An investigation into early placental ontogeny: allantoic attachment to the chorion is selective and developmentally regulated

Development ◽  
1995 ◽  
Vol 121 (2) ◽  
pp. 407-416 ◽  
Author(s):  
K.M. Downs ◽  
R.L. Gardner
Keyword(s):  
Developmental Regulation ◽  
Initial Attachment ◽  
Developmentally Regulated ◽  
Somite Stage ◽  
Differential Adhesion ◽  
Stage Of Development ◽  
Initial Stage ◽  
Directed Growth ◽  
Do So

Culture of postimplantation conceptuses was used in conjunction with microsurgery to investigate the timing, the mechanism and the developmental regulation of chorioallantoic fusion in the mouse. The timing of fusion was determined in both freshly recovered conceptuses and in those that had been cultured from as early as the mid-streak stage. Attachment of the allantois to the chorion was found to have occurred in most conceptuses by the 6-somite stage, irrespective of whether they had been cultured. In investigating the mechanism of fusion, we wished to determine whether it depended on directed growth of the allantoic bud or on its differential adhesion to the chorion. Microsurgery was used to transplant allantoic tissue into the exocoelomic cavity of conceptuses from which the resident allantois had been removed. In synchronous grafting experiments, transplanted allantoises typically attached to the chorion despite loss of their connection with the hindgut region of the fetus. Hence selective attachment of the allantois to the chorion clearly cannot depend simply on its directed growth. While the transplanted allantoic tissue attached to the chorion selectively, it did not attach to it precociously, despite being favourably positioned to do so. These findings argue that the initial attachment of the allantois to the chorion depends on a selective adhesive mechanism that is developmentally regulated. Further grafting experiments in which donor conceptuses were either more or less advanced than hosts revealed that attachment of the allantois to the chorion depends primarily on the stage of the allantois rather than on the stage of the chorion. Collectively, these findings support the hypothesis that the initial stage of chorioallantoic fusion depends on selective adhesion between regionally differentiated mesodermal surfaces which is governed principally by the stage of development of the allantois.

Expression of microinjected hsp 70/CAT and hsp 30/CAT chimeric genes in developing Xenopus laevis embryos

Development ◽  
1989 ◽  
Vol 106 (2) ◽  
pp. 271-281
Author(s):  
P.H. Krone ◽  
J.J. Heikkila
Keyword(s):  
Xenopus Laevis ◽  
Fusion Gene ◽  
Developmental Regulation ◽  
Hsp 70 ◽  
Inhibitory System ◽  
Developmentally Regulated ◽  
Promoter Sequences ◽  
Chimeric Genes ◽  
Stage Of Development ◽  
Tailbud Stage

The expression of microinjected chimeric genes containing Drosophila hsp 70 and Xenopus hsp 70 and hsp 30 promoters linked to the reporter gene coding for bacterial chloramphenicol acetyltransferase (CAT) was examined during early development of Xenopus laevis. Heat-inducible expression of fusion genes containing either the Drosophila hsp 70 promoter (1100 bp) or the Xenopus hsp 70 promoter (750 bp) was first detectable after the midblastula stage of development. This coincides with the embryonic stage at which the endogenous hsp 70 gene is first heat-inducible. A Xenopus hsp 30/CAT fusion gene containing 350 bp of promoter sequences was also heat-inducible after the midblastula stage unlike the endogenous hsp 30 genes which were not heat-inducible until the early tailbud stage (stage 23–24). Sequences that are present within either the coding or 3′ region of the hsp 30 clone do not cause the microinjected hsp 30 gene to be developmentally regulated in a normal manner. Additionally, microinjected hsp 30 gene sequences have no effect on the developmental regulation of endogenous hsp 30 genes which continue to be activated at the tailbud stage of development. Our data suggest, that an inhibitory system, which may control the expression of the endogenous hsp 30 gene during development, does not regulate the expression of the injected hsp 30 gene.

scholarly journals Identification and developmental regulation of a neuron-specific subunit of cytoplasmic dynein.

1996 ◽  
Vol 7 (2) ◽  
pp. 331-343 ◽  
Author(s):  
K K Pfister ◽  
M W Salata ◽  
J F Dillman ◽  
E Torre ◽  
R J Lye
Keyword(s):  
Axonal Transport ◽  
Developmental Regulation ◽  
Cytoplasmic Dynein ◽  
Retrograde Axonal Transport ◽  
Protein Isoforms ◽  
Cultured Neurons ◽  
Developmentally Regulated ◽  
Time Period ◽  
Intermediate Chains

Cytoplasmic dynein is the microtubule minus-end-directed motor for the retrograde axonal transport of membranous organelles. Because of its similarity to the intermediate chains of flagellar dynein, the 74-kDa intermediate chain (IC74) subunit of dynein is thought to be involved in binding dynein to its membranous organelle cargo. Previously, we identified six isoforms of the IC74 cytoplasmic dynein subunit in the brain. We further demonstrated that cultured glia and neurons expressed different dynein IC74 isoforms and phospho-isoforms. Two isoforms were observed when dynein from glia was analyzed. When dynein from cultured neurons was analyzed, six IC74 isoforms were observed, although the relative amounts of the dynein isoforms from cultured neurons differed from those found in dynein from brain. To better understand the role of the neuronal IC74 isoforms and identify neuron-specific IC74 dynein subunits, the expression of the IC74 protein isoforms and mRNAs of various tissues were compared. As a result of this comparison, the identity of each of the isoform spots observed on two-dimensional gels was correlated with the products of each of the IC74 mRNAs. We also found that between the fifteenth day of gestation (E15) and the fifth day after birth (P5), the relative expression of the IC74 protein isoforms changes, demonstrating that the expression of IC74 isoforms is developmentally regulated in brain. During this time period, there is relatively little change in the abundance of the various IC74 mRNAs. The E15 to P5 time period is one of rapid process extension and initial pattern formation in the rat brain. This result indicates that the changes in neuronal IC74 isoforms coincide with neuronal differentiation, in particular the extension of processes. This suggests a role for the neuronal IC74 isoforms in the establishment or regulation of retrograde axonal transport.

scholarly journals Biochemical changes in cultured foetal rat liver explants

1975 ◽  
Vol 150 (2) ◽  
pp. 269-273 ◽  
Author(s):  
P C MacDonnel ◽  
E Ryder ◽  
J A Delvalle ◽  
O Greengard
Keyword(s):  
Soluble Protein ◽  
Cell Damage ◽  
Tyrosine Aminotransferase ◽  
Culture Conditions ◽  
Total Soluble Protein ◽  
Mitochondrial Enzymes ◽  
Stage Of Development ◽  
Foetal Rat ◽  
Total Soluble Protein Content ◽  
Do So

Liver explants from 20-day-old foetuses cultured for 48h in the absence of serum released 70% of their total soluble protein content into the medium. In the presence of serum this loss still amounted to 60%. The concentration of total particulate protein remained unchanged but there was some translocation of mitochondrial enzymes to the cytosol, and enzymes expected to increase during this stage of development failed to do so. The addition of cortisol plus glucagon (to serum-containing media) did not decrease the loss of total soluble protein from the explants but induced considerable tyrosine aminotransferase activity which was not released into the medium. The observations suggest that under the usual culture conditions a minority of the cells retain their functional integrity. The extent of deterioration, not reflected in histologically visible necrosis or cell damage, can be conveniently monitored by the malate dehydrogenase activity released to the medium.

scholarly journals Rat lung lectin synthesis, degradation and activation. Developmental regulation and modulation by dexamethasone

1987 ◽  
Vol 245 (3) ◽  
pp. 683-690 ◽  
Author(s):  
L B Clerch ◽  
P L Whitney ◽  
D Massaro
Keyword(s):  
Binding Protein ◽  
Developmental Regulation ◽  
Fold Increase ◽  
Rat Lung ◽  
Absolute Rate ◽  
Lectin Activity ◽  
Developmentally Regulated ◽  
Rat Pups ◽  
The Absolute

Soluble lectins are widely distributed cell-agglutinating proteins. Their activity is developmentally regulated in several tissues, including the lung, but virtually nothing is known about the mechanisms of the developmental regulation or the turnover of these proteins. We studied mechanisms that might be responsible for the developmentally regulated changes in the activity of a lectin (beta-galactoside-binding protein) found in the lung, and determined if its activity or turnover could be modulated by treatment of rat pups with a glucocorticosteroid hormone (dexamethasone). Our studies on the activity and turnover of the lectin indicated that the peak of lectin activity (units/mg of protein) that occurred at age 12 days appeared to be brought about by two means: an increase in the activity of the lectin molecule itself (units/micrograms of lectin) that occurred at age 8 days, and 1.5-fold increase in the absolute rate of lectin synthesis at age 11 days. The decline in lectin activity was associated with a decrease in its rate of synthesis, return to the baseline extent of activation, and an increased rate of degradation. Treatment of rat pups with dexamethasone diminished the peak of lectin activity (units/mg of protein) by about 25%. This effect of dexamethasone was due, at least in part, to the complete prevention of activation of the lectin molecule (units/micrograms of lectin) and a premature increase in the rate of lectin degradation. Perhaps the normal fall in lectin activity after age 11 days is caused by mechanisms induced by the increase in serum corticosteroid that occurs at that age.

scholarly journals Artificial Intelligence to Improve the Business Efficiency and Effectiveness for Enterprises in Kazakhstan

2021 ◽  
pp. 34-41
Author(s):  
Mohamed Hamada ◽  
Daniya Temirkhanova ◽  
Diana Serikbay ◽  
Sanzhar Salybekov ◽  
Saltanat Omarbek
Keyword(s):  
Artificial Intelligence ◽  
Legal Framework ◽  
Legal Aspects ◽  
Stage Of Development ◽  
Initial Stage ◽  
Efficiency And Effectiveness ◽  
Business Efficiency ◽  
Big Picture ◽  
Data Extracting ◽  
Goals And Objectives

The main objective of the research is identifying the effectiveness of artificial intelligence in the business sphere of Kazakhstan. The urgency of this problem is due to the fact that the Kazakhstani market for artificial intelligence is at the initial stage of development. The main obstacle to the introduction of artificial intelligence is the unpreparedness of managers of small and medium-sized businesses for the application of artificial intelligence technologies and, of course, the high cost of their implementation. In the study, we proceeded from the key thesis that business in Kazakhstan is striving for digital transformation. We set a goal to determine the attitude and degree of readiness of Kazakhstani business to the implementation and practical application of artificial intelligence, to describe the cases of using artificial intelligence by Kazakhstani business, to identify the main questions that arise in business at this stage, to study the legal aspects of using artificial intelligence in business and to present the big picture compliance / inconsistency of the existing legal framework with the goals and objectives of the development of artificial intelligence, provide recommendations for eliminatinge xisting barriers and stimulating businesses to implement the technology. Within the framework of this study, the concept of artificial intelligence is defined in its broadest sense - as a set of technologies for processing various types of data and information, in particular those capable of interpreting such data, extracting knowledge and using it to achieve certain goals.

scholarly journals Initial stage of development and migratory behavior of Toxocara canis larvae in BALB/c mouse experimental model

2008 ◽  
Vol 7 (2) ◽  
pp. 444-450 ◽  
Author(s):  
M.L. Camparoto ◽  
B. Fulan ◽  
C.M. Colli ◽  
M.L. Paludo ◽  
A.L. Falavigna-Guilherme ◽  
...  
Keyword(s):  
Experimental Model ◽  
Toxocara Canis ◽  
Migratory Behavior ◽  
Stage Of Development ◽  
Initial Stage

scholarly journals Study on the development of nanotechnology in advanced countries and in Brazil

2009 ◽  
Vol 45 (2) ◽  
pp. 189-200 ◽  
Author(s):  
Carolina Fracalossi Rediguieri
Keyword(s):  
Reference Lists ◽  
Scientific Literature ◽  
Developed Countries ◽  
Public And Private ◽  
Stage Of Development ◽  
Research Institutes ◽  
Initial Stage ◽  
Private Investments ◽  
The World ◽  
The Developed Countries

The study shows how nanotechnology evolves in developed countries and Brazil, raising aspects of private and governmental initiatives. The investigation was based in scientific literature, electronic articles and conference reports. Several sources of literature were used, including electronic databases and reference lists. By this study, it was observed that, although nanotechnology is in initial stage of development all over the world, the developed countries have had growing public and private investments in the area each year. In those countries, there is a concern toward both, the formation of specialists in nanotechnology and the transference of technology developed in universities and research institutes to industry. In Brazil, the study showed that despite the growing concern of investigators, national research centers and financial centers toward the development of the nanotechnology, there is still a need for more investment and formation of area specialists.

Radiographic study of the initial stage of development of an underground explosion in sandy soil

1970 ◽  
Vol 6 (3) ◽  
pp. 320-326 ◽  
Author(s):  
L. V. Al'tshuler ◽  
A. V. Balabanov ◽  
V. A. Batalov ◽  
V. A. Rodionov ◽  
D. M. Tarasov
Keyword(s):  
Sandy Soil ◽  
Underground Explosion ◽  
Radiographic Study ◽  
Stage Of Development ◽  
Initial Stage
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