scholarly journals Subcellular location of glutamine synthetase and urea cycle enzymes in liver of spiny dogfish (Squalus acanthias).

1982 ◽  
Vol 257 (14) ◽  
pp. 8449-8453
Author(s):  
C A Casey ◽  
P M Anderson
Keyword(s):  
Glutamine Synthetase ◽  
Urea Cycle ◽  
Subcellular Location ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Urea Cycle Enzymes

scholarly journals Glutamine-dependent carbamoyl-phosphate synthetase and other enzyme activities related to the pyrimidine pathway in spleen of Squalus acanthias (spiny dogfish)

1989 ◽  
Vol 261 (2) ◽  
pp. 523-529 ◽  
Author(s):  
P M Anderson
Keyword(s):  
Glutamine Synthetase ◽  
Enzyme Activities ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Urea Synthesis ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Pyrimidine Nucleotide ◽  
Aspartate Carbamoyltransferase ◽  
Pyrimidine Pathway

The first two steps of urea synthesis in liver of marine elasmobranchs involve formation of glutamine from ammonia and of carbamoyl phosphate from glutamine, catalysed by glutamine synthetase and carbamoyl-phosphate synthetase, respectively [Anderson & Casey (1984) J. Biol. Chem. 259, 456-462]; both of these enzymes are localized exclusively in the mitochondrial matrix. The objective of this study was to establish the enzymology of carbamoyl phosphate formation and utilization for pyrimidine nucleotide biosynthesis in Squalus acanthias (spiny dogfish), a representative elasmobranch. Aspartate carbamoyltransferase could not be detected in liver of dogfish. Spleen extracts, however, had glutamine-dependent carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, dihydro-orotase, and glutamine synthetase activities, all localized in the cytosol; dihydro-orotate dehydrogenase, orotate phosphoribosyltransferase, and orotidine-5′-decarboxylase activities were also present. Except for glutamine synthetase, the levels of all activities were very low. The carbamoyl-phosphate synthetase activity is inhibited by UTP and is activated by 5-phosphoribosyl 1-pyrophosphate. The first three enzyme activities of the pyrimidine pathway were eluted in distinctly different positions during gel filtration chromatography under a number of different conditions; although complete proteolysis of inter-domain regions of a multifunctional complex during extraction cannot be excluded, the evidence suggests that in dogfish, in contrast to mammalian species, these three enzymes of the pyrimidine pathway exist as individual polypeptide chains. These results: (1) establish that dogfish express two different glutamine-dependent carbamoyl-phosphate synthetase activities, (2) confirm the report [Smith, Ritter & Campbell (1987) J. Biol. Chem. 262, 198-202] that dogfish express two different glutamine synthetases, and (3) provide indirect evidence that glutamine may not be available in liver for biosynthetic reactions other than urea formation.

scholarly journals Induction of urea cycle enzymes by glucagon and dexamethasone in monolayer cultures of adult rat hepatocytes.

1982 ◽  
Vol 257 (9) ◽  
pp. 5061-5067
Author(s):  
R C Lin ◽  
P J Snodgrass ◽  
D Rabier
Keyword(s):  
Urea Cycle ◽  
Rat Hepatocytes ◽  
Adult Rat ◽  
Monolayer Cultures ◽  
Adult Rat Hepatocytes ◽  
Urea Cycle Enzymes

scholarly journals Carnitine administration to juvenile visceral steatosis mice corrects the suppressed expression of urea cycle enzymes by normalizing their transcription.

1992 ◽  
Vol 267 (8) ◽  
pp. 5032-5035
Author(s):  
M Horiuchi ◽  
K Kobayashi ◽  
M Tomomura ◽  
M Kuwajima ◽  
Y Imamura ◽  
...  
Keyword(s):  
Urea Cycle ◽  
Urea Cycle Enzymes

Metabolic Rate and Energy Expenditure of the Spiny Dogfish, Squalus acanthias

1978 ◽  
Vol 35 (6) ◽  
pp. 816-821 ◽  
Author(s):  
J. R. Brett ◽  
J. M. Blackburn
Keyword(s):  
Energy Expenditure ◽  
Metabolic Rate ◽  
Key Words ◽  
Swimming Performance ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Metabolic Rates ◽  
Performance Curve ◽  
Power Performance ◽  
General Energy

The metabolic rate of spiny dogfish, Squalus acanthias, was determined in both a tunnel respirometer and a large, covered, circular tank (mass respirometer). Swimming performance was very poor in the respirometer, so that a power–performance curve could not be established. Instead, resting metabolic rates were determined, with higher rates induced by causing heavy thrashing (active metabolism). Routine metabolic rates were measured for the spontaneous activity characterizing behavior in the circular tank. For fish of 2 kg mean weight, the metabolic rates at 10 °C were 32.4 ± 2.6 SE (resting), 49.2 ± 5.0 SE (routine), and 88.4 ± 4.6 SE (active) mg O2∙kg−1∙h−1. Assuming that the routine rate represents a general energy expenditure in nature, this is equivalent to metabolizing about 3.8 kcal∙kg−1∙d−1 (15.9 × 103 J∙kg−1∙d−1). Key words: dogfish, metabolic rates, energetics, respiration

scholarly journals Bounds on Biomass Estimates and Energetic Consequences of Ctenophora in the Northeast U.S. Shelf Ecosystem

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Michael D. Ford ◽  
Jason S. Link
Keyword(s):  
Feeding Strategy ◽  
Marine Ecosystem ◽  
High Energy ◽  
Gelatinous Zooplankton ◽  
Squalus Acanthias ◽  
High Energy Density ◽  
Spiny Dogfish ◽  
Sampling Device ◽  
Large Marine Ecosystem ◽  
Major Increase

Previous descriptions have noted that the stomach samples of spiny dogfish, Squalus acanthias, showed a major increase in the overall occurrence and hence implied abundance of Ctenophora. This apparent and persistent gelatinous zooplankton outbreak is increasingly more common in the world’s oceans. We briefly explore the energetic ramifications of ctenophores in the spiny dogfish diet, inferring that the presence of gelatinous zooplankton represents an ambient feeding strategy. Relative to other prey, ctenophores are not a high energy density prey item. However, given varying assumptions of the amount of ctenophores consumed, they may be an important staple in the diet of spiny dogfish. We also examine the utility of using spiny dogfish as a gelatinous zooplankton sampling device. Using five calculation methodologies, we provide bounds on potential abundance and biomass estimates of ctenophores in the Northeast U.S. shelf ecosystem. We then contextualize these findings relative to the implications for the Northeast U.S. and any large marine ecosystem.

scholarly journals Parasites of North Sea spiny dogfish, Squalus acanthias L. (Selachiiformes, Squalidae)

1979 ◽  
Vol 09 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Krystyna Orłowska
Keyword(s):  
North Sea ◽  
Squalus Acanthias ◽  
Spiny Dogfish

Double deficiencies of urea cycle enzymes in human liver

1979 ◽  
Vol 21 (2) ◽  
pp. 226-233 ◽  
Author(s):  
Luisa Raijman
Keyword(s):  
Human Liver ◽  
Urea Cycle ◽  
Urea Cycle Enzymes
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