Laboratório de Metabolismo e Reprodução de Organismos Aquáticos, Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Brazil.
Original Amazon, São Paulo, SP, Brazil.
Comp Biochem Physiol A Mol Integr Physiol. 2019 Apr;230:106-114. doi: 10.1016/j.cbpa.2019.01.008. Epub 2019 Jan 17.
The Amazonian pirarucu, Arapaima gigas, belongs to a phylogenetically basal group of teleosts (family Osteoglossidae). The commercial importance and the overexploited status of natural stocks of A. gigas brought the interest to rear it in the Amazon region, but rearing techniques are not fully understood to obtain reproduction success. Gonadal steroids (plasma and cephalic liquid), lipids and proteins (muscles, liver and ovary) of wild A. gigas females were analyzed during one year on Mexiana Island (Amazon Basin, Brazil) and ovarian maturation stages were described. The sexual gender determination method based on 11-ketostestosterone (11KT) and estradiol (E) ratio was applied to check if the value is in agreement of the sex previously determined by direct observation. Adult females were classified into four reproductive stages according to ovary development stage: previtellogenic, maturation, mature, and regression/spawning. Immature females were also analyzed. All mature females were sampled during the rainy season. Lipids stored in the ventrecha (belly) are a possible source of this substrate for the developing ovary. Plasma steroid profile throughout A. gigas female reproductive stages is similar to that found in most teleosts, but plasma 11KT levels peaked at the mature stage, suggesting an important role of this androgen in female ovulation. The 11KT/E method was 100% efficient when sexing juveniles and adults at the beginning of their reproductive cycle and can successfully be applied to identify the sexual gender of animals. The steroid profile of the cephalic liquid suggests a possible role of this fluid as a pheromone, due to the high level of 17α-hydroxyprogesterone at the final stages of the reproductive cycle.
亚马逊巨骨舌鱼属于一个进化上基础的硬骨鱼（骨舌鱼科）组。巨骨舌鱼的商业重要性和过度开发的自然种群状况引起了在亚马逊地区养殖它的兴趣，但养殖技术还没有完全理解以获得繁殖成功。在墨西哥岛（亚马逊盆地，巴西）进行了一年的研究，分析了野生巨骨舌鱼雌性个体的性腺类固醇（血浆和头腔液）、脂质和蛋白质（肌肉、肝脏和卵巢），并描述了卵巢成熟阶段。应用 11-酮睾酮（11KT）和雌二醇（E）比值的性别决定方法检查该值是否与直接观察确定的性别一致。根据卵巢发育阶段，成年雌性个体分为四个生殖阶段：卵前体、成熟、成熟和退化/产卵。也分析了未成熟的雌性个体。所有成熟的雌性个体均在雨季进行采样。储存在腹（腹部）中的脂质可能是发育中的卵巢的这种底物的来源。在巨骨舌鱼雌性生殖阶段，整个血浆类固醇谱与大多数硬骨鱼相似，但在成熟阶段，血浆 11KT 水平达到峰值，表明这种雄激素在雌性排卵中起重要作用。在生殖周期开始时，11KT/E 方法对幼鱼和成年鱼的性别鉴定的效率为 100%，并且可以成功地应用于识别动物的性别。头腔液的类固醇谱表明，由于在生殖周期的最后阶段 17α-羟基孕酮水平较高，这种液体可能具有作为信息素的作用。
