Antisera to basal lamina and glial endfeet disturb the normal extension of axons on retina and pigment epithelium basal laminae

Development ◽  
1989 ◽  
Vol 107 (2) ◽  
pp. 281-297
Author(s):  
W. Halfter

In order to determine the role of the extracellular matrix in regulating the directed growth of embryonic neurites, antisera to retina (a-RBL I and II), to pigment epithelium (a-PBL) and to glomerular (a-GBL) basal lamina were probed for an effect on the ordered extension of neurites. In the assays, retina explants from chick and quail were cultured on basal lamina from embryonic chick retina and pigment epithelium either in the presence of anti-basal lamina antisera or in the presence of the corresponding preimmune sera. In the presence of all anti-basal lamina antisera, normal extension of axons was greatly inhibited both on retina and on pigment epithelium basal lamina. The antisera affected the growth pattern and the morphology of the individual axons in two ways: in the presence of a-RBL I the short axons were less directed, developed more and longer side branches, and the lamellipodia of the growth cones were reduced in size compared to axons from control cultures. In the presence of a-RBL II and a-GBL, axons grew slowly out from the explants as very thick bundles, strikingly different from axons in control cultures. The antiserum to pigment epithelium basal lamina induced both strong fasciculation and disorganization of the linear fiber extension, being intermediate between the two types of effects observed after antiserum addition. The results suggest that adhesive matrix molecules in basal laminae have important functions in elongation, fasciculation and in the morphology of growing axons.

1983 ◽  
Vol 61 (8) ◽  
pp. 967-979 ◽  
Author(s):  
R. J. Van Exan ◽  
B. K. Hall

The initiation of osteogenesis at 7 days in the embryonic chick mandibular mesenchyme depends on an epithelial induction in the mandible to day 4. This article reviews a series of experiments conducted to study the nature of this inductive mechanism. Transfilter tissue recombinations were used to determine whether direct tissue apposition was required for induction. Ultrastructural studies of the epithelial–mesenchymal interface were conducted to see if direct epithelial–mesenchymal cell–cell contacts occurred during the inductive stage in vivo. Epithelial cells were cultured on Millipore filters for 28 days and allowed to deposit extracellular products. These products were tested for inductive activity. Findings from these three sets of experiments were discussed with respect to the inductive mechanism. Our results indicate that the induction is not mediated by a diffusible substance and that direct apposition of the two tissues is required. The mechanism of induction, however, does not require direct epithelial–mesenchymal cell to cell contacts. This suggests that a nondiffusible component of the extracellular matrix may be involved. Epithelial extracellular products are inductively active and have the appearance of basal lamina. The active component of the extracellular product is proteinaceous, perhaps collagen, and appears to be situated in the epithelial basal lamina. The role of basal lamina in epithelial–mesenchymal interactions is discussed.


1996 ◽  
Vol 24 (4) ◽  
pp. 566S-566S
Author(s):  
J.C. Jeanny ◽  
L. Désiré ◽  
G. Raguenez ◽  
N.A. Fayein ◽  
M. Head ◽  
...  

Author(s):  
Anthony J. Godfrey

Aldehyde-fixed chick retina was embedded in a water-containing resin of glutaraldehyde and urea, without dehydration. The loss of lipids and other soluble tissue components, which is severe in routine methods involving dehydration, was thereby minimized. Osmium tetroxide post-fixation was not used, lessening the amount of protein denaturation which occurred. Ultrathin sections were stained with 1, uranyl acetate and lead citrate, 2, silicotungstic acid, or 3, osmium vapor, prior to electron microscope examination of visual cell outer segment ultrastructure, at magnifications up to 800,000.Sections stained with uranyl acetate and lead citrate (Fig. 1) showed that the individual disc membranes consisted of a central lipid core about 78Å thick in which dark-staining 40Å masses appeared to be embedded from either side.


Author(s):  
Beth Burnside

The vertebrate photoreceptor provides a drammatic example of cell polarization. Specialized to carry out phototransduction at its distal end and to synapse with retinal interneurons at its proximal end, this long slender cell has a uniquely polarized morphology which is reflected in a similarly polarized cytoskeleton. Membranes bearing photopigment are localized in the outer segment, a modified sensory cilium. Sodium pumps which maintain the dark current critical to photosensory transduction are anchored along the inner segment plasma membrane between the outer segment and the nucleus.Proximal to the nucleus is a slender axon terminating in specialized invaginating synapses with other neurons of the retina. Though photoreceptor diameter is only 3-8u, its length from the tip of the outer segment to the synapse may be as great as 200μ. This peculiar linear cell morphology poses special logistical problems and has evoked interesting solutions for numerous cell functions. For example, the outer segment membranes turn over by means of a unique mechanism in which new disks are continuously added at the proximal base of the outer segment, while effete disks are discarded at the tip and phagocytosed by the retinal pigment epithelium. Outer segment proteins are synthesized in the Golgi near the nucleus and must be transported north through the inner segment to their sites of assembly into the outer segment, while synaptic proteins must be transported south through the axon to the synapse.The role of the cytoskeleton in photoreceptor motile processes is being intensely investigated in several laboratories.


2013 ◽  
Vol 18 (2) ◽  
pp. 126-135 ◽  
Author(s):  
Frosso Motti-Stefanidi ◽  
Ann S. Masten

Academic achievement in immigrant children and adolescents is an indicator of current and future adaptive success. Since the future of immigrant youths is inextricably linked to that of the receiving society, the success of their trajectory through school becomes a high stakes issue both for the individual and society. The present article focuses on school success in immigrant children and adolescents, and the role of school engagement in accounting for individual and group differences in academic achievement from the perspective of a multilevel integrative model of immigrant youths’ adaptation ( Motti-Stefanidi, Berry, Chryssochoou, Sam, & Phinney, 2012 ). Drawing on this conceptual framework, school success is examined in developmental and acculturative context, taking into account multiple levels of analysis. Findings suggest that for both immigrant and nonimmigrant youths the relationship between school engagement and school success is bidirectional, each influencing over time the other. Evidence regarding potential moderating and mediating roles of school engagement for the academic success of immigrant youths also is evaluated.


Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.


2019 ◽  
pp. 22-29
Author(s):  
Н. В. Фрадкіна

The purpose and tasks of the work are to analyze the contemporary Ukrainian mass culture in terms of its value and humanistic components, as well as the importance of cultural studies and Ukrainian studies in educational disciplines for the formation of a holistic worldview of modern youth.Analysis of research and publications. Scientists repeatedly turned to the problems of the role of spirituality in the formation of society and its culture. This problem is highlighted in the publications by O. Losev, V. Lytvyn, D. Likhachev, S. Avierintsev, M. Zakovych, I. Stepanenko and E. Kostyshyn.Experts see the main negative impact of mass culture on the quality approach, which determines mass culture through the market, because mass culture, from our point of view, is everything that is sold and used in mass demand.One of the most interesting studies on this issue was the work by the representatives of Frankfurt School M. Horkheimer and T. Adorno «Dialectics of Enlightenment» (1947), devoted to a detailed analysis of mass culture. Propaganda at all socio-cultural levels in the form is similar in both totalitarian and democratic countries. It is connected, according to the authors, with the direction of European enlightenment. The tendency to unify people is a manifestation of the influence of mass culture, from cinema to pop. Mass culture is a phenomenon whose existence is associated with commerce (accumulation in any form – this is the main feature of education), in general, the fact that it exists in this form is related to the direction of the history of civilization.Modern mass culture, with its externally attractive and easily assimilated ideas and symbols, appealing to the trends of modern fashion, becomes a standard of prestigious consumption, does not require intense reflection, allows you to relax, distract, not teach, but entertains, preaches hedonism as the main spiritual value. And as a consequence, there are socio-cultural risks: an active rejection of other people, which leads to the formation of indifference; cruelty as a character trait; increase of violent and mercenary crime; increase in the number of alcohol and drug addicts; anti-patriotism; indifference to the values of the family and as a result of social orphanhood and prostitution.Conclusions, perspectives of research. Thus, we can conclude that modern Ukrainian education is predominantly formed by the values of mass culture. Namely, according to the «Dialectic» by Horkheimer and Adorno, «semi-enlightenment becomes an objective spirit» of our modern society.It is concluded that only high-quality education can create the opposite of the onset of mass culture and the destruction of spirituality in our society. It is proved that only by realizing the importance of cultivating disciplines in the educational process and the spiritual upbringing of the nation, through educational reforms, humanitarian knowledge will gradually return to student audiences.Formation of youth occurs under the influence of social environment, culture, education and self-education. The optimal combination of these factors determines both the process of socialization itself and how successful it will be. In this context, one can see the leading role of education and upbringing. It turns out that the main task of modern education is to spread its influence on the development of spiritual culture of the individual, which eventually becomes a solid foundation for the formation of the individual. Such a subject requires both philosophical and humanitarian approaches in further integrated interdisciplinary research, since the availability of such research will provide the theoretical foundation for truly modern educational and personal development.


2021 ◽  
pp. 104-109
Author(s):  
Chernysh O.O.

The urgency of the researched problem is connected with the growing role of mass media in modern conditions leads to change of values and transformation of identity of the person. The active growth of the role of the media, their influence on the formation and development of personality leads to the concept of “media socialization” and immutation in the media. The aim of the study is to outline the possibilities of the process of media socialization in the context of immutation in the media. The methods of our research are: analysis of pedagogical, psychological, literature, synthesis, comparison, generalization. The article analyzes the views of domestic and foreign scientists on the problem of immutation in the media and the transformation of the information space. In the context of the mass nature of the immutation of society, the concept of “media socialization” becomes relevant, which is the basis for reducing the negative impact of the media on the individual.The author identifies the lack of a thorough study of the concept of “media socialization” in modern scientific thought. Thus, media socialization is associated with the transformation of traditional means of socialization, and is to assimilate and reproduce the social experience of mankind with the help of new media.The article analyzes the essence of the concepts “media space”, “mass media” and “immutation”. The influence of mass media on the formation and development of the modern personality is described in detail.The study concluded that it is necessary to form a media culture of the individual, to establish safe and effective interaction of young people with the modern media system, the formation of media awareness, media literacy and media competence in accordance with age and individual characteristics for successful media socialization. The role of state bodies in solving the problem of media socialization of the individual was also determined. It is determined that the process of formation of media culture in youth should take place at the level of traditional institutions of socialization of the individual.The author sees the prospect of further research in a detailed analysis and study of the potential of educational institutions as an institution and a means of counteracting the mass nature of the immutation of society.Key words: immutation, media socialization, mass media, media space, information.


2014 ◽  
Vol 23 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Daniel Kopasker

Existing research has consistently shown that perceptions of the potential economic consequences of Scottish independence are vital to levels of support for constitutional change. This paper attempts to investigate the mechanism by which expectations of the economic consequences of independence are formed. A hypothesised causal micro-level mechanism is tested that relates constitutional preferences to the existing skill investments of the individual. Evidence is presented that larger skill investments are associated with a greater likelihood of perceiving economic threats from independence. Additionally, greater perceived threat results in lower support for independence. The impact of uncertainty on both positive and negative economic expectations is also examined. While uncertainty has little effect on negative expectations, it significantly reduces the likelihood of those with positive expectations supporting independence. Overall, it appears that a general economy-wide threat is most significant, and it is conjectured that this stems a lack of information on macroeconomic governance credentials.


Author(s):  
Gulbarshyn Chepurko ◽  
Valerii Pylypenko

The paper examines and compares how the major sociological theories treat axiological issues. Value-driven topics are analysed in view of their relevance to society in times of crisis, when both societal life and the very structure of society undergo dramatic change. Nowadays, social scientists around the world are also witnessing such a change due to the emergence of alternative schools of sociological thought (non-classical, interpretive, postmodern, etc.) and, subsequently, the necessity to revise the paradigms that have been existed in sociology so far. Since the above-mentioned approaches are often used to address value-related issues, building a solid theoretical framework for these studies takes on considerable significance. Furthermore, the paradigm revision has been prompted by technological advances changing all areas of people’s lives, especially social interactions. The global human community, integral in nature, is being formed, and production of human values now matters more than production of things; hence the “expansion” of value-focused perspectives in contemporary sociology. The authors give special attention to collectivities which are higher-order units of the social system. These units are described as well-organised action systems where each individual performs his/her specific role. Just as the role of an individual is distinct from that of the collectivity (because the individual and the collectivity are different as units), so too a distinction is drawn between the value and the norm — because they represent different levels of social relationships. Values are the main connecting element between the society’s cultural system and the social sphere while norms, for the most part, belong to the social system. Values serve primarily to maintain the pattern according to which the society is functioning at a given time; norms are essential to social integration. Apart from being the means of regulating social processes and relationships, norms embody the “principles” that can be applied beyond a particular social system. The authors underline that it is important for Ukrainian sociology to keep abreast of the latest developments in the field of axiology and make good use of those ideas because this is a prerequisite for its successful integration into the global sociological community.


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