45 ◽  
pp. 792-793
Author(s):  
T.A. Fassel ◽  
M.J. Schaller ◽  
M.E. Lidstrom ◽  
C.C. Remsen
Keyword(s):  
Cytoplasmic Membrane ◽  
Structural Features ◽  
Methylotrophic Bacteria ◽  
Type I ◽  
Type Ii ◽  
Membrane Complex ◽  
Oxidation Of Methane ◽  
Methane Oxidizing Bacteria ◽  
Wall Structures ◽  
Methylomonas Albus

Methylotrophic bacteria play an Important role in the environment in the oxidation of methane and methanol. Extensive intracytoplasmic membranes (ICM) have been associated with the oxidation processes in methylotrophs and chemolithotrophic bacteria. Classification on the basis of ICM arrangement distinguishes 2 types of methylotrophs. Bundles or vesicular stacks of ICM located away from the cytoplasmic membrane and extending into the cytoplasm are present in Type I methylotrophs. In Type II methylotrophs, the ICM form pairs of peripheral membranes located parallel to the cytoplasmic membrane. Complex cell wall structures of tightly packed cup-shaped subunits have been described in strains of marine and freshwater phototrophic sulfur bacteria and several strains of methane oxidizing bacteria. We examined the ultrastructure of the methylotrophs with particular view of the ICM and surface structural features, between representatives of the Type I Methylomonas albus (BG8), and Type II Methylosinus trichosporium (OB-36).

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