Glutamine synthetase activity in vivo and in primary cell cultures of rat hypothalamus

ABSTRACT The physiological regulation of glutamine synthetase (GS; EC6.3.1.2 ) in the axenic Prochlorococcus sp. strain PCC 9511 was studied. GS activity and antigen concentration were measured using the transferase and biosynthetic assays and the electroimmunoassay, respectively. GS activity decreased when cells were subjected to nitrogen starvation or cultured with oxidized nitrogen sources, which proved to be nonusable forProchlorococcus growth. The GS activity in cultures subjected to long-term phosphorus starvation was lower than that in equivalent nitrogen-starved cultures. Azaserine, an inhibitor of glutamate synthase, provoked an increase in enzymatic activity, suggesting that glutamine is not involved in GS regulation. Darkness did not affect GS activity significantly, while the addition of diuron provoked GS inactivation. GS protein determination showed that azaserine induces an increase in the concentration of the enzyme. The unusual responses to darkness and nitrogen starvation could reflect adaptation mechanisms of Prochlorococcus for coping with a light- and nutrient-limited environment.

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Encapsulation of glutamine synthetase in mouse erythrocytes: a new procedure for ammonia detoxification

Biochemistry and Cell Biology ◽

10.1139/o08-134 ◽

2008 ◽

Vol 86 (6) ◽

pp. 469-476 ◽

Cited By ~ 19

Author(s):

Elena A. Kosenko ◽

Natalia I. Venediktova ◽

Andrey A. Kudryavtsev ◽

Fazoil I. Ataullakhanov ◽

Yury G. Kaminsky ◽

...

Keyword(s):

Energy Metabolism ◽

Glutamine Synthetase ◽

Synthetase Activity ◽

Glutamine Synthetase Activity ◽

Cell Recovery ◽

Ammonia Detoxification ◽

Neurological Alterations

There are a number of pathological situations in which ammonia levels increase leading to hyperammonemia, which may cause neurological alterations and can lead to coma and death. Currently, there are no efficient treatments allowing rapid and sustained decrease of ammonia levels in these situations. A way to increase ammonia detoxification would be to increase its incorporation in glutamine by glutamine synthetase. The aim of this work was to develop a procedure to encapsulate glutamine synthetase in mouse erythrocytes and to assess whether administration of these erythrocytes containing glutamine synthetase (GS) reduce ammonia levels in hyperammonemic mice. The procedure developed allowed the encapsulation of 3 ± 0.25 IU of GS / mL of erythrocytes with a 70% cell recovery. Most metabolites, including ATP, remained unaltered in glutamine synthetase-loaded erythrocytes (named ammocytes by us) compared with native erythrocytes. The glutamine synthetase-loaded ammocytes injected in mice survived and retained essentially all of their glutamine synthetase activity for at least 48 h in vivo. Injection of these ammocytes into hyperammonemic mice reduced ammonia levels in the blood by about 50%. The results reported indicate that ammocytes are able to keep their integrity, normal energy metabolism, the inserted glutamine synthetase activity, and can be useful to reduce ammonia levels in hyperammonemic situations.

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Attempts to Demonstrate Peptide Localization and Secretion in Primary Cell Cultures of Fetal Rat Hypothalamus

Neuroendocrinology ◽

10.1159/000123138 ◽

1981 ◽

Vol 32 (2) ◽

pp. 96-102 ◽

Cited By ~ 11

Author(s):

Francine Denizeau ◽

Donald Dubé ◽

Tony Antakly ◽

André Lemay ◽

André Parent ◽

...

Keyword(s):

Cell Cultures ◽

Primary Cell ◽

Rat Hypothalamus ◽

Primary Cell Cultures ◽

Fetal Rat

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New Strategy in Spinal Cord Repair with Cryofrozen Primary Cell Cultures in Model In Vivo

Frontiers in Cellular Neuroscience ◽

10.3389/conf.fncel.2015.35.00020 ◽

2015 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Gomez Bello Rosa ◽

Sanchez Molina Magdy ◽

Vargas Brochero Daniela ◽

Botero Espinosa Lucia

Keyword(s):

Spinal Cord ◽

Cell Cultures ◽

Primary Cell ◽

Primary Cell Cultures ◽

New Strategy ◽

Spinal Cord Repair

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Review Article. Technical aspects of oxygen level regulation in primary cell cultures: A review

Interdisciplinary Toxicology ◽

10.1515/intox-2016-0011 ◽

2016 ◽

Vol 9 (3-4) ◽

pp. 85-89 ◽

Cited By ~ 7

Author(s):

Mazyar Yazdani

Keyword(s):

Cell Culture ◽

Cell Cultures ◽

Mammalian Cells ◽

Primary Cultures ◽

Essential Element ◽

Primary Cell ◽

Atmospheric Conditions ◽

Atmospheric Concentration ◽

Primary Cell Cultures

Abstract Oxygen (O2) is an essential element for aerobic respiration. Atmospheric concentration of O2 is approximately 21%. Mammalian cells, however, are generally adapted to O2 levels much lower than atmospheric conditions. The pericellular levels of O2 must also be maintained within a fairly narrow range to meet the demands of cells. This applies equally to cells in vivo and cells in primary cultures. There has been growing interest in the performance of cell culture experiments under various O2 levels to study molecular and cellular responses. To this end, a range of technologies (e.g. gas-permeable technology) and instruments (e.g. gas-tight boxes and gas-controlled incubators) have been developed. It should be noted, however, that some of these have limitations and they are still undergoing refinement. Nevertheless, better results should be possible when technical concerns are taken into account. This paper aims to review various aspects of O2 level adjustment in primary cell cultures, regulation of pericellular O2 gradients and possible effects of the cell culture medium.

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