Departamento de Morfologia Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Gen Comp Endocrinol. 2011 Jul 1;172(3):400-8. doi: 10.1016/j.ygcen.2011.04.007. Epub 2011 Apr 8.
Most fishes with commercial importance from the São Francisco basin are migratory and do not complete the reproductive cycle in lentic environments, such as hydroelectric plant reservoirs, hence natural stocks are declining and there is an urgent need to reduce the pressure of fishing on those wild populations. Therefore, studies on reproductive biology and its relationship with endocrine and environmental factors are key to improving the cultivation techniques of Brazilian fish species. This study examined the influence of water temperature on sex steroid concentrations (testosterone, 17β-estradiol and 17α-hydroxyprogesterone), spawning efficiency, fecundity, fertilisation rate, larval abnormality rates and involvement of the cytoskeleton during the final oocyte maturation of Prochilodus argenteus under experimental conditions. The results of our study showed that in captivity, sex steroid plasma concentrations and spawning performance of P. argenteus were clearly different for fish kept in water with different temperature regimes. In lower water temperature (23°C), it was observed that: 33% of females did not ovulate, fecundity was lower and vitellogenic oocytes after the spawning induction procedure exhibited a smaller diameter. Moreover, concentrations of 17β-estradiol and 17α-hydroxyprogesterone were lower and there was a delay in the final oocyte maturation and, consequently, ovulation and spawning. Our experiments showed direct influence of water temperature in the process of induced spawning of P. argenteus. Changes in water temperature also suggest the tubulin involvement in the nuclear dislocation process and the possible action of actin filaments in the release of polar bodies during final oocyte maturation of P. argenteus.
大多数具有商业重要性的圣弗朗西斯科流域鱼类都是洄游性的，它们不会在静水环境（如水电站水库）中完成生殖周期，因此自然种群正在减少，迫切需要减少对这些野生种群的捕捞压力。因此，研究生殖生物学及其与内分泌和环境因素的关系是提高巴西鱼类养殖技术的关键。本研究在实验条件下研究了水温对性类固醇浓度（睾酮、17β-雌二醇和 17α-羟孕酮）、产卵效率、繁殖力、受精率、幼虫异常率以及 Prochilodus argenteus 最后卵母细胞成熟过程中细胞骨架参与的影响。我们的研究结果表明，在圈养条件下，保持在不同温度条件下的鱼类的性类固醇血浆浓度和产卵性能明显不同。在较低水温（23°C）下，观察到：33%的雌鱼不排卵，繁殖力较低，产卵诱导程序后的卵黄生成卵母细胞直径较小。此外，17β-雌二醇和 17α-羟孕酮浓度较低，最后卵母细胞成熟和排卵及产卵延迟。我们的实验表明水温对 P. argenteus 诱导产卵过程有直接影响。水温的变化也表明微管蛋白参与核移位过程，以及肌动蛋白丝在 P. argenteus 最后卵母细胞成熟过程中释放极体的可能作用。
