scholarly journals The Behaviour of Epiblast Grafts Beneath the Primitive Streak of the Chick

1937 ◽  
Vol 14 (3) ◽  
pp. 302-318
Author(s):  
M. ABERCROMBIE
Keyword(s):  
Neural Induction ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Active Movement ◽  
Side Plate ◽  
Long Time ◽  
Epithelial Structure ◽  
Break Up ◽  
High Degree

1. Grafts consisting of area opaca ectoderm, presumptive epidermis, presumptive neural tissue, or presumptive mesoderm (axial or side-plate), were transplanted to a position immediately under the primitive streak of chick blastoderms in the primitive streak stage. 2. The grafts, though they sometimes remained as a non-neural epithelium, were usually neurally induced, contemporaneously and co-extensively with the neural induction of the host. The graft-derived neural tissue is often much thicker than the host neural tissue, and though usually forming an autonomous structure, it is frequently arranged with a high degree of symmetry relative to the host. If, however, the graft remains for a long time uninduced, lying in the host mesenchyme, it tends to break up into mesenchyme itself. 3. It is probable that all parts of the epiblast, whatever their presumptive fate, are competent to form neural tissue, provided their epithelial structure is maintained; and it is notable that this is true of presumptive mesoderm. 4. The dorso-ventral polarity of the grafts is maintained whatever their orientation in the host; but the irreversible determination of this polarity was probably not tested. The antero-posterior polarity of the grafts was without effect on their differentiation. 5. An elongation of the graft along the antero-posterior axis of the host usually occurred. It was often very marked, and generally consisted in the posterior end of the graft accompanying the host primitive node as it moved backwards. It is believed to be due to the induction of an active movement in the graft itself. 6. The host is considerably modified by the presence of the graft. In particular, the head-fold is usually suppressed. The formation of the foregut is frequently upset, but the closed foregut shows a considerable power of regulation.

Early posterior neural tissue is induced by FGF in the chick embryo

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 473-484 ◽  
Author(s):  
K.G. Storey ◽  
A. Goriely ◽  
C.M. Sargent ◽  
J.M. Brown ◽  
H.D. Burns ◽  
...  
Keyword(s):  
Chick Embryo ◽  
Cell Fate ◽  
Neural Induction ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Specific Aspect ◽  
Amphibian Embryo ◽  
Fgf Signalling ◽  
Unique Cell ◽  
Neural Cell Fate

Signals that induce neural cell fate in amniote embryos emanate from a unique cell population found at the anterior end of the primitive streak. Cells in this region express a number of fibroblast growth factors (FGFs), a group of secreted proteins implicated in the induction and patterning of neural tissue in the amphibian embryo. Here we exploit the large size and accessibility of the early chick embryo to analyse the function of FGF signalling specifically during neural induction. Our results demonstrate that extraembryonic epiblast cells previously shown to be responsive to endogenous neural-inducing signals express early posterior neural genes in response to local, physiological levels of FGF signal. This neural tissue does not express anterior neural markers or undergo neuronal differentiation and forms in the absence of axial mesoderm. Prospective mesodermal tissue is, however, induced and we present evidence for both the direct and indirect action of FGFs on prospective posterior neural tissue. These findings suggest that FGF signalling underlies a specific aspect of neural induction, the initiation of the programme that leads to the generation of the posterior central nervous system.

Chordin regulates primitive streak development and the stability of induced neural cells, but is not sufficient for neural induction in the chick embryo

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 507-519 ◽  
Author(s):  
A. Streit ◽  
K.J. Lee ◽  
I. Woo ◽  
C. Roberts ◽  
T.M. Jessell ◽  
...  
Keyword(s):  
Neural Induction ◽  
Neural Tissue ◽  
Primitive Streak ◽  
Neural Plate ◽  
Neural Cells ◽  
Morphogenetic Protein ◽  
Neural Markers ◽  
Bmp Signalling ◽  
The Stability ◽  
Area Pellucida

We have investigated the role of Bone Morphogenetic Protein 4 (BMP-4) and a BMP antagonist, chordin, in primitive streak formation and neural induction in amniote embryos. We show that both BMP-4 and chordin are expressed before primitive streak formation, and that BMP-4 expression is downregulated as the streak starts to form. When BMP-4 is misexpressed in the posterior area pellucida, primitive streak formation is inhibited. Misexpression of BMP-4 also arrests further development of Hensen's node and axial structures. In contrast, misexpression of chordin in the anterior area pellucida generates an ectopic primitive streak that expresses mesoderm and organizer markers. We also provide evidence that chordin is not sufficient to induce neural tissue in the chick. Misexpression of chordin in regions outside the future neural plate does not induce the early neural markers L5, Sox-3 or Sox-2. Furthermore, neither BMP-4 nor BMP-7 interfere with neural induction when misexpressed in the presumptive neural plate before or after primitive streak formation. However, chordin can stabilise the expression of early neural markers in cells that have already received neural inducing signals. These results suggest that the regulation of BMP signalling by chordin plays a role in primitive streak formation and that chordin is not sufficient to induce neural tissue.

scholarly journals Multicomponent Culinary Products Development for Cybersportsmen

Food Industry ◽  
2020 ◽  
Vol 5 (3) ◽  
pp. 52-60
Author(s):  
Zhanna Novikova ◽  
Anton Maksimkin ◽  
Evgeny Mukhanov
Keyword(s):  
Mathematical Modeling ◽  
Amino Acids ◽  
Negative Impact ◽  
Target Function ◽  
Food Products ◽  
Essential Amino Acids ◽  
The Body ◽  
Long Time ◽  
High Degree

Currently, eSports becomes particularly popular among young people. Computer sport induces significant loads on the human body, especially on the physiological and psychoemotional state. Tournament participants are to have a high degree of concentration and the ability to stay at a personal computer for a long time. These factors determine the need for increased energy consumption to maintain the body in a state of high activity. A man developed food products based on fundamental scientific achievements in the field of sports nutrition for athletes using special food technology. The high biological value of food products for eSports athletes makes them unique for maintaining active life in non-standard conditions and under increased loads during the preparation and conduct of competitions. To solve this problem, the authors performed mathematical modeling of the multicomponent culinary product recipe by the simplex method and automatization tools using the MS Excel software package. They chose the balance of essential amino acids as the optimization parameter. As a result of mathematical modeling, the researchers obtained eight ratios variants of the modified ingredients that meet the specified conditions. The replacement of bread wheat by the canihua is to improve the amino acids balance in proteins in the combined products. Organoleptic assessment of the culinary dish «Fish balls (steamed)», prepared according to the classic and developed recipes, allowed to conclude: the introduction of more than 34.0 % of canihua grain into the recipe has a negative impact on the product taste. The recipe optimization of a culinary product using canihua grain approved samples determination of multicomponent culinary products that corresponded to the selected parameters of the target function.

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

Tingkat Pemahaman Kompetensi Guru Pada Mahasiswa Pendidikan Geografi Sebagai Calon Guru Geografi

2020 ◽  
Vol 21 (1) ◽  
pp. 102-117
Author(s):  
Novia Zalmita ◽  
Muhajirah Muhajirah ◽  
Abdul Wahab Abdi
Keyword(s):  
Prospective Teachers ◽  
Prospective Teacher ◽  
Quantitative Description ◽  
Population Data ◽  
Geography Education ◽  
Teacher Competence ◽  
Education Department ◽  
Long Time

One that influences human resource indicators is education. The teacher is a profession as a job of academic specialization in a relatively long time in college. Understanding related to teacher competence is very important to have by a prospective teacher because it can affect the quality of performance as a professional teacher. The teacher's competence is known as pedagogic, professional, social and personality competencies. The issue in this study is how the competency of the teacher of the Department of Geography Education FKIP Unsyiah as a prospective teacher of geography? The purpose of this study was to determine the competence of teachers in the Department of Geography Education FKIP Unsyiah as prospective geography teachers. Quantitative description approach is used in this study to find answers to the issue. The population in this study were students of the Department of Geography Education FKIP Unsyiah class of 2015 and 2016 who had been declared to have passed the Micro Teaching and Magang Kependidikan 3 course totaling 50 people. Because the population is small and can be reached, the determination of the sample using total sampling techniques so that the sample in this study is the whole population. Data collection is done by distributing test questions to respondents. The data was analyzed using the descriptive statistics percentage formula. The results of the study indicate that the level of teacher competence of Geography Education Department students as prospective teachers is in the moderate category, namely as many as 22 respondents (44%). A total of 12 respondents (24%) were in the high category, 15 respondents (30%) were in the low category and 1 respondent (2%) were in the very low category.

scholarly journals Influence of the Share of Renewable Energy Sources on the Level of Energy Security in EECCA Countries

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 903 ◽  
Author(s):  
Ivan Trifonov ◽  
Dmitry Trukhan ◽  
Yury Koshlich ◽  
Valeriy Prasolov ◽  
Beata Ślusarczyk
Keyword(s):  
Renewable Energy ◽  
Energy Security ◽  
Structural Characteristics ◽  
Renewable Energy Sources ◽  
Energy Resource ◽  
Energy Sources ◽  
Structural Content ◽  
High Degree

In this study we aimed to determine the extent to which changes in the share of renewable energy sources, their structural complex, and the level of energy security in Eastern Europe, Caucasus and Central Asia (EECCA) countries in the medium- and long-term are interconnected. The study was performed through modeling and determination of the structural characteristics of energy security in the countries. The methodology of the approach to modeling was based on solving the problem of nonlinear optimization by selecting a certain scenario. For the study, the data of EECCA countries were used. The ability of EECCA countries to benefit from long-term indirect and induced advantages of the transformation period depends on the extent to which their domestic supply chains facilitate the deployment of energy transformation and induced economic activity. This study provides an opportunity to assess the degree of influence of renewable energy sources on the level of energy security of countries in the context of energy resource diversification. The high degree of influence of renewable energy sources on energy security in the EECCA countries has been proven in the implementation of the developed scenarios for its increase. Energy security is growing. At the same time, its level depends not only on an increase in the share of renewable sources but also on the structure of energy resources complex of countries, and the development of various renewable energy sources. Therefore, today the EECCA countries are forced not only to increase the share of renewable energy sources but also to attach strategic importance to the structural content of their energy complex.

scholarly journals Expression Level of Mature miR172 in Wild Type and StSUT4-Silenced Plants of Solanum tuberosum Is Sucrose-Dependent

2021 ◽  
Vol 22 (3) ◽  
pp. 1455
Author(s):  
Varsha Garg ◽  
Aleksandra Hackel ◽  
Christina Kühn
Keyword(s):  
Solanum Tuberosum ◽  
Wild Type ◽  
Potato Plants ◽  
Mature Leaves ◽  
In Vitro Plantlets ◽  
Long Time ◽  
Short Time ◽  
Cut Leaves

In potato plants, the phloem-mobile miR172 is involved in the sugar-dependent transmission of flower and tuber inducing signal transduction pathways and a clear link between solute transport and the induction of flowering and tuberization was demonstrated. The sucrose transporter StSUT4 seems to play an important role in the photoperiod-dependent triggering of both developmental processes, flowering and tuberization, and the phenotype of StSUT4-inhibited potato plants is reminiscent to miR172 overexpressing plants. The first aim of this study was the determination of the level of miR172 in sink and source leaves of StSUT4-silenced as well as StSUT4-overexpressing plants in comparison to Solanum tuberosum ssp. Andigena wild type plants. The second aim was to investigate the effect of sugars on the level of miRNA172 in whole cut leaves, as well as in whole in vitro plantlets that were supplemented with exogenous sugars. Experiments clearly show a sucrose-dependent induction of the level of mature miR172 in short time as well as long time experiments. A sucrose-dependent accumulation of miR172 was also measured in mature leaves of StSUT4-silenced plants where sucrose export is delayed and sucrose accumulates at the end of the light period.

Resistance to Outflow of Cerebrospinal Fluid Determined by Bolus Injection Technique and Constant Rate Steady State Infusion in Humans

Neurosurgery ◽  
1985 ◽  
Vol 16 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Michael Kosteljanetz
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Bolus Injection ◽  
Point Of View ◽  
Injection Technique ◽  
Communicating Hydrocephalus ◽  
Constant Rate ◽  
High Degree ◽  
Infusion Technique

Abstract Two methods for the determination of resistance to the outflow of cerebrospinal fluid, the bolus injection technique and the constant rate steady state infusion technique, were compared. Thirty-two patients with a variety of intracranial diseases (usually communicating hydrocephalus) were studied. There was a high degree of correlation between the resistance values obtained with the two methods, but values based on the bolus injection technique were systematically and statistically significantly lower than those obtained with the constant rate infusion test. From a practical point of view. both methods were found to be applicable in a clinical setting.

Sign in / Sign up

Export Citation Format

Share Document