Dogmas and controversies in the handling of nitrogenous wastes: Ammonia tolerance in the oriental weatherloach<i>Misgurnus anguillicaudatus</i>

Tsui, T. K. N.; Randall, D. J.; Hanson, L. E.; Farrell, Anthony P.; Chew, Shit F.; Ip, Yuen K.

doi:10.1242/jeb.00905

Cited by 31 publications

(22 citation statements)

References 38 publications

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“…Geographical distance with physical and environmental barriers in between, may keep these populations reproductively isolated from each other. Moreover, reproductive habits of the loach, adaptability to local environment, nonmigratory behavior and sticky nature of eggs to local substrate (Tsui et al, 2004) limit the gene flow even between nearby populations of the loach. There were pronounced pairwise genetic distances between sampling locations.…”

Section: Discussionmentioning

confidence: 99%

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Abbas¹,

Zhou²,

Wang³

2017

Turk. J. Fish. Aquat. Sci.

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The fish fauna in the Yangtze-based riparian ecosystem has been imperiled largely due to genetic degradation of populations. Regular genetic monitoring of the fish populations is required for an effective management and conservation. The genetic structure of Dojo loach, Misgurnus anguillicaudatus was investigated in twelve populations originating from the Yangtze River basin by using thirteen microsatellite loci. The number of alleles per locus varied between 2 and 8 with an average of 4.6 alleles per locus. Overall, low-to-moderate level of genetic diversity was observed in the loach populations. Significant deviations from Hardy-Wienberg equilibrium were observed in about 50% of the total locus-population combination tests. The AMOVA indicated that most of the variance existed among the individuals (90.50%) rather than among populations within groups (9.03%). Significant differentiation was found among the samples from scattered habitats with different connections to the Yangtze River (P<0.05). The clustering of sample populations in UPGMA dendrogram followed their geographic distribution except for Zigui and Xiaogan which clustered against their geographical origin. The factors involved in genetic differentiation and shaping the existing patterns of population structure of the loach were discussed so as to provide guidelines for conservation strategies and management programs.

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Section: Discussionmentioning

confidence: 99%

Untitled

Abbas¹,

Zhou²,

Wang³

2017

Turk. J. Fish. Aquat. Sci.

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“…Administration of MK801, a NMDA receptor antagonist, at a dosage of 2·µg·g -1 leads to significant improvement in clinical grading and slowing of electroencephalogram activity and provide significant protection in mouse given a lethal dose of ammonia (Marcaida et al, 1991). Recently, Tsui et al (2004) reported (as unpublished results) that MK801 (2·µg·g -1 fish) injected 15·min prior to the injection of CH 3 COONH 4 (21·µmol·g -1 fish) had a protective effect on the weatherloach Misgurnus anguillicaudatus, as reflected by a decrease in mortality from 60% to 0%. By contrast, MK801 (2·µg·g -1 fish) had no protective effect on P. schlosseri and B. boddaerti injected with a lethal dose of CH 3 COONH 4 (15 and 20·µmol·g -1 fish, respectively).…”

Section: Mk801 Did Not Have Protective Effects On Both Mudskippersmentioning

confidence: 90%

Chronic and acute ammonia toxicity in mudskippers,Periophthalmodon schlosseriandBoleophthalmus boddaerti: brain ammonia and glutamine contents, and effects of methionine sulfoximine and MK801

Leong

Sim

et al. 2005

Journal of Experimental Biology

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SUMMARY The objective of this study was to elucidate if chronic and acute ammonia intoxication in mudskippers, Periophthalmodon schlosseri and Boleophthalmus boddaerti, were associated with high levels of ammonia and/or glutamine in their brains, and if acute ammonia intoxication could be prevented by the administration of methionine sulfoximine [MSO; an inhibitor of glutamine synthetase (GS)] or MK801 [an antagonist of n-methyl d-aspartate type glutamate (NMDA) receptors]. For P. schlosseri and B. boddaerti exposed to sublethal concentrations(100 and 8 mmol l-1 NH4Cl, respectively, at pH 7.0) of environmental ammonia for 4 days, brain ammonia contents increased drastically during the first 24 h, and they reached 18 and 14.5 μmol g-1,respectively, at hour 96. Simultaneously, there were increases in brain glutamine contents, but brain glutamate contents were unchanged. Because glutamine accumulated to exceptionally high levels in brains of P. schlosseri (29.8 μmol g-1) and B. boddaerti (12.1μmol g-1) without causing death, it can be concluded that these two mudskippers could ameliorate those problems associated with glutamine synthesis and accumulation as observed in patients suffering from hyperammonemia. P. schlosseri and B. boddaerti could tolerate high doses of ammonium acetate (CH3COONH4)injected into their peritoneal cavities, with 24 h LC50 of 15.6 and 12.3 μmol g-1 fish, respectively. After the injection with a sublethal dose of CH3COONH4 (8 μmol g-1fish), there were significant increases in ammonia (5.11 and 8.36 μmol g-1, respectively) and glutamine (4.22 and 3.54 μmol g-1, respectively) levels in their brains at hour 0.5, but these levels returned to normal at hour 24. By contrast, for P. schlosseriand B. boddaerti that succumbed within 15-50 min to a dose of CH3COONH4 (15 and 12 μmol g-1 fish,respectively) close to the LC50 values, the ammonia contents in the brains reached much higher levels (12.8 and 14.9 μmol g-1,respectively), while the glutamine level remained relatively low (3.93 and 2.67 μmol g-1, respectively). Thus, glutamine synthesis and accumulation in the brain was not the major cause of death in these two mudskippers confronted with acute ammonia toxicity. Indeed, MSO, at a dosage(100 μg g-1 fish) protective for rats, did not protect B. boddaerti against acute ammonia toxicity, although it was an inhibitor of GS activities from the brains of both mudskippers. In the case of P. schlosseri, MSO only prolonged the time to death but did not reduce the mortality rate (100%). In addition, MK801 (2 μg g-1 fish) had no protective effect on P. schlosseri and B. boddaerti injected with a lethal dose of CH3COONH4, indicating that activation of NMDA receptors was not the major cause of death during acute ammonia intoxication. Thus, it can be concluded that there are major differences in mechanisms of chronic and acute ammonia toxicity between brains of these two mudskippers and mammalian brains.

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“…In response to ammonia intoxication, the over-activation of Nmethyl-D-aspartate type glutamate (NMDA) receptors in mammalian nervous tissue (brain) is proposed to incite excess ROS production (Hermenegildo et al, 1996;Brusilow, 2002;Felipo and Butterworth, 2002;Rose, 2002). For the piscine group, some evidence support overactivation of the glutamate NMDA receptors as the consequence of ammonia induced cellular oxidation (Tsui et al, 2004;Walsh et al, 2007). On the contrary, recent research suggest that ammonia can incite ROS production in other tissues e.g.…”

Section: Oxidative Stress Response Patternmentioning

confidence: 99%