The marble goby oxyeleotris marmoratus activates hepatic glutamine synthetase and detoxifies ammonia to glutamine during air exposure

1999 ◽  
Vol 202 (3) ◽  
pp. 237-245 ◽  
Author(s):  
L.Y. Jow ◽  
S.F. Chew ◽  
C.B. Lim ◽  
P.M. Anderson ◽  
Y.K. Ip
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Excretion Rate ◽  
Ammonia Excretion ◽  
Air Exposure ◽  
Urea Excretion ◽  
Experimental Fish ◽  
Urea Content ◽  
Specific Activities ◽  
Oxyeleotris Marmoratus

Ammonia levels in various tissues of the marble goby Oxyeleotris marmoratus remained constant throughout a 72 h period of air exposure. The rate of ammonia excretion in these experimental fish decreased to approximately one-fifth of that of the submerged control. Ammonia was not converted to urea during air exposure because there were no significant increases in urea content in the tissues. Also, urea excretion rate was lowered to one-fiftieth that of the submerged fish. After 24 h of air exposure, there was a significant increase in muscle glutamine content, which peaked at 48 h. The increase in glutamine content could account for the decreases in the amounts of ammonia and urea excretion during air exposure. The specific activities of hepatic glutamate dehydrogenase (amination) and glutamine synthetase in these experimental fish increased threefold and thirtyfold, respectively, in comparison with the submerged controls. Thus, O. marmoratus appears to be the first known teleost that responds to air exposure by activating hepatic glutamine synthetase to detoxify internally produced ammonia.

The Metabolism of Trichinosed Rats During the Early Phase of the Disease

1941 ◽  
Vol 19 (3-4) ◽  
pp. 87-104 ◽  
Author(s):  
W. P. Rogers
Keyword(s):  
Intestinal Mucosa ◽  
Great Increase ◽  
Trichinella Spiralis ◽  
Excretion Rate ◽  
Mechanical Damage ◽  
Ammonia Excretion ◽  
Protein Digestion ◽  
Crude Fibre ◽  
Urea Excretion ◽  
Time Of Infection

The changes in protein digestion, crude fibre digestion and the chief urinary constituents found in four rats after experimental infection with Trichinella spiralis are detailed.Diarrhoea and anorexia occurred during the period 8 to 12 days after infection when protein digestion fell to its lowest point. It is suggested that this was due to antiproteases secreted by the adult parasites and to mechanical damage in the intestinal mucosa caused by their movements.Urinary N rose immediately after infection in “non-resistant” rats. This was followed by a period of decreased N output after which the excretion rate rose steeply.The urea output also rose immediately after infection in “non-resistant” rats. During the period 4 to 12 days from the time of infection urea excretion fell. Thereafter there was a great increase in its rate of output. Most of these changes have been attributed to toxins elaborated by the adult parasites for massive larval invasion of the tissues probably did not occur till after the experiments were terminated.Ammonia excretion rose as urinary urea decreased. The fall in urea N was not compensated by the rise in ammonia N + the fall in dietary N intake. The ammonia output returned rapidly to normal suggesting that the excess ammonia was not produced in response to acidosis when the urea excretion rate rose.Creatine excretion showed a marked fall during the period 4 to 12 days after infection. Urinary creatine and creatinine rose steeply following this period. Possible reasons for these variations are discussed.

scholarly journals Induction of ornithine-urea cycle enzymes and nitrogen metabolism and excretion in rainbow trout (Oncorhynchus mykiss) during early life stages

1995 ◽  
Vol 198 (1) ◽  
pp. 127-135 ◽  
Author(s):  
P Wright ◽  
A Felskie ◽  
P Anderson
Keyword(s):  
Rainbow Trout ◽  
Urea Cycle ◽  
Larval Fish ◽  
Ammonia Excretion ◽  
Nitrogen Excretion ◽  
Carbamoyl Phosphate ◽  
Adult Liver ◽  
Air Exposure ◽  
Terrestrial Vertebrates ◽  
Urea Excretion

The ornithine­urea cycle (OUC) is present in elasmobranch fish and many terrestrial vertebrates. Recently, a functional OUC has been reported in a few teleost species, suggesting that all teleost fish have the genes for the OUC, but expression is relatively rare. We investigated the possibility that the OUC is expressed during early development in trout as a mechanism for detoxifying ammonia produced from the catabolism of yolk protein. We followed ammonia and urea excretion rates, tissue ammonia and urea levels and OUC enzyme activities in rainbow trout up to 93 days after fertilization. Both ammonia and urea tissue concentrations increased several-fold in the first 40 days after fertilization (embryo stage), peaking at 1.7 mmol N l-1 and 2.5 mmol N l-1, respectively. Ammonia excretion could be detected in 4-day-old embryos, but urea excretion was not initiated until after hatching (day 45). Urea excretion in larval fish (days 42­93) increased several-fold and by day 93 was 14 % of total nitrogen excretion, as found in adult trout. Glutamine synthetase (GSase) and arginase activities were detected in 'whole animal' homogenates just after hatching and the levels of activity increased markedly to day 93. Carbamoyl phosphate synthetase (CPSase) and ornithine transcarbamylase (OTCase) were first detected in 40-day-old embryos; activities peaked between days 53 and 71 and then subsequently decreased. Adult liver enzyme activity for GSase was several-fold lower than in whole larval trout and OTCase and CPSase III (glutamine- and N-acetylglutamate-dependent CPSase catalysing the first step of the OUC) activities were essentially absent in adult liver. We conclude that embryonic and larval trout are primarily ammoniotelic. Urea is synthesized immediately after fertilization, but is not excreted until after the embryo is hatched. The results provide evidence for the presence of the OUC in larval rainbow trout, since four of the OUC enzymes are induced just after hatching and the levels of activity are relatively high compared with those in adult liver tissue. Furthermore, we suggest that all teleosts have retained the OUC genes, which are expressed only during certain stages of development (embryogenesis), and in a few rare species expression is maintained throughout the life cycle to cope with unusual environmental conditions (e.g. alkaline water, air exposure).

Glutamine synthetase expression in liver, muscle, stomach and intestine ofBostrichthys sinensisin response to exposure to a high exogenous ammonia concentration

2002 ◽  
Vol 205 (14) ◽  
pp. 2053-2065 ◽  
Author(s):  
P. M. Anderson ◽  
M. A. Broderius ◽  
K. C. Fong ◽  
K. N. T. Tsui ◽  
S. F. Chew ◽  
...  
Keyword(s):  
Amino Acid ◽  
Glutamine Synthetase ◽  
Adaptive Strategy ◽  
Ammonia Concentration ◽  
Amino Acid Sequences ◽  
Mrna Levels ◽  
Air Exposure ◽  
Opsanus Beta ◽  
Cdna Sequences ◽  
Oxyeleotris Marmoratus

SUMMARYA previous study provided evidence that the adaptive strategy used by the teleost fish Bostrichthys sinensis (sleeper) for detoxifying ammonia during extended periods of air exposure was to synthesize and store glutamine,primarily in the muscle, accompanied by an increase in glutamine synthetase(GSase) activity in liver. The aim of the present study was to assess the effect on GSase expression in various tissues of exposure of B. sinensis to exogenous ammonia. Exogenous ammonia increases internal ammonia concentrations in fish, mimicking environmental situations such as air exposure that preclude loss of ammonia across the gills, and thus triggering alternative mechanisms for ammonia detoxification. The results reveal relatively high levels of GSase activity, not only in liver but also,unexpectedly, in muscle, and even higher levels in intestine and, in particular, stomach. Exposure to ammonia results in significant increases in GSase activity, GSase protein and GSase mRNA levels in all of these tissues except stomach. The amino acid sequences of GSases from liver and stomach deduced from the cDNA sequences are essentially identical and are >97 %identical to the amino acid sequences of GSases from Gulf toadfish(Opsanus beta) and marble goby (Oxyeleotris marmoratus).

Daily Pattern of Nitrogen Excretion and Oxygen Consumption of Sockeye Salmon (Oncorhynchus nerka) under Controlled Conditions

1975 ◽  
Vol 32 (12) ◽  
pp. 2479-2486 ◽  
Author(s):  
J. R. Brett ◽  
C. A. Zala
Keyword(s):  
Oxygen Consumption ◽  
Sockeye Salmon ◽  
Excretion Rate ◽  
Oncorhynchus Nerka ◽  
Ammonia Excretion ◽  
Nitrogen Excretion ◽  
Average Weight ◽  
Urea Excretion ◽  
Maintenance Ration ◽  
Exogenous Nitrogen

Measurements of the rate of ammonia and urea excretion of fingerling sockeye salmon (Oncorhynchus nerka) in fresh water were made at 2–3-hourly intervals throughout the day (average weight = 29 g; temperature = 15 C). One group of fish was fed a maintenance ration while another group was starved for 22 days. Ammonia excretion rose to a sharp peak of 35 mg N/kg per hour, 4–41/2 h after the start of feeding (at 0830) and fell to a baseline level of 8.2 mg N/kg per hour between 0200 and 0800. Urea excretion remained relatively steady at a mean rate of 2.2 mg N/kg per hour throughout the day, showing no diurnal response to feeding. Starved fish showed a nitrogen excretion rate close to that for both the steady state of urea excretion and the baseline rate of ammonia excretion of the fed fish. Oxygen consumption rose to a peak of 370 mg O2/kg per hour just before and during a 1-h feeding period, decreasing thereafter to a low of 170 mg O2/kg per hour at 0300 h. For the starved fish this diurnal metabolic fluctuation continued from the start in a variable and diminishing form whereas nitrogen excretion showed no such response. The results are discussed in relation to hatchery observations. We conclude that for nonstressed salmon at 15 C ammonia is the chief excretory product of exogenous nitrogen metabolism.

scholarly journals Metabolism of the mussel Mytilus galloprovincialis from two origins in the Ría de Arousa (north-west Spain)

2000 ◽  
Vol 80 (5) ◽  
pp. 865-872 ◽  
Author(s):  
Jose M.F. Babarro ◽  
María José Fernández-Reiriz ◽  
Uxío Labarta
Keyword(s):  
Oxygen Consumption ◽  
Rocky Shore ◽  
Mytilus Galloprovincialis ◽  
Excretion Rate ◽  
Ammonia Excretion ◽  
Dry Weight ◽  
North West ◽  
Cultivation Period ◽  
Seed Origin ◽  
Ammonia Excretion Rate

Mussel seed Mytilus galloprovincialis (Bivalvia: Mytilidae) from two origins (rocky shore and collector ropes) was cultivated on a raft in the Ría de Arousa (north-west Spain), from seeding to thinning out, for 226 d (November 1995–July 1996) and two aspects of metabolism, oxygen consumption rate (VO2) and ammonia excretion rate (VNH4-N) were studied in situ.The model derived from multiple analysis of oxygen consumption accounted for 91.9% of the variance, based on dry weight of the mussels and the environmental factors quality of food (organic content) and mainly chlorophyll-a. Seed origin also showed significant influence. The seasonal pattern of the oxygen consumption can be attributed mainly to the variation of chlorophyll-a, which showed a higher range of values in the spring months.Origin of seed did not show a homogeneous effect on oxygen consumption throughout the cultivation period. Collector rope mussels showed higher oxygen consumption values at the beginning of the cultivation period and after the first 15 d, but the rocky shore mussels showed a higher oxygen consumption between days 22 and 110. Energy-conserving patterns and lower condition index at the onset of the experiment for rocky shore mussels could explain these initial differences.Multiple analysis on the variation of ammonia excretion rate provided a model that accounted for 72.6% of the variance based on dry weight of mussels, seed origin and the environmental parameters chlorophyll-a and total particulate matter. The rocky shore mussels showed a significantly higher excretion values for most of the cultivation period, although there was no constant tendency throughout. High excretion values were recorded between January and March, whilst for the rest of the cultivation period values were low.The O:N index was higher in collector rope mussels for most of the cultivation period, which may suggest a more favourable energy metabolism and/or a more appropriate nutritional state for these specimens.

Regulation of glutamine-repressible gene products by the GLN3 function in Saccharomyces cerevisiae

1984 ◽  
Vol 4 (12) ◽  
pp. 2758-2766
Author(s):  
A P Mitchell ◽  
B Magasanik
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Opposite Effect ◽  
Nuclear Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Two Dimensional Gel Electrophoresis ◽  
Regulatory Circuit ◽  
Glutamate Dehydrogenase Activity ◽  
Glutamine Limitation

Mutants of the yeast Saccharomyces cerevisiae have been isolated which fail to derepress glutamine synthetase upon glutamine limitation. The mutations define a single nuclear gene, GLN3, which is located on chromosome 5 near HOM3 and HIS1 and is unlinked to the structural gene for glutamine synthetase, GLN1. The three gln3 mutations are recessive, and one is amber suppressible, indicating that the GLN3 product is a positive regulator of glutamine synthetase expression. Four polypeptides, in addition to the glutamine synthetase subunit are synthesized at elevated rates when GLN3+ cultures are shifted from glutamine to glutamate media as determined by pulse-labeling and one- and two-dimensional gel electrophoresis. The response of all four proteins is blocked by gln3 mutations. In addition, the elevated NAD-dependent glutamate dehydrogenase activity normally found in glutamate-grown cells is not found in gln3 mutants. Glutamine limitation of gln1 structural mutants has the opposite effect, causing elevated levels of NAD-dependent glutamate dehydrogenase even in the presence of ammonia. We suggest that there is a regulatory circuit that responds to glutamine availability through the GLN3 product.

The Mode of Excretion of Ammonia and Urea in Xenopus Laevis

1961 ◽  
Vol 38 (4) ◽  
pp. 695-705
Author(s):  
J. B. BALINSKY ◽  
E. BALDWIN
Keyword(s):  
Xenopus Laevis ◽  
Blood Concentration ◽  
Concentration Ratio ◽  
Ammonia Excretion ◽  
Ammonia Concentration ◽  
Mean Value ◽  
Urea Excretion ◽  
Wide Range ◽  
Glomerular Filtrate ◽  
The Mean

1. Eighty-two single determinations of ammonia and urea excretion by Xenopus laevis indicated that the percentage of ammonia varied from 40 to 80%, with a mean value of 62%. 2. Measurements of excretion on successive days after feeding showed that a large amount of ammonia was produced soon after feeding, but that ammonia excretion declined rapidly. Urea excretion, not so high initially, remained more or less constant until the third or fourth day, often exceeding ammonia excretion at that time. Thereafter, it also declined and the excretion of both substances reached a constant starvation level by the fifteenth day. 3. Both ammonia and urea excretion were equally affected by temperature. The Q10's were near 2 in the range 20-30° C., but greater in the range 10-20° C. 4. At least 86% of ammonia, and 81% of urea were excreted through the cloaca. 5. The mean 24 hr. urine output of Xenopus at 20% C. was 23.6 ml. per 100 g. body weight. 6. Although the blood ammonia concentration did not appear to be zero, the urine/blood concentration ratio of ammonia was greater than 100. The urine/blood concentration ratio of urea was not significantly different from unity, and constant over a very wide range of concentrations. 7. The above result is interpreted to indicate passive glomerular filtration of urea, and little or no tubular reabsorption of water. 8. It is suggested that ammonia is formed in the kidney, and actively secreted into the glomerular filtrate.

scholarly journals Ureotelism is inducible in the neotropical freshwater Hoplias malabaricus (Teleostei, Erythrinidae)

2004 ◽  
Vol 64 (2) ◽  
pp. 265-271 ◽  
Author(s):  
G. Moraes ◽  
V. L. P. Polez
Keyword(s):  
Specific Activity ◽  
Excretion Rate ◽  
Nitrogen Excretion ◽  
Urea Synthesis ◽  
Plasma Ammonia ◽  
Alkaline Water ◽  
Hoplias Malabaricus ◽  
Urea Excretion ◽  
Ammonia Transport ◽  
In The Wild

Increased environmental pH decreases ammonia transport through the gills, impairing nitrogenous waste. The consequent toxicity is usually drastic to most fishes. A few species are able to synthesize urea as a way to detoxify plasma ammonia. We studied three teleosts of the family Erythrinidae living in distinct environments, and assumed the biochemical behaviors would be different in spite of their being closely related species. Adult fish collected in the wild were submitted to alkaline water and the urea excretion rate was determined. The specific activity of urea cycle enzymes was determined in liver samples of fish from neutral waters. The studied species Hoplias lacerdae, Hoplerithrynus unitaeniatus, and Hoplias malabaricus are ureogenic. Urea synthesis is not a metabolic way to detoxify ammonia in H. lacerdae and Hoplerithrynus unitaeniatus exposed to an alkaline environment. The plasma ammonia profile of both species showed two distinct biochemical responses. Urea excretion of H. malabaricus was high in alkaline water, and the transition to ureotelism is proposed. The nitrogen excretion rate of H. malabaricus was among the highest values reported and the high urea excretion leads us to include this species as ureotelic in alkaline water.

Some biochemical and physiological aspects of growth and gametogenesis inCrassostrea gigasandOstrea edulisgrown at sustained elevated temperatures

1979 ◽  
Vol 59 (1) ◽  
pp. 95-110 ◽  
Author(s):  
Roger Mann
Keyword(s):  
Crassostrea Gigas ◽  
Elevated Temperatures ◽  
Excretion Rate ◽  
Ammonia Excretion ◽  
Live Weight ◽  
Gonadal Development ◽  
Ostrea Edulis ◽  
Shell Weight ◽  
Histological Assessment ◽  
Ammonia Excretion Rate

Crassostrea gigas (Thunberg) andOstrea edulis L.were grown at sustained temperatures of 12°, 15°, 18° and 21°C for a period of 19 weeks. Regular assays of weight specific ammonia excretion rate were made, following which animals were sacrificed for estimation of dry meat weight, dry shell weight, biochemical composition (percentage carbon, nitrogen, carbohydrate, ash) and gonadal development (histological assessment). Crassostrea gigas grew from an intial live weight of 5·2 g to values of 23·5, 28·2, 34·6 and 38·7 g at 120, 150, 180 and 21 °C respectively.

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