Barrionuevo W R, Fernandes M N, Rocha O
Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
Braz J Biol. 2010 May;70(2):425-34. doi: 10.1590/s1519-69842010000200027.
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 (MO2), critical tensions of oxygen (Pcrit), heart rate (fH) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) raised at 28 degrees C under normoxic (7.5 mgO2.L-1 or 80 mm.Hg-1) and hypoxic conditions (4.3 mgO2.L-1) 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.
为了验证从卵到成年阶段的斑马鱼在慢性和急性环境氧水平下的影响，测定了在28摄氏度下于常氧（7.5 mgO2·L-1或80 mmHg-1）和低氧条件（4.3 mgO2·L-1）下饲养并在不同发育阶段暴露于急性低氧的斑马鱼（Danio rerio，汉密尔顿，1822）的体内耗氧量（MO2）、临界氧张力（Pcrit）、心率（fH）和全身乳酸浓度（Lc）。我们的研究结果证实，非常早期的阶段对环境急性低氧没有有效的反应。然而，在对应30天龄的阶段之后，斑马鱼能够通过涉及有氧和无氧代谢的有效生理机制对急性低氧作出反应。对于在低氧条件下饲养的鱼类，这种反应更有效，这表明斑马鱼在适应轻度低氧的过程中生存能力增强。体重和体长的测量表明，在鱼达到60天龄之前，中度低氧对生长没有显著影响。此外，证实了低氧饲养的动物存在生长延迟。而且，在常氧和轻度低氧条件下饲养的动物中，斑马鱼从卵到幼体阶段的存活率分别为87.7%至62.4%。然而，在中度低氧条件下饲养的存活动物在暴露于急性低氧时表现出更好的调节有氧和无氧能力的适应性。
