scholarly journals A POSSIBLE MECHANISM FOR THE MORPHOGENESIS OF LAMELLAR SYSTEMS IN PLANT CELLS

1956 ◽  
Vol 2 (5) ◽  
pp. 597-608 ◽  
Author(s):  
A. J. Hodge ◽  
J. D. McLean ◽  
F. V. Mercer
Keyword(s):  
Normal Development ◽  
Layer Structure ◽  
Subsequent Development ◽  
Peripheral Zone ◽  
Compound Layer ◽  
Prolamellar Body ◽  
Membrane Structures ◽  
Prolamellar Bodies ◽  
Precursor Material ◽  
The Individual

A mechanism for the formation of lamellar systems in the plant cell has been proposed as a result of electron microscope observations of young and mature cells of Nitella cristata and the plastids of Zea mays in normal plants, developing plants, and certain mutant types. The results are compatible with the concept that lamellar structures arise by the fusion or coalescence of small vesicular elements, giving rise initially to closed double membrane Structures (cisternae). In the chloroplasts of Zea, the cisternae subsequently undergo structural transformations to give rise to a compound layer structure already described for the individual chloroplast lamellae. During normal development, the minute vesicles in the young chloroplast are aggregated into one or more dense granular bodies (prolamellar bodies) which often appear crystalline. Lamellae grow out from these bodies. In fully etiolated leaves lamellae are absent and the prolamellar bodies become quite large, presumably because of inhibition of the fusion step which appears to require chlorophyll. Lamellae develop rapidly on exposure of the plant to light, and subsequent development closely parallels that seen under normal conditions. The plastids of white and very pale green mutants of Zea similarly lack lamellae and contain only vesicular elements. A specialized peripheral zone immediately below the double limiting membrane in Zea chloroplasts appears to be responsible for the production of vesicles. These may be immediately converted to lamellae under normal conditions, but accumulate to form a prolamellar body if lamellar formation is prevented, as in the case of etiolation and chlorophyll-deficient mutation, or when the rate of lamellar formation is slower than that of the production of precursor material (as appears to be the case in the early stages of normal development).

The Neuropathic Diathesis, or the Diathesis of the Degenerate

1888 ◽  
Vol 34 (146) ◽  
pp. 167-176
Author(s):  
G. T. Revington
Keyword(s):  
Family History ◽  
Normal Development ◽  
Personal History ◽  
Striking Feature ◽  
General Paralysis ◽  
History Of ◽  
The Creation ◽  
The Individual ◽  
The Mind

I think that the foregoing statistics, and those which follow, together with the large number of cases which I quote, and which connect general paralysis with almost every form of neurotic manifestation, will prove conclusively that neurotic inheritance is a striking feature in the causation of general paralysis. I question whether a distinction between “the cerebral and the insane element” in general paralysis can be maintained. If general paralysis is not a degeneration of the mind-tissue, then the pathology of insanity has no existence, and I would say that the subtle influence for evil, which is transmitted from parents, whose brains are deteriorated by neurotic outbursts, or soaked in alcohol, or wrecked by physiological immorality, tends strongly towards such degeneration. If insanity is, as Dr. Savage says, a perversion of the ego, then a general paralytic is the in-sanest of the insane. We know that the children of a melancholic parent, for example, may develop any form of neurosis—in other words, it is not that melancholia or general paralysis, or any other definite disease, is transmitted, but that a certain tendency to deviate from normal development is transmitted. This tendency to deviate is the neurotic diathesis, and the form of its development is determined by collateral circumstances, and a certain series of collateral circumstances determine the development of general paralysis. Perhaps neurotic inheritance may mean in some cases a limited capital of nervous energy, and if this is wasted recklessly the individual breaks down suddenly and pathologically, as we all do slowly and physiologically. I would also point out that considering the number of histories of insanity which owing to ignorance or reticence we, do not receive, and considering that we never receive information as to the existence of the slighter neuroses, it is marvellous that we get so high a percentage as 51. Of the 145 general paralytics with a reliable history, 38 had a family history of insanity, 28 a family history of drink, 8 of both, 43 had a personal history of drink, 8 of a previous attack too remote to be considered, at least, according to our present ideas, as part of the disease, and the vast majority had a history of some physiological irregularity which must be considered as conducive to the creation of an acquired neurosis. We may now pass to some further statistics.

scholarly journals FINE STRUCTURAL CHANGES IN PROPLASTIDS DURING PHOTODESTRUCTION OF PIGMENTS

1964 ◽  
Vol 22 (2) ◽  
pp. 443-451 ◽  
Author(s):  
Shimon Klein ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Levulinic Acid ◽  
Structural Changes ◽  
Prolamellar Body ◽  
Membrane Structures ◽  
Lamellar Structures ◽  
Amino Levulinic Acid ◽  
Stroma Lamellae ◽  
Green Pigments ◽  
Bean Leaves

Etiolated bean leaves supplied δ-amino-levulinic acid in the dark synthesize large amounts of protochlorophyllide which is not converted to chlorophyllide upon illumination of the leaves. The fine structure of the proplastids is not affected by the treatment. When leaves containing "inactive" protochlorophyllide are exposed to light of 700 ft-c for 3 hours, they lose practically all their green pigments. During this period large stacks of closed membrane structures are built up in the region of the prolamellar body. These lamellar structures remain even when no or only traces of pigment are left in the leaves. In untreated control leaves the pigment content remained constant during similar illumination and the structural changes in the plastids consisted of a rearrangement of the vesicles from the prolamellar bodies into strands dispersed through the stroma; lamellae and grana formation occurred later.

scholarly journals Managing Balance: Pursuit of Equilibrium Permeates the History of Science and Influences Contemporary Investigations

2019 ◽  
Author(s):  
J. Kasmire
Keyword(s):  
Sustainability Science ◽  
Multiple Scales ◽  
Scientific Research ◽  
Subsequent Development ◽  
Scientific Development ◽  
Human Society ◽  
Carbon Neutrality ◽  
History Of ◽  
The Individual ◽  
Successes And Failures

AbstractThe word “sustainable” débuted in 1987 but has since become a hot topic issue, both for scientific research and wider society. Although sustainability may appear to be a thoroughly twenty-first century goal, sustainability science concepts and goals such as balance, endurance, order and change, reach back at least as far as the proto-scientific investigations of alchemy. Both alchemy and sustainability science can be understood as systems or strategies which individuals and societies can use to organise and manage themselves in a complex world filled with dynamic problems. Alchemy never created a panacea or transmuted base metals into gold because those goals proved to be based on fundamentally flawed theories and premises. Nevertheless, alchemy did succeed in helping adherents manage themselves and their societies in advantageous ways. Alchemy also positively and significantly influenced subsequent scientific development. Likewise, science helps humanity manage itself on multiple scales, from the individual to the international, and will certainly contribute to further scientific research and development. However, it is not yet known whether carbon neutrality, entirely renewable energy and other sustainability goals will be achieved or whether these goals will also come to be seen as based on flawed understandings and theories. For this reason, this article explores key features of alchemy, traces how they persisted through Enlightenment-era science and how they continue to be present and influential within scientific efforts today. The article goes on to reflect on how the history, development and continued use of concepts such as balance, endurance, order and change may be useful portents of how humans and human society will manage themselves in the future. Such reflections may also temper the zeal with which individuals that accept or reject sustainability goals treat each other, thereby offering a way for divergent groups to manage their interactions. Flawed theories prevented alchemy from achieving many of its primary stated goals. However, alchemy was very beneficial, both during its period of use and subsequently through its influence on subsequent development. This article identifies ideas from alchemy that were originally beneficial and that have persisted through Enlightenment-era science and into contemporary science. The article also explores how those ideas continue to influence scientific and sustainability goals today. Understanding and reflecting on alchemy’s successes and failures facilitates reflection on the potential successes and failures of sustainability and the human consequences of trying to manage a sustainable future.

scholarly journals A LARGE SCALE QUASI-CRYSTALLINE LAMELLAR LATTICE IN CHLOROPLASTS OF THE GREEN ALGA ZYGNEMA

1970 ◽  
Vol 45 (3) ◽  
pp. 522-531 ◽  
Author(s):  
Robert J. Mclean ◽  
George F. Pessoney
Keyword(s):  
Internal Structure ◽  
Green Alga ◽  
Thylakoid Membrane ◽  
Large Scale ◽  
Three Dimensional ◽  
Prolamellar Body ◽  
Dimensional Lattice ◽  
Filamentous Green Alga ◽  
Prolamellar Bodies ◽  
Single Membrane

A quasi-crystalline lamellar lattice was observed in chloroplasts of the filamentous green alga Zygnema. The lattice does not appear in the cells until cultures are at the end of the log phase of growth. Pseudograna are also present and become more numerous towards the middle of the log phase. The three-dimensional lattice superficially resembles the configuration of cubic prolamellar bodies but is about 10 times larger and is entirely different in internal structure. The lattice is composed of one or two appressed thylakoids in a stroma matrix which is bounded on each side by a single thylakoid membrane. This multilayered sandwich of membranes and matrix occupies a position equivalent to the single membrane of a cubic prolamellar body.

scholarly journals Competence Approach in the Scientific Paradigm of Russian Education

2018 ◽  
Vol 10 (2) ◽  
pp. 135-147 ◽  
Author(s):  
O.A. Ulyanina
Keyword(s):  
Subsequent Development ◽  
State Level ◽  
Theory And Practice ◽  
Professional Activity ◽  
Existing Problems ◽  
Third Stage ◽  
Educational Paradigm ◽  
The Individual ◽  
Russian Education ◽  
Training Of Personnel

The article analyzes the essence and content of the competence approach in education from the position of domestic researchers. The stages of formation and development of the indicated approach are described: the first stage of categorically–conceptual uncertainty; the second stage of the existence of multiple interpretations of key categorical units and the blurring of the boundaries of concepts competence / competence; the third stage of legal consolidation of the above–mentioned concepts at the state level. The necessity of changing the educational paradigm is substantiated, the existing problems in the preparation of specialists competitive on the labor market are noted. The circle of unresolved questions in the competence approach and the ambiguity of the interpretations of its key conceptual units are outlined. In this connection, the existing views of the scientific community are being studied both on the correlation of the concepts of competence / competence and on their content characteristics. Based on the examination of existing approaches, it is concluded that competence is a systemic concept, as an important new formation of the individual, which arises in the course of training and the subsequent development of professional activity, and competence as its component. Through the prism of the description of the categorical–conceptual apparatus of the competence approach, its conceptual positions in the theory and practice of modern education and training of personnel are examined.

Development of the Acrosome During Spermiogenesis in Arion Hortensis Ferussac (Stylommatophora, Pulmonata)

1977 ◽  
Vol 35 ◽  
pp. 614-615
Author(s):  
W. L. Maxwell
Keyword(s):  
Golgi Apparatus ◽  
Species Recognition ◽  
Subsequent Development ◽  
Longitudinal Section ◽  
Cellular Level ◽  
Accessory Structure ◽  
Level 1 ◽  
The Individual

It has been suggested that in internally fertilising animals the acrosome is of reduced importance where species recognition occurs at the individual rather than cellular level (1).However, a complex acrosome is present in the spermatozoon of Arion hortensis. and a specialised accessory structure is formed during acrosomal development.The proacrosomal granule is deposited at the presumptive nuclear apex early in spermiogenesis by the Golgi apparatus - but subsequent development occurs without any Golgi association. The granule is initially oblong when viewed in longitudinal section being 400nm long. There is no visible substructure as shown in Fig.l. During spermiogenesis the acrosome parallels the elongation of the nucleus. At about mid-spermio- genesis the columnar proacrosome is 600nm long and Fig.2 shows some internal differentiation. A central rod of material is visible with a basal concavity which is closely associated with the anterior tip of the maturing nucleus.

Red-Light Stimulation of Prolamellar Body Recrystallization and Thylakoid Formation in Barley Etioplasts

1971 ◽  
Vol 8 (1) ◽  
pp. 185-200
Author(s):  
D. R. BERRY ◽  
H. SMITH
Keyword(s):  
Red Light ◽  
Low Frequency ◽  
Chlorophyll Synthesis ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Exact Nature ◽  
Prolamellar Bodies ◽  
Barley Leaves ◽  
Fraction I ◽  
And Function

The etioplasts of fully dark-grown barley leaves exhibit a relatively low frequency of crystalline prolamellar bodies (ca. 16-20%). Brief red-light treatment leads to rapid disruption of all prolamellar bodies followed by a slow reformation in the subsequent dark period. When several red-light treatments are given with intervening 3-h dark periods, a marked increase in the proportion of crystalline prolamellar bodies is seen. It is suggested that this phenomenon may be associated with the regeneration of protochlorophyll. Red-light pretreatment stimulates the formation of granal thylakoids upon subsequent transfer to continuous white light. This response is correlated with the phytochrome-mediated shortening of the lag phase in chlorophyll-synthesis under identical conditions. Regular arrays of hexagonal tubules 16-19 nm in diameter have been observed often in close juxtaposition to the newly forming thylakoid membranes. These may be aggregations of Fraction I protein, although their exact nature and function is at present Unknown.

scholarly journals FINE STRUCTURE AND PIGMENT CONVERSION IN ISOLATED ETIOLATED PROPLASTIDS

1961 ◽  
Vol 11 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Shimon Klein ◽  
A. Poljakoff-Mayber
Keyword(s):  
Fine Structure ◽  
Photosynthetic Apparatus ◽  
Prolamellar Body ◽  
Submicroscopic Structure ◽  
Outer Membranes ◽  
Prolamellar Bodies ◽  
Bean Plants ◽  
Isolation Methods

Proplastids containing a prolamellar body were isolated from leaves of etiolated bean plants. The isolation methods do not necessarily lead to destruction of their submicroscopic structure and most of the isolated proplastids show well preserved outer membranes, lamellar strands, and the prolamellar body. Morphological intactness of the proplastids varies; certain leaf fractions contain single prolamellar bodies as well as proplastids. Since pellets after centrifugation between 350 g and 1000 to 3000 g contain intact proplastids and, as was shown by quantitative experiments, the same fractions show photoconversion of protochlorophyll to chlorophyll, it is supposed that the isolated particles probably retain many of the properties which are characteristic of them in situ. Isolated proplastids may thus be a valuable tool in investigations on the development of the photosynthetic apparatus.

On the intergranular coupling in soft nanocrystalline materials

1996 ◽  
Vol 11 (2) ◽  
pp. 512-517 ◽  
Author(s):  
J. M. González ◽  
N. Murillo ◽  
J. González ◽  
J. M. Blanco ◽  
J. Echeberría
Keyword(s):  
Nanocrystalline Materials ◽  
Magnetocrystalline Anisotropy ◽  
Characteristic Length ◽  
Magnetic Moments ◽  
Bias Field ◽  
Continuous Heating ◽  
Heating Rates ◽  
Precursor Material ◽  
Magnetic Softness ◽  
The Individual

The magnetic softness of nanocrystalline materials prepared from amorphous precursors is attributed to the average of the local magnetocrystalline anisotropy of the individual crystallites. In the present paper we have studied the effective magnetic anisotropy of Fe-based nanocrystalline samples with different microstructures. These microstructures were produced by using different heating rates when crystallizing the precursor material by means of continuous heating treatments. From the results of our study of the magnetic properties of the samples, carried out from the measurement of the bias field dependence of the transverse susceptibility, it was possible to discern the occurrence of intergranular coupling and to evaluate the typical dimensions of the coupled units. Since these dimensions were larger than the characteristic length of the microstructure, we suggest that the enhancement of the soft properties is linked to the decrease of the microstructure-magnetization interactions originating in large units of coupled magnetic moments.

5. Clinical Psychiatry and Neurology

1901 ◽  
Vol 47 (197) ◽  
pp. 393-412
Keyword(s):  
Cerebral Cortex ◽  
Mental Disorder ◽  
Structural Changes ◽  
Normal Development ◽  
Post Mortem ◽  
Psychic Life ◽  
Mental Disturbances ◽  
Minor Degree ◽  
The Individual ◽  
A Minor

The above was one of the subjects selected for discussion in the Section of Psychiatry at the International Medical Congress (held last August at Paris), and papers were contributed by Professor Marro of Turin, by Dr. Ziehen of Jena, and by Dr. Jules Voisin of Paris. The views of the last-named having been already epitomised,(1) it only remains to notice the papers of the two former. Professor Marro presented as his conclusions the following:—(1) That puberty exercises an important influence on the psychic life, and that pre-existent mental disturbances might thereby be invested with characters which previously they did not manifest, or manifested only in a minor degree; or indeed that it might open up the way to definite mental disorder. (2) That amongst psychoses affecting young persons of both sexes at the age of puberty, there was one in particular which might be regarded as specific—the hebephrenia of Hecker. (3) That the morbid manifestations of this form of psychosis combined in a special way the symptoms of certain other mental disorders, and that the post-mortem appearances showed morbid structural changes in the cerebral cortex and meninges—possibly consequent on a process of auto-intoxication, due to digestive irregularities and disordered metabolism. (4) The epoch of puberty and the precocious and abnormal exercise of sexual activity might be the means of originating morbid manifestations, stamping in some cases the individual with permanent peculiarity, although in others this might be effaced in after life under favourable circumstances. (5) The prophylaxis of mental disorder at this epoch demanded strict attention to avoid all causes which may interfere with the normal development of the organism, such as excess of physical or mental fatigue, and especially the precocious and abnormal exercise of sexual functions.

Sign in / Sign up

Export Citation Format

Share Document