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Titre du document / Document title

Multiple strategies of Lake Victoria cichlids to cope with lifelong hypoxia include hemoglobin switching

Auteur(s) / Author(s)

RUTJES H. A. (1) ; NIEVEEN M. C. (1) ; WEBER R. E. (2) ; WITTE F. (1) ; VAN DEN THILLART G. E. E. J. M. (1) ;

Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Institute of Biology, Leiden University, Leiden, PAYS-BAS
(2) Zoophysiology, Department of Biological Sciences, University of Aarhus, Aarhus, DANEMARK

Résumé / Abstract

-Many fish species adapt to hypoxia by reducing their metabolic rate and increasing hemoglobin-oxygen (Hb-O2) affinity. Pilot studies with young broods of cichlids showed that the young could survive severe hypoxia in contrast with the adults. It was therefore hypothesized that early exposure results in improved oxygen transport. This hypothesis was tested using split brood experiments. Broods of Astatoreochromis alluaudi, Haplochromis ishmaeli, and a tilapia hybrid (Oreochromis) were raised either under normoxia (NR; 80-90% air saturation) or hypoxia (HR; 10% air saturation). The activity of the mitochondrial citrate synthase was not different between NR and HR tilapia, but was significantly decreased in HR A. alluaudi and H. ishmaeli, indicating lowered maximum aerobic capacities. On the other hand, hemoglobin and hematocrit levels were significantly higher in all HR fish of the three species, reflecting a physiological adaptation to safeguard oxygen transport capacity. In HR tilapia, intraerythrocytic GTP levels were decreased, suggesting an adaptive increase of blood-O2 affinity. Similar changes were not found in HR H. ishmaeli. In this species, however, all HR specimens exhibited a distinctly different iso-Hb pattern compared with their NR siblings, which correlated with a higher intrinsic Hb-O2 affinity in the former. All HR cichlids thus reveal left-shifted Hb-O2 equilibrium curves, mediated by either decreased allosteric interaction or, in H. ishmaeli, by the production of new hemoglobins. It is concluded that the adaptation to lifelong hypoxia is mainly due to improved oxygen transport.

Revue / Journal Title

American journal of physiology. Regulatory, integrative and comparative physiology    ISSN  0363-6119   CODEN AJPRDO 

Source / Source

2007, vol. 62, no3, [Note(s): R1376-R1383] (52 ref.)

Langue / Language

Anglais

Editeur / Publisher

American Physiological Society, Bethesda, MD, ETATS-UNIS  (1977) (Revue)

Mots-clés anglais / English Keywords

Vertebrata

;

Pisces

;

Human

;

Enzyme

;

Tilapia

;

Adult

;

Adaptation

;

Hand

;

Capacity

;

Synthase

;

Mitochondria

;

Saturation

;

Biological transport

;

Early

;

Oxygen

;

Hemoglobin

;

Hypoxia

;

Strategy

;

Mots-clés français / French Keywords

Vertebrata

;

Pisces

;

Homme

;

Enzyme

;

Tilapia

;

Adulte

;

Adaptation

;

Main

;

Capacité

;

Synthase

;

Mitochondrie

;

Saturation

;

Transport biologique

;

Précoce

;

Oxygène

;

Hémoglobine

;

Hypoxie

;

Stratégie

;

Mots-clés espagnols / Spanish Keywords

Vertebrata

;

Pisces

;

Hombre

;

Enzima

;

Tilapia

;

Adulto

;

Adaptación

;

Mano

;

Capacidad

;

Synthase

;

Mitocondria

;

Saturación

;

Transporte biológico

;

Precoz

;

Oxígeno

;

Hemoglobina

;

Hipoxia

;

Estrategia

;

Mots-clés d'auteur / Author Keywords

hypoxia acclimation

;

isohemoglobins

;

P50

;

phenotypic plasticity

;

oxygen transport

;

Localisation / Location

INIST-CNRS, Cote INIST : 670 E, 35400016243488.0520

Nº notice refdoc (ud4) : 19061317



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