Induction of deep layer cortical neurons in vitro

Development ◽  
1997 ◽  
Vol 124 (4) ◽  
pp. 915-923 ◽  
Author(s):  
A.P. Bohner ◽  
R.M. Akers ◽  
S.K. McConnell
Keyword(s):  
Cortical Neurons ◽  
Short Range ◽  
Deep Layer ◽  
Ventricular Zone ◽  
Cell Contact ◽  
Low Density ◽  
Environmental Signals ◽  
Multipotent Progenitors ◽  
Short Time

Transplantation studies suggest that the laminar fates of cerebral cortical neurons are determined by environmental signals encountered just before mitosis. In ferret, E29 progenitor cells normally produce neurons of layers 5 and 6. When transplanted during S-phase into an older ventricular zone, E29 progenitors produce neurons that change their fates and migrate to layer 2/3; however, cells transplanted later in the cell cycle migrate to their normal deep-layer positions even in an older environment (McConnell and Kaznowski, 1991). Here we utilize three culture systems to investigate the nature of the environmental signals involved in laminar specification. E29 cells were first cultured at low density to ascertain whether cell contact and/or short-range cues are required for deep layer specification. Neurons transplanted after a short time in low-density culture failed to adopt their normal fates and migrated instead to the upper layers. When crude cell contacts were restored by pelleting E29 cells together, most transplanted neurons cells became specified to their normal deep layer fates. Finally, E29 cells were transplanted after being cultured in explants that maintained the architecture of the cerebral wall. Explants allowed normal deep layer specification to occur, as transplanted cells migrated to layers 5 and 6. These results suggest that short-range cues induce multipotent progenitors to produce deep layer neurons.

scholarly journals The V Antigen of Yersinia pestisRegulates Yop Vectorial Targeting as Well as Yop Secretion through Effects on YopB and LcrG

1998 ◽  
Vol 180 (13) ◽  
pp. 3410-3420 ◽  
Author(s):  
Matthew L. Nilles ◽  
Kenneth A. Fields ◽  
Susan C. Straley
Keyword(s):  
Hela Cells ◽  
Regulatory Protein ◽  
Eukaryotic Cell ◽  
Negative Regulator ◽  
Eukaryotic Cells ◽  
Cell Contact ◽  
Environmental Signals ◽  
Culture Model ◽  
Tissue Culture Model

ABSTRACT Yersinia pestis expresses a set of secreted proteins called Yops and the bifunctional LcrV, which has both regulatory and antihost functions. Yops and LcrV expression and the activity of the type III mechanism for their secretion are coordinately regulated by environmental signals such as Ca2+ concentration and eukaryotic cell contact. In vitro, Yops and LcrV are secreted into the culture medium in the absence of Ca2+ as part of the low-Ca2+ response (LCR). The LCR is induced in a tissue culture model by contact with eukaryotic cells that results in Yop translocation into cells and subsequent cytotoxicity. The secretion mechanism is believed to indirectly regulate expression oflcrV and yop operons by controlling the intracellular concentration of a secreted negative regulator. LcrG, a secretion-regulatory protein, is thought to block secretion of Yops and LcrV, possibly at the inner face of the inner membrane. A recent model proposes that when the LCR is induced, the increased expression of LcrV yields an excess of LcrV relative to LcrG, and this is sufficient for LcrV to bind LcrG and unblock secretion. To test this LcrG titration model, LcrG and LcrV were expressed alone or together in a newly constructed lcrG deletion strain, a ΔlcrG2mutant, of Y. pestis that produces low levels of LcrV and constitutively expresses and secretes Yops. Overexpression of LcrG in this mutant background was able to block secretion and depress expression of Yops in the presence of Ca2+ and to dramatically decrease Yop expression and secretion in growth medium lacking Ca2+. Overexpression of both LcrG and LcrV in the ΔlcrG2 strain restored wild-type levels of Yop expression and Ca2+ control of Yop secretion. Surprisingly, when HeLa cells were infected with the ΔlcrG2 strain, no cytotoxicity was apparent and translocation of Yops was abolished. This correlated with an altered distribution of YopB as measured by accessibility to trypsin. These effects were not due to the absence of LcrG, because they were alleviated by restoration of LcrV expression and secretion alone. LcrV itself was found to enter HeLa cells in a nonpolarized manner. These studies supported the LcrG titration model of LcrV’s regulatory effect at the level of Yop secretion and revealed a further role of LcrV in the deployment of YopB, which in turn is essential for the vectorial translocation of Yops into eukaryotic cells.

scholarly journals Coupling of proadipocyte growth arrest and differentiation. I. Induction by heparinized medium containing human plasma.

1982 ◽  
Vol 94 (2) ◽  
pp. 394-399 ◽  
Author(s):  
B R Krawisz ◽  
R E Scott
Keyword(s):  
Human Plasma ◽  
Adipocyte Differentiation ◽  
Growth Arrest ◽  
Culture Conditions ◽  
Cell Contact ◽  
Low Density ◽  
Prolonged Culture ◽  
Extensive Cell ◽  
High Concentrations

The differentiation of proadipocytes in vitro typically required prolonged culture of cells as a high density in high concentrations of serum and added hormones. With such culture conditions it is difficult to design experiments to determine the mechanisms that control the differentiation process. We now describe the rapid and parasynchronous growth arrest and differentiation of low density murine proadipocytes in heparinized medium containing only human plasma. When low density cells are cultured under these conditions, growth arrest at a distinct state in the G1 phase of the cell cycle occurs within 2 d and the differentiation of 80-100% of the cell population occurs within 4 d thereafter. The factors in human plasma which promote growth arrest and differentiation are heat labile and can be separated by barium adsorption. In the following paper we have used these methods to show that there are five separate phases which regulate the coupling of proadipocyte growth arrest and differentiation. The data reported in this paper establish that: (a) high cell density and extensive cell-to-cell contact are not required for adipocyte differentiation, (b) prolonged culture is not required for adipocyte differentiation, and (c) high concentrations of serum and/or added hormones are not required for adipocyte differentiation.

Semaphorins act as attractive and repulsive guidance signals during the development of cortical projections

Development ◽  
1998 ◽  
Vol 125 (24) ◽  
pp. 5043-5053 ◽  
Author(s):  
D. Bagnard ◽  
M. Lohrum ◽  
D. Uziel ◽  
A.W. Puschel ◽  
J. Bolz
Keyword(s):  
Cortical Neurons ◽  
Specific Binding ◽  
Ventricular Zone ◽  
Growth Cones ◽  
Axonal Guidance ◽  
Class Iii ◽  
Neuropilin 1 ◽  
Essential Components

Members of the semaphorin family have been implicated in mediating axonal guidance in the nervous system by their ability to collapse growth cones and to function as chemorepellents. The present findings show that recombinant Semaphorin D has similar effects on cortical axons and, in addition, inhibits axonal branching. In contrast, semaphorin E acts as an attractive guidance signal for cortical axons. Attractive effects were only observed when growth cones encountered increasing concentrations or a patterned distribution of Semaphorin E, but not when they are exposed to uniform concentrations of this molecule. Specific binding sites for Semaphorin D and Semaphorin E were present on cortical fibers both in vitro and in vivo at the time when corticofugal projections are established. In situ hybridization analysis revealed that the population of cortical neurons used in our experiments express neuropilin-1 and neuropilin-2, which are essential components of receptors for the class III semaphorins. Moreover, semD mRNA was detected in the ventricular zone of the neocortex whereas semE mRNA was restricted to the subventricular zone. Taken together, these results indicate that semaphorins are bifunctional molecules whose effects depend on their spatial distribution. The coordinated expression of different semaphorins, together with their specific activities on cortical axons, suggests that multiple guidance signals contribute to the formation of precise corticofugal pathways.

Observations on the in vitro Effects of Chylomicra, Low-Density Lipoproteins and Phospholipids on Human Plasma Euglobulin Lysis

1963 ◽  
Vol 09 (01) ◽  
pp. 164-174 ◽  
Author(s):  
Albert R Pappenhagen ◽  
J. L Koppel ◽  
John H Olwin
Keyword(s):  
Human Plasma ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Inositol ◽  
Plasma Lipoproteins ◽  
Low Density ◽  
Inhibitory Effects ◽  
Soybean Phospholipids ◽  
In Vitro Effects ◽  
Complete Precipitation

SummaryData have been presented on the in vitro effects of human chylomicra, low-density human plasma lipoproteins, and partially purified preparations of various phospholipids on human plasma euglobulin lysis. Euglobulin lysis was found to be accelerated by preparations of mixed soybean phospholipids (aso-lectin), cephalin, phosphatidyl inositol, phophatidyl serine and phosphatidyl ethanolamine. In contrast, it was found to be inhibited by preparations of human chylomicra, low-density human plasma liproproteins and lecithin. Inhibition of euglobulin lysis produced by any of these three agents could be diminished or completely overcome by the simultaneous presence of suitable levels of any one of the accelerating agents. In all cases studied, both inhibitory and accelerating effects were observed to be concentration-dependent. Evidence has been obtained to suggest that in the case of the accelerating agents the observed increased rate of euglobulin lysis is not a direct effect on lysis itself, but rather is due to more complete precipitation of plasminogen in the presence of these substances. On the other hand, it appears that the inhibitory effects observed are not related to the extent of plasminogen precipitation, but are actually true inhibitions of euglobulin lysis. The possible clinical significance of some of these observations has been briefly discussed.

Nonenzymatic glycosylation of low density lipoproteins in vitro. Effects on cell-interactive properties

Diabetes ◽  
1981 ◽  
Vol 30 (10) ◽  
pp. 875-878 ◽  
Author(s):  
B. Gonen ◽  
J. Baenziger ◽  
G. Schonfeld ◽  
D. Jacobson ◽  
P. Farrar
Keyword(s):  
Low Density Lipoproteins ◽  
Low Density ◽  
Nonenzymatic Glycosylation ◽  
In Vitro Effects

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

ECONOMIC PERSPECTIVES OF BIOTECHNOLOGIES USING IN ANIMAL FARMING

1970 ◽  
pp. 57-60
Author(s):  
I. F. Gorlov ◽  
A. A. Mosolov ◽  
G. V. Komlatskiy ◽  
M. A. Nesterenko ◽  
K. D. Nimbona ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Economic Effect ◽  
Dairy Herd ◽  
State Level ◽  
Modern Level ◽  
Economic Perspectives ◽  
The Cost ◽  
Short Time

The article presents materials on the study of the possibility of reproduction and increase in the herd of highly productive cows through the use of embryo transplantation technology. The classical (in vivo) and more modern, developing (in vitro) methods of embryotransfer, their positive and negative sides are considered in detail. The possibility of accelerating the breeding process by using the method of transplantation, in which from one cow can be obtained from 10 to 100 calves, which will allow for 4-5 years, almost any herd (of any size and breed) with the help of biotechnology to turn into a cattle-breeding enterprise of the most modern level. At the same time, heifers obtained from unproductive cows can be used as "surrogate" mothers who are transplanted with the best donor embryos, which allows to obtain a full-fledged offspring adapted to local environmental conditions. A detailed scheme of obtaining, evaluation, storage, as well as the cost and economic effect of embryo transplantation was calculated, the market was evaluated, the required annual volume of transplants and the number of donor cows for large livestock farms were determined. As a positive example of "Scientific-production enterprise "Centre of biotechnology and embryo transfer" in 2014, implemented a project for accelerated replacement and genetic improvement of the dairy herd, engraftment averaged 57-69%, and the economic effect of the enterprise from getting a single animal by the method of embryo transfer, compared with imports of similar close in quality, ranged from 60 to 100 thousand rubles on his head. It is shown that it is necessary to organize at the state level a developed service for embryo transplantation to reduce the cost of embryo transfer and the possibility of creating in a short time in the country's own highly productive breeding nucleus of dairy and beef cattle, which will reduce, and in the future completely eliminate, import dependence on cattle products.

scholarly journals Differential impact of Holder and High Temperature Short Time pasteurization on the dynamic in vitro digestion of human milk in a preterm newborn model

2020 ◽  
Vol 328 ◽  
pp. 127126 ◽  
Author(s):  
Stefano Nebbia ◽  
Marzia Giribaldi ◽  
Laura Cavallarin ◽  
Enrico Bertino ◽  
Alessandra Coscia ◽  
...  
Keyword(s):  
High Temperature ◽  
Human Milk ◽  
In Vitro Digestion ◽  
Preterm Newborn ◽  
Differential Impact ◽  
High Temperature Short Time ◽  
Short Time

scholarly journals Epothilone D alters normal growth, viability and microtubule dependent intracellular functions of cortical neurons in vitro

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. A. Clark ◽  
J. A. Chuckowree ◽  
M. S. Dyer ◽  
T. C. Dickson ◽  
C. A. Blizzard
Keyword(s):  
Cortical Neurons ◽  
Normal Growth ◽  
Epothilone D
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