Changes in collagen ultrastructure, macroscopic properties and chemical composition of chick embryo cartilage induced by administration of a β-D-xyloside

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 179-202
Author(s):  
J. T. Hjelle ◽  
K. D. Gibson
Keyword(s):  
Spatial Distribution ◽  
Chondroitin Sulfate ◽  
Drug Administration ◽  
Physiological Role ◽  
Ultrastructural Level ◽  
Interstitial Space ◽  
Collagen Fibrils ◽  
Embryonic Cartilage ◽  
Almost All

Nine-day chick embryos were injected with a β-xyloside and their sternal cartilage was examined 3 days and a week later. Sterna from 16-day embryos showed a reduction in size as compared to controls, with little or no change in the fraction of extracellular space, and a significant decrease in tensile strength. At the ultrastructural level, collagen fibrils in control sterna were dispersed evenly in the interstitial space, with few contacts between adjacent fibrils. In sterna from treated embryos, almost all collagen fibrils were aggregated into clumps and arrays throughout the interstitial space, with fibril-free areas in between. No abnormalities could be detected in the morphology of individual fibrils or in the ultrastructure of the chondrocytes. The changes in spatial distribution of collagen were fully evident 3 days after drug administration. The hydroxyproline/DNA ratio was the same in control and treated sterna, and no changewas observed in the type of collagen. The uronic acid/DNA ratio was reduced by 14% 3 days after drug administration and by 40% after a week. The degree of sulfation of chondroitin sulfate was reduced from 80% in control sterna to 40% in treated sterna; almost allof this chondroitin sulfate was attached to peptide and the sedimentation pattern of the proteoglycan resembled that of normal cartilage proteoglycan. The function of chondroitin sulfate in embryonic cartilage is discussed in terms of our results and others. It is suggested that a major physiological role of the proteoglycan is to control the spatial distribution of collagen fibrils as they assemble to form a cross-linked gel.

Chromosomal bacterial type II toxin–antitoxin systems

2012 ◽  
Vol 58 (5) ◽  
pp. 553-562 ◽  
Author(s):  
Mohammad Adnan Syed ◽  
Céline M. Lévesque
Keyword(s):  
De Novo ◽  
Physiological Role ◽  
Type I ◽  
Type Ii ◽  
Translation Process ◽  
Bacterial Physiology ◽  
The Subject ◽  
Almost All ◽  
Bacterial Type

Most prokaryotic chromosomes contain a number of toxin–antitoxin (TA) modules consisting of a pair of genes that encode 2 components, a stable toxin and its cognate labile antitoxin. TA systems are also known as addiction modules, since the cells become “addicted” to the short-lived antitoxin product (the unstable antitoxin is degraded faster than the more stable toxin) because its de novo synthesis is essential for their survival. While toxins are always proteins, antitoxins are either RNAs (type I, type III) or proteins (type II). Type II TA systems are widely distributed throughout the chromosomes of almost all free-living bacteria and archaea. The vast majority of type II toxins are mRNA-specific endonucleases arresting cell growth through the mechanism of RNA cleavage, thus preventing the translation process. The physiological role of chromosomal type II TA systems still remains the subject of debate. This review describes the currently known type II toxins and their characteristics. The different hypotheses that have been proposed to explain their role in bacterial physiology are also discussed.

Scanning electron microscopic study of collagen fibrillogenesis and extracellular compartmentalization in the chick embryo tendon

1986 ◽  
Vol 44 ◽  
pp. 208-209
Author(s):  
Grace C.H. Yang
Keyword(s):  
Chick Embryo ◽  
Extracellular Space ◽  
Fibroblast Cell ◽  
Collagen Fibrils ◽  
Electron Microscopic ◽  
Voltage Electron ◽  
Scanning Electron Microscopic Study ◽  
Microscopic Studies ◽  
And Function

The size and organization of collagen fibrils in the extracellular matrix is an important determinant of tissue structure and function. The synthesis and deposition of collagen involves multiple steps which begin within the cell and continue in the extracellular space. High-voltage electron microscopic studies of the chick embryo cornea and tendon suggested that the extracellular space is compartmentalized by the fibroblasts for the regulation of collagen fibril, bundle, and tissue specific macroaggregate formation. The purpose of this study is to gather direct evidence regarding the association of the fibroblast cell surface with newly formed collagen fibrils, and to define the role of the fibroblast in the control and the precise positioning of collagen fibrils, bundles, and macroaggregates during chick tendon development.

Michael Kelly, Hilary Footitt, Myriam Salama-Carr (eds.): The Palgrave Handbook of Languages and Conflict

2020 ◽  
Vol 55 (2) ◽  
Author(s):  
Ľubomír Zvada
Keyword(s):  
International Relations ◽  
Foreign Languages ◽  
Military Operations ◽  
Sources Of Information ◽  
War And Peace ◽  
Interdisciplinary Field ◽  
Speakers Of Other Languages ◽  
War And Conflict ◽  
Almost All

This Handbook maps the contours of an exciting and burgeoning interdisciplinary field concerned with the role of language and languages in situations of conflict. It explores conceptual approaches, sources of information that are available, and the institutions and actors that mediate language encounters. It examines case studies of the role that languages have played in specific conflicts, from colonial times through to the Middle East and Africa today. The contributors provide vibrant evidence to challenge the monolingual assumptions that have affected traditional views of war and conflict. They show that languages are woven into every aspect of the making of war and peace, and demonstrate how language shapes public policy and military strategy, setting frameworks and expectations. The Handbook's 22 chapters powerfully illustrate how the encounter between languages is integral to almost all conflicts, to every phase of military operations and to the lived experiences of those on the ground, who meet, work and fight with speakers of other languages. This comprehensive work will appeal to scholars from across the disciplines of linguistics, translation studies, history, and international relations; and provide fresh insights for a broad range of practitioners interested in understanding the role and implications of foreign languages in war.

ON EVALUATION OF THE ROLE OF THERMAL AND WIND FACTORS FOR A PHYSICAL MODEL OF THE WORLD OCEAN GENERAL CIRCULATION SYSTEM

2019 ◽  
Vol 47 (3) ◽  
pp. 80-91
Author(s):  
V. G. Neiman
Keyword(s):  
Physical Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
World Ocean ◽  
Circulation System ◽  
The Public ◽  
The World ◽  
Almost All ◽  
Conceptual Foundations

The main content of the work consists of certain systematization and addition of longexisting, but eventually deformed and partly lost qualitative ideas about the role of thermal and wind factors that determine the physical mechanism of the World Ocean’s General Circulation System (OGCS). It is noted that the conceptual foundations of the theory of the OGCS in one form or another are contained in the works of many well-known hydrophysicists of the last century, but the aggregate, logically coherent description of the key factors determining the physical model of the OGCS in the public literature is not so easy to find. An attempt is made to clarify and concretize some general ideas about the two key blocks that form the basis of an adequate physical model of the system of oceanic water masses motion in a climatic scale. Attention is drawn to the fact that when analyzing the OGCS it is necessary to take into account not only immediate but also indirect effects of thermal and wind factors on the ocean surface. In conclusion, it is noted that, in the end, by the uneven flow of heat to the surface of the ocean can be explained the nature of both external and almost all internal factors, in one way or another contributing to the excitation of the general, or climatic, ocean circulation.

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow

Methyl mercury in the dutch rhine delta

1994 ◽  
Vol 30 (10) ◽  
pp. 213-219 ◽  
Author(s):  
Hendrik Pieters ◽  
Victor Geuke
Keyword(s):  
Suspended Matter ◽  
Methyl Mercury ◽  
Mercury Contamination ◽  
Benthic Organisms ◽  
Considerable Decrease ◽  
Continuous Sedimentation ◽  
Highly Correlated ◽  
High Level ◽  
Almost All

Samples of yellow eel from various locations in the Dutch Rhine area have been analyzed for trend monitoring of mercury since 1977. In the western Rhine delta mercury levels in eels have hardly changed since the seventies, whereas in the eastern part of the Dutch Rhine area a considerable decrease of mercury concentrations in eel has occurred. Because of continuous sedimentation of contaminated suspended matter transported from upstream regions, accumulation rates and concentrations of mercury in eel in the western Rhine delta remained at a relatively high level. Analyses of methyl mercury in biota have been performed to elucidate the role of methyl mercury in the mercury contamination of the Dutch Rhine ecosystem. Low percentages of methyl mercury were observed in zooplankton (3 to 35%). In benthic organisms (mussels) percentages of methyl mercury ranged from 30 to 57%, while in fish species and liver of aquatic top predator birds almost all the mercury was present in the form of methyl mercury (> 80%). During the period 1970-1990 mercury concentrations of suspended matter in the eastern Rhine delta have drastically decreased. These concentrations seemed to be highly correlated with mercury concentrations of eel (R = 0.84). The consequences of this relation are discussed.

The Renal Outer Medullary Potassium Channel (ROMK): An Intriguing Pharmacological Target for an Innovative Class of Diuretic Drugs

2018 ◽  
Vol 25 (23) ◽  
pp. 2627-2636 ◽  
Author(s):  
Vincenzo Calderone ◽  
Alma Martelli ◽  
Eugenia Piragine ◽  
Valentina Citi ◽  
Lara Testai ◽  
...  
Keyword(s):  
Physiological Role ◽  
Clinical Use ◽  
Diuretic Activity ◽  
First Line ◽  
Potassium Homeostasis ◽  
Diuretic Drugs ◽  
Pharmacological Target ◽  
Diuretic Agents ◽  
Effective Drugs

In the last four decades, the several classes of diuretics, currently available for clinical use, have been the first line option for the therapy of widespread cardiovascular and non-cardiovascular diseases. Diuretic drugs generally exhibit an overall favourable risk/benefit balance. However, they are not devoid of side effects. In particular, all the classes of diuretics cause alteration of potassium homeostasis. <p> In recent years, understanding of the physiological role of the renal outer medullary potassium (ROMK) channels, has shown an intriguing pharmacological target for developing an innovative class of diuretic agents: the ROMK inhibitors. This novel class is expected to promote diuretic activity comparable to (or even higher than) that provided by the most effective drugs used in clinics (such as furosemide), with limited effects on potassium homeostasis. <p> In this review, the physio-pharmacological roles of ROMK channels in the renal function are reported, along with the most representative molecules which have been currently developed as ROMK inhibitors.

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