Distribution of Pyrenoids Among Some Brown Algae

1966 ◽  
Vol 1 (4) ◽  
pp. 449-454
Author(s):  
L. V. EVANS
Keyword(s):  
Electron Microscope ◽  
Relative Position ◽  
Brown Algae ◽  
Light Microscope ◽  
The Other ◽  
Taxonomic Character ◽  
The Subject

The distribution of pyrenoids among some orders of the brown algae has been investigated with the electron microscope and a report on their occurrence is given, with particular reference to the results obtained with the light microscope by Simon (1954). Some illustrated detail of the structure of the pyrenoids and of the chromatophores is included. Pyrenoids were found to be present in the representatives examined of the Ectocarpales, Sphacelariales, Scytosiphonales and Dictyosiphonales. Excepting the Sphacelariales, this is in agreement with the results of Simon. Pyrenoids were found to be definitely absent in all members of the Dictyotales and Laminariales examined, and disagreement is expressed with Bouck (1965) who reported their presence in Chorda filum, a member of the latter order. The situation in the Fucales is the subject of another communication elsewhere. The presence or absence of pyrenoids is regarded as an additional taxonomic character of possible phyletic use when more is known. The results are discussed from the standpoint of their possible value in assessing the relative position of the Phaeophyceae as a whole. Brown algal lamellations are composed of three, or occasionally four, parallel thylakoids which do not cohere and are not aggregated into stacks. This is thought to be more primitive than the condition in some of the other groups of the Chromophyta where there is adherence of thylakoids into stacks of two or three members as, for example, in the Haptophyceae, Xanthophyceae and Chrysophyceae. The Phaeophyceae are, however, regarded as much less primitive than the Rhodophyceae, where the widely spaced parallel thylakoids are arranged singly.

scholarly journals Additional facts respecting the fossil remains of an animal, on the subject of which two papers have been printed in the Philosophical Transactions, showing that the bones of the sternum resemble those of the Ornithorhynchus paradoxus

1833 ◽  
Vol 2 ◽  
pp. 82-83
Keyword(s):  
Relative Position ◽  
The Other ◽  
Fossil Bone ◽  
Fossil Remains ◽  
The Subject ◽  
Cartilaginous Fishes

In an engraving annexed to Sir Everard Home’s first paper upon the above subject, a portion of bone is shown lying upon the scapula, which he considered as a portion of a rib accidentally brought there; but which he now finds to be nearly in its original situation, and is found to resemble nearly the clavicular bone in birds, as far as regards relative position. The bones of the sternum were first pointed out to the author by Mr. Buckland; and their discovery destroys the analogy between this fossil animal and cartilaginous fishes. On comparing the general form of the sternum with that of the Ornithorhynchus paradoxus , a general agreement was discovered between them: they differ in the fossil skeleton having a clavicular bone, which is wanting in the other, and in the Ornithorhynchus having a long process from the scapula, which the fossil bone wants.

scholarly journals Studies on marine flagellates: VI. Chrysochromulina pringsheimii sp.nov

1962 ◽  
Vol 42 (2) ◽  
pp. 391-404 ◽  
Author(s):  
Mary Parke ◽  
Irene Manton
Keyword(s):  
Electron Microscope ◽  
New Species ◽  
Light Microscope ◽  
Preliminary Observation ◽  
The Other ◽  
Different Types ◽  
Evolutionary Consequences ◽  
Base Plates ◽  
A New Species ◽  
Unusual Type

SUMMARYA new species of Chrysochromulina with an unusual type of cocoon-like scaly covering has been described with the light microscope. The morphology and arrangement of the scales has been elucidated with the electron microscope. Salient features are the presence of four different types of scale (large and small plates and large and small spines) in characteristic positions in or on the case, the small plates having the normal two layers characteristic of primitive scales in this group, the other three types being specialized modifications of this. Some developmental and evolutionary consequences of the morphological observations are discussed. A preliminary observation on the thickness of micro-fibrils composing the base-plates of spined scales is given.

¿Pasaporte para amar?: Un corsé para el deseo. / Passport to love?: A corset for desire.

2016 ◽  
Vol 5 (09) ◽  
pp. 99-112
Author(s):  
Pilar Errázuriz Vidal
Keyword(s):  
Relative Position ◽  
The Other ◽  
Political Struggle ◽  
Other Hand ◽  
Postmodern Philosophy ◽  
The Subject ◽  
Political Intervention

En este artículo se propone una reflexión en torno a una cuestión paradojal: por más que en este siglo XXI las acciones políticas de la diversidad sexual han sido muy beneficiosas para erosionar el dogma paterno, como lo asegura el psicoanalista Michel Tort, a la vez han repetido el modelo hegemónico de categorizar, no ya ‘la diferencia sexual’ sino ‘las diferencias sexuales’, asegurando, hoy, diversas identidades que se definen como GLBTTTIQ, haciendo de cada casillero un lugar estanco para el deseo migrante, excéntrico e incoherente. El pensamiento post-moderno asegura la no existencia de “el sujeto” y nos remite a entendernos como una copia de la copia de la copia, de un original que no es. Paralelamente, el deseo que cabalga a ciegas en el riel transferencial de la búsqueda “del objeto” que al fin lo completará, a sabiendas de la castración simbólica que remite a “la falta” y al destino del eterno retorno. Solo que si abrazamos estas “verdades” que nos muestra tanto la filosofía de la postmodernidad como el análisis lacaniano, nuestra andadura sería fantasmática y no conectaría con una realidad socio-política que se impone sin ambigüedad. ¿Cómo conciliar lo uno y lo otro? ¿Son las nuevas clasificaciones, por eficaces que sean para el debilitamiento del sistema, un lugar más de represión, de compromiso y de definición difícil de transgredir? El rompecabezas que hay que dilucidar es cómo asimilar el saber de la postmodernidad sin renunciar a valores de la modernidad, que aunque nos parezcan efímeros y espejísmicos permiten la incidencia en la realidad, sin que nuestra singularidad se sienta traicionera a uno u otro prospecto y que podamos dar un respiro al Ello que busca, lúdicamente, el terreno de lo absurdo de la dinámica deseante. The proposal of this text is a sort of puzzle to be thought. On one hand we have the postmodern knowledge about the death of the subject, though a skeptical agenda for political definition. On the other hand, westill are produced by the modern schoolwhich let us learn about political struggle in order to fight the hegemonic power. Lacan’spsychoanalysis assure that identity is an illusion and that the desire search always, via transfer, an object to be completed, what is impossible because the symbolic castration of the subject. Postmodern philosophy pretend the non existence of the subject, and the total illusory sensation of being, whatgive a perspective which diminish the Egopretensions. How could we be aware of the relative position of an identity and, at the same time, not abandon our group of pairs for political intervention in the reality? The new sexual classification GLBTTTIQ we consider as a battle won against Father’s law. Is it a real liberation or, again, is another way of submit sexuality to a certain and only way of desiring? Could we belong to one of the categories and have the freedom of letting desire be nomadic?

The fine structure of the trunk and praesoma wall of Acanthocephalus ranae (Schrank, 1788), Lühe, 1911

Parasitology ◽  
1967 ◽  
Vol 57 (3) ◽  
pp. 475-486 ◽  
Author(s):  
R. A. Hammond
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Electron Microscope ◽  
Light Microscope ◽  
Body Wall ◽  
Technical Assistance ◽  
The Body ◽  
The Other ◽  
Fat Excretion ◽  
Research Grant

The wall of the trunk, that of the praesoma, and the lemnisci of Acanthocephalus ranae have been studied by electron microscopy. Striations visible in sections of the body wall under the light microscope do not correspond with the ‘striped layer’ revealed by the electron microscope.A new region, the ‘canal layer’, has been described. This contains canals running into the body wall from cuticular pores.Structurally the wall of the trunk and that of the praesoma are similar. The lemnisci resemble the ‘inner layer’ of the praesoma wall. However, it is suggested that the wall of the trunk differs physiologically from that of the praesoma, and from the lemnisci. The possible roles of the wall of the praesoma and the lemnisci in fat excretion or uptake have been discussed.The body wall of A. ranae has been compared with that of the other acantho-cephalans studied with the electron microscope.Grateful acknowledgement is made to D.S.I.R. (now S.R.C.) for a research grant to the Department of Zoology for the purchase of a Huxley ultramicrotome, a vacuum coating unit, and an AEI EM 6 electron microscope.I am grateful to Dr D. A. Erasmus for reading and criticizing the manuscript, and to Mr T. Davies for valuable technical assistance.

scholarly journals Ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia Campus, Depok, Indonesia

2020 ◽  
Vol 21 (9) ◽  
Author(s):  
Afiatry Putrika ◽  
Dhita Mutiara Nabella ◽  
Andi Salamah ◽  
Nisyawati NISYAWATI ◽  
Astari Dwiranti
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Surface ◽  
Light Microscope ◽  
Urban Forest ◽  
Wide Distribution ◽  
The Other ◽  
Wall Surface ◽  
The World ◽  
Scanning Electron

Abstract. Putrika A, Nabella DM, Salamah A, Nisyawati, Dwiranti A. 2020. Ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia Campus, Depok, Indonesia. Biodiversitas 21: 4184-4191. Lejeunea is one of liverworts genera that have a wide distribution in the world. It has many variations of the character that have not been revealed, such as variations of the cell surface. The purpose of this research was to study the ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia (UI) Campus, Depok, Indonesia. Six species of Lejeunea spp. were studied, i.e., L. anisophylla, L. cocoes, L. exilis, L. papilionacea, L. catanduana, and L. curviloba. The research methods carried out in this study consisted of the sample observation using a light microscope, sample preparation for Scanning Electron Microscope (SEM) observation (fixation, post-fixation, dehydration, drying, mounting), and observations using SEM. The results of observation using a light microscope showed the smooth cell surface of all samples studied. Meanwhile, the differences between six species of Lejeunea in the UI campus could be differentiated under SEM. L. catanduana could be distinguished from other species from its cell wall thickness and texture, ornamentation types, and the number of ornamentations per cell. The texture of the cell wall of L. catanduana was the roughest than the other species due to abundant ornamentation such as papillae on its the cell wall surface. Furthermore, only this species has mamillae on the cell surface. The number of papillae or mamillae was 1-4 per cell. On the other hand, L. cocoes has the thinnest cell wall and slightly rough texture. Only this species has the simple papillae on the cell surface. Thus, the results of this study suggested that the cell surface variations in Lejeunea might be potential to be used as taxonomic characters in grouping species.

The Alteration of the Pore Spaces in Sandstones

1973 ◽  
Vol 31 ◽  
pp. 210-211
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Coarse Grained ◽  
Depositional Fabric ◽  
Soluble Components ◽  
Scanning Electron ◽  
Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

Development of 200 kV Scanning-Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 410-411
Author(s):  
H. Koike ◽  
S. Sakurai ◽  
K. Ueno ◽  
M. Watanabe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
The Other ◽  
Morphological Observation ◽  
Magnetic Domains ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Backscattered Electron ◽  
Increasing Demand

In recent years, there has been increasing demand for higher voltage SEMs, in the field of surface observation, especially that of magnetic domains, dislocations, and electron channeling patterns by backscattered electron microscopy. On the other hand, the resolution of the CTEM has now reached 1 ∼ 2Å, and several reports have recently been made on the observation of atom images, indicating that the ultimate goal of morphological observation has beem nearly achieved.

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.

Selective Staining of Acid Mucopolysaccharides By Ruthenium Red

1968 ◽  
Vol 26 ◽  
pp. 38-39
Author(s):  
J. H. Luft
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Single Cells ◽  
Ruthenium Red ◽  
Collagen Fibers ◽  
Selective Staining ◽  
Pectic Substances ◽  
Solid Tissues

Ruthenium red is one of the few completely inorganic dyes used to stain tissues for light microscopy. This novelty is enhanced by ignorance regarding its staining mechanism. However, its continued usefulness in botany for demonstrating pectic substances attests to selectivity of some sort. Whether understood or not, histochemists continue to be grateful for small favors.Ruthenium red can also be used with the electron microscope. If single cells are exposed to ruthenium red solution, sufficient mass can be bound to produce observable density in the electron microscope. Generally, this effect is not useful with solid tissues because the contrast is wasted on the damaged cells at the block surface, with little dye diffusing more than 25-50 μ into the interior. Although these traces of ruthenium red which penetrate between and around cells are visible in the light microscope, they produce negligible contrast in the electron microscope. However, its presence can be amplified by a reaction with osmium tetroxide, probably catalytically, to be easily visible by EM. Now the density is clearly seen to be extracellular and closely associated with collagen fibers (Fig. 1).

Reconstruction of electron holograms recorded in a non-FEG, non-biprism TEM

1995 ◽  
Vol 53 ◽  
pp. 618-619
Author(s):  
Z.L. Wang
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Experimental Technique ◽  
Transmission Electron Microscope ◽  
The Other ◽  
Electron Holography ◽  
Transmission Electron ◽  
Coherent Sources ◽  
Imaging Theory ◽  
Normal Specimen

An experimental technique for performing electron holography using a non-FEG, non-biprism transmission electron microscope (TEM) has been introduced by Ru et al. A double stacked specimens, one being a single crystal foil and the other the specimen, are loaded in the normal specimen position in TEM. The single crystal, which is placed onto the specimen, is responsible to produce two beams that are equivalent to two virtual coherent sources illuminating the specimen beneath, thus, permitting electron holography of the specimen. In this paper, the imaging theory of this technique is described. Procedures are introduced for digitally reconstructing the holograms.

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