Aerobic and anaerobic metabolism for the zebrafish, Danio rerio, reared under normoxic and hypoxic conditions and exposed to acute hypoxia during development

Abstract

In order to verify the influence of chronic and acute ambient oxygen levels from egg to adult stage of the zebrafish, in vivo oxygen consumption (MO 2 ), critical tensions of oxygen (Pcrit), heart rate (f H ) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) ) and exposed to acute hypoxia during different developmental stages. Our findings confirmed that very early stages do not respond effectively to ambient acute hypoxia. However, after the stage corresponding to the age of 30 days, D. rerio was able to respond to acute hypoxia through effective physiological mechanisms involving aerobic and anaerobic metabolism. Such responses were more efficient for the fishes reared under hypoxia which showed that D. rerio survival capability increased during acclimation to mild hypoxia. Measurements of body mass and length showed that moderate hypoxia did not affect growth significantly until the fish reached the stage of 60 days. Moreover, a growth delay was verified for the hypoxic-reared animals. Also, the D. rerio eggs-to-larvae survival varied from 87.7 to 62.4% in animals reared under normoxia and mild hypoxia, respectively. However, the surviving animals raised under moderated hypoxia showed a better aptitude to regulate aerobic and anaerobic capacities when exposed to acute hypoxia.Keywords: hypoxia, anaerobic metabolism, Danio rerio, lactate, fish.Metabolismo aeróbico e anaeróbico do paulistinha Danio rerio, mantidos sob normóxia e hipóxia moderada e expostos a hipóxia aguda durante diferentes estágios de desenvolvimento Resumo A influência de diferentes níveis de oxigênio no desenvolvimento (ovos a adulto) do peixe paulistinha Danio rerio (Hamilton, 1822) foi verificada por meio de medidas experimentais de consumo de oxigênio (MO 2 ), tensões críticas de oxigênio (Pcrit), taxa de batimentos cardíacos (fH) e concentração total de lactato nos tecidos (Lc), para os animais mantidos a 28 ºC sob níveis normóxicos de oxigênio (7.5 mgO 2 .L -1 ou 80 mmHg) e hipóxicos (4.3 mgO 2 .L -1 ) e submetidos a hipóxia ambiental aguda, em diferentes estágios de desenvolvimento. Os resultados obtidos indicam que os peixes em estágios iniciais do desenvolvimento não variam suas respostas fisiológicas em função das oscilações ambientais nos níveis de oxigênio, visto que tais respostas iniciaram-se somente no estágio de 30 dias de vida. A partir deste estágio D. rerio apresentou capacidade em responder à hipóxia aguda por meio de mecanismos fisiológicos efetivos envolvendo metabolismo aeróbico e anaeróbico. Tais respostas foram mais efetivas para os peixes mantidos sob hipóxia, o que mostrou que a capacidade de sobrevivência de D. rerio aumentou durante o período de aclimatação à hipóxia moderada. As medidas de massa e comprimento corpóreos mostraram que a permanência dos peixes em hipóxia durante o desenvolvimento não afetou esses parâmetro até os peixes atingirem o estágio de 60 dias. A partir deste estágio foi observado ligeiro atraso no crescimento dos espécimes mantidos sob hipóx...

Aquatic surface respiration and swimming behaviour in adult and developing zebrafish exposed to hypoxia

“…A similar biphasic change in activity associated with decreasing P O2 was observed in sole (Solea solea; Dalla Via et al, 1998;McKenzie et al, 2008). Reports for P crit in adult zebrafish are ∼20 mmHg (Barrionuevo and Burggren, 1999;Barrionuevo et al, 2010), although a more recent study presented a considerably higher value that varied between males and females (Robertson et al, 2014). We therefore interpret the biphasic trends in swimming behaviour in zebrafish exposed to progressive hypoxia as a strategy to reduce activity and conserve energy at water P O2 levels above P crit ; but as P O2 falls below P crit , zebrafish may become agitated and initiate a response in an effort to escape hypoxia.…”

“…5) indicate that this may be an underestimate in larvae younger than 14 dpf. P crit for developing zebrafish is ∼75 mmHg in embryos and is later reduced to ∼70 mmHg at 20 dpf (Barrionuevo and Burggren, 1999;Barrionuevo et al, 2010). Thus, unlike in adults, the ASR threshold in larvae is markedly lower than P crit .…”

Serotonergic and cholinergic elements of the hypoxic ventilatory response in developing zebrafish

“…Critical P O2 for zebrafish under 10d.p.f. is about 70-75mmHg (Barrionuevo et al, 2010). At 5d.p.f., larvae were transferred to aquaria in which dechlorinated water was maintained at 28.5°C and bubbled with a mixture of compressed air and N 2 to achieve a P O2 of 75mmHg using a Pegas 4000 gas mixer (Columbus Instruments, Columbus, OH, USA).…”

Parental hypoxic exposure confers offspring hypoxia resistance in zebrafish (Danio rerio)

“…), convective circulation becomes necessary to maintain adequate oxygen supply to tissues (Jacob et al, 2002). It is during this time that cardio-ventilatory mechanisms begin to be evoked in response to hypoxia (Jacob et al, 2002;Pelster, 2002;Schwerte et al, 2003;Jonz and Nurse, 2005;Vulesevic et al, 2006a;Vulesevic and Perry, 2006b;Barrionuevo et al, 2010).…”

“…Zebrafish provide an excellent model for testing this hypothesis because both mature and developing zebrafish are sensitive to acute and chronic hypoxia, and exhibit behavioral, physiological, biochemical and molecular level responses (Pelster and Burggren, 1996;Barrionuevo and Burggren, 1999;Padilla and Roth, 2001;Rees et al, 2001;Jacob et al, 2002;Ton et al, 2003;Ngan and Wang, 2009;Barrionuevo et al, 2010;Yaqoob and Schwerte, 2010;Kamei et al, 2011;Lo et al, 2011). In our experiments we have assessed clutch size (i.e.…”