Memoirs: The Golgi Apparatus of Copromonas Subtilis, and Euglena sp

1938 ◽  
Vol s2-80 (320) ◽  
pp. 567-591
Author(s):  
J. BRONTË GATENBY ◽  
B. N. SINGH
Keyword(s):  
Cell Wall ◽  
Golgi Apparatus ◽  
Neutral Red ◽  
The Other ◽  
Contractile Vacuole ◽  
Daughter Cells ◽  
The Past ◽  
Early Stages ◽  
Contractile Vacuoles ◽  
Osmoregulatory Mechanism

1. In Copromonas subtilis , Dobell, and Euglena sp. there is a Golgi apparatus consisting of osmiophil material in the form of granules, which are associated with the osmoregulatory mechanism of the cell. 2. Inside the granules, water collects, so that they become spherical vacuoles, identical with what have in the past been called contractile vacuoles (Copromonas) or accessory contractile vacuoles (Euglena viridis). 3. In Euglena viridis, the Golgi apparatus is closely applied to the so-called contractile vacuole, and consists of numerous loaf-shaped osmiophil bodies which undergo a regular series of changes from systole to diastole, and vice versa. 4. In Copromonas, the osmiophil material may form a thick cortex surrounding what has been called the reservoir, it may be attached to the reservoir in fairly regular loafshaped bodies as in Euglena, or it may be completely detached from the reservoir. 5. The so-called contractile vacuoles of Copromonas are vesicles containing water, which are formed on the site of the osmiophil granules. 6. As far as we are able to say at present, the reservoir of Copromonas is indistinguishable from an enlarged contractile vacuole, and new reservoirs probably arise from swollen contractile vacuoles. It is difficult to believe that the reservoir divides into two, as has been claimed by Dobell. 7. During division of Copromonas, two reservoirs can nearly always be found in the early stages before the nucleus becomes dumb-bell shaped. These seem to have originated from the osmiophil vacuoles. 8. The remaining osmiophil material, when present, moves slightly down the cell, occupying a place in the mid-line. When the new cell-wall between the two organisms has passed down, about one-third the length of the dividing monad, the osmiophil material splits into two sub-equal groups and is so divided between the two organisms. There is therefore a definite dictyokinesis to be found in Copromonas. 9. Just at or after this period, the osmiophil material may become scattered about the upper middle and upper region of the dividing monads, but finally becomes situated in the region of the reservoir. 10. The osmiophil material (Golgi apparatus) persists throughout conjugation and encystment, even when a reservoir cannot be found. 11. There is a rhizoplast joining the basal granule of the flagellum with the intra-nuclear nucleolo-centrosome, and an axostyle is present, passing from the basal granule to the posterior end of the organism. 12. During cell division, the basal granule divides into two and appears to lose its connexion with the two nucleolo-centrosomes of the dividing nucleus. The axostyle appears to be absorbed in the early stages of division and cannot be stained at this epoch, but reappears in each moiety of the dividing organism, when the nucleus is dumb-bell shaped. It appears to reform when the two basal granules have taken their definitive position at the anterior end of the cells. 13. We agree with Wenyon that one flagellum passes over intact to one of the daughter cells at division, the other flagellum arises from the other basal granule. 14. Numerous fat granules are found throughout the organism; what have been called volutin granules in other Protozoa are present in Copromonas, and stain in neutral red. 15. Mitochondria are present mainly in the posterior region of the organism.

Memoirs: The Golgi Apparatus and Pyrenoids of Chilomonas paramecium, with remarks on the Identification of Copromonas subtilis

1940 ◽  
Vol s2-81 (324) ◽  
pp. 595-617
Author(s):  
J. BRONTÉ GATENBY ◽  
J. D. SMYTH
Keyword(s):  
Golgi Apparatus ◽  
Osmium Tetroxide ◽  
Daughter Cell ◽  
Neutral Red ◽  
The Other ◽  
Contractile Vacuole ◽  
Daughter Cells ◽  
Osmium Tetroxide Solution ◽  
Cortical Substance ◽  
Two Bodies

1. In Chilomonas paramecium the contractile vacuole is surrounded by a cortical substance (Golgi apparatus) which has the power of reducing osmium tetroxide solution and thus impregnating black (Nassonow). 2. This cortex blackens thus in over 99 per cent, of individuals in a culture which has not been dividing. In a culture in which the individuals have been rapidly dividing, the percentage of unimpregnated contractile vacnoles increases considerably, up to about 5 per cent. 3. During division of Chilomonas in about 70 per cent. of cases the osmiophile substance is very equally divided between the daughter cells. The dividing cortex comes away from the contractile vacuole, which eventually collapses, new contractile vacuoles arising in the site of the divided osmiophile material. In about 25 per cent, of division stages osmication of the cortex fails to a greater or lesser degree. There is always a very distinct tendency for this failure to take place even in the best of preparations. 4. In some cases (about 3 per cent.), during division, the entire contractile vacuole and its cortex goes over whole to one individual. A new vaeuole, apparently without cortex, arises spontaneously in the other individual. It is unlikely that all of these cases are due to failure of impregnation in one of the individuals, though this possibility cannot be roled out completely. 5. The behaviour of the original contractile vacuole cavity before separation of the daughter cells is as follows. The lipoid, having partially retreated from the vacuole, becomes separated into two parts, and the centrally placed vacuole disappears (figs. 4 and 6, Pl. 36; figs. 10 and 15, Pl. 37). New vacuoles appear in the site of the lipoid bodies in each daughter cell (fig. 5, Pl. 36). 6. Two ellipsoidal accessory bodies or pyrenoids lie on a level with the vestibule. In older cultures the two bodies are often exactly the same size and colour (corrosive osmic followed by neutral red or haematoxylin), but in rapidly dividing cultures, one body may be of normal size, whereas the other may be absent or much smaller. During cell division, one body is carried across to each daughter. No exception to this was ever found. 7. Identification of the smaller Peranemidae is in a confused state. Probably several species, and possibly even genera, have been described by various authors as Scytomonas (Copromonas) subtilis.

Memoirs: The Effect of Ultra-Centrifuging Vertebrate Neurones

1936 ◽  
Vol s2-79 (313) ◽  
pp. 73-90
Author(s):  
R. H. J. Brown
Keyword(s):  
Golgi Apparatus ◽  
Living Cell ◽  
Neutral Red ◽  
The Other ◽  
Cytoplasmic Inclusions ◽  
Fixed Material ◽  
Diffuse Form ◽  
Similar Density ◽  
Nissl Substance

1. The Golgi apparatus may appear as a network or incomplete reticulum; it is lighter than the other cytoplasmic inclusions but its form makes its displacement difficult. Its parts never approach the periphery of the cell. The neutral-red bodies have no part in its composition. 2. There exists a separate canalicular system which is connected with the surface of the cell, and otherwise is of similar dimensions to the Golgi apparatus. It is thought to represent the trophospongium of Holmgren. It is unaffected by the centrifuge. 3. The vacuome appears in the form of isolated granules which can be osmicated after staining in neutral red. They are lighter than the cytoplasm and are separate from the Golgi apparatus, though on account of their similar density they are thought to have some spatial connexion with it. 4. The mitochondria are in the form of rods and granules which are very slightly denser than the cytoplasm, and show no evidence of having any connexion with the Golgi apparatus. 5. The Nissl substance occurs as large irregular bodies in the fixed material. It is thought to be in a diffuse form in the living cell. It is much denser than the cytoplasm.

Ultrastructure of mitosis in the chloromonadophycean alga Vacuolaria virescens

1978 ◽  
Vol 31 (1) ◽  
pp. 37-51
Author(s):  
P. Heywood
Keyword(s):  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Genetic Material ◽  
Membrane Vesicles ◽  
Contractile Vacuole ◽  
Basal Bodies ◽  
Anterior Surface ◽  
Daughter Cells ◽  
Interphase Cells ◽  
Unusual Type

During preprophase in the chloromonadophycean alga Vacuolaria virescens microtubules are present around the flagellar basal bodies and extend over the anterior surface of the nucleus. These microtubules assist in the separation of the flagella and later enter the nucleus through polar gaps. During prophase the nucleoli begin to disperse and the chromosomes become condensed. At metaphase the nucleus assumes an elliptical shape and an equatorial plate of chromosomes becomes aligned across the long axis of the nucleus; kinetochores are recognizable on some of the chromosomes. The nuclear envelope remains intact over most of the surface and in places it forms folds. During anaphase chromosomes are less distinct and vesicles are present in the elongating nucleus. Most of the new nuclear envelope around the progeny nuclei is formed by coalescence of these membrane vesicles during late anaphase and telophase, although some of the original nuclear envelope may also become incorporated. During telophase disintegration of the original nuclear envelope becomes pronounced and portions of this structure are recognizable in the cytoplasm after completion of mitosis. It is suggested that this unusual type of nuclear envelope behaviour may be important in ensuring the segregation of the Golgi apparatus and contractile vacuole to progeny cells. Interphase cells contain a single extensive Golgi apparatus which is located between the anterior surface of the nucleus and the contractile vacuole. The Golgi apparatus and contractile vacuole act as an osmoregulatory system and their presence is presumably essential to the existence of the organism. Formation of a new contractile vacuole and division of the Golgi apparatus occur early in mitosis and thereafter a Golgi apparatus and contractile vacuole become associated with each of the poles of the nucleus. They retain this location throughout mitosis and during cytokinesis, with the result that an osmoregulatory system is present in each of the daughter cells. In a similar manner, microbody-like organelles are associated with the nuclear envelope during mitosis but not at interphase. Growth of the nuclear envelope during mitosis may serve as the means of partitioning these organelles to the progeny cells. Thus mitosis in Vacuolaria virescens is responsible not only for the equal segregation of the genetic material but also for the correct distribution of some of the cytoplasmic components.

Is autosporulation a feature of Nannochloris?

1983 ◽  
Vol 61 (10) ◽  
pp. 2647-2657 ◽  
Author(s):  
Lewis M. Brown ◽  
Beverly Elfman
Keyword(s):  
Cell Wall ◽  
Parental Cell ◽  
The Other ◽  
Wall Structure ◽  
Daughter Cells ◽  
Green Algal ◽  
Chlorophylls A And B ◽  
Binary Division ◽  
Algal Genus ◽  
Division Mechanism

The green algal genus Nannochloris Naumann was originally described as having a simple binary division mechanism and lacking autosporulation and a parental cell wall. An initial observation of autosporulation in one isolate ascribed to this genus encouraged a broader investigation to determine whether or not autosporulation is restricted to only certain forms or is the reproductive mechanism used in the genus as a whole. Five cultures were examined; all had typically chlorophycean ultrastructure and both chlorophylls a and b. Nannochloris atomus differed from the other forms (two Nannochloris spp., Nannochloris bacillaris, and Nannochloris maculants) in having a pyrenoid and different wall structure and other ultrastructural features. However, reproduction in all five was by autosporulation with a thin, yet clearly defined, parental wall surrounding the two–four daughter cells in electron micrographs. These and related findings of other workers point to the need for a redefinition of the genus.

Memoirs: The Cytology of Amoeba Proteus ‘Y’ and the Effects of Large and Small Centrifugal Forces

1938 ◽  
Vol s2-80 (320) ◽  
pp. 601-634
Author(s):  
B. N. SINGH
Keyword(s):  
Golgi Apparatus ◽  
Nile Blue ◽  
Cyst Formation ◽  
Neutral Red ◽  
Amoeba Proteus ◽  
Contractile Vacuole ◽  
Osmic Acid ◽  
Culture Solution ◽  
Food Material ◽  
Sudan Iv

1. When Amoeba proteus is subjected to high centrifugal force most of the cytoplasmic bodies are thrown out of the cell, so this work was done with the ordinary electrical centrifuge. 2. The stratification of the various cytoplasmic components according to their specific gravity is as follows: the contractile vacuole and the fat, being the lightest, occupy the centripetal position; then there is a layer of cytoplasm followed by mitochondria, neutral-red bodies, crystals, and nutritive spheres. The nucleus occupies a position in between the crystals and the nutritive spheres (Text-fig. 2). 3. The redistribution of the various cytoplasmic components takes place within a few minutes after amoebae have been centrifuged by the electrical centrifuge. Ultra-centrifuged organisms kept in culture solution remain rounded for 10-15 days, and no cyst formation takes place. The crystals and nutritive spheres are reformed; the former seem to be the products of excretion formed by the metabolic activity of the cell. 4. The nutritive spheres contain glycogen as reserve food material, and give positive tests for glycogen with iodine and Best's carmine. 5. There is no evidence that the bodies which stain with neutral red are the homologue of the metazoan Golgi apparatus, although they are pre-existing bodies in Amoeba proteus . The contractile vacuole does not blacken even after prolonged osmication. No certain homologue of the Golgi apparatus was found in Amoeba proteus. 6. Fat and glycogen are two distinct types of storage material present in Amoeba proteus. The former is very well seen with osmic acid, Sudan IV, and Nile blue tests.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Golgi Apparatus and Melanogenesis: Ultrastructural Study of a Human Cellular Blue Nevus (Melanocytoma)

1973 ◽  
Vol 31 ◽  
pp. 380-381
Author(s):  
S.R. Allegra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
The Other ◽  
Blue Nevus ◽  
Normal Complement ◽  
Golgi Vesicles ◽  
Golgi System ◽  
The Subject ◽  
Cellular Blue Nevus

The respective roles of the ribo somes, endoplasmic reticulum, Golgi apparatus and perhaps nucleus in the synthesis and maturation of melanosomes is still the subject of some controversy. While the early melanosomes (premelanosomes) have been frequently demonstrated to originate as Golgi vesicles, it is undeniable that these structures can be formed in cells in which Golgi system is not found. This report was prompted by the findings in an essentially amelanotic human cellular blue nevus (melanocytoma) of two distinct lines of melanocytes one of which was devoid of any trace of Golgi apparatus while the other had normal complement of this organelle.

Applications of Through-Focus Dark Field Image Shifts to Phase Identification

1975 ◽  
Vol 33 ◽  
pp. 178-179
Author(s):  
Prakash Rao
Keyword(s):  
Dark Field Image ◽  
Thin Foil ◽  
Dark Field ◽  
The Other ◽  
Stereo Image ◽  
Phase Identification ◽  
The Past ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Recent Extension

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.

“I’ve got you under my skin”: borderline states in couple relationships

2020 ◽  
Vol 10 (1) ◽  
pp. 59-71
Author(s):  
Perrine Moran
Keyword(s):  
The Other ◽  
Couple Relationships ◽  
Early Stages ◽  
Popular Songs ◽  
The Relationship

Many couples who come for therapy are struggling with separating from unconscious phantasies and beliefs that enmesh each partner with the other, resulting in states that popular songs powerfully epitomise. While this borderline experience is common and functional in the early stages of being in love its persistence paralyses the development of the relationship. Facing separation from and loss of illusion is a challenge couple therapists are often asked to help with. The argument is illustrated by a case, and by references to some of Cole Porter’s best known songs.

‘Newness which never perishes’? Schoenberg’s ambivalent reception of Haydn

2010 ◽  
Vol 51 (1-2) ◽  
pp. 215-224
Author(s):  
Alexander Carpenter
Keyword(s):  
The Other ◽  
Major Influence ◽  
Musical Style ◽  
The Past ◽  
Other Hand ◽  
The Future ◽  
Music Tradition

This paper explores Arnold Schoenberg’s curious ambivalence towards Haydn. Schoenberg recognized Haydn as an important figure in the German serious music tradition, but never closely examined or clearly articulated Haydn’s influence and import on his own musical style and ethos, as he did with many other major composers. This paper argues that Schoenberg failed to explicitly recognize Haydn as a major influence because he saw Haydn as he saw himself, namely as a somewhat ungainly, paradoxical figure, with one foot in the past and one in the future. In his voluminous writings on music, Haydn is mentioned by Schoenberg far less frequently than Bach, Mozart, or Beethoven, and his music appears rarely as examples in Schoenberg’s theoretical texts. When Schoenberg does talk about Haydn’s music, he invokes — with tacit negativity — its accessibility, counterpoising it with more recondite music, such as Beethoven’s, or his own. On the other hand, Schoenberg also praises Haydn for his complex, irregular phrasing and harmonic exploration. Haydn thus appears in Schoenberg’s writings as a figure invested with ambivalence: a key member of the First Viennese triumvirate, but at the same time he is curiously phantasmal, and is accorded a peripheral place in Schoenberg’s version of the canon and his own musical genealogy.

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