10.1371/journal.pone.0084298PLoS ONE812-POLN

A Aperia

A Nishi

AG Therien

AM Loong

AR Jayakumar

ASL Tay

AT Blei

Biyun Ching

C Hermenegildo

C Li

CR Bosoi

DM Balshaw

E Kosenko

EA Jewell

G Blanco

G Crambert

G Kala

GE Shull

H Ogawa

H Pasantes-Morales

Harold A. Burgess

I Dostanic-Larson

IM Glynn

J Felsentsein

J Horisberger

Jasmine L. Y. Ong

JB Lingrel

JL Cooper

JP Morth

JR Freney

JW Semple

K Taguchi

Kum C. Hiong

KW Peng

L Gerwick

L Peng

LJ McGuffin

MD Miñana

MD Norenberg

MM Bradford

MP Wilkie

MS Feschenko

NB Illarionova

Nicklaus L. J. E. Wee

P Beguin

P Ott

PA Wright

PL Jørgensen

R Hosoi

R Zahler

S Guynn

SF Chew

Shit F. Chew

SW Brusilow

TA Hall

UK Laemmli

V Felipo

Wai P. Wong

WJ McLean

WS Zaugg

Xiu L. Chen

YK Ip

YL Tay

You R. Chng

Yuen K. Ip

YYM Tng

Z Xue

PubMed

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PLoS ONE

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

<div>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 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 nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 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 nkaα1, nkaα3a and nkaα3b. 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 nkaα2 expression, (2) high K+ specificity of K+ binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα 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.</div

Xiu L. Chen (400992)

Nicklaus L. J. E. Wee (504292)

Kum C. Hiong (446856)

Jasmine L. Y. Ong (400993)

You R. Chng (400994)

Biyun Ching (400995)

Wai P. Wong (400996)

Shit F. Chew (400998)

Yuen K. Ip (400990)

The Francis Crick Institute

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

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 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 nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 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 nkaα1, nkaα3a and nkaα3b. 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 nkaα2 expression, (2) high K(+) specificity of K(+) binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα 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

Xiu L Chen

Nicklaus L J E Wee

Kum C Hiong

Jasmine L Y Ong

You R Chng

Wai P Wong

Shit F Chew

Yuen K Ip

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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.

Wee Nicklaus L. J. E.

Hiong Kum C.

Ong Jasmine L. Y.

Chng You R.

Ching Biyun

Wong Wai P.

Chew Shit F.

Ip Yuen K.

Public Library of Science (PLOS)

, Which Has Unusually High Brain Ammonia Tolerance

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http://scholarbank.nus.edu.sg/bitstream/10635/101469/1/2013-properties_expression_ATPase_%ce%b1-subunit_isoforms-pub.pdf

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

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

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