Dataset Information

Properties and expression of Na+/K+-ATPase ?-subunit isoforms in the brain of the swamp eel, Monopterus albus, which has unusually high brain ammonia tolerance.

ABSTRACT: The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l(-1)) and accumulate ammonia to high concentrations in its brain (4.5 µmol g(-1)). Na(+)/K(+)-ATPase (Nka) is an essential transporter in brain cells, and since NH4(+) can substitute for K(+) to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka ?-subunits, some of which might have high K(+) specificity. Thus, this study aimed to clone and sequence the nka ?-subunits from the brain of M. albus, and to determine the effects of ammonia exposure on their mRNA expression and overall protein abundance. The effectiveness of NH4(+) to activate brain Nka from M. albus and Mus musculus was also examined by comparing their Na(+)/K(+)-ATPase and Na(+)/NH4(+)-ATPase activities over a range of K(+)/NH4(+) concentrations. The full length cDNA coding sequences of three nka? (nka?1, nka?3a and nka?3b) were identified in the brain of M. albus, but nka?2 expression was undetectable. Exposure to 50 mmol l(-1) NH4Cl for 1 day or 6 days resulted in significant decreases in the mRNA expression of nka?1, nka?3a and nka?3b. The overall Nka protein abundance also decreased significantly after 6 days of ammonia exposure. For M. albus, brain Na(+)/NH4(+)-ATPase activities were significantly lower than the Na(+)/K(+)-ATPase activities assayed at various NH4(+)/K(+) concentrations. Furthermore, the effectiveness of NH4(+) to activate Nka from the brain of M. albus was significantly lower than that from the brain of M. musculus, which is ammonia-sensitive. Hence, the (1) lack of nka?2 expression, (2) high K(+) specificity of K(+) binding sites of Nka?1, Nka?3a and Nka?3b, and (3) down-regulation of mRNA expression of all three nka? isoforms and the overall Nka protein abundance in response to ammonia exposure might be some of the contributing factors to the high brain ammonia tolerance in M. albus.

SUBMITTER: Chen XL

PROVIDER: S-EPMC3877266 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Properties and expression of Na+/K+-ATPase α-subunit isoforms in the brain of the swamp eel, Monopterus albus, which has unusually high brain ammonia tolerance.

Chen Xiu L XL Wee Nicklaus L J E NL Hiong Kum C KC Ong Jasmine L Y JL Chng You R YR Ching Biyun B Wong Wai P WP Chew Shit F SF Ip Yuen K YK

PloS one 20131231 12

The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l(-1)) and accumulate ammonia to high concentrations in its brain (4.5 µmol g(-1)). Na(+)/K(+)-ATPase (Nka) is an essential transporter in brain cells, and since NH4(+) can substitute for K(+) to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka α-subunits, some of which might have high K(+) specificity. Thus, this study aimed to clone and sequence the nka α-subunits fr ...[more]

PMID: 24391932

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Project description:A high-carbohydrate diet lowers the rearing cost and decreases the ammonia emission into the environment, whereas it can induce liver injury, which can reduce harvest yields and generate economic losses in reared fish species. Macroalgae Saccharina japonica (SJ) has been reported to improve anti-diabetic, but the protective mechanism of dietary SJ against liver injury in fish fed a high-carbohydrate diet has not been studied. Therefore, a 56-day nutritional trial was designed for swamp eel Monopterus albus, which was fed with the normal diet [20% carbohydrate, normal carbohydrate (NC)], a high carbohydrate diet (32% carbohydrate, HC), and a HC diet supplemented with 2.5% SJ (HC-S). The HC diet promoted growth and lowered feed coefficient (FC), whereas it increased hepatosomatic index (HSI) when compared with the NC diet in this study. However, SJ supplementation increased iodine contents in muscle, reduced HSI, and improved liver injury, such as the decrease of glucose (GLU), total bile acid (TBA), and alanine aminotransferase (ALT) in serum, and glycogen and TBA in the liver. Consistently, histological analysis showed that SJ reduced the area of lipid droplet, glycogen, and collagen fiber in the liver (p < 0.05). Thoroughly, the underlying protective mechanisms of SJ supplementation against HC-induced liver injury were studied by liver transcriptome sequencing coupled with pathway analysis. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the differentially expressed genes (DEGs), such as the acetyl-coenzyme A synthetase (acss1), alcohol dehydrogenase (adh), interferon-induced protein with tetratricopeptide repeats 1 (ifit1), aldo-keto reductase family 1 member D1 (akr1d1), cholesterol 7-alpha-monooxygenase (cyp7a1), and UDP-glucuronosyltransferase (ugt), indicated that the pathway of glycolysis/gluconeogenesis was the main metabolic pathway altered in the HC group compared with the NC group. Meanwhile, hepatitis C, primary BA biosynthesis, and drug metabolism-cytochrome P450 were the three main metabolic pathways altered by SJ supplementation when compared with the HC group. Moreover, the BA-targeted metabolomic analysis of the serum BA found that SJ supplementation decreased the contents of taurohyocholic acid (THCA), taurochenodeoxycholic acid (TCDCA), taurolithocholic acid (TLCA), nordeoxycholic acid (NorDCA), and increased the contents of ursocholic acid (UCA), allocholic acid (ACA), and chenodeoxycholic acid (CDCA). In particular, the higher contents of UCA, ACA, and CDCA regulated by SJ were associated with lower liver injury. Overall, these results indicate that the 2.5% supplementation of SJ can be recommended as a functional feed additive for the alleviation of liver injury in swamp eel-fed high-carbohydrate diets.

Dataset Information

Properties and expression of Na+/K+-ATPase ?-subunit isoforms in the brain of the swamp eel, Monopterus albus, which has unusually high brain ammonia tolerance.

Publications

Properties and expression of Na+/K+-ATPase α-subunit isoforms in the brain of the swamp eel, Monopterus albus, which has unusually high brain ammonia tolerance.

Similar Datasets

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